Transonic Wall-Slip Analysis for Expanding Micro Diffuser Flows for Cold Gas Propulsion Systems

The use of highly diluted and supersonic gas flow is in the scope of application of cold gas thrusters for space applications. Satellites and small spacecrafts are navigated to their orbital trajectory with these nozzles (Fig. 1). Inside these propulsion systems high density gradients are dominating the efficiency and the thrust steering behavior of the propulsion systems. In the present study a trans-sonic nozzle flow is computed by using a calibrated velocity slip model which depends on the Knudsen number. The Knudsen numbers are lower the Kn=1 at the nozzle neck of the propulsion system. The results are compared with simulation results of a uniform channel flow and computations of the corresponding no-slip approach. The differences in the supersonic region are following discussed.