Are you calculating assuming isentropic compression? If yes then the difference can be explained.

PV^gamma = constant

Practically there is no ideal gas in nature. Better check the properties of the gas you are compressing.

This explains it. CFX simulates real compression and not idealised isentropic compression.

@ Rakesh

So you telling me that what I got is correct during the simulation ?

what model or cycle you used for calculation 74bar?

@ Aydin :

It is the pressure I got during simulation in CFX. while 45 bar is calculated using PV^gamma equation.

I think your cfx simulation failed,please check setup and boundary conditions , what is is your heat transfer or heat adition model in this case ?

I am using SST model

In domain heat transfer is total energy and in boundary I gave heat transfer as adiabatic. See my mesh motion is correct and I am getting correct clearance volume in the result.

If you simply use perfect gas law, you may get a better estimate. I am not sure how did you carry cfc so cannot comment whether it is write or not. Just to be clear I am not telling you anything.

Nick

You better check your initial condition( pressure,volume,temperature or compression ratio) and final condition and then the properties of the gas you are compressing ( gamma value) .If all this is OK, I think you should check calibration of the pressure gauge that is giving you 74 bar instead of near 45 bar. It seems there is something wrong some where either experimentally or in your equations ?

Thank you for your answer