The effects of stator-rotor interaction on unsteady characteristics of turbine tip leakage flow

Abstract

The unsteady flow characteristics of tip leakage flow significantly affect the operation stability of the turbine blade. However, there is currently a lack of research on the unsteady flow characteristics of the tip leakage flow under the stator-rotor interaction. Through experiments with a rotating turbine and simulations of the entire stage and full-annulus turbine stage flow using a self-adaptive method, this study investigates both experimentally and theoretically the impacts of rotor-stator interaction on the dynamic behavior of the tip leakage flow in the turbine. The impacts of stator-rotor interaction on pressure oscillations, mixing, and vortex evolution within the tip leakage flow are investigated. Furthermore, the mechanisms underlying the influence of stator-rotor interaction on the dynamic behavior of the tip leakage flow at different rotor speeds and different tip gaps are also analyzed. The results indicate that the passage vortex (PV) of the guide vane aggravates the instability phases experienced by the tip leakage vortex (TLV), namely vortex wandering and breakdown. Besides, the pulsation intensity of the tip leakage flow decreases, while the pulsation frequency increases as the rotational speed increases. Additionally, it is also observed that there is a significant increase in high-frequency and large-amplitude oscillations in the tip leakage flow with increasing tip gap heights.