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Wankel Engines
Posted by: Jim Crank (IP Logged)
Date: January 19, 2002 06:36PM
<HTML>If any of you are interested in the Wankel engine and the possibility of converting one to steam, there is a very good new book out that you should read. First new one in decades on the Wankel engine.
It is not some weighty tome full of formulas,that you can find in the SAE papers. What it is, is a complete modern history of the engine, who made them and the problems they had and how they solved them, and who is making them now. Good racing history too.
"The Wankel Rotary Engine" by John B. Hege.
The price is $35.00 and well worth it.
Publishers: McFarland & Co. Box 611, 960 HHWY 88 West, Jefferson, North Carolina 28640-0611
www.mcfarlandpub.com
Orders: 800-253-2187
-----------
Note:Here is a quick link to this title @ Amazon.com
[www.amazon.com]
Thanks for the reference Jim!
JW - admin</HTML>
It is not some weighty tome full of formulas,that you can find in the SAE papers. What it is, is a complete modern history of the engine, who made them and the problems they had and how they solved them, and who is making them now. Good racing history too.
"The Wankel Rotary Engine" by John B. Hege.
The price is $35.00 and well worth it.
Publishers: McFarland & Co. Box 611, 960 HHWY 88 West, Jefferson, North Carolina 28640-0611
www.mcfarlandpub.com
Orders: 800-253-2187
-----------
Note:Here is a quick link to this title @ Amazon.com
[www.amazon.com]
Thanks for the reference Jim!
JW - admin</HTML>
Re: Wankel Engines
Posted by: Peter Brow (IP Logged)
Date: January 21, 2002 11:09AM
<HTML>Sounds interesting!
Another related link is at Andy Patterson's website:
[www.greenhills.net]
Includes animated drawings of steam Wankel concepts, including a compound version.
Some years ago I discussed the idea with Andy, who is now working on a piston engine due to various thermal problems with the steam Wankel, including wiping losses from the high surface area to volume ratio and heat migration to the drive shaft. We kicked around various ideas to solve these. For lower temp use (700°F inlet, 500°F surface temps), the non-wearing rotor face could be covered with mechanically retained fiberglass-reinforced hi-temp silicone sheet (which I am investigating to cut wiping losses in an engine I am building). For higher temps, perhaps machineable carbon vane stock like the stuff at Morgan Advanced Materials, mamat.com. The flat sides of the rotor chamber might also benefit from this carbon material, if it will stand the wear. Carbon side plates could be added to a conversion. Maybe this carbon could also be used for the rim of the chamber in a scratch-built steam Wankel, but would that wear acceptably with the apex seals riding on it?
Advanced ceramics would be ideal, but are very pricey for large parts. One company quoted me prices for ceramic cylinder liners which made solid gold cylinders look cheap in comparison. Adhesion may be an issue with advanced heat-barrier coatings in steam service; one steam developer reported flaking problems. This may have been from corrosion working its way under the coating. Several types of coatings work well in highly demanding IC applications, however, and coatings are relatively affordable and rapidly improving. Several people are reportedly trying these in piston steam engines, but I have not seen reports of results.
There are definitely lots of unexplored possibilities!</HTML>
Another related link is at Andy Patterson's website:
[www.greenhills.net]
Includes animated drawings of steam Wankel concepts, including a compound version.
Some years ago I discussed the idea with Andy, who is now working on a piston engine due to various thermal problems with the steam Wankel, including wiping losses from the high surface area to volume ratio and heat migration to the drive shaft. We kicked around various ideas to solve these. For lower temp use (700°F inlet, 500°F surface temps), the non-wearing rotor face could be covered with mechanically retained fiberglass-reinforced hi-temp silicone sheet (which I am investigating to cut wiping losses in an engine I am building). For higher temps, perhaps machineable carbon vane stock like the stuff at Morgan Advanced Materials, mamat.com. The flat sides of the rotor chamber might also benefit from this carbon material, if it will stand the wear. Carbon side plates could be added to a conversion. Maybe this carbon could also be used for the rim of the chamber in a scratch-built steam Wankel, but would that wear acceptably with the apex seals riding on it?
Advanced ceramics would be ideal, but are very pricey for large parts. One company quoted me prices for ceramic cylinder liners which made solid gold cylinders look cheap in comparison. Adhesion may be an issue with advanced heat-barrier coatings in steam service; one steam developer reported flaking problems. This may have been from corrosion working its way under the coating. Several types of coatings work well in highly demanding IC applications, however, and coatings are relatively affordable and rapidly improving. Several people are reportedly trying these in piston steam engines, but I have not seen reports of results.
There are definitely lots of unexplored possibilities!</HTML>
Re: Wankel Engines
Posted by: Jim Crank (IP Logged)
Date: January 23, 2002 02:23PM
<HTML>Hi Peter,
I am already deep into thermal barrier coatings for the flanks of the rotors. Such are readily available from racing sources. They have been used since the Porsche 917 days in their exhaust manifolds to keep the heat up going into the turbos. Very affordable and MOST effective. Also used on piston heads in dragsters and Formula One engines.
