汽轮机低压排气缸内流场的PIV实验研究

摘要

使用时间分辨粒子图像测速仪(TR-PIV)对汽轮机低压排气缸模型内流场进行了研究.通过对某些特征平面的测量,获得了其平均流场的速度矢量与涡量,发现其内部流动从上部至出口呈现多个涡合并为一个通道涡的过程,通道涡主导了蜗壳通道内的流动,其涡量沿主流方向逐渐降低.实验还发现,在排气缸下部加装的隔板能有效阻止非主流方向上的流动,这将有利于有效通流面积的增加和降低流动损失.%The flow structure in a low-pressure exhaust hood model of a stream turbine was investigated using a time-resolved particle image velocimetry (TR-PIV). The velocity vector and the vorticity contours of some characteristic plane of the exhaust hood model were gained through measurement. Several vortexes were observed at the top of the model, and they combined together to form a large passage vortex during flowing down to the outlet. This passage vortex movement played a main role in the flow field of the model with the vorticity of it decreasing gradually. Another invention of the experiment was that baffles arranged at the bottom of the model could compel the fluid to flow along the direction of the mainstream, which would give a positive impact on the improvement of the performance of the exhaust hood.