Numerical Investigation of Centrifugal Compressor Performance in a Miniturbojet Engine

Abstract

Numerical investigations on the performance of the miniature centrifugal compressor in a SR-30 minijet engine are conducted in this study. A numerical framework is built on the basis of the grid independence and wall treatment sensitivity studies. The simulation results show that the compressor pressure ratio and isentropic efficiency is 2.65% and 70.1%, respectively, at 80,000 rpm. The experiments on the SR-30 engine were conducted at a testing rig for minijet engines. It is found that at 80,000 rpm, the experimental results of the compressor exit temperature is about a 9.2% difference from the simulation results and the difference in the pressure ratio is less than 4%. The compressor isentropic efficiency and pressure ratio are evaluated as a function of mass flow rate. Both the isentropic efficiency and pressure ratio show peak values at a specific mass flow rate. Continuously increasing or decreasing the mass flow rate leads to drops in both the pressure ratio and efficiency. Furthermore, the compressor surge and choke phenomena are discussed according to the mass flow rate range. Flow distribution in the impeller inlet area is mapped to illustrate the surge and choke phenomena.