Performance evaluation of film holes used for cooling the optical window of a sensor probe

In this paper, three types of film holes (namely cylindrical hole, round-to-slot hole, slot hole) are applied to provide cooling protection for a sensor probe's optical window while considering the structural size limitations. The film cooling performance, discharge coefficients and pressure drop of three types of film holes are discussed and compared in terms of both the blowing ratios and the outlet heights of the film holes through numerical simulation. The results demonstrate that, compared to the cylindrical holes, the round-to-slot holes and slot holes exhibit significantly improved film coverage performance. Among these, the RTSH-0.6 hole exhibits the best comprehensive performance, the film cooling effectiveness of the RTSH-0.6 hole is higher than 0.99 under all three blowing ratios with the lowest pressure drop ratio less than 0.5.