Hello Everyone,
This is the RotoMax Rotary Engine prototype design. It is a Tesla â€" Wankel â€" Mason HHO Hybrid.
Completion of the HHO PCT project a few weeks ago allowed me the time to finally get to work on developing the vague concept that I had in mind when I designed the Linear Firing Valve. It has now fully matured, faster than anticipated, and I present it to you. Enjoy :)
Let us begin at the beginning...
The LFV was designed to solve a number of problems with utilising HHO as a fuel.
I first removed the combustion chamber from the engine. Hydrogen experiences automatic ignition at temperatures of 500 degrees C and above. This problem is made worse because HHO is in a gaseous state and must be compressed in order to charge the chamber, this further decreases the auto ignition temperature, especially with a compressed oxidiser also present.
By removing the combustion chamber to the outside of the engine casing we are able to water cool it separately and also reclaim some energy as discussed in the HHO PCT thread, energy which I intend to be used to fire the Buzz Coil Ignition System.
I was also able to incorporate the Energy Conversion Insert into the design which changed the process output from high heat and compression to lower heat and velocity.
By applying this velocity to a Tesla Boundary Layer Turbine we can effectively use this energy.
The Tesla Boundary Layer Turbine suffers from a few problems. It is highly dependant on a very large disc surface area to fully maximise the transference of energy from the supersonic fluid to the disc surface through the Boundary Layer Effect.
Tesla knew this and was the primary reason his turbines became progressively larger in size until he reached 60 inches! The problem with going large diameter is that the turbine must be spun slower because the disc material experiences far greater forces at the tip than the centre due to the speed differential creating massive shear forces within the disc material itself, causing it to critically fail.
The other problem with the Tesla Turbine is that it is a hot rotor and as such has no seals. This causes valuable pressure to be lost between the disc stack and housing inner wall, effecting efficiency in a negative way. We try and limit this pressure loss by having close tolerance clearance but there is always going to be a gap, which is typically about 1mm or 0.040â€.
So the Tesla Turbine is not sufficient on its own to utilise the high velocity fluid the LFV is producing. This is where we examine the Wankel Rotary Engine.
The Wankel is a fantastic design but also suffers from some problems in light of what we are trying to do. It is relatively complicated to build requiring exacting tolerances and precision gear ratios. It also has the combustion chamber inside the engine which may present a problem with automatic ignition.
It does however have only a single rotor and produces bags of Torque with a smooth torque curve all the way to maximum RPM, which is about 10,000 RPM, half of a Tesla Turbines 20,000 RPM.
The Wankel also has a wonderful rotor edge to casing seal in the form of a spring loaded gate!
So now lets examine the RotoMax and see why it is different...
The output from the LFV and the input to the RotoMax chamber is high velocity fluid. In order to utilise this energy effectively I have reversed the function of the ECV and converted the high velocity fluid back to compression pressure.
Due to the potential difference created via linear distance from the pivot centre to the area of maximum compression in the compression chamber a high torque rotational moment occurs.
Following the compression phase the fluid experiences expansion maximising the energy potential remaining and then experiences parallel flow into the Tesla Boundary Layer Stabilisation area.
After spiralling around it comes into contact with the Winglets arranged at a suitable angle and generates lift forces which also create a turning moment increasing efficiency by stripping more energy from the fluid.
The aim of the game being to balance the system so that all of the velocity is removed from the fluid by the time it exits the exhaust parallel to the shaft.
As we have once again gone full circle and are dealing with a compression rotor sealing becomes extremely important. This is why I have adopted the Wankel approach with a spring loaded gate seal between the rotors edge and the inner ring casing wall.
This solves the problem of rotor tip sealing but leaves us with a problem sealing the disc face to the housing wall. To solve this I have used a static spring loaded ring that pushes against the face of the spinning rotor.
You can see there are two compression chambers formed by two gate seals located 180 degrees from each other.
As the rotor spins the LFV is phase angle fired as the first gate seal passes the LFV parallel flow tube. The LFV must have completely finished its firing cycle by the time the second gate seal at the back of the chamber passes the LFV. With the speed of the hydrogen combustion reaction this should not be a problem as the LFV chamber size will be tuned to the compression chamber size and desired operating rotational speed.
The Energy Conversion Winglets are critical to the design, they come in pairs, and work together to create the compression, expansion and parallel flow stabilisation as well as creating the dimensions of the compression chamber itself.
I have omitted the rotor compression and hub mount bolts for clarity. You will have to decide how many you need and where to place them.
The entire rotor is made with two side discs and shaped spacers that form the RotoMax chamber in exactly the same way as a Tesla Turbine is constructed. I recommend we go with a chamber width between the discs of 0.75mm or 0.030†to use 50% crossed boundary layers for maximum efficiency. This is because we are dealing with a high velocity and low mass flow rate fluid.
Each RotoMax Rotor is a separate unit and multiple units can be mounted on the same shaft, providing increased power and more flexible firing and charging ratio options.
If you place more than one RotoMax Rotor inside the same housing you will lose efficiency due to an inability to seal the inter rotor gap causing pressure to bleed from one rotor into the other.
You can try a prototype in 316 and have it up and running in days, especially if you already have a few LFV's built and functional. If excessive operating temperature becomes a problem and 316 cannot handle it then there is another option.
Ceramic Carbon Brake discs (or the variant called Carbon â€" Carbon). These were pioneered in Formula 1 racing and are now commonly found on high end sports cars. The disc shape is already an established manufacturing process so no problem there. The spacers will require new mould techniques maybe and a bit of R & D.
Ceramic Carbon is a good choice because it has a very high operating temperature, is very hard, creates little dust and is much lighter than steel. Its almost like it was developed for this engine!
I know the RotoMax diagram looks like a four year old drew it, but I never was very good at drawing. :)
Here are some links for further reading;
Here you can see the Wankel gate seals:
http://www.youtube.com/watch?v=eTbg92mRUG4&feature=related
Here is some information on Ceramic Carbon:
http://www.systemst.com/technical-information/
http://en.wikipedia.org/wiki/Disc_brake
http://en.wikipedia.org/wiki/Reinforced_carbon-carbon
I will have a look later after some sleep and see if I missed anything out.
Have fun :)
RM :)
Hello Everyone,
Here is the original RotoMax concept with a single Energy Conversion Winglet. I wanted to get the dual ECW version out of the way first while it was fresh in my mind.
The RotoMax is designed to run on any fluid, so lets talk about those possibilities first:
To run on HHO the chamber spacing must be 0.75mm or 0.040†as already discussed. This is because HHO combustion produces a high velocity, low mass flow rate fluid. The parallel flow input tube must have the same bore diameter as the chamber.
The engine will also run on low pressure air with high mass flow rate or pulses of high pressure compressed air (800 â€" 3000 psi), which is a high velocity, low mass flow rate fluid. More on this later.
The engine will also run on pulses of high pressure water with either a high pressure, low mass flow rate or low pressure, high mass flow rate.
