机匣处理改善某单级跨声轴流压气机性能的机理研究

采用全三维数值方法研究了轴向倾斜缝机匣处理对某单级跨声轴流压气机性能的影响.数值结果表明:机匣处理不仅扩宽压气机稳定工作范围,而且还略微提高了单级跨声轴流压气机峰值效率.通过详细分析压气机转子内部流场,揭示了该机匣处理对该单级跨声轴流压气机性能及流场影响的机理,在倾斜缝中形成的回流作用下,使叶顶吸力面气流分离的起始位置向下游推移,并削弱了分离流与叶顶间隙泄漏流相互作用造成的恶劣影响,提高了叶顶通道的流通能力,进而推迟压气机失速的发生.      

轴向倾斜缝机匣处理影响压气机性能的机理

为了揭示缝式机匣处理影响轴流压气机性能的流动机理,对带轴向倾斜缝机匣处理的轴流压气机转子进行全三维非定常数值模拟,试验与数值结果均表明机匣处理在有效地扩大压气机稳定工作范围的同时,也使压气机等熵效率减少。通过详细地分析压气机内部流场,揭示了该机匣处理对该压气机转子性能及流场影响的机理,即倾斜缝内的回流具有抽吸或吹除端部低能流体的能力,在倾斜缝中形成的喷射流的作用下,叶顶通道内的低速气团得到了有利的激励,从而推迟转子的失速。但也使转子叶顶加功量下降,同时缝内的回流及其与叶顶主流的相互作用带来大的流动损失,最终降低压气机转子等熵效率。     

反叶片角向缝机匣处理影响轴流压气机性能的机理

采用试验和非定常数值模拟方法研究了反叶片角向缝机匣处理对亚声速轴流压气机性能的影响.试验与数值计算结果均指出反叶片角向缝机匣处理后,转子在降低12%左右最大等熵效率的基础上获得30.1%左右的失速裕度改进量.详细的转子叶顶流场分析表明反叶片角向缝机匣处理改善了叶顶间隙泄漏流动,消除了实体壁机匣时叶顶通道低速泄漏流形成的堵塞,因此转子稳定性得以提高.同时转子叶片与处理缝的相对位置变化会影响处理缝的扩稳能力.处理缝中回流、处理缝形成的喷射流与叶顶通道主流的相互作用都造成较大的流动损失,进而使转子等熵效率降低.反叶片角向缝机匣处理前移约55%叶顶轴向弦长的数值研究结果表明,与反叶片角向缝机匣处理比较,反叶片角向缝机匣处理前移获得的失速裕度改进量降低约10.4%,但等熵效率的恶化程度降低近64%.      

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。     

压气机端壁自适应流通延迟失速的数值分析

端壁自适应流通方式是轴流压气机主动控制失速方法的有效措施之一,即在机匣上结合喷气与引气的方式来延迟压气机的失速,其特点是自适应流通的喷气或吹气量将随压气机的工况自我调整。采用数值模拟方法研究了端壁自适应流通方式对某轴流压气机气动性能的影响,数值计算结果表明,端壁自适应流通方式能有效地延迟失速并略微提高压气机的效率,通过详细地分析端壁自适应流通方式对压气机顶部区域流场结构的影响,揭示了其改善压气机性能的机理。     

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。     

高负荷两级轴流压气机耦合型机匣处理的设计研究

为了提升高负荷两级轴流压气机的失速裕度,在分析传统缝式机匣处理无法扩稳的流动机理基础上,设计了一种耦合型机匣处理结构,采用三维数值模拟对该结构进行了优化设计。针对优化的耦合型机匣处理进行了非定常数值模拟,阐述了该机匣处理的扩稳机理以及机匣处理作用下压气机新的失速机制。研究表明,两级高负荷压气机的失速由第一级转子叶顶强激波诱发的附面层分离引起,缝式机匣处理无法有效消除该附面层分离引起的通道堵塞,因而无法提高该压气机的失速裕度。耦合型机匣处理结合了缝式机匣处理和自循环机匣处理各自的优势,将第一级转子叶顶的低能流体抽吸至进口导叶通道,极大改善了转子叶顶的流动状况,使压气机的稳定工作范围提高了49.3%,设计点效率提升了0.54%。在耦合型机匣处理的作用下,静子通道内集中脱落涡诱发的通道堵塞成为触发压气机失速的新因素。     

轴流压气机折线缝式机匣处理扩稳机理

1引言风扇/压气机的气动失稳不但会对其气动性能造成恶劣影响,而且还有可能对发动机结构造成毁灭性的破坏。因此,如何延迟风扇/压气机气动失稳的发生,拓展稳定工作范围,一直是提高其性能的关键技术之一。机匣处理是一种扩大压气机稳定工作范围的有效措施,然而,大多数机匣处理在     

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。     

轴流压气机机匣处理数值研究

 本文采用带进口总压梯度的无粘模型和Denton J D.格式,首次对压气机机匣处理三维流场进行了数值求解,对奇点边界及数值稳定性作了探讨。并在定性解释机匣处理试验结果及机理中符合一致。     

