Reduction of Heat Transfer on the Endwall in the Upstream Junction Region of a Symmetric Airfoil With Vortex Generator Pair

Heat transfer on the endwall upstream of the junction of the stator vane/rotor blade with the hub becomes very high due to the vortices generated as a result of an adverse pressure gradient. Control of this high heat transfer is very vital for safe operation of gas turbines. In the present experimental study, a pair of vortex generators is employed to reduce the high heat transfer on the endwall close to the junction region. A pair of winglet vortex generators upstream of a symmetric airfoil have been employed. The steady state liquid crystal thermographic method is used to measure the surface temperature of the endwall. Different cases are studies depending on various lateral gaps of the vortex generator pair while keeping the yaw angle and streamwise position relative to the airfoil constant. It is found from the experiments that all positions of the vortex generators reduce the heat transfer on the junction region of the endwall compared to the base case. The level of reduction and local distribution of heat transfer is dependent on the position of vortex generators. The aerodynamic performance of a stator vane/rotor blade is the main objective in gas turbines, therefore the pressure drop is also measured experimentally and results show that pressure loss is recovered with the installation of vortex generator compared to the airfoil without the vortex generator.