surprised RG didn't mention the Rolls Royce Diesel engine which used the Larger rotor to compress the mixture which was then passed to the smaller rotor and compressed further before ignition. Same idea- the larger rotor acts as a supercharger for the smaller. You could probably call it an Atkinson cycle rotary and get away with it:)



https://www.rx8club.com/attachment.p...1&d=1211091531

what book is that^^^ ?

Guaya Guaya Caravana de RX8
 

um what? how bout a translation

water pump?

Supercharger.

It's not an atkinson cycle. If it were, there wouldn't be a second rotor. There'd just be a combustion chamber where nothing gets further compressed. However we have an actual 4 cycle engine in there as well which is what the second rotor is. Calling this an Atkinson cycle would mean we would have to call every single turbocharged engine out there an atkinson cycle. That's not even remotely accurate.

You misunderstand what the intention of turbo compounding really is all about. It's not about boosting power through the use of a turbocharger. Everyone assumes that a turbo is only good for adding power. What this is intended to be used for isn't so much a power adder but rather an efficiency booster. There is more to it than simple boost. The goal is only a small power increase through the use of boost. It is also intended to capture some wasted energy and send it back to the crank which it does.

While it may appear that spinning another rotor is an awful lot of energy, it probably isn't as bad as you think it is. Let's compare it to another crank driven device, a centrifugal supercharger. These things are HUMONGOUS parasitic draws on an engine. Why anyone in their right mind would ever want to strap one on their engine is beyond me as it's a product that is a dead end with little real world potential. While another rotor is a parasitic draw, it is compressing air and sending it to another rotor. This means boost which means more power than normal to overcome this rotor. Then some energy is being reabsorbed back by this rotor and sent back to the crank. The result should be a power level that is noticably greater than a 1 rotor on it's own but with lower fuel consumption than the 1 rotor on it's own. Not to mention the noise reduction. That's a win/win design. It's not about max power. The great power wars are coming to an end and it's about time. It's time to shift to efficiency because at the end of the day, that's what is going to sell the most to average buyers.

Ignore the use of a rotor as only a supercharger. That's only part of it. I'd like to see this idea pursued more or rather at all by Mazda which I doubt they'll do.

subscribing

Sorry for that. I was thinking Miller cycle actually sinc eit uses a supercharger for increased efficiency much like this rotor idea uses its 1st rotor. However i wasnt taking into account the unequal relationship between the power and exhaust stroke of the atkinson cycle.. my bad

It was admittedly fairly easy to see it that way. It's not quite a jet engine yet!

you mean 16X-based, turbo compounded, side port, direct injected, quad rotor, and a single variable geometry turbo...

pfft...been there...done that...went back to hamster wheels...heh...

......*Mind Explodes*

This is a very good read. I can't wait to see how it goes further.

I just shot an email over to info@moller.com asking anyone of them to come over and join the dicussion. I'm not sure they will but hey, it can't hurt :)

something like this?

http://www.rotaryeng.net/Turbo-compound2-3D.jpg

i kid...

A response from Moller
 

Hey guys, the General Manager just shot back a reply to my e-mail earlier today :)

Thanks, Brian. I will ask Dr. Moller to take a look. He typically does not personally talk on-line, but he may be able to address some specific questions for you.

We are a bit reluctant to show the porting arrangements until the patents are approved but most of your commenters seemed to get the idea pretty well already. If Dr. Moller can reveal some of the technical details without risk I am certain he would be pleased to share it with your readers.

As for the comment on the Skycar not being able to do much except brief vertical take offs and landings I'd like to remind this person that most planes don't do this at all...and we did this with our air-cooled 70 hp Rotapower (rotary) engines versus the 140 hp (twin-rotor) engines we have available now. Over the course of the volantor's development path, Dr. Moller has built and flown 5 different prototype aircraft, each with progressively more capabilities. The latest, commonly known as the Skycar, is a four-passenger, 2,400 lbs AUW aircraft capable of helicopter-like VTOL and yet is anticipated to be nearly three times faster than a helicopter with a 350 mph dash speed and 230+ mph cruise speed @ 20+ mpg. The schedule has, as one would expect for a totally new type of aircraft, slipped a number of times. It is a very costly project and we have run out of funding numerous times, but unlike the other dozen or so companies that started on a "personal" VTOL some 20 years ago, we are still in business and still moving forward. With the exception of Boeing, we are the only ones left that help create the preliminary FAA "Powered Lift - Normal" classification, and I don't see Boeing providing an affordable private aircraft anytime soon. So we are it for now and absolutely dedicated to making the Rotapower rotary engines a success in this and in other non-aviation products.

Regards,

Bruce *****
General Manager
Moller International
www.moller.com

Discuss :lol:

For the record....
I'm an engineer at a combined cycle powerplant - which means we take waste heat from combustion turbines and use it to fuel a steam cycle... so i know the concepts of reusing waste heat.

The fact is you have a finite amount of energy to use with compounding or turbocharging. Either way your reusing the energy to increase efficiency by reducing the losses in the combustion process during the intake stroke and taking a minimal hit in the exhaust stroke. How well you utilize the energy comes down to how efficient the process is that you use to convert it... and i do not see a dead rotor approaching the 75-78% efficiency of a turbo.

the problem is turbo does not increase fuel efficiency, because all a turbo does is force more air into the combustion chamber, combined with increase injection of fuel to increase the power output per volume.

Think of the 2nd rotor as a Hot side of a turbo with no cool side, the hot exhaust just spins the "turbine" which help spins the shaft mechanically. there is no power boost, just attempt to suck all the power of the 1st combustion cycle by forcing the exhaust to push 2 rotors.. i am sure there is a bypass for start up when exhaust velocity/energy is low, but when it's higher, it can harnass the exhaust.

It seems to me that feeding the exhaust stroke into the face of a rotor would capture more (nearly all) energy from that exhaust than simply blowing it past the face of a fan where only a portion of that gass makes physical contact with the blades.

If noise reduction in this system directly corelates with the amount of energy harnessed I wouldn't be surprised at all to see this surpass turbos in efficency. Keep in mind w/o any combustion taking place on this rotors face it can be made out of much lighter material than the rotor in the combustion chamber.

Wonder how it is lubricated, without pushing unburned oil out the ports (unless it uses side ports?)...or if the exhaust gas temps would be enough to burn it.

Also, I wonder what the long term effects would be on the rotor from soot build up from the exhaust.

I know it is a new design and they are working on it, but wonder how it will end up work out. Awesome to hear more development outside of mazda on the rotary.

the compression rotor can be made lighter and from a material which will not need to withstand the combustion cycle...

then you cram that into the smaller rotor which could be made from a more expensive material to withstand higher temps/stress...

materials engineering in this case will be a huge factor for efficiency and design i would imagine...

Some turbos like the Greddy kit can only feed air on the current Renesis up to 7-7.5K rpm? Given rotaries naturally have higher rpms, in order to have a turbo feed air throughout the complete rev range, wouldn't the turbo have to be larger? Versus on a regular engine of the same displcement? So wouldn't a larger turbo be less efficient as far as mpg go? Or if they'd use a smaller turbo on the 16x with a lower redline than the current 13b, would it be more efficient?

I'm knew to this, my head hurts......lol.

In this case, the front rotor (supercharger) is a positive displacement unit.

Does anyone have a flow map of a rotary based supercharger? What kind of efficiency range would it have?

LOL! Reminds me of how I convinced my wife (a tree hugger) that a turbocharger for my Miata was actually a green device since it recycled otherwise wasted exhaust heat energy. OK, maybe it wasn't turbo compounding, but the point is it worked.