LDV实验测量气冷环形涡轮叶栅内部流场

Experimental Measurement of the Flow Field in an Air-cooled Annular Turbine Cascade by Using LDV(laser-Doppler velocimetry)

采用LDV对气冷环形涡轮叶栅流场三维平均速度进行实验测量,研究孔射流对环形涡轮叶栅流场的影响。实验结果表明,由于孔射流的影响,在孔下游靠近叶片表面处形成回流区,回流区速度随着下游距离的增加逐渐减弱,同时射流在与主流的掺混过程中产生反向涡对。在涡轮叶片的吸力面和压力面,由于壁面曲率、来流附面层状态和压力梯度的差异,射流与主流的掺混以及流场结构也有所不同。在压力面侧,射流与主流掺混形成的反向涡对比较明显,射流尾迹的影响范围也较吸力面大。

An experimental measurement was performed of the three-dimensional average speed in the flow field of an air-cooled annular turbine cascade by using LDV method to study the impact of hole jet flow on the flow field in an annular turbine cascade.The test results show that due to the influence of hole jet flow a return flow zone will be formed downstream of the hole near the blade surface.The speed in the return flow zone will be gradually lowered with an increase of the distance away from the hole at the downstream.Meanwhile the jet flow will produce a reverse vortex pair during its mingling and dilution with the main flow.At the blade suction and pressure surface due to the difference in wall surface curvature,incoming-flow boundary layer status and pressure gradient,the mingling and dilution of the jet flow with the main flow as well as the structure of flow field will also be somehow different.At the pressure side,the reverse vortex pair formed by the mingling and dilution of the jet flow and the main flow is relatively evident and the range of area influenced by the wake of the jet flow is also much larger than that at the suction side.