If we were to change the chamber spacing to say 5.4mm for example the engine will now be suitable to run on low pressure, high mass flow rate fluids. The reason I say 5.4mm is that this is the bore diameter of 1/8†Schedule 80 pipe, making it simple to mount an off the shelf parallel flow tube. 6mm will be an acceptable compromise utilising ECW spacers cut from 6mm 316 sheet.
I have also updated the RotoMax Section View with a more accurate schematic. This now shows the shaft, hub and mounting bolts as well as the rotor compression bolts that lock the ECW in position.
Note that I changed the design slightly to remove the ring spacer compression spring, this will simplify construction and instead relies on a very close tolerance the same as the Wankel Rotary does. This will still leave a slight gap for pressure to bleed through but will be an improvement over no seal at all. You can try both designs if you want to find the most efficient.
Now, lets talk about high pressure air and water pulsing prototyping...
I have provided a cut-away view of the K valve (¼ NPT threads) that is used in the cleaning industry for high pressure wands. This will act as the pulse trigger for either high pressure water or high pressure air.
Here is the manufacturer:
http://www.westpakusa.com/Page150/Control_Valve.aspx
And here is one of the ebay retailers you can buy it from:
http://cgi.ebay.com/K-Valve-Handle-Stainless-wands-carpet-2000-PSI-/200457562946?pt=LH_DefaultDomain_0&hash=item2eac33ab42
We must construct a voice coil firing trigger that will be timed via either an opto-interruptor or a reed switch using a timing disc. This will momentarily activate the coil, attracting the magnet, which will hit the K valve piston and open it.
The K Valve piston will slam open allowing the high pressure fluid to flow. When the circuit is closed, the coils magnetic field will collapse and the magnet will be pushed back by the spring, allowing the spring in the K valve to close, shutting off the flow.
If you were to use a paintball high pressure tank rated at 3000 psi then you would have the ability to pulse high pressure air at either the 800 psi output from the regulator or remove the compression spring or belleville washers and run the output unregulated at 3000 psi. You can also add belleville washers or a new compression spring and change the regulator output pressure to a new value.
As always BE CAREFULL!
If you were to run timed tests ie 30 seconds for example then you would be able to compare the properties of the RotoMax chamber with different variables of the ECW spacers.
Low pressure fluids at say 100 â€" 120 psi from a compressor or jet washer can just be run constant with 100% duty cycle as you will need a very high mass flow rate at low pressure.
The area of maximum compression in the RotoMax chamber will set the variable for how fast the fluid will pass through the ECW into the expansion and parallel regions, so change the gap, change the performance of the rotor.
There are so many possibilities for this new type of engine that I have tried to cover the operating principles and a basic outline of what you need to test for and how you can go about doing that.
Get creative :)
Here are some resources:
Drill blanks:
http://www.drill-service.co.uk/Product.asp?Parent=020620040000&Tool=363
Note: Drill blanks always come in under size, if you order a 5.4mm you will get a 5.37mm.
Ring Magnets:
https://www.hkcm.de/advanced_search_result.php?keywords=ring&prof=off&hkcm=engineering&dna=2&mwst=on&des=
Note: You want an axially magnetised ring not a diametric. Loctite them on permanent.
RM :)
Hello Everyone,
Here is the RotoMax 12 LFV. It combines into one turbine the principles of impulse, reaction and boundary layers.
I have not written on the drawing the information as I am sure you have all grasped the principles of operation by now. By using 12 ECW's I have removed the balance issues with the rotor.
This is the final version and is designed to be used with 12 Linear Firing Valves with one valve located every 30 degrees around the rotor casing.
This allows us the flexibility of priming / firing ratios as discussed in the HHO PCT thread.
We can see that each valve will have its own compression chamber, creating an equal and opposite reaction, causing an impulse rotary moment around the pivot magnified by the potential difference.
The fluid will then experience parallel flow around a curve (I have drawn straight lines as curves were simply to difficult to accurately draw freehand). The inter disc spacing is set at 0.75mm or 0.030†causing 50% crossed boundary layers. The inter vane gap is also set at 0.75mm or 0.030†causing another 50% crossed boundary layers 90 degrees out of phase from the original.
This will create a central region of 0.25mm or 0.010†where 4 boundary layers are experiencing crossover creating a much larger effect.
Each vane will work with the one either side to create the parallel curved channels that will spiral around 180 degrees and directly feed the leading edge of their own lift winglets.
Each compression chamber is sealed from the next via spring loaded gate seals as already discussed.
So, four rotors mounted on the same shaft will become a 48 Valve system with pulsed detonation phase angle timing.
Have Fun :)
RM :)
RM
WOW!
I have watched the Vids you posted[Linked to]also above ,
Unfortunately my computor doesn't get sound.
I believe a design for HHo will be very important in the near future,And you have most definately given this serious attention!
At what kind of efficiency do you feel these concepts are at right now?Or ultimately capable of?
Thanks
Chet
Hi Chet,
Don't worry about no sound, you did not miss anything, there was nothing to hear :)
That is a very difficult question for me to answer but I will try...
I have always had the ability to build machines in my mind, I can set the operating parameters and run it and also change the variables within the system on the fly, by understanding the relationships in the environment, and calculating the outputs.
So, if your asking me how “finished†do I think the RotoMax is ? Well...
Erm... about 90%
The remaining 10% has to do with two concerns I have that I have not mentioned.
The first is the disc side face to housing side plate seal. Being a compression engine primarily we can get away with a very close tolerance as the Wankel Rotary does but I will never be happy with any pressure loss, as it is a loss of energy. This is the reason for the side ring seal.
The issue with the side ring seal is:
Will the resulting friction on the disc, causing drag, be worth the wear to the disc and the increased load ? Or will the pressure retained within the rotor more than compensate for it ?
Unknown at present to me.
The second issue concerns the Linear Firing Valve. Will the coefficient of thermal expansion of the material be at a suitable limit to prevent the semi mechanical seal of the piston poppet expanding to a diameter that causes it to jam in its sleeve ?
This will not be a safety concern as the pressure wave from detonation will be so powerful the valve will slam shut no matter what (unless foreign objects obstruct), but the spring pressure may not be enough to open the valve again. This is a materials issue and not a theoretical issue, as I believe the theory is sound.
The ideal scenario would be that when the LFV chamber is up to operating temperature the chamber wall and the piston poppet will be at maximum expansion and create the close tolerance seal. As I do not know what the operating temperature will be I cannot calculate the clearance required for the components at room temperature. So my best guess was 10 microns maximum, if it jams you need a larger clearance :)
The other alternative being that once you know the expansion variables you warm the chamber and poppet to operating temperature before you turn the machine on, using a glow plug.
When it comes to the aerodynamic properties of the rotor inter disc gap itself I consider it to be complete. In my opinion I can not improve on the design I have presented. 12 compression chambers being at the limit of what it will be practicable to build leaving suitable material thickness and spacing for the ECW's and Vanes. It also balances the rotor very well :)
I designed the RotoMax to outperform all known turbines and rotary engines. I am hesitant to state that it will because I just do not know the answer yet until it is built and tested, but I “expect†its power to weight ratio to exceed any engine known today.
