非定常机匣处理扩大压气机稳定裕度实验

从非定常角度出发,设计了一种通过改变斜槽和气室来调节壁面阻抗边界条件的非定常处理机匣,并对其开展扩大轴流风扇/压气机旋转失速稳定性的实验研究.研究工作包括:对非定常处理机匣进行流量-压比特性实验,研究其扩稳效果;对处理机匣的结构参数(斜槽、气室)进行可调节特性实验;对机匣处理的效率特性进行实验评估.结果表明:这种非定常机匣处理在三台低速风扇/压气机实验台上,通过调节机匣参数,不仅能够实现在不同的工作转速下对压气机稳定裕度有显著效果,而且效率没有明显改变.      

非定常机匣处理对失速先兆波的抑制作用实验研究

非定常机匣处理在不影响效率的前提下可以明显提高压气机的稳定工作范围,针对这种通过改变斜槽和气室来调节壁面阻抗边界条件的新型处理机匣,从非定常角度,开展其对失速先兆波产生及发展的影响的实验研究.在压气机转子前缘附近沿圆周均匀布置八支高频响压力传感器,采集壁面动态压力信号,进行周向傅立叶分析(SFT)和功率谱密度分析(PSD),捕捉到旋转失速先兆波的出现和发展的动态细节,比较光壁和处理机匣两种情况的结果,证实了处理机匣并非阻止了失速先兆波的出现,而是有效的抑制了其非线性发展.非定常机匣处理改变了压气机系统的阻抗边界条件,能够在全过程中对低频扰动波进行有效的抑制,从而推迟旋转失速的发生,实现压气机的扩稳目的.      

处理机匣/压气机非定常相互作用分析

实验研究了三个不同槽数圆弧斜槽处理机匣对压气机气动性能的影响,实验结果显示,只有当处理槽数确定的处理机匣/压气机非定常相互作用频率锁定在压气机分离绕流流场非定常特征频率附近时,处理机匣才能展示出满意的扩稳能力.实验利用25孔总压耙测量压气机静子出口S3流面总压流场结构,测量结果表明,处理机匣/压气机非定常相互作用不但大幅度改善了压气机分离绕流流场结构,还影响了压气机总压升径向分布.      

周向槽调控轴流压气机非定常间隙泄漏流机理初探

以某压气机转子为载体,针对其顶部间隙泄漏流的非定常特性,设计了一种周向槽处理机匣,利用数值模拟的方法研究了其对压气机转子性能及顶部非定常间隙泄漏流动特性的影响,结果表明:该处理机匣的引入能够在不恶化压气机性能的前提下使得其流量裕度提高约6.5%。与实壁机匣结构相比,周向槽处理机匣减小了间隙泄漏流轴向动量,抑制了叶顶间隙泄漏流非定常性的出现,从而提高了压气机的稳定工作裕度。     

处理机匣对跨声压气机进气畸变的响应

对带处理机匣的压气机转子Rotor 37在总压畸变进口条件下的流场进行了三维数值模拟.分别计算了光壁、斜缝处理机匣和带背腔斜缝处理机匣在有畸变和无畸变进气时的转子特性参数,分析了均匀进气时斜缝处理机匣的扩稳机理,并比较分析了两种处理机匣在畸变进气时对压气机的稳定性影响.结果表明:在均匀进气时两种处理机匣都具有较好的扩稳作用,但在畸变进气时带背腔斜缝机匣的扩稳作用比均匀进气时的扩稳作用减弱,而无背腔斜缝机匣会使压气机的稳定裕度下降.     

低雷诺数条件下跨声速转子轴向倾斜缝处理机匣扩稳研究

采用非定常数值方法对低雷诺数条件下50%,75%和100%三种不同轴向叠合量的轴向倾斜缝处理机匣结构对NASA Rotor 37跨声速压气机转子的扩稳效果进行了研究.结果表明,引入处理机匣后,附面层径向涡得到了很好的抑制,由附面层径向涡所引发的叶顶阻塞区大为减小,虽然又引发了由叶顶间隙涡对叶顶所造成的阻塞,但引入处理机匣后对压气机稳定性仍有较大的改善,能有效提高压气机转子的失速裕度.      

