Nozzle guide vane shock wave propagation and bifurcation in a transonic turbine rotor

A study of the propagation of a Nozzle Guide Vane (NGV) trailing edge shock wave through a transonic turbine rotor passage is presented. The work was based on experimental tests carried out in the Isentropic Light Piston Tunnel in Oxford University using a rotating bar NGV shock wave simulator, together with schlieren photography and wide band width surface pressure and heat transfer rate measurements. The study identifies a previously unexplained interaction between the incoming wave and the rotor leading edge, which causes the nucleation of a Vortical Bubble. This bubble has been shown to enhance the thermal loading on the early pressure surface of the blade. A method of controlling this bubble and heat loading is also considered. A previously unseen "Lambda" interaction between the shock wave and the rotor pressure surface is also identified.