轴流风扇“尖峰型”失速起始特征及其物理机制的实验及数值研究

Experiment and Numerical Investigation of Spike Rotating Stall Inception and Physical Mechanism with Single Stage Axial-Flow Fan

为了探索风扇失速起始特征及诱因,采用动态流场测量试验与三维粘性流场数值模拟技术,对单级轴流风扇NPU-fan的"尖峰型"旋转失速流场和基本特征进行了研究。实验研究结果表明,轴流风扇NPU-fan在设计转速和非设计转速下均出现了典型的"尖峰型"全叶展失速的旋转失速现象,动态探针测量捕捉到了"尖峰型"失速先兆波及其特征,并且测量得到扰动波的初始转速均约为70%转速;三维流场计算表明,静子叶根角区失速会严重影响风扇的效率,但并未触发压气机的失稳。NPUfan风扇的失速情形符合Vo等提出的尖峰波失速先兆出现准则,是典型的叶尖区流动诱发的风扇/压气机失稳。

In order to investigate the property and inducement of stall inception, this paper presents the flow fields of sudden rotating stall and basic principle for a single stage axial fan named NPU-fan with using dynamic flow field measurement experiment and three-dimensional viscous CFD method.The experimental results show that the spike-type stall inception can be verified by dynamic probe,and the inception speed of disturbance wave is all about 70% the speed of fan.It is verified typical sudden all-spanwise rotating stall whether at design or off-design speed.The CFD results show that the efficiency of fan reduced sharply by corner stall of stator,but the whole flow of fan is still stabilized.It is investigated that the stall of NPU-fan is typical fan instability caused by tip of rotor and is in accord with the criterion of spike-type stall inception by Vo.