I also designed it to be incredibly cheap and easy to construct. Not a problem for running it on air or water as 316 is more than suitable, but there is a ? over 316 for HHO, which is why I have also offered carbon â€" ceramic as a potential solution.
There is another material that may be even better and that is ceramic matrix composite:
http://en.wikipedia.org/wiki/Ceramic_Matrix_Composite
However this is still cutting edge and extremely expensive. Scroogle search there is lots of information out there on it.
So lets talk about my choice of layout for the different functions of the design...
As already discussed the Tesla Turbine operates on the boundary layer principle, but suffers from the problem of extracting the torque from the fluid in a short time component, requiring large discs.
Its impossible to get around this due to the nature of the boundary layer effect itself, so in order to maximise the torque extraction I have doubled the surface area for the fluid to interact with by enclosing the fluid in a square box. This will have benefits in crossed boundary layers and 90 degree out of phase crossed boundary layers, which are as of this moment an unknown potential.
The other benefit is that the box can now be used as a guide for injecting fluid at the correct angle of attack for the Winglet aerofoil section.
The Winglets do not function primarily by extracting torque from the fluid via the boundary layer effect. The boundary layer effect serves as the medium of interaction between the surface of the Winglet and the fluid.
The Winglets generate lift via creating a pressure differential between the upper and lower surfaces. The amount of force generated is directly related to the angle of attack, the properties of the curves of the aerofoil section, the velocity of the fluid, and the distance the Winglet is from the pivot.
By moving the Winglet close to the exhaust, rather than at the outer edge of the disc we are losing force potential due to a smaller linear distance between the Winglet and the pivot but we are not losing (much) force due to reduced fluid velocity over the Winglet. This is because the ECW inlet lets “some†velocity through the small gap relatively untouched, this is at the very beginning of the detonation pulse and can be considered the leading edge of the pressure wave.
The other point is that the Winglets also have an upper limit of fluid velocity that they can utilise. Velocity exceeding this value has no added lift effect. The Winglets also only need the boundary layer to operate, any fluid further away than that is ignored.
The area of maximum compression is where the majority of the energy is extracted by creating a partial blockage. By placing this Impulse at the furthest point from the pivot maximum rotary moment is generated far exceeding what would be possible from a Winglet, because the limiting factor on the compression phase conversion is the velocity of the fluid. The larger the input velocity to the compression phase the larger the Impulse created.
So in summary, we could swap the different functions around, but I do not see an increased benefit in doing so for the reasons stated.
As for the potential of this engine... well... how about this...
A huge field of solar panels in the desert, running massive dry cell HHO generators that run the LFV's, that power the RotoMax engines, to generate electricity to pump seawater and distil it, to turn the deserts green.
I like that idea very much :)
RM :)
RM
Quote:
As for the potential of this engine... well... how about this...
A huge field of solar panels in the desert, running massive dry cell HHO generators that run the LFV's, that power the RotoMax engines, to generate electricity to pump seawater and distil it, to turn the deserts green.
I like that idea very much
RM
-------------------------------
Now thats what I call potential!![also put a huge smile on my face}
Thanks for the responce!
Chet
I forgot to tell you all about something so here it is...
As the fluid enters the compression chamber it goes through the processes of compression, expansion and then parallel flow following the principles we have learned about with the Energy Conversion Valve.
When the fluid potential enters the parallel region it is fully converted to maximise the velocity remaining.
As the fluid travels around the box section formed between the discs and the vanes it "tightens" into a 180 degree spiral towards the centre.
The discs will always have the same clearance at 0.75mm or 0.040". The inter vane gap gets smaller as it travels around the spiral and "squeezes" the fluid towards the winglets.
This has the effect of creating a gradual compression of the box section boundary layers, in 2 dimensions (inter vane gap), extracting more energy from the fluid.
I have added the HELP Boundary Layer Spacing Properties diagram below to help you understand what I mean, and the description for the diagram is Reply No. 4 in the HELIS thread:
http://www.overunity.com/index.php?topic=10218.0
In order to calculate the spiral inter vane gaps use Sacred Geometry, as I did, and then simply change the straight lines to curves when you program the CAD file.
By adding a compression phase to the boundary layer flow we maximise the potential for energy extraction and also create a highly focused jet of fluid to feed the winglet leading edge.
RM :)
Hi Everyone,
I have been prototyping in my mind and have come across a few issues I want to share with you.
I do not like presenting you with problems before I have a potential solution... so...
First of all I have been running through firing cycles for 12 LFV's on a single Rotor, and I see a potential problem if each LFV is fired individually. As the Rotor rotates it will pass the next LFV which is in its priming cycle.
Pressure has an equal and opposite reaction and so there is a possibility of the pressure pushing the poppet piston away from the sealing cone. We do not want this to happen.
The potential solution I see is to fire all 12 LFV's simultaneously. This will solve the reverse pressure problem and also make it simple for a single buzz coil signal to fire all the LFV's at the same moment.
The problem this will cause however is that the Rotor is either going to be driven by the LFV's firing, or slowing due to the load applied while the LFV's are priming for the next firing cycle.
This will cause the Rotor RPM to “hunt†excessively and is undesirable.
If we were to mount 12 Rotor's on the drive shaft, we would regain our ability to control the energy input to the drive shaft. 1 Rotor firing while 11 are priming for example.
This is going to be a beast of an engine with 12 Rotor's and 144 LFV's!
The other issue may be the parallel flow tube, we want it to be the same bore diameter as the inter disc gap in the rotor, this being 0.75mm or 0.030â€.
Finding a suitable tube with a bore of 0.75mm and suitable wall thickness is going to be a problem if not impossible, it also means that the LFV will be very small and we may not be able to get a large enough HHO charge in there to maximise Rotor performance.
So...
How about we build a rectangular box section LFV ?
The entire LFV can be built out of laser or water jet cut sheet. This will also give us the advantage of being easily able to prototype different radii for the compression phase of the ECV.
Ceramic Paper may offer the seal we need to use compression bolts to hold the LFV side plates together, and the rear plate can simply be tapped to accept a fitting for HHO line connection.
Hopefully the water/steam that will continuously be present in the chamber will provide suitable lubrication.
If we are going to need 144 LFV's for a 12 Rotor system as I suspect then this may be an excellent cost effective alternative to cylindrical construction.
The other advantage being that a rectangular slot cut in the Ring Pipe Housing will allow us to massively increase the area for fluid injection into the Rotor while still maintaining the 0.75mm width of the Rotor gap.
Have a think about it and see if you can find any problems with this line of reasoning.
RM :)
Hello Everyone,
Following on from my previous comments regarding the probable requirement for a 12 LFV RotoMax to fire all LFV's simultaneously I have some further thoughts on the matter.
As already discussed the principle form of initial energy input to the Rotor is an Impulse operating on the equal and opposite reaction principle. We want the largest Impulse to the ECW compression area that we can get and then we want that pressure to bleed away as quickly as possible.
