Piston travel speed is not constant through its stroke, the piston "parks" briefly at TDC and BDC, and it travels at its fastest speed at the middle of the stroke. This provides significant leverage to the ignited mixture to force the piston down for the longest time while the combustion chamber volume expands ever so slowly (at the same speed as the piston is traveling). Racing engine builders take maximum advantage of this phenomenon by using the longest con rods they can fit, as the longer the con rods are the longer the piston will remain “parked” at TDC and BDC, improving the engine’s efficiency. A Wankel rotor, on the other hand, keeps a constant movement speed through its elliptical phase, so it doesn’t count on this phenomenon to improve efficiency.

So a piston engine’s combustion chamber allows for the igniting mixture more time to completely burn, and its expansion is restricted for a longer time so that the pressure force of this expansion coming from the heat of the ignition event is better converted into motive power and thus cooling down the now completely burnt gases. A Wankel engine’s combustion chamber is always expanding at a constant pace, so the igniting mixture doesn’t get burnt as well as on a piston engine’s in this regard. Add to this the fact that a Wankel’s combustion chamber’s shape in itself is far from optimum (the optimum will be a sphere that expands in all directions after combustion, but since this is impossible to make, a piston engine’s cylindrical combustion chamber is the closest to optimum achievable) plus its high area to volume ratio given its “moving chamber” characteristics and you end up with a very inefficient way of converting a flammable air/fuel mixture into motive power. All these inefficiencies combined are good reasons for the high exhaust temps coming out of a Wankel.

Another inherent reason for the hot exhaust temps is the fact that you get a huge, fully open, unrestricted (at least on a peripheral type) and thus very free flowing exhaust port in less “crank angle time” than on a poppet valve piston engine.

Before anyone else pontificates with certainty on how a rotary works, they must read and study the writings of Mr Yamamoto.

http://www.rotaryrefs.net/rotaryrefs...-KYamamoto.pdf

From EFINI:

1 "the piston "parks" briefly at TDC and BDC"

Nope1. The piston acceleration is at it's (absolute) maximum at TDC, and near max at BDC. Long arms will make it move more slowly through these positions, but it never parks, with zero acceleration. There is an instant at zero velocity, just as there is an instant at 4K rpm if you go wot with no load and rev the engine to redline. (I do think long arms increase peak piston speeds).

2 "A Wankel rotor, on the other hand, keeps a constant movement speed through its elliptical phase, so it doesn’t count on this phenomenon to improve efficiency."..."A Wankel engine’s combustion chamber is always expanding at a constant pace, so the igniting mixture doesn’t get burnt as well as on a piston engine’s in this regard"

Nope2. Expansion for both engines is described by similar sine/cosine curves. The wankel volume change slows at BDC and TDC, just like a piston engine. In fact, the volume change curve for a wankel chamber will be the same, over the displacement cycle, as a piston of same displacement, with very long rods.

3 "So a piston engine’s combustion chamber allows for the igniting mixture more time to completely burn"

Nope3. Already noted that wankel would be similar to piston engine with extreme long rods, regarding slowing down at TDC, based on an engine stroke or cycle. Time is a loaded variable for comparison. At same crank speed , rotary power cycles take 50% more time. Both these facts gives the rotary more time for completing combustion at say 10% of the power stroke (or cycle).

4 "... plus its high area to volume ratio ..... All these inefficiencies combined are good reasons for the high exhaust temps coming out of a Wankel."

Nope4. The high area/vol ratio results in more heat loss to the cooling system during the power and exhaust cycles, lowering exh gas temperatures.

5 "Another inherent reason for the hot exhaust temps is the fact that you get a huge, fully open, unrestricted (at least on a peripheral type) and thus very free flowing exhaust port in less “crank angle time” than on a poppet valve piston engine."

Yup5. Can't comment on crank angle factor now. But can add that a wankel port is shared among 3 chambers, and as such will be flowing exh gas about 75% of the time vs 25% for a boinger exh port. So in any minute, a boinger port will be flowing exh gas for 15 seconds, while a wankel exh port will be flowing for 45 out of the 60 seconds. That would suggest less heat loss during travel through a hotter port.