缝式处理机匣轴向位置对压气机特性影响的机理研究

文中对轴向倾斜缝处理机匣轴向位置的改变如何影响轴流压气机性能进行研究。试验与数值结果均表明三个轴向位置的机匣处理均扩宽压气机的稳定工作范围,轴向位置不变时扩稳效果最好,轴向位置后移的最差。同时轴向位置前移或后移使压气机等熵效率损害程度降低。通过详细地分析压气机内部流场表明：机匣处理轴向位置后移使叶顶机匣约1/3的轴向弦长宽度无机匣处理,因此不能抑制叶顶泄漏流的发展,后移处理机匣缝的抽吸能力弱,致使扩稳效果差;与处理机匣轴向位置未变的比较,轴向位置前移或后移能够减少了间隙流及二次流带来的流动损失,并使叶顶加功量上升,使压气机转子等熵效率提高。     

Recent development of casing treatments for aero-engine compressors

Casing treatment is a mature stabilization technique which has been widely applied on aero-engines for modern aircrafts and turbo-chargers for automobiles. After the investigations of half century since the 1960s, this technique has been well developed for various configurations with different effectiveness. From the perspective of stabilization mechanism, this paper roughly categorizes the configurations of casing treatment into two types: traditional ones which work by affecting the flow structure of blade tip region; a novel one named as Stall Precursor-Suppressed (SPS) casing treatment. The effectiveness of both types will be demonstrated for their applications on axial compressors and centrifugal compressors with uniform or distorted inlet. And the stabilization mechanism of casing treatments for regular types and SPS one will also be explained respectively. In addition, this review will summarize the methodologies of casing treatments with the numerical simulations for regular grooved configurations and the eigenvalue approach for SPS casing treatment. Looking forward to the future of compressor stabilization, casing treatment technique will still exist as a general and inexpensive option, and the exploration for its effectiveness and mechanism will be deeper with the development of computational fluid dynamics and advanced measurement techniques.     

Dual stability enhancement mechanisms of axial-slot casing treatment in a high-speed mixed-flow compressor with various tip clearances

The influence of Axial-Slot Casing Treatment (ASCT) on the performance and stability enhancement mechanisms of ASCT were experimentally and numerically investigated in a high-speed mixed-flow compressor under three different tip clearances. Unsteady simulations showed the compressor stalled through end-wall stall route, i.e. the spike stall inception originating from rotor tip region, which was validated by dynamical measurements. When the ASCT was applied, greater than 20% of Stall Margin Improvement (SMI) could be achieved for the compressor under each tip clearance size. The streamwise velocity contours and flow structures in the tip region and axial slots were deeply analyzed to explore how the so called “suction and injection effects” generated by the ASCT manipulate tip clearance flow and enhance the stability of compressor under different tip clearances. It was found that the dominant stability enhancement mechanisms of ASCT varies with tip clearance size for the mixed-flow compressor. (A) For the small tip clearance, the dominant mechanism of stability enhancement is the blockage reduction generated in the blade passage by the suction effect of ASCT. (B) For the large tip clearance, the injection effect of the ASCT is the dominant mechanism of stability enhancement with ASCT, which plays the leading role in delaying the spillage of incoming/tip leakage flow interface at the rotor Leading Edge (LE) plane.     

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.     

自适应流通处理机匣喷气位置对压气机性能的影响

采用数值模拟方法研究了跨声风扇转子Rotor 67的失速机理和3个喷气位置的自适应流通处理机匣对转子性能的影响.结果表明:叶顶间隙泄漏涡中低速团是诱发失稳的主要原因;3个喷气位置的处理机匣均增大了压气机的稳定工作范围,喷气位置居中和后移的处理机匣综合稳定裕度改进量分别为13.43%,9.47%,均大于前移的2.72%;喷气位置居中和后移有利于抑制间隙泄漏流的发展,减小低能流体泄漏范围;相比前移和居中,后移不能激励压力面前缘处的低速团和抑制低能流体从叶顶前部泄漏.      

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.     

带周向槽叶尖处理机匣轴流压气机容总压畸变特性

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，对轴流压气机叶尖处理机匣容总压畸变特性进行了详细分析，并建立了处理机匣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，叶尖处理机匣虽能有效提高转子叶排抗总压畸变能力，但对其后的静子叶排抗畸变产生了明显不利影响，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。     

“前置凸台周向槽式”机匣处理的设计和实验

为了获得一种新型的“前置凸台周向槽式”处理机匣的设计参数和处理效果，借助于一单级轴流压气机实验台详细研究了“前置凸台”结构，“周向槽”结构，凸台前部尺寸、叶顶形状对压气机性能的影响，实验结果表明凸台前部尺寸和叶顶几何形状对压气机的裕度和效率均有较大影响，并分析了该处理机匣的作用机理。