The heat transfer into the eccentric shaft has to be calculated. With the cooling oil in the rotor blocked off, easy to do, and just going to the bearings, and the rotor coatings, this may not be a problem. We shall see.
The latest Mazda racing tip seals work extremely well and last. $65.00 per seal; but that is acceptable, as they really work.
They use very little oil, not like the old Mazda RX-2 days.
They do need the hard chrome surface, or moly coating for the seals to run against, and the aluminum housing has to be changed to iron.
Yes, the surface to volume ratio is bad; but thoroughly insulating the whole engine will certainly minimize the heat losses. Obviously it has to be warmed up before running; but that is an acceptable chore. Once up to temperature and well insulated, this should not be a fatal problem, I hope. We have to calculate this very thoroughly. No worse a problem than insulating the cylinders of a reciprocating engine.
Oil in the steam is the absolute worst thing in a steam car engine; but using the Lamont steam generator in place of the old Doble monotube really minimizes the carbon buildup that plagued the Doble systems. The Lamont is very tolerant of slight traces of oil.
Using a Wankel does mean a good oil separator in the exhaust steam line.
I wonder how many of the fraternity are really looking seriously at the Wankel?
Jim</HTML>
I am already deep into thermal barrier coatings for the flanks of the rotors. Such are readily available from racing sources. They have been used since the Porsche 917 days in their exhaust manifolds to keep the heat up going into the turbos. Very affordable and MOST effective. Also used on piston heads in dragsters and Formula One engines.
The heat transfer into the eccentric shaft has to be calculated. With the cooling oil in the rotor blocked off, easy to do, and just going to the bearings, and the rotor coatings, this may not be a problem. We shall see.
The latest Mazda racing tip seals work extremely well and last. $65.00 per seal; but that is acceptable, as they really work.
They use very little oil, not like the old Mazda RX-2 days.
They do need the hard chrome surface, or moly coating for the seals to run against, and the aluminum housing has to be changed to iron.
Yes, the surface to volume ratio is bad; but thoroughly insulating the whole engine will certainly minimize the heat losses. Obviously it has to be warmed up before running; but that is an acceptable chore. Once up to temperature and well insulated, this should not be a fatal problem, I hope. We have to calculate this very thoroughly. No worse a problem than insulating the cylinders of a reciprocating engine.
Oil in the steam is the absolute worst thing in a steam car engine; but using the Lamont steam generator in place of the old Doble monotube really minimizes the carbon buildup that plagued the Doble systems. The Lamont is very tolerant of slight traces of oil.
Using a Wankel does mean a good oil separator in the exhaust steam line.
I wonder how many of the fraternity are really looking seriously at the Wankel?
Jim</HTML>
Re: Wankel Engines
Posted by: Peter Brow (IP Logged)
Date: January 24, 2002 09:42AM
<HTML>Hi Jim,
The flanks of Wankel rotors are roughly analogous to the piston skirts of a piston engine, and here heat barrier coatings have also been a great success in IC engines. Hot rodders use coated piston skirts (and crowns), and Cima-Mahle sells graphite-coated piston skirts for aircooled VW performance parts. Oil temp (and friction) reductions are reportedly substantial with these goodies. Your mention of chrome plating brings to mind a thought I had some time ago: if corrosion-related coating flaking happened in an experimental steam engine (Dutcher, I think reported this), then perhaps coating over chrome plating would solve it. But coatings have improved so much since the 70s that flaking may no longer be a problem. There are thermal and also friction- and wear-reduction coatings: graphite, ceramic, and even diamond, but I'm sure you are well acquainted with these. I am keeping an eye open for results in steam service, as I would like to use these coatings too. I think lower steam consumption is possible in a counterflow piston engine with thermal-coated steam passages.
I think external heat loss is manageable for a steam Wankel. It is the wiping losses I wonder about, esp if high expansion ratios are used. However, if thermal coatings will survive "the steam test", then I won't wonder any more -- problem solved. I have read that higher rpms can also cut these losses by reducing steam/surface exposure time. Have you done any flow analysis for a steam Wankel? I wonder what kind of rpms are possible mit der dampfenwankel.
Agree on oily feedwater in high-temp full-counterflow monotubes. The oil tolerance of the Lamont is one thing that impresses me about the design, also the simple controls and really low circulator pump hp, like 1/10 hp? This has got me penciling a circulating boiler. Perhaps the Lamont can benefit from the anti-corrosive and anti-scale properties of trace oil which Doble claimed in Doble-Detroit literature. The key word is "trace". Without an oil separator upline (or frequent blowdowns), the Lamont's drum might foam up, kicking oil into the superheater and perhaps carbonizing it. Fortunately, there are several proven methods to reduce feedwater oil to a tiny trace, and more are possible.
