Doods, check out my design

  • Thread starter chhitiz
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  • #26
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in this design, the piston stops all by itself ...
Now I'm really lost. I don't see how that is even possible.
 
  • #27
Mech_Engineer
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but, it would help, if you could assume that what i have designed is possible to build and seal, and then guide me as to how to calculate, at least in theory the efficiency, or simulate this design on some software. as far as i know, ansis or pro-e won't do.
Assuming it is possible to build is a big leap, but even if we make that leap there really is no easy way to calculate the efficiency of the engine. Just making a guess based on engines with similar compression ratios is your best bet IMO, and that will likely be around 15-20%.

It's useless to calculate the efficiency of the engine anyway since I'm not seeing some critical stuff like how the pistons are attached to a crankshaft, or where your intake/exhaust valves are.
 
  • #28
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Just making a guess based on engines with similar compression ratios is your best bet IMO, and that will likely be around 15-20%.
what are the engines with similar compression ratios? any of them toroidal?
can we simply guess the efficiency based on c.r.? is there a way to calculate the precise efficiency of a completely new design?
 
  • #29
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i think for a 'normal' IC engine, the starting point for the efficiency would b the Otto cycle. lots of assumptions there...i think it ll give a very rough guess in terms of the proposed compression ratio and the temperatures you would expect. dunno if it applies to that, but you might make some of your own assumptions...and then work from there...dunno
 
  • #30
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Gas turbine engineering solved all the sealing (clearances and rotor/stator designs), coupling of "pistons (buckets)" to output shaft, and ignition and combustion problems a long time ago with many fewer parts. Efficiencies are in the 50-60% range for large installations.
 
  • #31
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i think you have confused mechanical design with an idea. there are no calculations or measurements provided. Perhaps if you can draft the pictures out or use CAD and provide some of the formulas etc , then people can better assess how workable this project may be.
 
  • #32
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@ grey it is not otto cycle.more like a three stroke cycle.
@ bystander yes, but we can't use gas turbines in automobiles. for one thing, they operate at very high temperatures and pressures
@ blade well, i'm trying to, but could people anyways suggest a way to calculate efficiency or something
 
  • #33
It looks like you made that in Abaqus (?). If so, did you run an FE simulation to see what types of stresses are in the engine? One of the biggest concerns in efficiency is thrust to weight ratio (T/W). If you want to take this to the next step, I recommend seeing what your stresses are like, and determining if you have too much / too little material. Factors of safety are also important.
 
  • #34
I didn't see anything.
 
  • #35
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... guide me as to how to calculate, at least in theory the efficiency ...
... can we simply guess the efficiency based on c.r.? is there a way to calculate the precise efficiency of a completely new design?
... could people anyways suggest a way to calculate efficiency or something ...
What exactly do you mean by 'efficiency'? Can you write down what you mean in words, and then take a stab and quantifying it? Why do you think calculating it is any different then the 'efficiency' calculations described in the automotive engineering textbooks?
 
  • #36
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It looks like you made that in Abaqus (?). If so, did you run an FE simulation to see what types of stresses are in the engine? One of the biggest concerns in efficiency is thrust to weight ratio (T/W). If you want to take this to the next step, I recommend seeing what your stresses are like, and determining if you have too much / too little material. Factors of safety are also important.
it was made in catia. and as far as i know, there is no way of getting the stresses in it.

What exactly do you mean by 'efficiency'? Can you write down what you mean in words, and then take a stab and quantifying it? Why do you think calculating it is any different then the 'efficiency' calculations described in the automotive engineering textbooks?
efficiency is how much of the chemical energy of the fuel is actually converted into useful work. and calculating it is different because this design will have a totally different thermodynamic cycle
 

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