In isentropic compression, similar to aircraft refrigeration cycle, what is ram efficiency?
In isentropic compression, similar to the aircraft refrigeration cycle, the ram efficiency is the Ratio of actual pressure rise to isentropic pressure.
Ram efficiency is defined as the ratio of actual pressure rise in Ram diffuser to the ideal pressure rise.
Ambient air at pressure Po and temperature to renters the Ram diffuser at a velocity equal to that of aircraft. (In fact, the air is stationary and the plane is moving).
Due to the diverging cross-section of the Ram diffuser, the velocity of air is reduced to zero, and its pressure and temperature increase.
These values of pressure and temperature are known as stagnation pressure and temperature.
If the pressure rise takes place in an isentropic manner. It may be represented by vertical lines 0-1 on the T-S diagram.
But in practice, due to the reversibility involved in the process, the actual rise in pressure is less than the theoretical rise in pressure. Therefore, the vertical line 0-1 is replaced by the curve 0-1.
This process may be assumed as a combination of an isentropic rise in pressure and temperature as given by 0-l and then isothermal pressure reduction as represented by 1-1'.