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在小转角透平叶栅中,端部横向二次流损失在总损失中占主要比例。对于此类叶栅采用倾斜叶片,压力面与端壁成锐角侧的流动能得到改善。采用压力面与两端壁均成锐角的正弯叶片,可将锐角侧的改善作用引入同一叶栅。对于大转角透平叶栅,上、下通道涡的形成、发展及汇合在叶栅中部产生的二次旋涡损失是总损失的主要部分。在这种情况下,要弄清叶片的倾斜是否仍能改善锐角侧的流动,叶片怎样弯曲才能减少二次旋涡损失,仅测量栅前与栅后流场是远远不够的,必须详细测量流道内部的流动。
In small-angle turbine cascades, the loss of lateral transverse flow losses is the major contributor to total losses. For such cascades with inclined vanes, the flow on the acute side of the pressure face and the end wall can be improved. A positive curved blade with an acute angle between the pressure surface and both end walls introduces the improved effect of the acute angle into the same cascade. For large-angle turbine cascades, the formation and development of vortices in the upper and lower channels and the secondary vortex losses in the middle of the cascade are the major contributors to the total losses. In this case, it is not enough to measure the flow field before and after the gate just to find out whether the inclination of the blade can still improve the flow on the acute angle side and how the blade is bent to reduce the secondary vortex loss. The flow must be measured in detail Road internal flow.