Isentropic flow of a perfect gas

The study of the isentropic one-dimensional flow of a perfect gas leads to the notion of nozzle flow, which is found in many thermal machines. In this case, by considering the pipe as fixed (or relative motion if the pipe is mobile), the basic equations are simplified, as the flow takes place without any exchange of mechanical energy with a machine. Given the assumption of isentropy, the equation for isentropic transformations of ideal perfect gases (24) is added to these equations.

We then have the following system of equations (2) ,...