Study of Tandem Rotor Dual Wake Interaction With Downstream Stator Under Unsteady Numerical Approach

Abstract

This paper highlights the intricate rotor–stator interaction between a tandem bladed rotor and a single-bladed stator in the light of unsteady numerical simulations. A low-speed tandem bladed compressor stage has been conceptualized and experimentally validated against targeted performance goal. With the evident pressure rise capability of the tandem bladed compressor stage, it becomes obligatory to investigate the rotor–stator interaction owing to its dominant effect on overall stage performance. The multipassage rotor–stator unsteady simulations have been performed using blade transformation methods in ANSYS CFX. Due to the presence of two highly loaded rotor blades, the tandem rotor exhibits peculiar rotor–stator interaction in terms of multiple wake impingement on the stator. Incorporating tandem blading on the rotor instead of the stator (which is more common) constricts the design envelope in terms of choice of blade axial overlap and percentage pitch. The variation of aerodynamic loading from hub to tip for both the rotor blades results in spanwise varying wake strength. The initially distinct wake structures merge resulting into a thicker wake. Additionally, the rotor blades are highly loaded in the tip region, which results in the complex interaction between end-wall boundary layer and tip leakage flow. Cumulatively, these conditions constitute a challenging aerodynamic field for the downstream stator. The study focuses on the qualitative interaction between the rotor wakes and blockage with the downstream stator and put forwards some aspects of the tandem rotor-single stator stage design especially for core compressors of aero engine application.