I am sure that by "parks" he means the same thing that you stated-- it stops. My car seems to stop when it is parked. It is also true that a longer rod allows the piston to remain at TDC longer or stays within a set parameter of degrees of TDC as measured at the crankshaft.

The exhaust is hot for several reasons--- check post #13
Actually the combustion gases are no hotter in a Wankel than they are in a boinger; assuming they are stoichiometrically correct. Fuel at the correct AFR all burns at the same temp all factors being equal. The heat is derived from the amount and type of fuel burned----- BTU's-----heat. One way it is rated is in BTU's per pound.

Car parked ... not the same. While you are sitting there, you are not at a high g load. Long rods ... sounds like we agree.

If high heat is just due to the unobstructed port, I would think egt's would be much lower on an RX8, vs a na 13B, at same power?

So you think 3x the mass flow rate through the port (vs boinger) is not related?

Parked---- STOP. What has high G loads have to do with the fact that he was only saying that the piston dwells at TDC longer? A piston which remains at TDC longer allows the pressure to build and results in a greater thrust- force applied to the piston. A greater impulse force if you will. It is analogous to hitting a golf ball. Do golfers simply swing to the point of impact or are they taught to "follow through"? They are taught to follow through same in baseball and other stick and ball sports. The follow through allows the club (force provider--ie combustion) to stay in contact for a fraction of a second longer and transfer more of it's energy to the ball(piston).

I never said that it was the ONLY reason why the exhaust was hot. The new side exhaust rotary engines don't have valves! It is still an unobstructed port compared to a piston engine.

Golf?

My only point is a parked car analogy is not correct and misleading, as it implies duration with no velocity, which is not true for a 13B or a boinger. Basic kinematics. You can look at varied time near TDC, as you noted at one point, but "at TDC" is an instantaneous event.

Agree the exh valve will have a significant cooling effect.

Parked --- stopped. What don't you get? Who said that it stayed that way? You said yourself that the piston STOPPED at TDC. The analogy is correct. What do you do when you park your car? You stop. That is all that was meant. If you want to talk about piston speeds, or piston forces we can do that to but it has nothing to do with the Wankel's exhaust temp. It only provides some means of comparison.

There is nothing wrong with Efini's post in reference to the piston at TDC, He only overstated that the rotary engine's combustion expands at a constant pace----Which it does from the standpoint of engine rpm but not from a volumetric stand point. I understand his statements and also understand how he meant them.


What part of the golf example needs more explanation?

Who wants more reasons why it is "hotter"?

Ups, sorry for pontificating. :) BTW, I've been trying to get a hold of Mr. Yamamoto's essay for quite some time, thanks for pointing me to it.

My views were based from simple observation on the movement of the rotor through its ellipse: as I saw that its apex traveled through the peritrochoid at a constant speed, I thought that the chamber volumes would also change at a constant speed as well. Thanks for clarifying this for me.

But the other 2 points remain valid: the Wankel’s far from optimum combustion chamber shape and constantly moving characteristic that creates its high area-to-volume ratio are the basics for its inherent inefficiencies.

Im still wondering how the exhuast gas is so hot if it loses so much heat to the coolant.

sccagt3:

Ok, here is a roughly valid "parked" car analogy for you. Slam on the brakes from 60 mph, and just before you "stop", slam it in reverse at wot. You will soon reach a point/instant where forward velocity is zero and you immediatly accelerate in reverse.

"My car seems to stop when it is parked" Hope you can see the diff, otherwise let it go.

I did not bring up TDC activity, I responed to others.

Tiger and Anika have great follow throughs, but I have never heard it linked the to ignition initiation specifics of the power stroke in the tech/sae papers I read. The goal it have the spark advanced sufficiently to result in a pressure peak about 10-15 deg atdc, closer to the point of optimum torqe leverage. A peak at TDC would waste heat (and drop pressure) to all metal boundaries, as it can not create torque there, wankel or recip. The pressure history will determine how effectively torque is created. Mabe that's like a good chip shot from off the green...

