旋转蛇形通道内冷气流动和换热的数值模拟

对于具有近真实发动机参数的涡轮叶片蛇形内冷通道,数值模拟了旋转状态下光滑、前后缘带肋及环肋结构的内流场和温度场分布,对比分析了其流动和换热特性。结果表明,带肋通道各面换热均明显好于光滑面通道;旋转对各通道进气段的影响比出气段明显;哥氏力在环肋通道中产生了最为强烈的截面二次流;光滑通道出气段换热受弯管效应的影响最为显著。 

Prediction of Turbulent Flow and Heat Transfer within Rotating U-Shaped Passages

Numerical predictions of three-dimensional flow and heat transfer in the rotating serpentine passages with and without rib turbulators were presented.The coolant air is pressurized and its operating conditions are selected to closely match with the real turbine operating parameters.Two different arrangements of rib turbulators were studied:(1) transverse ribs on the leading and trailing walls and (2) transverse ribs on all four walls.The rib height-to-hydraulic diameter ratio (h/Dh) is 0.143;the rib pitch-to-height ratio (s/e) is 7.Results for the roughened rib serpentine passages were compared with those of smooth ones found in the literature.It is disclosed that a significant enhancement is achieved by means of rib turbulators in a serpentine passage in steady state as well as in rotating state.In the radially-outward flow passages, effect of rotation on heat transfer is relatively prominent.The secondary flows induced by the Coriolis forces are most intensive in the channel with four ribbed surfaces.The heat transfer after 180° sharp turn in the smooth channel is influenced more by the sharp-turn induced flow than in the roughened rib ones.