轴流压气机端壁失速的耦合扩稳方法及机理研究

为了探索可有效控制轴流压气机端壁失速的扩稳方法,将缝式处理机匣与叶顶喷气进行耦合设计,参数化研究了缝的长度、位置和角度对压气机性能的影响,结合非定常数值模拟阐释了"耦合型处理机匣"的扩稳机理以及影响压气机效率的作用机制。研究结果表明,在"耦合型处理机匣"作用下,压气机失速裕度提高18%,压气机效率在小流量工况略有提高,在设计工况降低0.21%。缝长度是影响压气机性能的关键,其最大长度不应超过叶顶轴向弦长的50%,缝的位置和角度的影响程度有限。"耦合型处理机匣"内存在缝内循环和由缝到喷嘴间的循环两种主要流动形式,这两种循环在有效控制叶顶泄漏涡的同时降低了叶顶负荷,是提高压气机失速裕度的主要原因。"耦合型处理机匣"与压气机间的作用具有自适应性,这种自适应性降低了其对压气机工作点效率的负面影响,同时保证了对叶顶堵塞的控制效果。缝与喷嘴的耦合设计具有不降低压气机效率的同时,大幅度提高压气机失速裕度的潜力。     

带导流叶排的轴流压气机级叶尖处理机匣容畸变特性

基于叶尖处理机匣轴流压气机叶排实验特性,应用畸变传递的矩阵分析模型,分析了进口导流叶排对叶尖处理机匣结构容总压畸变特性影响,初步建立了在进口导流叶排下几种处理机匣结构对总压畸变及其沿轴流压气机叶排衰减特性影响规律。计算结果表明,叶尖处理机匣虽均能有效提高压气机级的稳定工作范围,但削弱了转子叶排和静子叶排的抗总压畸变能力,这对设计合理的扩大轴流压气机稳定裕度处理机匣结构尤为重要。      

低雷诺数下跨声速转子周向槽处理机匣扩稳研究

采用数值方法模拟了低雷诺数条件下NASA Rotor 37跨声速压气机转子内部流场。结果表明,附面层径向涡是该压气机转子流动失稳的一个很重要的原因。周向槽处理机匣结构对压气机流场的改善较为有限,而引入抽吸处理机匣后,抽吸槽可以将叶顶间隙涡和附面层径向涡及其引发的低能阻塞流团抽吸至处理槽内,叶顶流场大为改善,有效地提高了压气机转子的失速裕度。     

新型机匣处理结构研究

以提高压气机裕度而又不牺牲效率为前提,在分析了多种机匣处理结构形式及其扩稳机理的基础上,设计了一种新型处理机匣。借助单级轴流压气机实验台,详细地研究了该处理机匣多种几何尺寸下的扩稳效果,提出了该处理机匣扩稳机理的假设,它有重要的工程实用价值。     

Influence of SPS casing treatment on axial flow compressor subjected to radial pressure distortion

The present work is about the stall margin enhancement ability of a kind of stall precursor-suppressed (SPS) casing treatment when fan/compressor suffers from a radial total pres-sure inlet distortion. Experimental researches are conducted on a low-speed compressor with and without SPS casing treatment under radial distorted inlet flow of different levels as well as uniform inlet flow. The distorted flow fields of different levels are generated by annular distortion flow gen-erators of different heights. The characteristic curves under these conditions are measured and ana-lyzed. The results show that the radial inlet distortion could cause a stall margin loss from 2% to 30% under different distorted levels. The SPS casing treatment could remedy this stall margin loss under small distortion level and only partly make up the stall margin loss caused by distortion in large level without leading to perceptible additional efficiency loss and obvious change of charac-teristic curves. The pre-stall behavior of the compressor is investigated to reveal the mechanism of this stall margin improvement ability of the SPS casing treatment. The results do show that this casing treatment delays the occurrence of rotating stall by weakening the pressure perturbations and suppressing the nonlinear amplification of the stall precursor waves in the compression system.     

Response and stabilization of a two-stage axial flow compressor restricted by rotating inlet distortion

This paper considers effects of Rotating Inlet Distortion (RID) on a two-stage axial compressor and the stabilization effects of a casing treatment subjected to the considered RID. In multi-spool engines, the downstream compressor suffers a RID when the upstream fan/compressor is in rotating stall. A controlled rotating sectional screen upstream of the compressor was adopted to generate the RID in different intensities, and co- or counter spinning direction compared with the rotor. The response of the compressor to inlet distortion was interpreted as the changes of stall margin. Results show that there are two peaks for the stall margin degradation where the distortion screen rotates near 20% and 70% of the rotor’s rotational frequency, respectively. Based on the measurements taken during the pre-stall process, it is suggested that the two frequencies are associated with the eigen frequencies of the compressor. Specifically, the first is associated with a stall precursor that is suspected as an initial disturbance existing in compressor and the second is related to a spike-type stall precursor. At last, a kind of Stall Precursor-Suppressed (SPS) casing treatment was applied to enhance the compressor stability in RID conditions. The result indicates that the stall margin is improved by 6% at an average level and there is nearly no efficiency loss caused by the application of such casing treatment.     

