Unsteady Analysis Of Casing Treatment In Transonic Compressor And Numerical Simulation Of Inlet

Casing Treatment(CT) is one kind of technique which can improve stall margin of compressor and has been studied and applicated in an earlier time. It has lots of merits such as simpler and convenient structure, lower cost, higher reliability and good effect. But traditional design relys on experiment and modification over and over, it's very blindness. The lack of realization at the respect of unsteady flow in slot and the essence of extending stability is still being. The numerical simulation using CFD is still staying on assumption of steady, and has more limitation. It is very urgent to do some research on unsteady.This paper is based on the first full stage of three-stage transonic fan, a complex and nice CT with cavity was designed using AUTOGRID/IGG module of NUMECA, It has -42%～52% overlaps comparing with the rotor. Then unsteady numerical simulation and analysis were carried out. The most important innovation is finding out a way to unsteady research of CT.Concrete contents are as follows: grid model identification with smooth wall, unsteady computation and flow analysis with CT, bringing forward effect of unsteady parameter. The results show that, in order to simulate flow field accurately for specific designed grid model, we must use unsteady method to compute before and after CT; The axial skewed slots CT can pump tip clearance leakage flow(TCLF) and congestion into slots continually. by typical injection and suction, changing the position of shock wave and inflow situation at blade tip, reducing the load of pressure side and intensity of TCLF, inhibiting the occurrence of TCLF, as a result, large blockage fluid clustering disappeared basically and stall margin of compressor is improved efficiently; The magnitude of parameter n in unsteady computation has slightly influence on result.Besides, numerical simulation and analysis of three flight condition points are executed in the paper. It shows that, the results have evident effects on the flow of outlet section on the premise of neglecting fuselage, especially as to distortion index DC60.