Oil can be tough to get completely out of the feedwater. I once brought up an idea for oil separation on another steam discussion list. McMaster-Carr lists an exhaust head oil separator, a low-restriction cyclonic type, which is claimed to remove 99% of the oil from exhaust steam. As I recall, the flow rates were in the steam car range. Combine this with their "floating oil filter", a bag of highly oleophilic hollow polyethylene fibers which floats in the water tank, to absorb most of the other 1% when it floats to the surface, then dewater/recycle the recovered oil from the separator, and a steam car could (theoretically) go 100,000 miles on a gallon of oil at Stanley lube rates, with virtually oil-free feedwater. Now that assumes that the separator and filter are as good as McMaster claims. At low and variable loads, 99% oil recovery may be a bit optimistic for a cyclone.
Besides you and Andy Patterson, I don't know of any steam folks looking into the Wankel. I have been fascinated with Wankels since assembling & running a see-through plastic model as a child (it was battery-driven and had timed blinking lights to simulate spark plugs firing, wish I still had it), but don't know Wankels well enough to try one with confidence. I'm going to study up on it, though. Maybe the perception of highly specialized fabrication work discourages steam experimenters. Then again, Andy said that a steam Wankel, converted or scratch-built, is quite achievable in a well-equipped home shop, so steamerites may be missing out on a very promising technology.
I read that the RX8 has valve ports in the side walls of the chamber. I wonder if this would be useful in a steam Wankel?
Peter</HTML>
The flanks of Wankel rotors are roughly analogous to the piston skirts of a piston engine, and here heat barrier coatings have also been a great success in IC engines. Hot rodders use coated piston skirts (and crowns), and Cima-Mahle sells graphite-coated piston skirts for aircooled VW performance parts. Oil temp (and friction) reductions are reportedly substantial with these goodies. Your mention of chrome plating brings to mind a thought I had some time ago: if corrosion-related coating flaking happened in an experimental steam engine (Dutcher, I think reported this), then perhaps coating over chrome plating would solve it. But coatings have improved so much since the 70s that flaking may no longer be a problem. There are thermal and also friction- and wear-reduction coatings: graphite, ceramic, and even diamond, but I'm sure you are well acquainted with these. I am keeping an eye open for results in steam service, as I would like to use these coatings too. I think lower steam consumption is possible in a counterflow piston engine with thermal-coated steam passages.
I think external heat loss is manageable for a steam Wankel. It is the wiping losses I wonder about, esp if high expansion ratios are used. However, if thermal coatings will survive "the steam test", then I won't wonder any more -- problem solved. I have read that higher rpms can also cut these losses by reducing steam/surface exposure time. Have you done any flow analysis for a steam Wankel? I wonder what kind of rpms are possible mit der dampfenwankel.
Agree on oily feedwater in high-temp full-counterflow monotubes. The oil tolerance of the Lamont is one thing that impresses me about the design, also the simple controls and really low circulator pump hp, like 1/10 hp? This has got me penciling a circulating boiler. Perhaps the Lamont can benefit from the anti-corrosive and anti-scale properties of trace oil which Doble claimed in Doble-Detroit literature. The key word is "trace". Without an oil separator upline (or frequent blowdowns), the Lamont's drum might foam up, kicking oil into the superheater and perhaps carbonizing it. Fortunately, there are several proven methods to reduce feedwater oil to a tiny trace, and more are possible.
Oil can be tough to get completely out of the feedwater. I once brought up an idea for oil separation on another steam discussion list. McMaster-Carr lists an exhaust head oil separator, a low-restriction cyclonic type, which is claimed to remove 99% of the oil from exhaust steam. As I recall, the flow rates were in the steam car range. Combine this with their "floating oil filter", a bag of highly oleophilic hollow polyethylene fibers which floats in the water tank, to absorb most of the other 1% when it floats to the surface, then dewater/recycle the recovered oil from the separator, and a steam car could (theoretically) go 100,000 miles on a gallon of oil at Stanley lube rates, with virtually oil-free feedwater. Now that assumes that the separator and filter are as good as McMaster claims. At low and variable loads, 99% oil recovery may be a bit optimistic for a cyclone.
Besides you and Andy Patterson, I don't know of any steam folks looking into the Wankel. I have been fascinated with Wankels since assembling & running a see-through plastic model as a child (it was battery-driven and had timed blinking lights to simulate spark plugs firing, wish I still had it), but don't know Wankels well enough to try one with confidence. I'm going to study up on it, though. Maybe the perception of highly specialized fabrication work discourages steam experimenters. Then again, Andy said that a steam Wankel, converted or scratch-built, is quite achievable in a well-equipped home shop, so steamerites may be missing out on a very promising technology.
