Unsteady Vane Boundary Layer Response to Rotor–Rotor Interactions in a Multistage Compressor

Abstract

Experiments have been performed in a three-stage axial compressor to investigate unsteady stator boundary-layer transition in an embedded stage environment. Quasi-wall shear stress data have been acquired on the suction surface of the second stage stator, in addition to unsteady flow angle measurements at the stator inlet. With two rotor blade rows upstream of the instrumented stator, blade row interactions representative of a multistage environment are present. The different blade counts for the upstream rotors provide an unsteady flowfield at the stator inlet featuring a beating pattern. There is no portion of fully laminar boundary-layer flow on this vane. The vane boundary layer is transitional near the leading edge, and transition to a fully turbulent boundary layer is complete by 45% suction side length. The presence of the rotor 1 wakes, when arriving in between the rotor 2 wakes, increases the normalized quasi-wall shear stress in the leading-edge region by 4% and decreases the amount of laminar transitional flow.