This is because the Piston Poppet inside the LFV will remain closed while the back pressure from the Rotor Chamber is greater than the spring pressure trying to push the Poppet forward.
So...
I have put up a new schematic of how I feel the RotoMax 12 will most efficiently operate.
I have removed the gate seals from the Rotor edge, I have done this because the gate seals concept was formed when the RotoMax only had a single or a dual ECW chamber and one or two LFV's respectively. This required a mechanism to separate the compression cycles on that particular design.
As the concept developed to the final 12 ECW version the requirement arose for simultaneous firing of all LFV's and so we no longer require ECW chamber separation. This has the added benefit of simplifying construction, and the resultant Rotor will run with a small edge clearance the same as a Tesla Turbine.
The other major change is I have dropped the Static Ring Seal idea. The reason I have done this is because we will require the Rotor to bleed pressure not being immediately utilised by the ECW so that the Piston Poppet spring will act allowing the LFV's to prime for the next firing cycle.
So the RotoMax should run on a similar efficiency to a Tesla Turbine when considering Rotor to Housing pressure bleed. The most suitable tolerance for clearance will become a tuning issue as we are actually going to use the pressure loss as a function of the system.
This will still have advantages to us as with a Tesla Turbine it is a constant pressure loss from a steady state fuel supply. The RotoMax being a Pulse Detonation Engine will use less fuel.
Moving on, if we examine the Rotor edge we can see two ECW Locking and Rotor Compression Bolts for each ECW. These serve the dual purpose of positioning the ECW and also stabilising the Rotor components via Compression.
The Winglets will also require two locking bolts, one of them small as it is closer to the trailing edge of the Winglet and serves to compress the Rotor, the other larger as it is nearer the larger leading edge of the Winglet and also serves the dual function of mounting the Rotor and carries the rotating load.
The Heat Deflection Rings have made a comeback and now serve an additional purpose of becoming an off the shelf Hub to Rotor mount adaptor plate. With the bolt holes on different radii this should work well :)
I have omitted the Ring Housing to Side Plate Housing sealing mechanism, you have two choices, the Ring Groove or the alternative inner and outer Ring Plates as discussed in the HHO PCT thread.
The last thing I am going to talk about here is radial and lateral runout. Have a look at these resources and research until you understand if you do not already:
http://www.youtube.com/watch?v=oxZl5K7PFp0
http://www.youtube.com/watch?v=dMp5G9J1P48
http://www.youtube.com/watch?v=H_1ySs7liS4
http://www.youtube.com/watch?v=M60H8VpuCrU&feature=related
Understanding radial and lateral runout is essential for Rotary Engine or Turbine building. It is not optional.
I consider you should be aiming for 0.002†maximum deviation. With components cut from sheet you will get a very uniform disc face and a very true circumference when turned on a lathe.
RM :)
Hello Everyone,
Here is the RotoMax 12 final evolution.
It is a Rotary Engine that uses a sequence of airfoils to extract Torque from the high velocity fluid.
The fluid repeatedly passes through areas of compression and expansion and transfers energy to the Rotor.
The areas of maximum compression cause an Impulse via the pressure increase having an equal and opposite reaction. They also allow the repeated opportunity to cross boundary layers in 3 dimensions.
Each airfoil occupies 30 degrees and creates a lift force in the same way as a Winglet. Each expansion region is 10 degrees.
Instead of propelling an airfoil through the air as an aircraft does, we are propelling the fluid over the surfaces of the airfoil and creating a Rotary Moment.
The Lift Winglets around the exhaust serve to maximise the area available, as if we only used the boundary layer effect as in a Tesla Turbine design the linear distance of such a small circle is almost insignificant.
You can experiment with different airfoil sections very easily and compare Rotor performance.
Each airfoil also now has a larger area than a vane allowing compression bolts to lock them in place and prevent vibration which would occur with the original vanes having only two locking bolts at the top.
Here are some resources to help you get a grasp on the Principles of Flight:
http://www.pilotsweb.com/principle/lift.htm
http://www.pilotsweb.com/principle.htm
Pay particular attention to the section on Lift as it is noted that the NASA Glenn Research Centre published a paper stating that the established theory as taught for decades by schools and government agencies is wrong. :)
This helps me understand why I was always arguing with my teachers during my aircraft apprenticeship, as quite simply what they were teaching was nonsense and could be proven so, although it was startling how many students just sat there and never questioned it!
We will eventually get around to why I believe some of the fundamental principles are incorrect but that is for another day. Have a read of the resources and see if they make sense to you.
RM :)
Hello Everyone,
Here is an idea for a Steam powered RotoMax.
I was thinking about the conversation for desert hydrating and solar panels may not be the best option.
Here is a solar powered parabolic mirror, that could be used on a large scale to boil water:
http://mikephilbin.blogspot.com/2011/02/solar-death-ray-power-of-5000-suns.html#
So you take an old satellite dish, stick thousands of these mirror mosaic tiles to it:
http://cgi.ebay.com/1000-SILVER-Mirrors-Mosaic-Tiles-Art-Supplies-1-2-/370489487628?pt=Mosaic_Tiles&hash=item5642e4f10c
Make a pressure container for steam with a clear window in the side to focus the beam through. As the focal point is in the centre of the steam chamber and not the clear wall it should not melt.
Some kind of Pyrex might be a good option as its optically clear and made for high temperatures.
The K Valve then becomes our Pulse Trigger for a 12 valve RotoMax.
If the O-rings inside the K Valve cannot handle the temperature of the Steam then there may be some other options.
Have a look here and scroll down to near the bottom and there are two entries for Steam...
> 149 C and < 149 C
http://www.allorings.com/compatibility.htm
So, we might be able to use the power of the Sun to create Steam Pressure to run a RotoMax, that if coupled directly to a Tesla Turbine Pump, would pump the seawater.
This method could also be used to distil the salt and impurities out of the water. Pure water for drinking, growing food, heating, and hydrating the desert.
So anyone see any problems with implementing this idea ?
RM :)
Eehmm... Clouds ? ;D
But I'm still trying to grasp the basics of your design.
Is it a bit like a reversed vane engine/compressor?
Funny, Did build and run that one:
Regards, Johan
Hello Cherryman,
Thankyou for the reply :)
I have spent a lot of time in the deserts of Iraq and clouds are not a problem, you rarely see one, let alone enough to block out the sun for any length of time.
As this is an intended desert application clouds will not be a problem. :)
I love the animation of the vane engine compressor :) which is a variant of the Wankel type Rotor. It operates on Impulse only and so is slightly similar to my design. However since I decided on simultaneous detonation for all chambers the “vane's†are no longer needed.
The basics of the RotoMax are:
It combines the principles of Impulse, Boundary Layers, and Reaction into one engine.
It was primarily designed as a Pulse Detonation Engine with HHO in mind.
The LFV was removed to the outside of the casing to allow cooling for HHO, but the RotoMax will run on any type of fluid injection.
By utilising repeated compression and expansion phases we extract the maximum amount of Torque from the fluid before it exits the exhaust.
