Flow in a turbine duct is highly complex, influenced by the upstream turbine stage flow structures, including tip leakage flow and non-uniformities originating from the upstream HPT vane and rotor. The complexity of the flow makes the prediction using numerical methods difficult, hence there exists a need for experimental validation. This paper presents experimental data including both aerodynamic and heat transfer measurements within an intermediate turbine duct. These have been conducted in the Oxford Turbine Research Facility, a short duration high speed test facility enabling the use of an engine sized turbine, operating at the correct non-dimensional parameters relevant for aerodynamic and heat transfer measurements. The current configuration consists of a HPT stage and a downstream duct including a turning vane, for use in a counter rotating turbine configuration. With a stator-to-stator vane count of 32-to-24, instrumentation was installed on three adjacent intermediate turbine duct vanes and endwalls to investigate its influence. Flow phenomena such as trailing edge wakes and vortex structures from the upstream HPT vane travels through the rotor and forms an inlet condition to the intermediate turbine duct with tangential variations. Time-averaged experimental data show this effect to be distinguishable although varying in the spanwise direction. Comparisons with results from numerical predictions are included to further analyse the flow through the 1.5 stage.

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