Effects of Periodic Wake Passing Upon Aerodynamic Loss of a Turbine Cascade: Part II — Time-Resolved Flow Field and Wake Decay Process Through the Cascade

Abstract

This paper, Part II of the study on wake-passing effect upon the aerodynamic performance of the turbine cascade, demonstrates the detailed measurements of the time-varying flow field downstream of the turbine cascade as well as of the moving bars. The experiment employs a single hot-wire probe to measure pitchwise distributions of the ensemble-averaged velocity at the blade midspan. The resultant data consequently provide clear images of the incident bar wakes that are bowed and directed to the suction side of the blade wake. A custom-made total pressure probe, instrumented with a miniature fast-response pressure transducer, are also adopted to understand time-resolved feature of the wake-affected stagnation pressure fields downstream of the cascade. Furthermore, a decay process of the bar wake through the test cascade is examined in detail, which serves for the discussion related to wake recovery and its impact on the stage loss.