I'd like to hear your opinion on the effect of a common exhaust port with high duty cycle, vs boinger, as I asked before. And of course any more reasons the gas is hotter. Righ now I agree with your exhaust valve cooling.

I answered EFINI's post and he recently replied, obviously capable of speaking for himself.

EFINI:

glad the link helped. It also shows that apex seal velocity is a sine curve with a high mean value and low cyclic content, vs piston velocity.

The area thing clearly dumps more usable heat (and thus lowers pressure) to the walls, and yes that would explain high BSFC, or poor thermal efficiency, but not hotter exhaust as you had stated earlier.

Yep, from further reading Mr. Yamamoto's I dig the rotor's apex doesn't travel at a constant speed, something that from mere casual watching of a model running can't quite come up as the variation is ever so slight compared to its piston analogy, in which a piston reaches a speed of 0 at TDC and BDC. "Park" was my choice of wording, it is not very much unlike "stop" in a figurative meaning, so as long as everybody understands what I meant it's just fine then, I guess. In the meantime, I've got Mr. Yamamoto's fine essay to read and digest, so I'll be busy doing this for the time being. Until then, I'll just stop and park...

Does anyone have the math skills to plot the increase in area from ignition event to when the leading apex seal reaches the exhaust port, over time (in degrees) vs that of a piston engine? This would be some serious calculus though heh.

Also, bare in mind the speed of the piston does not ever reach "zero", it asymtopically slows to zero and then goes in the other way, just like a graph of y=x².

Regardless, even with the heat loss, the data tell us that its either not completely using the energy of the charge to do work to move the cylinder, or its still burning when the exhaust port is open.

Ive been up to long to remember this but I know there are certain things you can do to the timing of a piston engine to increase EGTs... could the same effective thing be happening here?

I have the skills to do it but you would not understand it since you can't seem to grasp the concept of a piston's speed having to be ZERO in order for it to change direction. You are in Raleigh? Head over to NC State and take a physics course they have excellent professors at least they did when I was there.

The "parked" term is a common term used by engine builders. Talk to them.
I used the golf analogy to show why it was advantageous to use a longer rod in a piston engine; because the piston is parked at TDC longer. The longer rod allows the piston to dwell within TDC longer which in turn reduces the need to advance the timing and initiate the burning. This brings us to the golf analogy, the longer rod allows the combustion to pack more punch on the piston----just like the impulse force applied to the golf ball. The longer the club head stays in contact with the golf ball the greater the transfer of force.

Efini can speak for himself and has after your post-- It seems his meaning was understood by some myself included.

You guys need to think about the intake/exhaust overlap. The time that both the intake and the exhaust are open at the same time. This was eliminated on the renesis. Think about how this might affect efficiency.

In a post to why someone would want a rotary engine i just finished watching a show in which they explained how the engine was light weight and compact which is ideal for for faster times. they raced an fd tuned with about $6000 with 350hp and a BNR34 same tuning but 600hp and the fd came out on top. this engine with less hp is lighter and in turn you can have better cornering, lower you car more because its compact design and ultimately compete against the bigger hp cars with a much much less weighted car

area comparison
 

I did a "snap shot" area comparo analysis in '02, at tdc and bdc.

https://www.rx7club.com/forum/showth...t=thermal+area

Velocity is the slope of the displacement vs time curve. So at tdc and bdc, slope is zero, as is velocity, at that instant.

"Do golfers simply swing to the point of impact or are they taught to "follow through"? They are taught to follow through same in baseball and other stick and ball sports. The follow through allows the club (force provider--ie combustion) to stay in contact for a fraction of a second longer and transfer more of it's energy to the ball(piston)."

Follow through allows maximum club head speed to be achieved, which is what distance is all about. Longer contact with the ball is a secondary effect.

