Numerical analysis and experimental validation of the jet impingement cooling of a turbine-blade leading edge at different rotation speeds

A detailed experimental and numerical validation studies are conducted on internal channel jet impingement cooling where seven jets impinging inside a rotating semi-cylindrical channel. The study objective is to mimic the cooling flow structure in gas turbine leading edge by using the rotating the semi-circular channel. These studies are conducted by considering a jet Reynolds number of 7500 at five different rotation speeds (ranging from 0 to 200 rpm). Numerical analysis is performed using the shear stress transport (SST) k−ω turbulence model with a properly analyzed fine mesh containing around eight million nodes. A test setup with required instrumentation is developed inhouse for this study. Two temperature measurement techniques, namely thermochromic liquid crystals (TLCs) and thermocouples, are adopted. Further, the target surface temperature contours are precisely analyzed by comparing the TLC temperature measurements with the numerical temperature results. The captured temperature contours indicated points of minimum-temperature regions, which corresponded to the jet impingement regions. By examining the temperature distribution along the axial centerline, a good agreement has been established between the numerical results and the experimental measurements. For a jet Reynolds number of 7500, increasing channel rotation speed from 0 to 250 rpm has reduced the variation in temperature between different jets. The size of inlet port used to guide flow to the feeding duct has a strong impact on jet formation and flow structure, and it has led to different mass flow rate across jets. Furthermore, a small deviation between numerical and experimental data can be observed near the end side of the channel owing to the radial and lateral heat transfer losses and outlet flow restriction.