I read that the RX8 has valve ports in the side walls of the chamber. I wonder if this would be useful in a steam Wankel?
Peter</HTML>
Wankel Engines
Posted by: Jim Crank (IP Logged)
Date: January 24, 2002 02:49PM
<HTML>Hi Peter,
You are right, the coatings I am familiar with do not flake off, they are driven in as a spray at some 30,000 psi and do not come off.
There are so many available now that I think what would be smart is for me to visit some of the race car shops I know and take the guys out to lunch and ask questions about this. They are used with turbo engines where you want to have all the heat you can get into the turbocharger.
Definitely, coat the piston head and the cylinder head. The more you keep the heat inside the working cylinder, recip or Wankel the better you can make the engine.
If the whole engine is well insulated, then radiation losses are way down, this goes for any steam engine. So it takes a few minutes to warm up the engine, big deal.
In the Wankel, if so insulated, the conduction losses to the outside world are a heck of a lot less than with the reciprocating engine.
I bought a wrecked 12-B engine and pulled it apart. When looking at one rotor in the housing you can easily see that the expansion ratio can be dramatically increased if you work from before TDC to past TDC on both sides. I don't think wiping is the problem some think it is, as long as you forget the idea of having two inlet ports per chamber. That gives away far too much expansion ratio.
I don't know how fast you can run a steam conversion; but my old RX-3 with all the Racing Beat goodies was good for 10,000 rpm with safety. With the steamer I want to hold it down to about 4-5,000. I want that effortless low speed performance the steam engine can give. Maybe a two speed transmission, as I have to provide one for reverse and neutral anyhow. I won't bother with all the transfer valve mess of trying to make it reversible directly, not worth the effort.
The Lamont is a God given gift to us, and I have George Nutz to thank for opening my eyes to what it provides. After decades of working on Dobles, I really don't like the maintenance problems of the monotube. Besides, the Lamont is HALF as big as the equivilent monotube and so wonderfully sides steps all the problems of a Doble type steam generator. I wouldn't want any other type now.
Yes the circulating pump is a tiny loss, buried in the noise level. And, if one makes a canned pump with the field coils on the outside, using AC current, even the packing gland loss goes away. Easy technology today.
Trace oil I would use just for what you say, corrosion protection.
Doble E-14 has a good cyclone separator in the exhaust line that Becker made years ago, and it really works, the oily muck on the bottom going to a filter under the car and then back to the tank.
This problem I have to address; but I know a separator can be used with 100% oil removal, it has been done years ago and can be done again. The people with monotubes have no idea what a problem oil is in such a generator.
The Wankel on steam cannot use the aluminum housings, the differential expansion between them and the iron side plates would qqquickly ruin it. That is also where an overheated racing Wankel gets into problems. The side O rings fail.
I would use metal O rings, like the seal rings used in dragster engines. They work perfectly and an all iron engine minimizes the problem.
The work to make a steam Wankel is not hard, really, and except for having to make a valve gear, can be done. Machining and grinding the housings is nothing now, there are firms in the US that do that, like Petite Racing in Florida. I will have the iron castings made and ship them to Petite for machining.
I don't think the bretheren want to take that big step of really looking at other possibilities beyond the recip. engine. For myself, I want to push the steam car into at least the late 20th century if not the 21st and I know it can be done and done well.
For my case, there just is no room in the transmission tunnel of the XKE V-12 roadster to put any type of recip. I am settled on the three rotor Mazda 20-B engine for conversion. Besides when you look at all those forces and strains in a powerful recip engine, they look horrible. I want 250 hp and at least 400 lb/ft torque and the three rotor Wankel gives me that.
The new RX-8 does have nothing except side ports. Using it is possible; but then you are risking leakage to the bearing oil with an all side port engine. Not nice. No, I will stick with the 20-B engine for conversion; but it does have side ports AND radial ports, so both are there to use. This I will decide on when I get further into this project.
Where do you live? If you are close, let's get together and take my Doble to lunch, you drive it.
Keep in touch.
Jim</HTML>
You are right, the coatings I am familiar with do not flake off, they are driven in as a spray at some 30,000 psi and do not come off.
There are so many available now that I think what would be smart is for me to visit some of the race car shops I know and take the guys out to lunch and ask questions about this. They are used with turbo engines where you want to have all the heat you can get into the turbocharger.
Definitely, coat the piston head and the cylinder head. The more you keep the heat inside the working cylinder, recip or Wankel the better you can make the engine.
If the whole engine is well insulated, then radiation losses are way down, this goes for any steam engine. So it takes a few minutes to warm up the engine, big deal.
In the Wankel, if so insulated, the conduction losses to the outside world are a heck of a lot less than with the reciprocating engine.
I bought a wrecked 12-B engine and pulled it apart. When looking at one rotor in the housing you can easily see that the expansion ratio can be dramatically increased if you work from before TDC to past TDC on both sides. I don't think wiping is the problem some think it is, as long as you forget the idea of having two inlet ports per chamber. That gives away far too much expansion ratio.