Experimental investigation on SPS casing treatment with bias flow

Generally, casing treatment（CT） is a passivity method to enhance the stall margin of fan/compressor. A novel casing treatment based on the small disturbance theory and vortex and wave interaction suggestion is a method combining passive control and active control, which has been proved effective at enhancing the stall margin of fan/compressor in experiment. In order to investigate the mechanism of this kind of casing treatment, an experimental investigation of a stall precursor-suppressed（SPS） casing treatment with air suction or blowing air is conducted in the present paper. The SPS casing treatment is designed to suppressing stall precursors to realize stall margin enhancement in turbomachinery. The experimental results show that the casing treatment with blowing air of small quantity can improve the stall margin by about 8% with about 1% efficiency loss. By contrast, the SPS casing treatment with micro-bias flow does not improve the stall margin much more than that without bias flow, even worse. Meanwhile, the present investigation has also attempted to reveal the mechanism of stall margin improvement with the casing treatment.It is found that the stall margin improvements vary with the modification of the unsteady shedding flow and the unsteady wall boundary impedance. The experimental results agree fairly well with the theoretical prediction using a flow stability model of rotating stall.     

离心压气机自循环预旋喷气机匣处理的设计和验证

采用一种预旋喷气机匣处理提高离心压气机特定转速范围内的稳定裕度.通过引气加大离心叶轮进口基元级流量降低通道堵塞,并借助回流预旋喷气改变前缘攻角抑制叶背分离是该机匣处理扩稳的主要机理.基于这样的认识,对机匣处理做了几何参数设计研究,发现轴向搭接位置、搭接长度和开槽角度是影响机匣处理性能的3个主要参数.通过几何参数的合理选取,在尽量提高80%设计转速稳定裕度的同时兼顾100%设计转速的效率.压气机部件性能试验验证了该设计方法的有效性,并观测到在低转速时,机匣处理可以同时提高稳定裕度和效率.      

机匣处理对压气机性能和气流结构影响的试验研究

本文对实壁机匣和三种不同型式的轴向斜槽处理机匣进行了较为详细的试验研究。发现这类机匣处理结构不仅对压气机总性能有很大影响,而且对旋转失速的类型,失速团的空间传播和发展以及转子出口的流场均有很大影响。文中的试验结果对建立失速团的三维传播及发展模型,开发机匣处理的其它功能以及机匣处理结构实际应用都有工程价值。     

用小波变换对机匣处理抑制旋转失速的机理研究

本文利用小波变换对轴流压气机旋转失速时的压力信号进行时频分析。通过Ｍｏｒｌｅｔ连续小波变换,详细分析压气机失稳过程中非定常信号的变化,并研究旋转失速初始扰动信号在处理机匣气室中的局部行为。通过对比实壁机匣与处理机匣的失速初始信号相干波形的结构特性,发现不同机匣结构对相干波形结构中压力脉动信号的不同影响,提出处理机匣抑制旋转失速初始扰动发展的机理。     

带机匣处理的轴流压气机过失速性能的研究

 针对一种可提高压气机裕度而又不牺牲效率的新型机匣处理,实验研究了亚音速单级轴流压气机孤立转子机匣处理前后的过失速性能,借助于压缩系统的一维逐级可压流数学模型,发展了一种可用于带机匣处理的压气机过失速性能预测程序,并用它解释了机匣处理后转子所特有的失速现象。     

多级轴流压气机机匣处理级的探讨

本文提出了一种确定多级轴流压气机机匣处理级的新方法。首先,预测多级轴流压气机各级的级极限负荷,依此确定旋转失速发生时率先失速的级并得到实验证实;其次,将率先失速级作为待处理的级,并在一亚音速双级轴流压气机实验台上针对四种不同型式的机匣处理,进行了较为系统的实验验证。实验结果证实在率先失速级上进行机匣处理会取得很好的扩稳效果,用级极限负荷来确定多级轴流压气机机匣处理级的方法具有广阔的应用前景。     

间隙流触发压气机内部流动失稳机制及周向槽扩稳机理

利用高频响动态压力传感器对某低速轴流压气机转子的失速先兆和顶部流场进行了详细的测试,探明该压气机内部存在与叶顶间隙泄漏流相关的突发型失速先兆,对压气机转子内部流场进行了单通道定常和非定常数值模拟,详细分析了压气机内部流动失稳过程中顶部流场结构的变化,揭示顶部间隙泄漏流触发轴流压气机内部流动失稳机理.在此基础上,利用周向槽处理机匣结构对顶部间隙泄漏流进行控制,并探讨了周向槽处理机匣结构提高压气机稳定工作裕度机理.