By using a radial disc design instead of an axial design we are able to massively reduce the cost and increase the efficiency of the Turbine.
By using a vane spacer system we are able to cross boundary layers in planes that are 90 degree out of phase with each other. This is an unknown potential at present.
By utilising Energy Conversion Winglets we are able to create a Reaction force.
So, instead of using the restriction of expansion as in a traditional combustion engine and converting that to linear travel, we are converting the combustion to rotary moment via conversion of static potential (pressure) to linear velocity in the ECV, and then repeatedly converting that velocity back to compression inside the rotor chamber.
By using a radial design we are able to magnify the equal and opposite reaction of every compression phase because it will be magnified by the potential difference ( distance of point of compression from pivot ) and create a turning moment.
We should end up with a combustion engine that operates as a single rotor turbine and combines the three main principles of operation for a turbine into one engine.
The pressure wave of a HHO combustion reaction is so fast that a Tesla Turbine would need massive discs to maximise energy transfer.
By using compression phases instead to primarily extract the energy we can control the time component of the fluid as it passes through the rotor.
RM :)
Hi E-Ape,
I start to get the picture,
I did some testing myself to design an engine around some HHO production, i see a lot of people trying to produce HHO to run an existing engine (which would be very handy I agree) But i was thinking, reverse it, try to see what you can do with the HHO you can easaly produce.
The goal was to shoot an magnetic object around in circles, by HHO combustion (Or any other kind of pressure) As you i started half way to think that the principle could be used with any kind of pressure difference.
Sadly it is on the shelf for now. I need some new motivation.
Here is a youtube of the stage i stopped.
http://www.youtube.com/watch?v=10ObhgrNRF0 (http://www.youtube.com/watch?v=10ObhgrNRF0)
And here is my original old post about it if you are interested:
http://www.overunity.com/index.php?topic=9048.0 (http://www.overunity.com/index.php?topic=9048.0)
But after seeing a lot of designs around here, I agree with you , If you have enough sunlight, a parabolic mirror would be the most efficient and parts friendly power-supply! As solar panels provide around 20% efficiency, I think a parabolic mirror will top that easily.
This guy is experimenting a lot with Fresnel and parabolic s, not rocket science, but he does some basic groundwork, explained simply:
http://www.youtube.com/user/GREENPOWERSCIENCE#g/a (http://www.youtube.com/user/GREENPOWERSCIENCE#g/a)
Question: Did you ever build your HHO unit?
Good luck, I follow your progress!
Hi Cherryman,
Have a read here:
http://www.overunity.com/index.php?topic=10425.0
This has a list for all of my technologies.
It has taken me 7 months to write up 10 years work. All projects ran concurrently and by the time I finished the HELT I was out of cash. I busted myself trying to prototype it.
So I released all my work for others to pursue.
I have not built the RotoMax, I only started serious work on it 2 weeks ago. I wanted to get everything else out of the way first and with the HHO Pulse Combustion Turbine I finished everything that I had been working on.
The free time I suddenly had on my hands allowed me to get to work on the RotoMax which was always at the back of my mind and my intended end goal.
I will have a look at the links you posted but I don't have time now, the missus wants to go shopping, and I am in enough trouble for working too much as it is! lol :)
RM :)
I see what you mean with the combustion ring, I have done similar, however the LFV converts the pressure to velocity and thus reduces heat in the chamber, and converts it back to pressure inside the rotor.
Because the compression phases are mechanically attached to the disc a torque is created and that rotary moment can be tapped from the shaft.
The problems I see with your design are sealing around the spheres edge (as is the problem in paintball), wear on components, unable to tap the mechanical velocity of the sphere, and magnets cannot handle such high temperature and are fragile.
But I really like the “conceptâ€, Ill have a think about it :)
Thanks,
RM :)
Hello Everyone,
This is a RotoMax variant that works on exactly the same principles as the other designs but does not include the vane layout. The vane layout was included because it is easier to accurately control the 10 degree expansion phase angle.
Impulse via compression is still the primary means of extracting Torque and controlling the flow of fluid through the Rotor. Boundary Layers and Reaction are also in effect.
I have exaggerated the distance between the aerofoils for clarity on the drawing but in practice they will be close tolerances, 0.75mm would be a good place to start as a control rotor.
I was also thinking about cooling possibilities for 316 and HHO. If we were to have a secondary valve set, that fired a pulse of high pressure cold water from a K valve, in between each LFV, then we could alternate pulses of HHO and Water to run the engine.
This might keep the 316 temperature within acceptable operating limits. Just a thought. :)
The K Valve water pulse must also be "shaped" to effectively convert the static pressure into fluid velocity. You can do this simply with a HELIS nozzle insert centred in the parallel flow injector tube.
RM :)
A working fluid contains potential energy (pressure head) and kinetic energy (velocity head). The fluid may be compressible or incompressible. Several physical principles are employed by turbines to collect this energy:
Impulse turbines
These turbines change the direction of flow of a high velocity fluid or gas jet. The resulting impulse spins the turbine and leaves the fluid flow with diminished kinetic energy. There is no pressure change of the fluid or gas in the turbine rotor blades (the moving blades), as in the case of a steam or gas turbine, all the pressure drop takes place in the stationary blades (the nozzles).
Before reaching the turbine, the fluid's pressure head is changed to velocity head by accelerating the fluid with a nozzle. Pelton wheels and de Laval turbines use this process exclusively. Impulse turbines do not require a pressure casement around the rotor since the fluid jet is created by the nozzle prior to reaching the blading on the rotor. Newton's second law describes the transfer of energy for impulse turbines.
Reaction turbines
These turbines develop torque by reacting to the gas or fluid's pressure or mass. The pressure of the gas or fluid changes as it passes through the turbine rotor blades. A pressure casement is needed to contain the working fluid as it acts on the turbine stage(s) or the turbine must be fully immersed in the fluid flow (such as with wind turbines). The casing contains and directs the working fluid and, for water turbines, maintains the suction imparted by the draft tube. Francis turbines and most steam turbines use this concept. For compressible working fluids, multiple turbine stages are usually used to harness the expanding gas efficiently. Newton's third law describes the transfer of energy for reaction turbines.
In the case of steam turbines, such as would be used for marine applications or for land-based electricity generation, a Parsons type reaction turbine would require approximately double the number of blade rows as a de Laval type impulse turbine, for the same degree of thermal energy conversion. Whilst this makes the Parsons turbine much longer and heavier, the overall efficiency of a reaction turbine is slightly higher than the equivalent impulse turbine for the same thermal energy conversion.
Steam turbines and later, gas turbines developed continually during the 20th Century, continue to do so and in practice, modern turbine designs will use both reaction and impulse concepts to varying degrees whenever possible. Wind turbines use an airfoil to generate lift from the moving fluid and impart it to the rotor (this is a form of reaction). Wind turbines also gain some energy from the impulse of the wind, by deflecting it at an angle.
