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低雷诺数工作条件下涡轮流场特征及其控制设计,是航空发动机低压涡轮部件设计的难点和重点。针对低雷诺数涡轮叶栅流场开展了实验研究工作,利用油流显示、表面静压、边界层压力探针等测量手段研究了涡轮叶片边界层的分离和转捩。结果表明雷诺数降低导致了流动损失的增大,且存在一个临界雷诺数。当雷诺数小于临界雷诺数时,发生在吸力面的流动分离是开式的层流分离泡,不会再附与叶片;当雷诺数大于临界雷诺数时,分离流会在尾缘前重新附着于叶片吸力面,形成闭式分离泡。随着雷诺数的减小,出口尾迹变宽,出口流动损失、出口速度亏损和出口气流角偏离增大,尾迹中心向吸力面方向移动。
Turbine flow field characteristics and control design under low Reynolds number operating conditions are the difficulties and key points in the design of aero-engine low-pressure turbine components. Experimental research on flow field of turbine cascade with low Reynolds number has been carried out. The flow field, surface static pressure and pressure probe of boundary layer are used to study the separation and transition of turbine blade boundary layer. The results show that the decrease of Reynolds number leads to the increase of flow loss, and there exists a critical Reynolds number. When the Reynolds number is less than the critical Reynolds number, the flow separation occurring on the suction side is an open laminar separation bubble that will not be attached to the blade. When the Reynolds number is greater than the critical Reynolds number, the separation flow reattaches before the tail edge In the blade suction surface, the formation of closed separation bubble. With the decrease of Reynolds number, the outlet wake broadens, the outlet flow loss, the exit velocity loss and the divergence of exit airflow angle increase, and the wake center moves toward the suction surface.