Experimental Investigation Into the Effects of the Steady Wake Tip Clearance Vortex Interaction in a Compressor Cascade

Abstract

An important aspect of the aerodynamic flow field in the tip region of axial compressor rotors is the unsteady interaction between the tip clearance vortex (TCV) and the incoming stator wakes. In order to gain an improved understanding of the mechanics involved, systematic studies need to be performed. As a first step toward the characterization of the dynamic effects caused by the relative movement of the blade rows, the impact of a stationary wakeinduced inlet disturbance on a linear compressor cascade with tip clearance will be analyzed. The wakes were generated by a fixed grid of cylindrical bars with variable pitch being placed at discrete pitchwise positions. This paper focuses on experimental studies conducted at the newly designed lowspeed cascade wind tunnel in Dresden. The general tunnel configuration and details on the specific cascade setup will be presented. Steady state flow field measurements were carried out using fivehole probe traverses upand downstream of the cascade and accompanied by static wall pressure readings. 2Dparticle image velocimetry (PIV) measurements complemented these results by visualizing the bladetoblade flow field. Hence, the structure of the evolving secondary flow system is evaluated and compared for all tested configurations.