【作者】 李亮；

【导师】 胡骏；

【作者基本信息】 南京航空航天大学 ， 航空宇航推进理论与工程， 2013， 博士

【摘要】 风扇/压气机内部气流流动的强增压过程决定了其具有气动失稳的特性，而作为发动机中的增压部件，其稳定性决定了发动机的稳定性。为了满足当代飞机非常规机动、超声速巡航等指标，就需要增加发动机的推重比和降低其燃油率，这就要求风扇/压气机朝着更高的压比和更高的级负荷方向发展。但这使要想保证其气动稳定性将显得更加困难。因此，发展提高风扇/压气机稳定裕度的方法显得十分迫切，在这些方法中，喷射气流以其较强的扩稳能力、在需要时才施加到流场等特点越来越受到研究者的青睐。如果要想使该方法得到有效地实施，就必须对压气机内部流场以及动态失速过程有着深入的了解。为了探索轴流压气机内部流动失稳机理，为叶尖射流对压气机稳定性影响的实验研究做好准备，为喷射系统的整体布局提供必要的依据，本文以一台双级低速轴流压气机为实验对象，从压气机整体特性和级特性出现拐头现象出发，分析了第1级静子和第2级静子出口和通道内流场的流动现象和第1级转子叶尖泄漏流的变化发展，发现压气机失速与静子叶片吸力面附面层分离有着密切关系；并着重分析了该压气机的动态失速过程，发现它是由模态波扰动引起的失速，并且该扰动信号和随后出现的失速团都首先出现在第1级压气机的叶尖处。综合以上因素，喷射系统应该布置在该压气机进口上游的外机匣上。为了研究定常叶尖微射流对压气机稳定性的影响及其扩稳机理，本文加工了满足不同射流要求的喷嘴，搭建了一套定常喷射系统，在该双级低速压气机上验证了均匀进气条件下定常叶尖射流的有效性，为实际应用中喷射系统的布置以及射流参数设计提供指导性建议；在参数化研究结果的指导下，探索了叶尖射流提高压气机稳定裕度的机理，发现叶尖射流扩大压气机的稳定裕度是因为叶尖射流从频率、幅值和轴向结构三个方面抑制了模态波向失速团的发展，并在此基础上总结出了在叶尖射流作用下模态波沿压气机周向发展的物理模型，该模型能合理地解释叶尖射流扩稳的原因；另外，还分析了叶尖射流对第1级转子的叶尖流场、叶尖负荷以及叶尖处模态波轴向结构的影响，进一步揭示了叶尖射流提高压气机稳定性的原因。为了增强压气机的抗畸变能力，使它在进口流场较恶劣的情况下也能正常工作，开展进气畸变条件下叶尖射流能否提高压气机稳定性的研究具有较高的实用价值。本文研究了周向总压畸变和径向总压畸变对叶尖射流扩稳效果的影响，获得了周向畸变条件下叶尖射流也能有效地提高压气机的稳定裕度、周向畸变条件的扩稳原因与均匀进气条件下的扩稳原因一致以及与均匀进气结果相比周向总压畸变减弱了射流扩稳效果的结论；本文还研究了两种形式的径向进气畸变，由于根部径向畸变改变了失速起始的位置，将均匀进气条件的叶尖位置转移到叶根位置，所以这使叶尖射流扩稳效果甚微，尖部径向畸变由于叶尖处扰动脉动强度大以及叶中处模态波的发展，这同样使叶尖射流扩稳效果不佳。为了获得叶尖射流对高速轴流压气机稳定性的影响。本文以高速、高负荷NASA Rotor37为研究对象，以数值计算方法为手段，深入分析了不同转速下压气机失稳的原因，并在此基础上研究了不同射流量对压气机稳定性的影响，揭示了定常射流提高压气机稳定裕度的机理。更多还原

【Abstract】 Fan/compressor is one of the aero engine’s most important parts, whose stability directlyinfluences aero engine stability. In order to meet up-to-date aero craft flight target such asunconventional flexibility, supersonic cruise, a higher thrust-to-weight ratio needs to be increasedwhile fuel rate needs to be decreased, which requests higher pressure rise and loading per stage for thefan/compressor. Therefore, these demands make it difficult to ensure their aerodynamic stability. Themethods to enlarge fan/compressor stable margin such as using air injection and casing treatmentcome to appearance. Thoroughly understanding the compressor especially stall inception isindispensable if effective execution of these methods needs to be achieved.In order to explore axial compressor flow instability mechanism, and be ready for micro airinjection experiment on the compressor stability. Based on the turning of through compressorcharacteristic and stage characteristic, the the first stage stator and the second stage stator outlet andpassage flow field and blade tip leakage flow on top of the first stage rotor development are analyzed,and the result is that compressor stall has close relation with boundary layer separation of the blade tipsuction surface; according to the research of the stall inception, the compressor rotating stall isincepted by modal wave, which appears in the blade tip of the first stage. With all these in condition,injection system should be set in the outer casing of the compressor inlet upstream.In the uniform inflow, the effect of injection parameter such as the injection mass flow, injectornumber, circumference configuration of the injection system on the compressor stall margin wasstudied. The results indicate: under the condition that not less than four injectors are equally spacedcircumferentially, injection angle is a certain number to the counter rotation and momentum perinjector is as large as possible, the enhancement stability effect of the injection arrives at the most;under the guide of the parametric investigation, the mechanism of the micro injection enhancing thecompressor stability could be gotten, because the micro injection suppresses the modal wavedevelopment to the rotating stall from the facet of frequency, magnitude and axial structure. Based onthis, a physical model explaining how the micro injection enhance the compressor stability is putforward. At the same time, the micro injection delays tip leakage flow movements toward the rotorleading edge face and ameliorate the rotor tip loading.In order to strengthen the compressor ability against inlet distortion, so that it can work normallyadverse inlet flow field, the investigation to test whether the micro injection improves compressor stability under the condition of inlet distortion has high value for practical purpose. The researchresults indicate under the condition of the uniform inflow, the reason why the micro injectionenhancement the compressor stability under the condition of the inlet distortion is that the microinjection suppresses the modal wave development towards the rotating stall. When the total pressuredistortion style is different, the effect of micro injection enhancing compressor stability is different,too. For example, that effect isn’t obvious for the pure radial total pressure inlet distortion, however, itis obvious for the pure circumference total pressure inlet distortion. At the condition of the totalpressure inlet distortion, the enhancement with equally spaced circumference is the best, the effect ofenhancement stability for injection pooling in the low pressure area is better than that in the highpressure area.Steady tip injection on an isolated axial flow compressor, NASA Rotor37, has been studied inthe paper by using the method of numerical simulation. At first, the compressor stall reason can befound at the100%and50%designed rotating speed. At the designed rotating speed, the interactionbetween the shock wave and tip leakage flow leads to the blockage in the blade tip area, which resultsin the stall finally. Second, the effect of micro injection on the compressor stability at the two rotatingspeed are studied. The results indicate at the designed rotating speed, even if the injection is at thechoked condition, the effect of steady injection on the compressor stability is little; at the50%designed rotating speed, when injection mass flow reaches a certain value, that effect is obvious.更多还原