Gas pressure is always in contact with the piston, from ignition to exhaust opening. If you can get higher peak pressures in the combustion event (ATDC) this will carry through the power stroke for more torque generated, but duration of the contact in not a variable.

But, in simple terms, a bigger bang in the chamber will get more power, as a harder (proper) hit of a golf ball will get more distance. I can buy that.

Total duration is variable. Timing of the ignition sooner or later varies the time that combustion pressure is applied. Long rods allow more time spent at the sweet spot of the combustion process which allows for a greater "shove" to the piston.

Longer contact is not a secondary effect. What if contact time were reduced to zero. One analogy might be the surviveability to a high g load event. People can survive high g loads if the time they are exposed is limited- very limited, because there is less total transfer of energy to the person. Why is pine tar limited on major league bats? Because it allows the bat to stay in contact with the baseball for a fraction of a second longer---more transfer of energy from the bat to the ball. Not to mention it is a might messy. The first thing I do is "rough up" my aluminum bats.

"Total duration is variable. Timing of the ignition sooner or later varies the time that combustion pressure is applied."

It does not count before TDC, as this is creates negative torque. The time pressure is applied in a productive way is constant, for a given rpm, defined by mechanical events, as I said. I'll agree to disagree here.

It is variable, engines don't ignite the air fuel after TDC they do it before. A small block Chevy can run 28 to 36 degrees of advance on the ignition. This VARIES the time that the combustion gases have time to do their work. It Is variable however there is one "sweet" spot that provides the greatest combustion pressure at the right time to send the piston on its way which is dependent on many factors and changes with RPM. As an engine speeds up the combustion gases have less time to be at the optimum pressure for the cylinder, this is why the ignition is advanced--ignited sooner as engine speed increases.

So I guess its settled then that its a matter of the rotary cant as compeltely burn all of the fuel air charge as a piston engine before it has to exhaust it?

sccagt3 - I havent taken calculus yet, but it looked to me like it never in reality actually came to a stop unless the engine wasn't spinning. If you want to correct someone you dont have to flame them in a TECH forum. :dunno:

I don't feel like I have flamed anyone. Sorry if it came out that way. I was getting a little tired of explaining it though. Good luck with your studies.

i didn't notice any flames...

By definition a piston has to stop at top and bottom dead centres. The piston velocity is also not nessesarily sinusoidal either (offset gudgeon pins). The fact that the piston is stopped or has a low velocity at the point of highest cylinder pressure is why a piston ring and liner wear much more in this area.

Ok, taking snippets of information from chapter 4, "PERFORMANCE AND COMBUSTION" of Mr. Yamamoto's essay, you can see some indications that low thermal efficiency does, in fact, promote high exhaust temps:


4.1.5"FUEL CONSUMPTION PERFORMANCE":

"In the rotary engine, the surface to volume ration of the working chamber is greater and the time required for one-cycle is 1.5 times longer than those of the reciprocating engine, causing a greater cooling loss. The greater surface area/volume ratio of the working chamber also causes a greater loss of unburned gas."

See Fig. 4.5, the % of heat attributed to unburned gas.

4.5.2"VOLUME OF ROTOR RECESS"

"The compression ratio depends mainly on the volume of the rotor recess. A smaller volume of the rotor recess increases the compression ratio improving the theoretical thermal efficiency. (...)Fig. 4.36 through 38 show the effect of the compression ratio on fuel consumption performance, performance at W.O.T. and exhaust emission. As shown, the smaller volume of the rotor recess improves fuel consumption and performance at W.O.T., but, at the same time, increases the amount of emission of NOx and HC."

In Fig. 4.38 you can see that the higher the compression ratio (and thus its thermal efficiency) the lower the exhaust temps are.

So I guess low thermal efficiency and high volume of unburned air/fuel mixture both contribute to high exhaust temps.

That would definitely explain the high BSFC!

".... you can see some indications that low thermal efficiency does, in fact, promote high exhaust temps...

