Both of these engines combust fuel and a non-reciprocal motion occures. Both cases produces a circular motion.
However both of these engines are quite different. What explains the differences in power output and efficiencies?
They are different in the following ways:
Steam engines and steam turbines produce circular motion without combustion of fuel. They'll run on compressed air just as well. All such engines depend on the expansion of a gas. Reciprocating engines are much less efficient as they have more moving parts than the single moving part of a turbine and subject to more friction. Gearboxes are inefficient and it is the overall efficiency of the system (including transmission) that determines watts per dollar, even for an electric elevator or refrigerator pump. A rail locomotive is far more efficient than a Formula 1 racing car, in terms of passenger-miles per dollar. In terms of winning a race, it is not efficient at all. Do not compare apples and pears with bacon and eggs.
Gas Turbine is continuous flow process using Brayton cycle.
Rotary (Wankel) engine is intermittent usually using Otto cycle, a few have been made to use the Diesel cycle.
All suck, squeeze, bang and blow.
Early reciprocating piston aero engines are also called rotary as the crank was bolted to the airframe and the whole crankcase with cylinders rotated with the propeller. This ensured good air flow over the air cooled cylinders and heads at low airspeeds.
Sounds like homework.
Which sort of rotary engine did you have in mind?
What research have you done?
Mark L. Fergerson
Early turbines were not so efficient at all. This efficiency has improved over the years.
Yes, they both "produce" circular motion, but in the broad sense so does a reciprocating engine. The rotary "piston" does not move in a circular path, remember. The turbine is circular.
If you had to cool a turbine, and limit the pressures, as you do in a rotary what do you think would happen to the efficiency?
Is this a homework question?
Two things: think about the combustion rate, and think about where heat is going.
Also think about what happens when the load changes.
--scott
A windmill is a rotary engine.So is a paddle wheel being pushed around and around by the water. Motors are motors, engines are engines. Ford Engine Company.Chrysler Engines Corporation. cuhulin
Spinning is 87% better than going up and down. Electric motors prove that by 100% The wheel is in My Spin is in theory is Nobel stuff.Nature's universe is a huge fly wheel and is constructed with wheels in wheels in wheels TreBert
A turbine is worn on the head by a Sikh.
HardySpicer wrote in news:72f1ded7-97e0-47a8-9cc6- snipped-for-privacy@fv1g2000vbb.googlegroups.com:
That joke made me Sikh.
Dental (Dentist) drills are high speed turbines. cuhulin
,
Friction becomes stiction at TDC and BDC. To obtain a longer moment arm during the expansion stroke and thus better torque, engines with large offset of cylinder bore have been made by Honda and Toyota. Most engines have 1 or 2 mm offset so thrust face changes before TDC. Honda and Toyota are using offset in region of 15-20% bore diameter.
But there are limits as the rod angle at BDC produces a much higher thrust load that gives an excessive amount of friction.
article,
Some are, some arent. There are still some of those old belt powered jobs around.
Dentists may say that the the old ones are more precise for delicate work, the turbine drills move a lot of tooth very quickly.
jim beam wrote in news:NI-dnQjrbIVzcH7RnZ2dnUVZ snipped-for-privacy@speakeasy.net:
while that cite didn`t center on the ofset work being done now there are several manufactures expermenting with that very idea. (which is a much larger ofset than being used for noise and thrust face loadiing being used now.)
It most certainly did. can you not read???? KB
it's an old idea and has been used for many decades.
ok, i re-read - it does. but i was lost again when he said "It makes use of crank offset to create the required piston motion aimed at engine efficiency improvements through thermodynamic performance gains." since there is no relationship that correlates thermodynamic efficiency with physical configuration.
jim beam wrote in news:ss- dnbGWpc7YzXjRnZ2dnUVZ snipped-for-privacy@speakeasy.net:
only as a noise and thrust face friction reducer, not as is now being expermented with as a power and efficiency enhancer.
Ok if you ofset the crank and thus the piston also then at TDC the dwell time is increased (which gives more burn time at TDC and when the piston does start the downward motion the rod arm angle is a more direct push down creating greater torque and possible improved burn time before the exaust valve opens which can increase efficiency. Newer type concept for offset if they can keep the thrust face friction problems at bay. the old offset just offset the piston pin for cold start noise, ect. KB
that's mechanical efficiency not thermodynamic.
jim beam wrote in news:U9OdncACze_FUnjRnZ2dnUVZ snipped-for-privacy@speakeasy.net:
I never even mentioned it was thermodynamic, they are always working on inprovemnets, not all are thermodynamic in nature. KB
but your cite did. and you certainly didn't make the effort to clarify.
some people work on their spelling, not always without the assistance of their computer's built-in spell checker.
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