I don't know how fast you can run a steam conversion; but my old RX-3 with all the Racing Beat goodies was good for 10,000 rpm with safety. With the steamer I want to hold it down to about 4-5,000. I want that effortless low speed performance the steam engine can give. Maybe a two speed transmission, as I have to provide one for reverse and neutral anyhow. I won't bother with all the transfer valve mess of trying to make it reversible directly, not worth the effort.
The Lamont is a God given gift to us, and I have George Nutz to thank for opening my eyes to what it provides. After decades of working on Dobles, I really don't like the maintenance problems of the monotube. Besides, the Lamont is HALF as big as the equivilent monotube and so wonderfully sides steps all the problems of a Doble type steam generator. I wouldn't want any other type now.
Yes the circulating pump is a tiny loss, buried in the noise level. And, if one makes a canned pump with the field coils on the outside, using AC current, even the packing gland loss goes away. Easy technology today.
Trace oil I would use just for what you say, corrosion protection.
Doble E-14 has a good cyclone separator in the exhaust line that Becker made years ago, and it really works, the oily muck on the bottom going to a filter under the car and then back to the tank.
This problem I have to address; but I know a separator can be used with 100% oil removal, it has been done years ago and can be done again. The people with monotubes have no idea what a problem oil is in such a generator.
The Wankel on steam cannot use the aluminum housings, the differential expansion between them and the iron side plates would qqquickly ruin it. That is also where an overheated racing Wankel gets into problems. The side O rings fail.
I would use metal O rings, like the seal rings used in dragster engines. They work perfectly and an all iron engine minimizes the problem.
The work to make a steam Wankel is not hard, really, and except for having to make a valve gear, can be done. Machining and grinding the housings is nothing now, there are firms in the US that do that, like Petite Racing in Florida. I will have the iron castings made and ship them to Petite for machining.
I don't think the bretheren want to take that big step of really looking at other possibilities beyond the recip. engine. For myself, I want to push the steam car into at least the late 20th century if not the 21st and I know it can be done and done well.
For my case, there just is no room in the transmission tunnel of the XKE V-12 roadster to put any type of recip. I am settled on the three rotor Mazda 20-B engine for conversion. Besides when you look at all those forces and strains in a powerful recip engine, they look horrible. I want 250 hp and at least 400 lb/ft torque and the three rotor Wankel gives me that.
The new RX-8 does have nothing except side ports. Using it is possible; but then you are risking leakage to the bearing oil with an all side port engine. Not nice. No, I will stick with the 20-B engine for conversion; but it does have side ports AND radial ports, so both are there to use. This I will decide on when I get further into this project.
Where do you live? If you are close, let's get together and take my Doble to lunch, you drive it.
Keep in touch.
Jim</HTML>
Re: Wankel Engines
Posted by: George Nutz (IP Logged)
Date: January 24, 2002 04:40PM
<HTML>Peter,
Last year Rod and I(both of Lamont and engine tests) had TAFA-PRAXAIR apply the latest coatings to his double acting boat engine. They make most of the equipment for thermal and plasma spraying, there company has built a new facility in Concord, NH.
The thin Doble like pistons were coated with zirconium oxide that reduced the heat transfer by a factor of 6 to 8. The slide valves were coated with a molybdenum hard arc sprayed coat that would reduce the valve friction and protect against gauling.
The deal was for free if I would write a paper of this application for the Journal of Thermal Spray Technology---we still need to run a lot more tests.
I believe this is about the latest technology available. The zirconium oxide has been used very successfully on dragster pistons and high output diesel pistons, it increases thermal efficiency, insulates the pistons very well and reduces the piston metal temperatures.
The Molybdenum coatings have been used on very high output engines on both rings and valve stems that run extremely hot---I have heard that the rings seat in much faster and there has been no seizure of the valve stems in quarter mile dragster engines.
Best, George</HTML>
Last year Rod and I(both of Lamont and engine tests) had TAFA-PRAXAIR apply the latest coatings to his double acting boat engine. They make most of the equipment for thermal and plasma spraying, there company has built a new facility in Concord, NH.
The thin Doble like pistons were coated with zirconium oxide that reduced the heat transfer by a factor of 6 to 8. The slide valves were coated with a molybdenum hard arc sprayed coat that would reduce the valve friction and protect against gauling.
The deal was for free if I would write a paper of this application for the Journal of Thermal Spray Technology---we still need to run a lot more tests.
I believe this is about the latest technology available. The zirconium oxide has been used very successfully on dragster pistons and high output diesel pistons, it increases thermal efficiency, insulates the pistons very well and reduces the piston metal temperatures.
The Molybdenum coatings have been used on very high output engines on both rings and valve stems that run extremely hot---I have heard that the rings seat in much faster and there has been no seizure of the valve stems in quarter mile dragster engines.
