Surface Thin Film Gauge Measurements in a Two-Stage Low Pressure Turbine at Low Reynolds Number

A two-stage low pressure axial turbine has been tested in cooperation between the Institute of Aircraft Propulsion Systems (ILA) and MTU Aero Engines GmbH (MTU). The experimental results taken in the Altitude Test Facility are used to assess blade row performance of vane 2 at mid height over a range of Reynolds numbers from as low as 35,000 up to 88,000. Both Mach and Reynolds similarity are preserved. Surface thin film gauges at midspan on vane 2 suction side are used to analyse the unsteady behaviour of the boundary layer. Unsteady data from area traverses downstream of vane 2 using X-hotfilm probes complement the analysis describing the unsteady wake evolution at mid height. The nature of the unsteady transitional low Reynolds number boundary layer is discussed.