Influence of unsteady non-uniform back pressure variations in a radial compressor with vaneless diffuser

Abstract

[EN] The aim of this Project is to study the influence of unsteady pressure waves on the performance of a radial compressor with a vaneless diffuser. The impeller was composed of 15 main and 15 splitter blades. The pressure ratio of the compressor was 4. The design flow rate for the original compressor is 4.39 kg/s at a rotational speed of 21,789 RPM. The outlet of the compressor was exposed to five circumferential equally spaced pressure distortions. Different cases were performed depending on the intensity of the pressure distortion and on its frequency using Unsteady Reynolds Averaged Navier–Stokes solutions with the help of the software NUMECA. The pressure distortion chosen for the simulation had an amplitude of 2 bars (peak pressure of 4.7 bars) and a frequency of 80 Hz. In order to characterize the effects of the imposed back pressure some parameters such as velocities, entropy, Mach number, incidence angles and pressures were studied and compared.