层板内部压力分布及流阻特性实验

在冲击雷诺数为1×104~6×104条件下,针对不同气膜孔开孔率两种层板模型,实验研究了靶面、冲击面、扰流柱面压力系数分布以及冲击射流、绕流、溢流的局部损失和整体损失系数.结果表明:靶面由于滞止区加速流动向着壁面射流区减速流动过渡,压力系数出现二次峰值.两股冲击射流在靶面相汇形成低压力系数区,相汇后翻卷回冲击面形成低压力系数区.距离冲击孔较远的两排扰流柱表面压力系数分布受雷诺数影响较大.雷诺数Re≤3×104时,压力分布表现为横掠单管的绕流特征.雷诺数Re≥4×104时,压力分布表现为翻卷绕流特征.溢流损失系数最大,绕流损失系数次之,冲击射流损失系数最小.开孔率减小一半,冲击射流损失和绕流损失变化较小,气膜孔溢流损失升高至少4倍. 

Experiment on pressure distribution and flow resistance characteristics of internal lamilloy.

Two kinds of lamilloy models with different percentages of film hole opening were experimentally studied at the Reynolds numbers of 1×104-6×104,target surface, impingement surface and pressure coefficients of pin fins surface,local and total loss coefficients of impingement jet, arounding flow,effusion were experimented to explore the mechanism of flow loss. Results showed that,the pressure distributions were characterized by the second maximum value because of the transition from an accelerating stagnation region flow to a decelerating wall jet. The low pressure coefficients on the target and impingement surfaces were caused by the sink of two jets and the backflow, respectively. The pressure coefficients distributions on two rows of pin fins relatively far away from the impingement hole were significantly affected by Reynolds numbers. At the Reynolds number less than or equal to 3×104, the pressure distributions were similar with flow across cylinder. At the Reynolds number greater than or equal to 4×104, it also had characteristics of backflow. The effusion loss coefficients were biggest, the impingement jet loss coefficients were smallest and the arounding flow loss coefficients were moderate. As the percentages of opening decreased one half, the effusion loss coefficients of film holes increased at least 4 times while the loss coefficients of impingement jet loss and arounding flow had slight changes.