Studies on High-Lift LP Turbine Airfoils of Aero Engines (Understanding of Time-Averaged Behaviour of Separated Boundary Layer under the Influence of Incoming Wakes)

Abstract

This paper details experimental studies on the flow field around a low-pressure linear turbine cascade whose solidity is changeable. Highly loaded low-pressure turbine (LPT) blades or ultrahigh lift airfoils are one of the key paths to successful future aero-engines, however those blades are usually accompanied with separation bubble, eventually leading to the increase in aero dynamic loss. The purpose of this study is to clarify the effect of incoming wakes upon the aerodynamic loss of the rotor blade cascade, through the measurements of wake-affected boundary layers upon including separation bubble for low Reynolds number conditions and/or low solidity conditions. Cylindrical bars on the timing belts work as wake generator to emulate upstream stator wakes that impact the rotor blade. Hot-wire probe measurement is conducted over the blade suction surface to understand to what extent and how the incoming wakes affect the boundary layers containing separation bubble. In particular, from the viewpoint of providing database for blade designing, this paper focuses on time-averaged characteristics of the separated boundary layer influenced by the wake passing.