Unsteady measurements of film cooling effectiveness with fast-response PSP in a linear turbine vane cascade

Film cooling is a complex flow and unsteady phenomenon due to the mixing of mainstream and coolant flow. Therefore, it is important to evaluate the unsteady behavior to improve the performance of film cooling. In addition, since the vane surface curvature and secondary flow have a significant effect on the film cooling, it is essential to measure the film cooling on the vane pressure-side surface as well as on a simple flat plate. In this study, unsteady film cooling was measured using PC-PSP (Polymer Ceramic Pressure Sensitive Paint), which is a fast response PSP prepared in-house. The PC-PSP was dynamically calibrated by a shock tube, and its response time was confirmed to be less than 500μs. PC-PSP measurements were performed on the vane pressure surface with blowing ratios (BR) of 0.50 to 2.0. The effect of mainstream turbulence intensity and cooling hole geometry were evaluated from mean film cooling effectiveness and time-average RMS of film cooling effectiveness.