大转角透平叶栅叶片反弯曲的实验研究

同常规直叶栅相比 ,叶片反弯曲可改善端壁前缘区流动 ,降低前缘涡和通道涡强度 ,减小前缘涡损失及通道涡粘性耗散损失 ,整个叶栅的通流能力提高 3.2 % ,质量流量平均总损失降低19.1% ,同时 ,叶栅出口气流条件也得到改善。因此 ,对于大转角透平叶栅 ,在进行弯曲叶片的弯扭气动联合成型时 ,迫切需要研究和采用这种新的叶片叠积方式 ,以使二次流损失降低。

AN EXPERIMENTAL STUDY ON BLADE NEGATIVE CURVING IN A TURBINE CASCADE WITH A LARGE TURNING ANGLE

Turbine rectangular cascades with conventional straight blades and negative curved ones at obtuse angles between their pressure surfaces and both endwalls were investigated in a low speed plane cascade wind tunnel.The measuring planes with five hole micro spherical probes were arranged as 3 before,6 in and 1 after the cascades.The experimental results show that the origination and development of horseshoe vortices and passage vortices as well as the meeting of the passage vortices in the midspan region almost dominate the whole flow field of conventional straight cascade.In comparison with those of conventional straight cascade,blade negative curving improves the flows around blade leading edges near both the endwalls,and reduces the intensities and viscous dissipation losses of leading edge vortices and passage vortices.As a result,the flux capability of the cascade increases by 3 2%,the mass flux averaged overall loss coefficient is cut down by 19 1%,at the same time the good inlet condition is provided for the rotor cascade.