高负荷涡轮叶栅风洞流动周期性研究

Research on the Flow Periodicity of High-Load Turbine Cascade in Wind Tunnel

为设计符合要求的平面叶栅试验段以开展跨音速高负荷平面叶栅气动试验,以高负荷涡轮转子叶栅为研究对象,采用数值模拟方法研究了不同来流攻角和不同出口等熵马赫数对高负荷涡轮平面叶栅进口流场的均匀性与叶栅通道流场周期性的影响.结果表明:平面叶栅进口流场沿周向呈现出不均匀的波动分布,靠近吸力面侧壁的三个通道的来流均匀性和准确性普遍较差,叶栅中部和靠近压力面侧壁的通道进口均匀性和准确性较好;进口流场品质直接影响着叶栅通道内流场的周期性,而来流攻角对叶栅进口流场品质的影响比出口等熵马赫数更明显,在正攻角下,攻角偏差极限值约为0.7°,不同叶栅通道进口流场均匀性和准确性较好;从亚音速流动到超音速流动,靠近试验件吸力面侧壁的叶栅通道产生强激波,致使叶片80%轴向弦长处压力误差值增大,叶栅通道流场周期性下降.

To meet the requirements for transonic high-load aerodynamic tests of a linear cascade,a numerical simulation method was taken to investigate the uniformity of inlet flow field and periodicity of cascade channel flow field in a high-load turbine rotor cascade with varying inlet flow angles of incidence and outlet isentropic Mach numbers.The results indicate that the inlet flow field of linear cascade presents an uneven trapezoidal distribution along the circumference,and the inlet flow uniformity and accuracy of the three passages near the suction side wall are generally poor,while the inlet flow uniformity and accuracy of the passages near the middle of the cascade and the pressure side wall are better,the quality of inlet flow field directly affects the periodicity of flow field in the cascade channel,and the influence of inlet flow angles of incidence on the quality of inlet flow field is more obvious than that of outlet isentropic Mach number.Under the positive angle of incidence,the angle of incidence deviation is about 0.7°,and the uniformity and accuracy of inlet flow field of different cascade passages are better.From subsonic flow to supersonic flow,the cascade channel near the suction side wall of the test piece produces strong shock waves,leading to an increase in pressure error at 80%axial chord length of the blades and a decrease in the periodicity of the cascade channel flow field.