I would like to calculate the mass flow through an annular channel of 0.05 mm height (constant), 15 mm length with an inner diameter of about 150 mm. In my case the inlet pressure is about 15 bar and the outlet (static) pressure is 1 bar (atmosphere).

I would expect the flow to be adiabatic but not isothermal because of the high velocity at the outlet for larger pressure differences. For higher pressure differences, the maximum mass flow that can pass through the channel is limited by a maximum velocity of Ma = 1 at the outlet. The Mach number is a function of the temperature and density at the outlet. Since I expect the flow to be non-isothermal, the static temperature at the outlet must be calculated.

I would appreciate any information you can provide on how to solve this problem. Also, experimental data on this type of flow would be great!

Thanks in advance!