An Unsteady Flow Control Technology Based on Vortex Injection for Centrifugal Compressor

Abstract

The flow structures at the blade tip in a centrifugal compressor usually have an important impact on compressor performance, especially the TLV, which often plays a dominant role in its performance. In order to weaken TLV and improve compressor performance, an unsteady flow control method based on the concept of vortex injection is proposed. The numerical simulation shows that VID method can enlarge the stall margin of the compressor by 8.5%. Meanwhile, the total pressure ratio and efficiency of the compressor can be slightly improved from the design point to the stall point. The maximum efficiency increment and the maximum pressure ratio increment are 0.56% and 0.75%, respectively. A proof experiment on a micro centrifugal compressor shows that the VID can enlarge stall margin of 6.6% and the maximum relative pressure can increase by 2.6%. Therefore, both the simulation and experiment prove that the VID method is effective which utilizes both unsteady excitation and injection of negative circulation to weaken TLV. Finally, enhancing the efficiency of each unsteady jet/suction and separation flow interaction is highly recommended.