Experimental investigation of effects of suction-side squealer tip geometry on the flow field in a large-scale axial compressor using SPIV

It is well known that the non-uniform tip geometry is a promising passive flow control technique in turbomachinery.However, detailed investigation of its effects on the unsteady flow field of turbomachinery is rare in the existingliteratures. This paper presents an experimental investigation of effects of suction side squealer tip configurationon both the steady and unsteady flow field of an isolated compressor rotor. The flow field at 10% chord downstream from the trailing edge was measured using a mini five-hole probe. Meanwhile, the unsteady flow field inside the passage was investigated using stereo particle image velocimetry (SPIV). The steady results show that the SSQ tip configuration exerts positive effect on the static pressure rise performance of this compressor,and the radial equilibrium at the rotor outlet is obviously rearranged. The SSQ tip configuration would create a stronger tip leakage vortex at the formation phase, and it experiences a faster dissipation process around the rear chord. Also, the splitting process of the tip leakage vortex is severer, which is the main cause of the relatively higher probability of the presence of the streamwise reverse flow. The quantitatively analysis of the tip leakage vortex indicates that the velocity loss inside the blockage region is direct response of the evolutionary procedure of the tip leakage vortex. It keeps increasing until the end of the splitting process. Although the blockage coefficientgrows sustainably, the velocity loss will reduce once the turbulent mixing procedure is dominant.