Crossflow turbines are designed as an impulse machine, with a nozzle, but in low head applications maintain some efficiency through reaction, like a traditional water wheel. Turbines with multiple stages may utilize either reaction or impulse blading at high pressure. Steam Turbines were traditionally more impulse but continue to move towards reaction designs similar to those used in Gas Turbines.
At low pressure the operating fluid medium expands in volume for small reductions in pressure. Under these conditions (termed Low Pressure Turbines) blading becomes strictly a reaction type design with the base of the blade solely impulse. The reason is due to the effect of the rotation speed for each blade. As the volume increases, the blade height increases, and the base of the blade spins at a slower speed relative to the tip. This change in speed forces a designer to change from impulse at the base, to a high reaction style tip.
Classical turbine design methods were developed in the mid 19th century. Vector analysis related the fluid flow with turbine shape and rotation. Graphical calculation methods were used at first. Formulae for the basic dimensions of turbine parts are well documented and a highly efficient machine can be reliably designed for any fluid flow condition. Some of the calculations are empirical or 'rule of thumb' formulae, and others are based on classical mechanics. As with most engineering calculations, simplifying assumptions were made.
Velocity triangles can be used to calculate the basic performance of a turbine stage. Gas exits the stationary turbine nozzle guide vanes at absolute velocity Va1. The rotor rotates at velocity U. Relative to the rotor, the velocity of the gas as it impinges on the rotor entrance is Vr1. The gas is turned by the rotor and exits, relative to the rotor, at velocity Vr2. However, in absolute terms the rotor exit velocity is Va2.
The velocity triangles are constructed using these various velocity vectors. Velocity triangles can be constructed at any section through the blading (for example: hub , tip, midsection and so on) but are usually shown at the mean stage radius. Mean performance for the stage can be calculated from the velocity triangles, at this radius, using the Euler equation.
The turbine pressure ratio is a function of and the turbine efficiency.
Modern turbine design carries the calculations further. Computational fluid dynamics dispenses with many of the simplifying assumptions used to derive classical formulas and computer software facilitates optimization. These tools have led to steady improvements in turbine design over the last forty years.
Computational fluid dynamics
Computational fluid dynamics (CFD) is a branch of fluid mechanics that uses numerical methods and algorithms to solve and analyze problems that involve fluid flows. Computers are used to perform the calculations required to simulate the interaction of liquids and gases with surfaces defined by boundary conditions. With high-speed supercomputers, better solutions can be achieved. Ongoing research, however, yields software that improves the accuracy and speed of complex simulation scenarios such as transonic or turbulent flows. Initial validation of such software is performed using a wind tunnel with the final validation coming in flight tests.
By understanding Energy Conversion Theory you can perform the calculations in your head with your biological supercomputer.
So...
An Impulse Turbine creates change in the direction of flow of a high velocity fluid or gas jet. The resulting Impulse spins the turbine and leaves the fluid flow with diminished kinetic energy.
Reaction Turbines develop torque by reacting to the gas or fluid's pressure or mass. The pressure of the gas or fluid changes as it passes through the turbine rotor blades.
CrossFlow Turbines tell us...
http://en.wikipedia.org/wiki/Banki_turbine
And Brayton Cycle tells us:
http://en.wikipedia.org/wiki/Brayton_Cycle
Methods to increase power
The power output of a Brayton engine can be improved in the following manners:
Reheat, wherein the working fluidâ€"in most cases airâ€"expands through a series of turbines, then is passed through a second combustion chamber before expanding to ambient pressure through a final set of turbines. This has the advantage of increasing the power output possible for a given compression ratio without exceeding any metallurgical constraints (typically about 1000 °C).
The use of an afterburner for jet aircraft engines can also be referred to as reheat; it is a different process in that the reheated air is expanded through a thrust nozzle rather than a turbine. The metallurgical constraints are somewhat alleviated enabling much higher reheat temperatures (about 2000 °C). Reheat is most often used to improve the specific power (per throughput of air) and is usually associated with a reduction in efficiency; this is most pronounced with the use of afterburners due to the extreme amounts of extra fuel used.
Overspray, wherein after a first compressor stage water is injected into the compressor, thus increasing the mass-flow inside the compressor increasing the turbine output power significantly and reducing compressor outlet temperatures[6]. In a second compressor stage the water gets completely evaporated.
Where Overspray can be used and we have Impulse Driver via K Valve Pulsing, Cooling via Temperature Differential, and Reaction via Liquid â€" Gas Conversion resultant Expansion forces and Boundary Layer Effects.
So, we use the Water Pulsing and HHO Pulsing together to create an environment where a low velocity, low temperature, high mass flow rate fluid is providing impulse, cooling, and reaction via conversion and expansion. And also acts as a buffer to absorb and slow down the HHO Pulse Wave, and a very high velocity, high temperature, low mass rate fluid is providing impulse, reaction, heat and boundary layer effects.
You will be creating a pulsed detonation impulse rotary engine, with complimentary system fluids, where all of the outputs contribute to creating an environment for the application of closed system crossover and produce a very new type of gas. If you wanna push it that far ;)
Have Fun :)
RM :)
The RotoMax is an evolution on from the HELT / HELP devices...
It is driven by a combination of hot, high velocity, low mass flow rate fluid in the form of HHO combustion, and by cold, relatively low velocity, and high mass flow rate liquid in the form of water.
It is cooled by the temperature differential balancing of the two fluids.
The Water present will be undergoing rapid compression and expansion forces, rapid temperature changes, rapid velocity changes, and will be subjected to DC arc jumping via closed system crossover.
This is an environment that stresses the water molecule to its limits, as both a dynamic pressurised liquid and gas, and at high temperature undergoing Electromagnetic field disruption.
RM :)
(Adding a safety notice here: If the RotoMax runs hotter than the autoignition temperature of hydrogen and oxygen in this environment then closed system crossover for HHO production will be a bad idea. Also the High temperature jet of HHO combustion might not be cooled sufficiently quick enough by the water within the turbine to prevent ignition. In both instances if your producing HHO then the RotoMax will go boom and you will either get an increase in efficiency from localised combustion within the turbine, or the turbine will blow up. So if you do decide to try this one day be carefull it could be dangerous.) RM :)
Hi Everyone,
I came across this today:
http://www.infiniacorp.com/powerdish.html
and an animation of the Stirling Engine used:
http://www.infiniacorp.com/howitworks.html
So remembering the conversation I was having with Cherryman about a solar powered RotoMax, the steam generator and additional turbine may not be necessary anymore.
The Powerdish by Infinia converts the solar energy straight to AC, so if we were to add a DC rectifier to the circuit output then this could directly power a dry cell distribution bank:
http://www.overunity.com/index.php?topic=10153.0
From looking at the specifications of the Powerdish it seems perfectly suited to a desert application.
So, it appears that the LFV is going to become the critical component:
http://www.overunity.com/index.php?topic=10274.0
If it can be made to work, and the RotoMax with water cooling proves to be able to handle the high temperatures, then that's it...
We would have a complete system for desert application :)
I am now more excited than ever about prototyping results for the LFV and RotoMax! If they are proven, mission accomplished!
