STALL DEVELOPMENT IN A CENTRIFUGAL COMPRESSOR: COMPUTATIONAL AND EXPERIMENTAL INVESTIGATION

摘要

At low mass flow rates, a radial compressor is limited by stall and surge. Surge is characterized by a sudden drop in the pressure delivery accompanied by pulsating flow that may be very harmful, and can lead to the failure of the compressor and the bearing system. In general, stall can occur in the compressor wheel or in the diffuser depending on the operational conditions and the design of the radial compressor. The objective of this research is to study effective operational range for a centrifugal compressor with a ported shroud. This device has been proven to delay occurrence of stall. The scope of this project is to assess the surge characteristics by performing measurements of the flow at the inlet to the compressor wheel using 2D and stereoscopic PIV and of the pressure levels and fluctuations at the outlet of and within the compressor housing. On another hand, detailed numerical computations of the flow using Large Eddy Simulations (LES) in the entire compressor section under similar operating conditions are also carried out. The full paper will focus on surge cycle characterization and actual development of instabilities through the housing. Those additional experimental measurements and computations are expected to yield a good contribution to the understanding of surge in centrifugal compressors.