Thermal performance of impinging jet-row onto trapezoidal channel with different effusion and discharge conditions

Abstract The present work was aimed at investigating the effects of row number of effusion holes and coolant discharge ratio from channel tip on the thermal performance of an emulated cooling passage typical in the leading portion of a gas turbine blade. With each effusion and discharge condition, the full-field heat transfer data along with the channel averaged Fanning friction coefficients and thermal performance factors were measured at channel Reynolds numbers of 5000, 7500, 10,000, 12,500 and 15,000 with the corresponding axial distributions of the jet mass flow rate detected. Without effusion, the strong crossflow effects acted with the weakened jet momentum near the sealed channel hub to substantially reduce the regional heat transfer rates. With effusion, the flow confinement formulated by the cavity-like channel hub and the crossflow developed along the test channel were suppressed, leading to the even distribution of jet flow and the recovered impinging-jet heat transfer properties over the channel hub region. While the row number of effusion holes affected the overall heat transfer properties, the impacts of tip extraction were less evident; but the overall heat transfer performance was improved by reducing tip discharge. With leading-edge cooling applications to a gas turbine blade, three sets of heat-transfer and pressure-drop correlations were devised.