Computational Analysis of Stall and Separation Control in Centrifugal Compressors

A 3D 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 show that flow reversal first occurs near the blade leading edge. If left unchecked, the reversed-flow region grows spatially and temporally. Injection of air upstream of the compressor face was found to modify the local flow near the blade leading edge and to suppress rotating stall and surge. Even a moderate amount of air, typically around 5 percent of the total mass flow rate, was sufficient to extend the useful operating range of the compressor. (Author)