Best, George</HTML>
Coatings for Wankel Engines
Posted by: Jim Crank (IP Logged)
Date: January 24, 2002 10:37PM
<HTML>Peter,
George has said it. Zirconium oxide is the trick heat barrier coating and moly is the great stuff to reduce friction. Moly is what I have used before and it really works.
I checked with some rabid race types today and they said the same thing.
See, the stuff is really out there for us to take and use.
Isn't science wonderful!!
Jim</HTML>
George has said it. Zirconium oxide is the trick heat barrier coating and moly is the great stuff to reduce friction. Moly is what I have used before and it really works.
I checked with some rabid race types today and they said the same thing.
See, the stuff is really out there for us to take and use.
Isn't science wonderful!!
Jim</HTML>
Re: Wankel Engines
Posted by: Peter Brow (IP Logged)
Date: January 26, 2002 11:34AM
<HTML>Hi Jim,
Pretty amazing stuff! I like the canned AC circulating pump; adios seals. What material would be used for the container between the field coils and the rotor?
The steam fraternity might take an interest in the Wankel once they see the results. In the meantime, the bright spot is that you have no competition in developing this technology.
I am almost sold on ceramic coatings. In IC engines they handle higher temps, some steam in combustion products, more O2, more extreme thermal cycling, and even traces of water, nitric and sulphuric acid on cooldown -- much more brutal conditions for a thin coating than in a superheated steam engine. If it lasts in an IC engine, it should last in a steam engine. The remaining question is the cost. I have seen figures for coating IC pistons, but don't recall them now. I do recall that heat-barrier coatings are considered affordable for hot rod engines, and a steam engine (recip or rotary) has much less area to coat.
You seem to have all the bases covered with the steam Wankel. Before-TDC inlet opening hadn't occurred to me, and sounds good. What kind of valve gear are you looking at?
Just about fell out of my chair after reading your gracious invitation. Thanks; wouldn't miss that for anything! I'm in San Diego, but will be passing thru SF in February, which, if I recall your location correctly, makes a visit to Doble Central more feasible.
Peter</HTML>
Pretty amazing stuff! I like the canned AC circulating pump; adios seals. What material would be used for the container between the field coils and the rotor?
The steam fraternity might take an interest in the Wankel once they see the results. In the meantime, the bright spot is that you have no competition in developing this technology.
I am almost sold on ceramic coatings. In IC engines they handle higher temps, some steam in combustion products, more O2, more extreme thermal cycling, and even traces of water, nitric and sulphuric acid on cooldown -- much more brutal conditions for a thin coating than in a superheated steam engine. If it lasts in an IC engine, it should last in a steam engine. The remaining question is the cost. I have seen figures for coating IC pistons, but don't recall them now. I do recall that heat-barrier coatings are considered affordable for hot rod engines, and a steam engine (recip or rotary) has much less area to coat.
You seem to have all the bases covered with the steam Wankel. Before-TDC inlet opening hadn't occurred to me, and sounds good. What kind of valve gear are you looking at?
Just about fell out of my chair after reading your gracious invitation. Thanks; wouldn't miss that for anything! I'm in San Diego, but will be passing thru SF in February, which, if I recall your location correctly, makes a visit to Doble Central more feasible.
Peter</HTML>
Re: Coatings for Wankel Engines
Posted by: Peter Brow (IP Logged)
Date: January 26, 2002 11:45AM
<HTML>Hi George and Jim,
Thanks for the info and sources; really amazing stuff! Definitely looks promising. I will look into local sources for coating services, but the parts involved are small and light enough to ship to remote shops too.
Peter</HTML>
Thanks for the info and sources; really amazing stuff! Definitely looks promising. I will look into local sources for coating services, but the parts involved are small and light enough to ship to remote shops too.
Peter</HTML>
Re: Wankel Engines
Posted by: David K. Nergaard (IP Logged)
Date: January 28, 2002 12:53PM
<HTML>I can understand the interest in the Wankel engine as an Otto cycle machine. Simple porting gives free inlet and exhaust flow at high speeds and the engine has very good mechanical balance. I don't know what its octane requirements are and I suspect it is less efficient than a Burt-McCullem engine of equal volume, but its small size and smooth running should make it atractive for small aircraft.
However, I do not see it has any attractive features as a steam engine. The inlet and compression parts of the Otto cycle are counter productive in a steam engine, to say the least. To get reasonable expansion ratios, it must be fitted with some kind of external valve gear. This valve gear must be very fast indeed. If I remember correctly, the Wankel has three power impulses for each crank shaft revolution, and that implies the steam valve gear must run three times as fast for a Wankel as it must for a piston engine. And, as exceleration forces go as the square of the speed, it must be made nine times as strong!
