Computational analysis of stall and separation control in centrifugal compressors

A three-dimensional compressible Navier-Stokes code has been used to model the steady and unsteady flowfield within a low-speed centrifugal compressor configuration tested at NASA Lewis Research Center. Near-design conditions , the performance map, pressure field, and the velocity field were in good agreement with measured data. At off-design conditions, the calculations sh ow that flow reversal first occurs near the blade leading edge. If left unc hecked, the reversed-flow region grows spatially and temporally. Injection of air upstream of the compressor face was found to modify the local flow n ear the blade leading edge and to suppress rotating stall and surge. Even a moderate amount of air, typically around 5% of the total mass flow rate, w as sufficient to extend the useful operating range of the compressor.