Experimental investigation of effects of suction side squealer tip on the aeroelastic stability of a linear oscillating compressor cascade

This paper investigates the unsteady tip flow characteristics and their effects on the aeroelastic stability of a linear oscillating compressor cascade experimentally. Two test cases with different tip clearance configurations were tested, including a suction side squealer configuration and a control test. The unsteady pressure on the blade surface was measured at three blade vibration frequencies, and then was utilized to establish the aero-damping of the cascade. The results show that the impact of suction side squealer tip clearance on the tip clearance flow mainly exists at the region where it rolls up, and the unsteady flow induced by the vibration blade has no effect on the time-averaged result. In tip area of the blade, the leakage vortex plays a dominant role in determining the distribution of the first harmonic of unsteady static pressure. Compared with the baseline test case, the suction side squealer tip geometry exhibits better aerodynamic stability at high oscillating frequency. The aerodynamic response (phase angle) of the leakage flow lags behind the vibration of blade, and its streamwise variation implies strongly associated with the development of the tip leakage vortex. The spanwise three-dimensional unsteady characteristic of suction side squealer tip geometry is more obvious than that of the baseline test case.