Numerical investigation on transpiration cooling performance of turbine blades with non-uniform porosity

Abstract

As an active thermal protection technology with high cooling efficiency, transpiration cooling can achieve effective thermal protection for turbine blades. However, most of the studies are usually carried out using the flat plate geometry. In this paper, the cooling and flow characteristics of the real C3X blades are investigated numerically. The cooling efficiency and flow field distribution along the blade surface under different coolant mass flow ratios were compared and analyzed. Meanwhile, the total pressure loss and flow distribution of the coolant in the internal channel were studied. The results show that the coolant flow distribution in the leading edge and trailing edge regions has a significant effect on the development of the blade flow boundary layer and the overall cooling performance. In addition, the influence of different porosity on the transpiration cooling performance of the blade was studied. Aiming at the problem that the local region of the blade is prone to mainstream intrusion and the cooling efficiency is reduced, a non-uniform porosity strategy in different regions and a gradient porosity strategy with uniform variation along the path is proposed. By adjusting the permeability of the region along the blade, the optimal flow distribution of coolant in the local area is achieved. The results show that compared with the uniform porosity, reasonable distribution of porosity in different regions of the blade can significantly improve the uniformity of the temperature distribution on the blade surface and obtain the highest cooling efficiency of 13.97 %.