Pressure distribution on a semi-circular concave surface impinged by a single row of circular jets

The higher gas turbine entry temperatures for increased gas turbine engine performance require active cooling of the turbine blade. Arrays of impinging jets are one of the potential methods used to reduce the blade temperature on the mid-chord and leading edge regions. The impingement cooling of turbine blade leading edge is modeled by considering impingement of a row of jets on semi-circular concave surface. The experimental model of the present study mimics the scaled-up gas-turbine blade cooled at the leading edge by a row of impinging jets. The local distribution of convective heat transfer rates depend on fluid flow characteristics. Hence, the present study focuses on the experimental investigations of the influence of curvature ratio (D/d = 4.28–8.6), jet-to-jet distance (s/d = 2.4–5.6) and jet-to-plate distance (z/d = 1.0–6.0) on the wall static pressure distribution of a semi-circular concave surface impinged by a single row of multiple jets at a Reynolds number of 20,000. Wall static pressure measurements are made along the spanwise line through the stagnation and two other circumferential locations. The wall static pressure coefficients are seen to decrease with higher jet-to-plate distances. A secondary peak in the distribution of wall static pressure coefficient is observed between the adjacent jets at larger pitches. These are up-washes which may occur due to the collision of wall jets along the longitudinal line of the cylindrical concave surface.