... So I guess low thermal efficiency and high volume of unburned air/fuel mixture both contribute to high exhaust temps."

easy now. I'm not sure you are extracting the right conclusions.

4.5.2 just says a smaller dish (and higher cr) results in more nox and hc. This is due to less natural egr with high compression and small compressed chamber volumes, and is true for boingers too.

4.1.5 is more relevant. I read the "heat balance" graph differently, regarding unburned gases. In combustion analysis, "unburned gases" = unburned mixture of air and fuel, and is considered to be at a much lower temperature than burned gases. Like coolant and oil, it would be considered a heat sink, and as such the graph could read "heat absorbed by unburned gases". By "heat of exhaust", I interpret this as burned gas.

If the quantity of unburned gas is decreased, per the graph, note that all other components increased. Less unburned gasses, more exhaust heat beause more mixture is burned. more effective heat too.

So, I see nothing here that suggests why rotaries have high egt. I'm glad your digging into the document..... a lot there.

As I said, check fig. # 4.38, which is related to the quoted text. You will see that, indeed, as you said, as CR goes up, NOx and HC levels go up too, but it shows, too, that exhaust temps, on the contrary, go down. NOx emissions, as I understand on boingers or Wankels or more clearly on diesels, rise due to higher combustion temps, which a higer CR will usually promote, and I say usually because this can be joggled with by the design of the combustion chamber on a boinger. Engineers actually add EGR to bring down high levels of NOx. HC levels, on the other hand, develop mostly due to high levels of unburned mixture, and the mechanics for this is explained in further detail earlier in the document at 4.3.1 "FLAME PROPAGATION". As I understand it, the higher thermal efficiency of a high compression ratio better translates the heat generated from the ignition event to working load and thus exhaust temps go down. So I guess that, if thermal efficiency is improved by other means, like using heat reflecting ceramic coatings to cover all the chamber areas, exhaust temps would go down, too, in the same way as higher CRs get you lower exhaust temps. I remember reading people in here finding that their cermet coated housings and/or ceramic coated rotors did not rise their exhaust temps, but that their fuel mileage improved significantly. Maybe since they were expecting higher exhaust temps from these coatings (if heat wasn’t taken away by the coolant and the oil, then it must go out as high exhaust temps, right?), they didn’t realize that maybe they were actually running lower exhaust temps than before, as more heat went through the eccentric shaft as power.

Yeah, they don’t explain very clearly how to read the graph, as it only shows heat generated as a % and not by total measurement, like BTUs or the like, nor do they say at what moment of the combustion process . But doesn’t “unburned gases” mean mixture that didn’t burn while the combustion chamber was at a position where its burning will translate into work? Doesn’t this unburned gas ultimately gets burned later during the expansion stroke, where it doesn’t help turn the shaft and thus goes out as a very hot exhaust gas?

Have to, cuz I've read the later SAE papers on the 13B-T second gen, the 13B-REW and the 13B-MSP (a.k.a. Renesis) and I had to fill some voids left on them as these documents don't explain rotary basics in depth.

4.38, it's not a contrary effect that exh gas temp went down with higher CR. more unburned gas in the power stroke means cooler gas mixing with hot, or cooler exh. Putting this with CR vs power plot: higher CR gets more power, more unburned gas, and lower exh temp., per this paper for the wankel.

4.3.1 does not mention exh temps, but I think you are right on exh temps dropping with high CR.

If the unburned gas was burned, it would not be unburned. I think most of the HC measurements are going on at the exh manifold, not in the chamber.

Questions follow questions
 

I'm no pro, but a pretty good observer. Excuse me if I fall for tricks easily.

Exhaust Temp and piston speeds seem to become entwined in this thread. I do know that limits on piston speeds are more closely tied to friction/lubrication between sliding elements and flame propagation. Have you noticed how "flat" piston crowns are these days?

Well, On to "heat in exhaust". First let's remember there are two aspects to heat. Temperature, which is really a measure of speed of motion (think electron volts)
And Calories. It's like volts and amps, pressure and flow volume.

