Hot Streak Migration in a Turbine Stage: Integrated Design to Improve Aerothermal Performance

Abstract

Hot streaks can cause localized hot spots on the blade surfaces in a high pressure turbine, increasing the heat load locally and even leading to material loss in regions such as the rotor blade tip. This study explores numerically the effect of the hot streak’s clocking position at the stator inlet on the rotor blade heat load and on the tip in particular. The inlet boundary conditions are taken from the hot streak experiment conducted in the axial turbine facility “LISA” at ETH Zurich. Using a particle tracking tool, in conjunction with time resolved simulations, a detailed analysis of the migration pattern of the hot streak is performed and the underlying mechanisms are discussed. The effect of clocking the hot streak from midpitch to the stator pressure side and in the opposite direction is examined. By clocking this particular hot streak even 10% of the stator pitch toward the pressure side up to 24 K reduction in the rotor blade tip adiabatic wall temperatures could be achieved under realistic engine conditions. Finally, based on the observations made, the implications for an integrated combustor-turbine design strategy are discussed.