A much better bet might be the "Spiro" turbine, which provided a ten to one expansion ration with simple porting. The "Spiro" was never used as a prime mover in power plants, but unlike some rotary engines I could mention, it did see commercial use for auxilliary loads like pumps and fans.</HTML>
However, I do not see it has any attractive features as a steam engine. The inlet and compression parts of the Otto cycle are counter productive in a steam engine, to say the least. To get reasonable expansion ratios, it must be fitted with some kind of external valve gear. This valve gear must be very fast indeed. If I remember correctly, the Wankel has three power impulses for each crank shaft revolution, and that implies the steam valve gear must run three times as fast for a Wankel as it must for a piston engine. And, as exceleration forces go as the square of the speed, it must be made nine times as strong!
A much better bet might be the "Spiro" turbine, which provided a ten to one expansion ration with simple porting. The "Spiro" was never used as a prime mover in power plants, but unlike some rotary engines I could mention, it did see commercial use for auxilliary loads like pumps and fans.</HTML>
Re: Wankel Engines
Posted by: Jim Crank (IP Logged)
Date: January 28, 2002 03:57PM
<HTML>David,
Yes, the Wankel engine needs an inlet valve gear. If one dismantles a Mazda engine and watches the motion of the rotor around the central gear, you can see that the expansion phase of the engine can be enlarged by quite a bit when used as a steam engine, more than what they use as an I.C. engine.
Doing this also eliminates any possibility of having two inlet valves and two exhaust ports in one rotor chamber, as some suggest. That is unless you want to give up a lot of expansion.
It just could be an occulting engine, others are working that idea; but then you would subject the side seals to steam pressure, and that may not be too good an idea. It certainly bears looking into, though.
The rotor turns one third the speed of the output shaft, so some cam operated poppet valve gear is quite usable and at, let us say, 3,000 rpm on the output shaft, it sees ony 1,000 rpm on the camshaft. The rubbing speed of the apex seal is also reduced by one third of what you would think.
Making the Wankel self reversing is a large design problem with transfer ports and valves and really is not worth the effort, considering the complications. I will use a two speed transmission with neutral and reverse. Off the shelf racing hardware.
They are very tolerant of low octane fuel as an I.C. engine. When we had that government manufactured phony "oil shortage" I was then driving a souped up Maxda RX-3. I bought a barrel of naptha and a barrel of JP-A jet fuel, mixed them 50/50 and drove all over the place and anywhere I wanted. It smelled good too. Did put in one heat range hotter spark plugs. Also, strangely, the engine was much quieter.
Jim</HTML>
Yes, the Wankel engine needs an inlet valve gear. If one dismantles a Mazda engine and watches the motion of the rotor around the central gear, you can see that the expansion phase of the engine can be enlarged by quite a bit when used as a steam engine, more than what they use as an I.C. engine.
Doing this also eliminates any possibility of having two inlet valves and two exhaust ports in one rotor chamber, as some suggest. That is unless you want to give up a lot of expansion.
It just could be an occulting engine, others are working that idea; but then you would subject the side seals to steam pressure, and that may not be too good an idea. It certainly bears looking into, though.
The rotor turns one third the speed of the output shaft, so some cam operated poppet valve gear is quite usable and at, let us say, 3,000 rpm on the output shaft, it sees ony 1,000 rpm on the camshaft. The rubbing speed of the apex seal is also reduced by one third of what you would think.
Making the Wankel self reversing is a large design problem with transfer ports and valves and really is not worth the effort, considering the complications. I will use a two speed transmission with neutral and reverse. Off the shelf racing hardware.
They are very tolerant of low octane fuel as an I.C. engine. When we had that government manufactured phony "oil shortage" I was then driving a souped up Maxda RX-3. I bought a barrel of naptha and a barrel of JP-A jet fuel, mixed them 50/50 and drove all over the place and anywhere I wanted. It smelled good too. Did put in one heat range hotter spark plugs. Also, strangely, the engine was much quieter.
Jim</HTML>
Re: Wankel Engines
Posted by: Andy Patterson (IP Logged)
Date: March 12, 2004 10:42PM
<HTML>Hi Jim
Forget about rotor speed, crank speed relations for the moment. That is just the mechinics of the dang thing.