So, the RX's "could" have hotter exhaust gas temperatures due to many variables (I honestly don't know which ... yet) It's not likely that the gas burned with oxygen in a rotary is any hotter than gasoline burned in a recip, so we should disregard that. If the gas/air mix burns, it will attain some temperature, then it can only cool if it gives up it's heat by the usual mechanisms of Radiation or conductance. Well, there is the third, expansion. (read turbo charger or "extractor exhaust" etc.) It could be that the heat loss to metal in a poppet valved engine is the difference. Exhaust valves burn in short time if they are not allowed to cool by contacting the valve seats. But modern engines have pretty efficient exhaust ports.
Does anyone know if a rotary engine requires more or less water cooling capacity than an equal output recip? The heat would need to go some where.

or. The RX's might put out the same temperature exhaust, Has anyone got some EGT measurement values? only more of it. Heck these simple two bank rotarys have only two holes going out. Maybe there is a clue. The heat from a familiar four (or more) cylinder passing out through two pipes.

Also, I know that I can get any recip to run it's exhaust pipe red hot just by retarding the spark a bit. Forcing some fuel to be burned in the exhaust rather than the combustion chamber. This Has to be an obvious reason, for how else could the "reactor" work and these engines are noted for poor economy and poping in the exhaust.

I conjecture. That the rotor faces just do not allow a geometry useful to complete combustion. Unburned fuel is caught at the edges and the apex areas during the combustion phase only to be expelled into the exhaust port when the time comes.

An EGT and a lamda (Oxygen) sensor would tell us a lot!

An additional note: The exhaust note and intensity has everything to do with temperature of the exhaust gas (velocity) and the SPEED at which the exhaust port opens. Frequency is it's own thing.

Perhaps we could fit marine type water cooled exhaust systems to these RX's and bring the temp down to a point where there are only drips of water and a little puff of "air" comming out the tail pipe. ;-)

Can anyone point me to a theoretical discussion of "tuned exhaust" for these rotarys?
Extraction systems would seem counter productive to economy.

Has anyone an idea what the volumetric efficiency of a rotary engine is? Recips frequently run well over 100%.

What about BMEP.

It's all thermodynamics. The rest is just guessing.

Regards

CalG

Me neither :)

An excerpt from Paul Yaw's pages



We have already discussed how insufficient exhaust flow reduces volumetric efficiency, but the presence of exhaust gasses in the intake charge (Exhaust gas dilution) causes other problems as well. The rotary engine is known for its poor combustion characteristics. Due to the shape of the chamber, and the location of the spark lugs, a large percentage of the intake charge does not burn in the chamber. The end result is a fair amount of unburned gasses, or hydrocarbons being passed into the exhaust system. This reduces power output, because a portion of the mixture that we tried so hard to put into the engine did not burn. This also reduces fuel economy, and increases emissions. Another effect that is not often realized is excessive exhaust gas temperatures. These hydrocarbons will then burn in the exhaust system raising the exhaust gas temperatures.

The addition of exhaust gasses to the intake charge will reduce the already poor combustion quality. The end result is that the mixture is harder to ignite, and when it finally does light up it will burn at a slower rate further reducing power output. In a turbocharged engine excessive exhaust gas dilution will cause its own unique set of problems.


Regards

CalG

"What about BMEP."

this is a very theoretical energy based valve, for work done on piston/rotor from tdc to bdc. It can be determined by p1, p2, and deltaV. Or, for a given rpm, it's just a function of engine torque and engine displacement, that's all. rotary's have relatively low torque, so this value will be low, compared to boingers, except at high rpm.

"These hydrocarbons will then burn in the exhaust system raising the exhaust gas temperatures."

Yaw has a lot of good stuff posted, but not sure about this. When tuning based on egt, rich mixtures with high unburned hc's tend to drop temps, lean ones raise egt's. This is consistant with Yamamoto's heat balance in 4.1.5. air ratio is lambda, and at .85 slightly less normalized working heat, vs much less exhaust heat. I would expect lower egt too.