RM :)
Hi Everyone,
Here is the 01 to Rotary Moment Energy Conversion System :)
I have shown a 4 Dish System in the diagram as the system is modular.
The Powerdish would take the energy from the Sun and convert it straight to DC removing the need for a rectifier and simplifying the design.
The DC output from the Powerdish would power the Dry Cell Bank directly producing fuel in the form of HHO.
The HHO output from the Dry Cell Bank would become the input to the LFV, this would then be converted to High Velocity Fluid.
The High Velocity Fluid would be used as the input to the Rotary Turbine, which would convert it to Rotary Moment.
This system would allow you to take the Potential Difference energy supplied free of charge by nature, and provide a Rotary Moment output, instead of the traditional Electrical or Heat outputs.
So...
You harness something you get for free, and turn it into clean fuel. You blow this fuel up and convert it to high velocity fluid. You make this high velocity fluid turn a rotary turbine.
The rotary system output will be free to you, unless there is a tax slapped on sunlight! :o
Should the HHO act as a system input energy amplifier, as I suspect it will, the system output may well be overunity. If it is, the Rotary Moment can be used to create exponential energy growth as shown here:
http://www.rumormillnews.com/cgi-bin/archive.cgi?noframes;read=184723
RM :)
Hi Everyone,
Quick update for anyone considering a compressed air application for RotoMax testing.
Below is information on Belleville washers (or springs) from this site:
http://www.leespring.com/uk_int_learn_belleville_wash.asp
Single: One washer
Parallel: All washers stacked the same way
Series: All washers stacked opposite each other
Series-Parallel: A combination of the two
A single Belleville Spring Washer has a specific load for a given deflection. Two washers stacked in parallel will yield double the load of a single washer for the same deflection;three washers will yield triple the load; four washers will yield four times the load, etc. Alternatively, two washers stacked in series will yield double the deflection of a single washer for the same load; three washers will yield triple the deflection; four washers will yield four times the deflection, etc.Various series-parallel combinations therefore can provide a wide variety of combined results of load versus deflection for the stack. Consequently, depending upon the application, the designer can:
• Stack in "parallel" to increase load
• Stack in "series" to increase deflection
• Adjust the load and deflection of a washer stack by adding or removing individual
washers and/or the sequence in which they are used, whether in series or parallel.
This information will help you when adjusting the regulator pressure on a paintball tank. I personally believe Series â€" Parallel is the way to go with a minimum of 2 washers in each stage to prevent the rapid cycling and high pressure changes from crushing the washers.
Add washers to increase pressure, remove washers to reduce pressure. Construct a pressure testing assembly using a K valve, a non return valve, a tee, and a pressure gauge. The K valve acts as the pressure relief valve when the trigger is pressed to release the pressure.
A compressor would be handy as testing of different spring pressures requires the cylinder to be emptied and filled repeatably. However if you don't have access to a compressor at 3000 psi then there is another option:
http://cgi.ebay.co.uk/WEBLEY-Pre-Charged-Air-Gun-Rifle-Stirrup-PCP-HAND-PUMP-/230597647196?pt=UK_SportingGoods_Hunting_ShootingSports_ET&hash=item35b0b0db5c
These are the new pumps by Webley and are built sturdy and solid with excellent design. Never cycle more than 80 slow pumps in one go, you must allow the pump to cool for minimum 5 minutes or you will blow the seals. I work to 50 pumps and leave a lot longer than 5 minutes between filling sessions.
In addition, in order to remove the regulator from the paintball tank you may be tempted to get a blow torch on it to loosen the permanent grade loctite (red) applied by the manufacturer.
Do not under any circumstances do this!
It will alter the heat treatment of the metal in the regulator and bottle and may make the bottle unsafe at high pressure.
A better way is to remove the male 1/8 bsp quick release nipple and then use a threaded piece of bar or schedule 80 pipe in that socket. Secure the bottle in a vice with some thick rag to protect it (without crushing it) and then muscle the regulator off.
SAFETY NOTICE:
ALWAYS CHECK THAT THE BOTTLE IS AT ZERO PRESSURE BEFORE REMOVING REGULATOR OR COMPONENTS!
If you do damage the regulator in the process of removing it a replacement can be got on ebay from china for cheap. They sell both 3000 psi and 4500 psi versions but in practice it will be the same regulator with different markings. They will have a 3 to 1 safety ratio anyway.
http://shop.ebay.co.uk/?_from=R40&_trksid=p5197.m570.l1313&_nkw=paintball+regulator&_sacat=See-All-Categories
Hope that helps, and as always be carefull!
RM :)
Hi Everyone,
I have scoured the net for some background resources for what I want to talk about today, and that is material selection for turbine discs. There is much more information in the links provided, I have simply grabbed some relevant parts and reproduced them here to provide structure. I do advise reading through all the links. :) A summary is provided at the end...
304 = 1.4301
321 = 1.4541 (Titanium stabilised 304)
316L = 1.4404 (Low Carbon < 0.03%)
316Ti = 1.4571 (Titanium stabilised 316)
=====
http://www.bssa.org.uk/topics.php?article=71
The presence of titanium to 1.4571 does, however, give some improvements to mechanical strength, especially, at elevated temperatures above about 600 C. and care must therefore be exercised in selecting 1.4404 as a substitute under these conditions.
=====
http://www.euro-inox.org/pdf/map/Stabilised_LowCarbonAust_EN.pdf
As a conclusion, it can be stated that the use of grade 1.4571 over 1.4404 and 1.4541 over 1.4307 is only technically justified when high temperature strength is a consideration. A summarised comparison between the Ti-stabilised and low carbon stainless steels is presented in the table.
=====
http://www.askzn.co.za/tech/tech_grade_316.htm
SX 316 Ti, the titanium-stabilised version, is used for its resistance to sensitization during prolonged exposure in the 550 C - 800 C temperature range.
=====
http://www.alleghenytechnologies.com/ludlum/Documents/316ti.pdf
Stress Corrosion Cracking
Austenitic stainless steels are susceptible to stress corrosion cracking (SCC) in halide environments. Although the Type 316, 316L and 316Ti alloys are more resistant to SCC than the 18 Cr-8 Ni alloys, they still are quite susceptible. Conditions that produce SCC are:
(1) Presence of halide ion (generally chloride),
(2) Residual tensile stresses, and
(3) Temperature in excess of about 140°F (60°C).
Stresses result from cold deformation or thermal cycles during welding. Annealing or stress relieving heat treatments may be effective in reducing stresses, thereby reducing sensitivity to halide SCC. Although the stabilised Type 316Ti and low carbon grades offer no advantage as regards SCC resistance, they are better choices for service in the stress relieved condition in environments which might cause intergranular corrosion.
