轴流压气机叶顶喷气扩稳机理试验研究

Experimental Investigation of Stability Enhancement Mechanism with Tip Air Injection in Axial Compressor

轴流压气机叶顶喷气已经被证实能够有效拓宽压气机的失稳裕度。在一台低速单转子轴流压气机上进行叶顶喷气试验研究,采用喷气动量比作为衡量失速裕度改善的指标,并通过改变叶顶间隙和喷气角度对不同喷气量的扩稳效果进行分析,试验中发现随着叶顶喷气动量比的增加,压气机失速裕度的变化会出现两个拐点,即存在两个喷气动量比分界点,并将喷气动量比分界点前后的三个阶段对应的喷气量分别定义为微喷气,大喷气和超大喷气。通过试验测量压气机进出口气动参数以及壁面动态压力信号对喷气动量比分界点前后叶顶喷气扩稳机理进行详细的分析。试验分析结果表明:微喷气扩稳仅仅是因其能够减弱叶顶间隙泄漏涡和叶顶间隙泄漏流非定常性;大喷气则能够同时减小进口气流攻角,推迟叶片吸力面分离和抑制叶顶间隙泄漏涡,推迟叶顶间隙泄漏流非定常性的产生;超大喷气虽能够推迟叶顶间隙泄漏流非定常性的产生,但喷气的影响区域已严重向叶片通道内部转移,甚至影响了压气机的做功能力。

Tip air injection is a stability enhancement approach known to be effective in suppressing stall in axial compressor.Experiments were performed in a low speed axial compressor by using tip air injection, the injected momentum /free stream momentum is chosen as a measurement index, two critical injected momentum ratio is existed with the change of stall margin improvement（SMI）, and the three stage of injected momentum below and above the two critical injected momentum is defined as micro injection, large injection and overlarge injection respectively. Then the inlet, outlet aerodynamic parameters and dynamic pressure on the casing wall are measured to analyze the stability enhancement mechanism under different injected momentum ratio.Experimental results demonstrate that micro injection can only to weaken the tip leakage vortex（TLV） and unsteadiness of tip leakage flow（UTLF） to enhance the stall margin; large injection can both decrease inlet flow angle-of-attack to delay the separation of suction surface and suppress the TLV, delay the generation of UTLF; overlarge injection can delay the generation of UTLF, but the effect area of tip air injection is shifted to the blade passage, and influencing the aerodynamic load seriously.