实际叶片前缘冲击冷却流动和换热的数值研究

Numerical Study on Flow and Heat Transfer of Impingement Cooling on Leading Edge of Actual Turbine Blade

应用数值方法研究了射流孔径对燃汽轮机透平叶片前缘内部冲击冷却流动和换热的影响,并采用商用计算流体力学软件CFX11.0求解稳态可压时均N-S方程,且SSTκ-ω湍流模型的总体求解精度为二阶.以某典型燃汽轮机透平叶片前缘中截面拉伸的曲面为研究对象,同时考虑了相同射流量下的4种不同射流孔径的影响,经研究表明:在计算条件下,随着射流孔径增大,靶面上平均努塞尔数和弧长方向平均努塞尔数沿展向的分布都更为均匀,从中截面到叶顶位置的分布更是如此;靶面上的努塞尔数和弧长方向平均努塞尔数的最小值随着射流孔径的增大而增大,这说明采用大射流孔径可以有效提高冲击冷却的换热量,减小冲击冷却引起的热应力.

A numerical study was performed to simulate the flow and heat transfer of impinge ment cooling on the leading edge of a turbine blade. Calculations were done by using a commercial CFD software CFX11. 0 to solve Reynolds-averaged N-S equations in conjunction with the SST κω two-equation turbulence model with an overall accuracy of the second order. The influences of four jet nozzle diameters at the same mass flow rate were considered for a target surface stretched by the middle cross section of the internal leading edge of a typical modern gas turbine blade. The result shows that the Nusselt number at the turbine blade leading edge and the streamwise average Nusselt number are more even when the jet nozzle diameter is larger, especially from the mid- dle span to the tip of the blade. The minimum values of Nusselt number of the turbine blade leading edge and streamwise average Nusseh number will increase with the jet nozzle diameter, indicating that larger jet nozzle diameters will improve the performance of impingement cooling on the leading edge of a turbine blade.