Steady-unsteady measurements of the flow field downstream of a transonic high-pressure turbine stage

Abstract The three-dimensional flow field of a transonic high-pressure turbine stage has been studied experimentally in the von Karman Institute short duration compression tube facility. The test programme encompasses two Reynolds numbers (Re2,c = 1.0 × 106, 1.26 × 106) and three different pressure ratios (Po1/Ps3 = 2.3, 3.1, 4.1). The steady flow angle, pressure and temperature measurements rely on five-hole pneumatic probes and micro-thermocouples. Fast response pressure and cold wire resistance thermometer probes measure the unsteady pressure and temperature. The experimental time-averaged spanwise distributions are compared with steady state three-dimensional Navier-Stokes stage simulations; zones of secondary flows are identified in the spanwise distributions. The stage exit pitchwise traverses show that the stator exit flow field affects the stage exit flow. Downstream of the stator vane, large time-resolved static pressure fluctuations are identified, attributed to the variation of the origin, the incidence and strength of the stator trailing edge shock. At the stage outlet, large total temperature fluctuations appear owing to the periodic passage of the tip leakage flow. For the high-pressure ratio, the rotor is choked and large pressure and temperature fluctuations are recorded owing to the rotating rotor trailing edge shock system. Zones of high mixing (secondary flows) tend to attenuate these fluctuations.