[ghlin2.greenhills.net]
The wankel can start two (just 2) power strokes per rotor per revoloution. From the crank timming. It can start a power stroke ever 180 degrees. The expansion is over 270 degrees of crank rotation. And the exhaust-compresion takes another 270 degrees of crank rotation. 540 degrees of crank rotation total. It is a bit hard to understand this. You do have 3 cycles running at all times though. You have to look at it as a cycle starting every 180 degrees and lasting 540 degrees. The idea of a lot of surface area to volume is just not the case. Or at least not as bad as one would expect. First expansion occures through only 90 degrees of rotor rotation. and exhust through the next 90 degrees of rotor rotation. You have inlet on one side of the engine and exhaust on the other. A uniflow like engine. And if you are to have long cutoff operation you need you inlet and exhaust passages placement far out from the center. Look at my single expansion anamation. Back the volume area thing. If you calculate that swept area you will find it not all that much greater then a piston engine of the same displacement. And again the rotor is swiping over the chamber area. This should be a great set up. Better then the piston uniflow. Not only are you uniflowing the steam. You are sweaping the expansion around also makeing at temperature gradient around the chamber surfice. If all thst uniflow hype is correct. The Wankel suould be the ultimate uniflow engine. Just check out my steam Wankel anamation. The valves are timed of the main crank shaft. Two sets of valves. One for each chamber half. For reverse I would reverse the valve functioning. The inlet would become the exhaust and viseversa. To fully utilize steam in a Wankel you do need two sets of valves per rotor. There is one problem that shows up in my anamation. The exhaust passage will get a bit of a charge when the inlet opens. One would wont to keep the volume is small as posable. There isn't a lot of choice in placement there as it must provide a steam exit when the rotor is at max volume. And it does need to be inside the face when the rotor is at min volume if one wishes to reverse the engine. I expect it would not be all that much of a problem to get that volume to almost nill.
As far as expansion is conserned. The min volume to max volume is deturmined by the K factor of the engine. The K factor is the ratio of the roter radius to the crank throw. Rotor radious being the distance from it's center to an apex. The min volume is also effected by the K factor. The actual min volume can be adjusted by the rotor shape. It does need to always clear. But you can reduce clearance quite a bit with high rotor dome. But you will always have a bit more clearance then can be had with a piston engine. With close tollerance one might reduce the problem with inlet steam in the exhaust passage. If the rotor is real close to the chamber at tdc you might get some throttling slowing the steam flow to thge exhaust side. It would soon open up as the rotor progressed. Don't know if I would wont to try that though. Seams a bit risky.
Jim I think that you really need to look at the Wankel timming in relation to the crank. Not the rotor. The rotor is just the piston. Though an odd one.
Andy</HTML>
Forget about rotor speed, crank speed relations for the moment. That is just the mechinics of the dang thing.
[ghlin2.greenhills.net]
The wankel can start two (just 2) power strokes per rotor per revoloution. From the crank timming. It can start a power stroke ever 180 degrees. The expansion is over 270 degrees of crank rotation. And the exhaust-compresion takes another 270 degrees of crank rotation. 540 degrees of crank rotation total. It is a bit hard to understand this. You do have 3 cycles running at all times though. You have to look at it as a cycle starting every 180 degrees and lasting 540 degrees. The idea of a lot of surface area to volume is just not the case. Or at least not as bad as one would expect. First expansion occures through only 90 degrees of rotor rotation. and exhust through the next 90 degrees of rotor rotation. You have inlet on one side of the engine and exhaust on the other. A uniflow like engine. And if you are to have long cutoff operation you need you inlet and exhaust passages placement far out from the center. Look at my single expansion anamation. Back the volume area thing. If you calculate that swept area you will find it not all that much greater then a piston engine of the same displacement. And again the rotor is swiping over the chamber area. This should be a great set up. Better then the piston uniflow. Not only are you uniflowing the steam. You are sweaping the expansion around also makeing at temperature gradient around the chamber surfice. If all thst uniflow hype is correct. The Wankel suould be the ultimate uniflow engine. Just check out my steam Wankel anamation. The valves are timed of the main crank shaft. Two sets of valves. One for each chamber half. For reverse I would reverse the valve functioning. The inlet would become the exhaust and viseversa. To fully utilize steam in a Wankel you do need two sets of valves per rotor. There is one problem that shows up in my anamation. The exhaust passage will get a bit of a charge when the inlet opens. One would wont to keep the volume is small as posable. There isn't a lot of choice in placement there as it must provide a steam exit when the rotor is at max volume. And it does need to be inside the face when the rotor is at min volume if one wishes to reverse the engine. I expect it would not be all that much of a problem to get that volume to almost nill.
As far as expansion is conserned. The min volume to max volume is deturmined by the K factor of the engine. The K factor is the ratio of the roter radius to the crank throw. Rotor radious being the distance from it's center to an apex. The min volume is also effected by the K factor. The actual min volume can be adjusted by the rotor shape. It does need to always clear. But you can reduce clearance quite a bit with high rotor dome. But you will always have a bit more clearance then can be had with a piston engine. With close tollerance one might reduce the problem with inlet steam in the exhaust passage. If the rotor is real close to the chamber at tdc you might get some throttling slowing the steam flow to thge exhaust side. It would soon open up as the rotor progressed. Don't know if I would wont to try that though. Seams a bit risky.
Jim I think that you really need to look at the Wankel timming in relation to the crank. Not the rotor. The rotor is just the piston. Though an odd one.
Andy</HTML>
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