FABRICATION AND WELDING
Fabrication
The austenitic stainless steels, including the Type 316Ti alloy, are routinely fabricated into a variety of shapes ranging from the very simple to very complex. These alloys are blanked, pierced, and formed on equipment essentially the same as used for carbon steel. The excellent ductility of the austenitic alloys allows them to be readily formed by bending, stretching, deep drawing and spinning. However, because of their greater strength and work hardenability, the power requirements for the austenitic grades during forming operations are considerably greater than for carbon steels. Attention to lubrication during forming of the austenitic alloys is essential to accommodate the high strength and galling tendency of these alloys.
Annealing
The austenitic stainless steels are provided in the millannealed condition ready for use. Heat treatment may be necessary during or after fabrication to remove the effects of cold forming or to dissolve precipitated chromium carbides resulting from thermal exposures. For the Type 316Ti alloy the solution anneal is accomplished by heating in the 1900 - 2150°F (1040 - 1175°C) temperature range followed by air cooling or a water quench, depending on section thickness. For maximum resistance to sensitization, Type 316Ti should be given a stabilizing heat treatment at 1550-1650°F (845-900°C) to precipitate titanium carbides and prevent the precipitation of chromium carbides during lower temperature exposure. Type 316Ti cannot be hardened by heat treatment.
Welding
The austenitic stainless steels are considered the most weldable of the stainless steels. They are routinely joined by all fusion and resistance welding processes. Two important considerations for weld joints in these alloys are (1) avoidance of solidification cracking, and (2) preservation of corrosion resistance of the weld and heataffected zones. Type 316Ti stainless steel often is welded autogenously. If filler metal must be used for welding Type 316Ti, it is advisable to utilize the low carbon Types 316L or E318 filler metals. Contamination of the weld region with copper or zinc should be avoided, since these elements can form low melting point compounds, which in turn can create weld cracking.
Stabilized austenitic stainless steels, such as Type 316Ti, can be attacked by intergranular corrosion under certain special conditions after welding. One such condition results in what is known as knifeline attack This manifests itself as a very narrow band of severe corrosion adjacent to a weld. This occurs when the metal adjacent to the weld is heated to a high temperature (greater than 2100°F) so that the titanium carbides are dissolved, and then subsequently exposed to temperatures in the sensitizing region (800°–C - 1500°F; 425°C - 815°C). At these temperatures, the rate of formation of titanium carbides is sluggish, and the free carbon reacts with chromium to form grain boundary carbides in the heat affected zone.
=====
http://en.wikipedia.org/wiki/Corrosion
Weld Decay and Knifeline Attack
Stainless steel can pose special corrosion challenges, since its passivating behavior relies on the presence of a minor alloying component (Chromium, typically only 18%). Due to the elevated temperatures of welding or during improper heat treatment, chromium carbides can form in the grain boundaries of stainless alloys. This chemical reaction robs the material of chromium in the zone near the grain boundary, making those areas much less resistant to corrosion. This creates a galvanic couple with the well-protected alloy nearby, which leads to weld decay (corrosion of the grain boundaries near welds) in highly corrosive environments. Special alloys, either with low carbon content or with added carbon "getters" such as titanium and niobium (in types 321 and 347, respectively), can prevent this effect, but the latter require special heat treatment after welding to prevent the similar phenomenon of knifeline attack. As its name applies, this is limited to a small zone, often only a few micrometres across, which causes it to proceed more rapidly. This zone is very near the weld, making it even less noticeable.
=====
Summary:
Ok, a lot to take in :)
The two main grades we are looking at here are 316L and 316 Ti.
316L is going to be suitable for both the HELP and the HELT devices. The reason I say this is that I do not expect the operating temperature of either to exceed 400 C. Should prototyping prove a continuous temperature greater than 400 C then 316L is not going to be suitable for any length of time. This is because at temperatures above 400 C 316L will rapidly lose its strength properties, and as the turbine discs will be rotating at high speed any significant loss in strength could cause the blades to critically fail from the tensile stresses of centrifugal force.
This problem would be further increased by the HELP and HELT being used in Closed System Crossover mode and the electrolysis function would weaken the blades and cause corrosion. The HELP and HELT will have a maximum operating life, measured in hours run, before the entire disc stack and shaft must be completely replaced with new components.
The RotoMax is a different animal altogether and is not enduring the effects of CSC. I expect the RotoMax will probably have to deal with a constant operating temperature in the range 400 - 800 C. This means that 316 Ti would be a much better choice than 316L as it has a far higher strength in this temperature range. Should normal operating temperature exceed 800 C then there is the potential option of using ceramic carbon composite as already talked about. As there is no CSC occurring, all components can be made of metal to withstand the high rotational stresses and temperatures.
The discs are probably going to be laser cut, which means a localised rapid high temperature increase on the resultant edges (similar to welding). The metal must be carefully de-burred and then stress relieved via suitable heat treatment process before being spun up in the turbine, or the discs might tear themselves apart.
In addition, it might pay dividends to run the RotoMax when powering down purely on a constant flow of cold water. This would bring the disc rotors that have been operating in the 400 - 800 C range for extended periods of time rapidly down to ambient temperature and mimic the stress relieving process.
The last point is hydrogen embrittlement...
http://en.wikipedia.org/wiki/Hydrogen_embrittlement
The mechanism starts with lone hydrogen atoms diffusing through the metal. At high temperatures, the elevated solubility of hydrogen allows hydrogen to diffuse into the metal (or the hydrogen can diffuse in at a low temperature, assisted by a concentration gradient). When these hydrogen atoms recombine in minuscule voids of the metal matrix to form hydrogen molecules, they create pressure from inside the cavity they are in. This pressure can increase to levels where the metal has reduced ductility and tensile strength up to the point where it cracks open (hydrogen induced cracking, or HIC).
High-strength and low-alloy steels, nickel and titanium alloys are most susceptible. Austempered iron is also susceptible.[citation needed] Steel with an ultimate tensile strength of less than 1000 MPa or hardness of less than 30 HRC are not generally considered susceptible to hydrogen embrittlement. Jewett et al.[1] reports the results of tensile tests carried out on several structural metals under high-pressure molecular hydrogen environment.
These tests have shown that austenitic stainless steels, aluminum (including alloys), copper (including alloys, e.g. beryllium copper) are not susceptible to hydrogen embrittlement along with few other metals.[2] For example of a severe embrittlement measured by Jewett, the elongation at failure of 17-4PH precipitation hardened stainless steel was measured to drop from 17% to only 1.7% when smooth specimens were exposed to high-pressure hydrogen.
I have highlighted the part in bold that states that austenitic stainless steels are not susceptible to hydrogen embrittlement, however I personally do not know if this is true. Prototyping and people who know more about this subject than me are going to be required to resolve the issue.
As an example of how complicated hydrogen embrittlement gets:
http://www.msm.cam.ac.uk/phase-trans/2006/hydrogen.Yamasaki.PRA.2006.pdf
The important thing to remember about all of this is that we are attempting proof of theory of these concepts. If the theory is sound, and we get results that we can work with, then the material development will come with the investment of interest in these technologies. The off the shelf materials may be suitable in their own right, but will most certainly be able to be improved with directed investment over time.
Hope this is helpfull to you all :)
RM :)