Measurement of film-cooling effectiveness on a turbine endwall using a liquid crystal image method

The accurate evaluation of heat transfer and film-cooling effectiveness plays a crucial role in the design of efficient turbomachines. Liquid crystal (LC) thermography is a reliable measurement tool to obtain detailed, full-field maps of surface temperature. In this paper, a steady-state LC technique was employed for measuring the film-cooling effectiveness of a turbine endwall. The experiments were performed in a blow-down type wind tunnel housing a large-scale high-pressure turbine blade cascade. The endwall regions immediately upstream and in a passage of the cascade featured discrete holes, arranged according to two different discrete-hole arrangements. Liquid crystal images and reconstructions of the adiabatic film-cooling effectiveness are provided for the Reynolds number (based on the chord length and the isentropic exit velocity) of 960000 and for the blowing ratios of 2.5 and 3. Results for both discrete-hole configurations are presented and compared.