""unburned gases" = unburned mixture of air and fuel, and is considered to be at a much lower temperature than burned gases. Like coolant and oil, it would be considered a heat sink, and as such the graph could read "heat absorbed by unburned gases". By "heat of exhaust", I interpret this as burned gas."

I might have been off on this :(. Other heat balance literature would say the "heat of unburned gas" is just the potential btu value of gasoline that was not burned. The heat of the exhaust is based on total exhaust mass flow and temperature.

KevinK2

There is a LOT more "heat" in a small mass of Unburned fuel than there is in the same "volume" of spent exhaust gasses. That's what infurnal combustion is all about ;-)

If that heat is released by the mechanism of continued combustion, even though the temperature is lower, the abount of calories (heat) is greater.

The subjective "measurement" of hot exhaust pipes is only the difference of heat in and heat out. So.... more low temperature "heat" could easily manifest as "hotter" than a smaller quantity of higher temperature gas. Hot gasses do not actually carry a lot of "heat". I like to use this analogy: You can place you bare hand into a hot oven and not get burned. Just don't touch anything!"

I consideration, There must be a lot of heat given up to the intruding poppet valve, guide and exhaust tract even in a modern four cycle recip. It is interesting how "cool" a high performance two cycle engine exhaust is.

Perhaps none of this is true, but there is some good stuff here

CalG

"There is a LOT more "heat" in a small mass of Unburned fuel than there is in the same "volume" of spent exhaust gasses. That's what infurnal combustion is all about ;-)"

lbm for lbm, yes.

That is what fig 4.5 shows. At lambda = .85 (12.5 A/F), the energy of unburned fuel equals the hot exhaust energy, and each is greater than the fuel energy that does work.

what he meant was that if you look at it in terms of velocity, it did stop at TDC or BDC, however, the acceleration is what drives the velocity to zero. It's just an intergral of the forumla. If you take diff eq and visualize a spiral vector, you'll see that the acceleration is constantly changing in both the vector and its angle causing the velocity to be constant but yet with a circular direction.

I think you're thinking of it as acceleration instead of a vector in velocity form.

There is such a device. It was developed and has been in use since the 1950's.

https://en.wikipedia.org/wiki/Turbo-compound_engine
https://en.wikipedia.org/wiki/Napier_Nomad
https://en.wikipedia.org/wiki/Wright...Duplex-Cyclone
Detroit Diesel DD16; Detroit?s Biggest Compound Turbocharged Heavy Haul Engine
https://www.dieselnet.com/tech/engin...pound.php#mech

Hi I'm hoping someone could tell me why there isn't an extra rotor on the motor that the exhaust passes through in order to bring up fuel efficiency? That way the main rotors are turning the extra rotor that only gets exhaust. I think that's what a piston engine does or maybe I'm remembering it wrong.

Why isn't there a turbine engine available? So the blades are an inch thick and the hole in the space pushes the gas then covers the hole trapping the gas between the blades. They are then ignited and a few mm of space opening to the second blade would be how the gas escapes the chamber turning the rotors. It would continue through many of these mashed together. The spacers can contain lots of these holes for the gas to get trapped in that are compressing and igniting the gas and even turn the exhaust around so it goes back the other way in the engine making it very fuel efficient and high torque and hp. Sorry this makes sense in my head but don't know if I'm explaining it properly so you can imagine what I'm saying. A turbine ignites fuel to turn the blades. Place spacers between each set of blades where the air is trapped momentarily then ignited so each set of spacers are igniting the mixture to turn the next set of blades. Directing the gas using the spacers will slow the movement creating better efficiency.

it’s maybe not as efficient as you think, more like adding additional inefficiency to an already inefficient engine.

https://www.adrianflux.co.uk/influx/culture/gas-turbine

when you find the free lunch, please let me know where the line starts. :)
.