Effect of cooling-hole distributions on heat transfer and cooling effectiveness on turbine blade tip

Heat transfer and film cooling performance on the rotor blade tip were investigated by solving the Reynolds averaged Navier-Stokes (RANS) equations. At three different tip clearances (1.31 mm, 1.97 mm and 3.29 mm), two kinds of cooling-hole distributions (single-hole array located at the camber line and two-hole array located at the camber line and near pressure side) and two blowing ratios (1 and 2), heat transfer coefficient and film cooling effectiveness were numerically evaluated and compared with the existing experimental data. The results show that for the cooling-hole array located at the camber line, coolant injection can effectively cool the pressure side of the squealer tip region. Moreover, as the blowing ratio increases, the high heat transfer coefficient area on the squealer tip shrinks near the leading edge suction side, and a lower heat transfer coefficient near the pressure side of the squealer tip can be achieved as well. However, the film cooling effectiveness near the pressure side of the squealer tip increases significantly. As the tip clearance increases, the high heat transfer coefficient area extends from the suction side to the pressure side near the leading edge, and the averaged heat transfer coefficients on the squealer tip increase as well. However, the film cooling effectiveness near the pressure side and trailing edge decreases. For the case with two cooling-holes array, coolant injection from the pressure side can effectively cover the squealer rim and blade trailing edge, and enhance the cooling effectiveness near the pressure side of the squealer tip. As the blowing ratio increases, heat transfer coefficients near the pressure side and on the squealer rim and blade trailing edge decrease obviously while the film cooling effectiveness at these regions increases significantly. As the tip clearance increases, the high heat transfer coefficient area extends from the suction side to the pressure side near the leading edge. And the heat transfer coefficients near the pressure side of squealer tip, on the squealer rim and on the blade trailing edge increase significantly while the film cooling effectiveness decreases. © 2016, Editorial Office of Journal of Xi'an Jiaotong University. All right reserved.