轴流压气机非轴对称轮毂造型对间隙流控制研究

对带静子间隙的单级轴流压气机进行了全三维数值模拟,流场分析表明静子间隙泄漏流在通道端壁区引起较大的流动分离。为控制流动损失,对静子轮毂进行了非轴对称造型,造型后的压气机总性能得到改善。流场分析表明:非轴对称端壁造型改变了壁面静压分布,改善了间隙泄漏流在通道内的流动结构,消除了通道出口处的回流损失区,使压气机总压比增加,等熵效率提高0.9%。     

两种径向间隙处理对1.5级高负荷轴流压气机性能影响的比较研究

采用数值模拟方法研究了机匣直沟槽处理和斜沟槽处理对压气机气动性能的影响,对两种处理方式下压气机各叶栅通道的熵产、涡量、回流范围和强度、静压分布、负轴向速度进行了定量计算和定性分析。结果表明：与光壁机匣相比,直沟槽和斜沟槽处理均使压气机的稳定运行范围拓宽了3%以上,直沟槽机匣处理压气机比斜沟槽机匣处理压气机的失速裕度更高,但绝热效率略低。     

某压气机进口级流动损失及静叶流场分析

采用三维雷诺平均N-S方程求解方法,对某燃气轮机压气机进口级流动进行模拟,研究了峰值效率点及近失速点的性能及流动特性,探索叶片通道中引起高损失的原因,分析了静叶通道内复杂的流动结构及吸力面角区分离的产生机制。结果表明:当该压气机级向近失速工况推进时,静叶中的能量损失较导叶、动叶增长更快;静叶下端壁大范围低速流体是损失的主要来源;通道涡及泄漏涡是静叶通道内主要二次流,其共同作用造成大面积总压损失;近失速工况下沿流向和展向的逆压梯度增大且二次流增强,导致静叶吸力面下端壁角区分离现象的出现。     

自循环机匣处理对某型柴油机增压器压气机的稳定工况范围及性能影响研究

针对某型柴油机增压器压气机,基于整级全通道数值模拟和正交试验设计方法,研究了自循环机匣处理实现高亚声速压气机扩稳增效的潜力。结果表明：自循环机匣能够在提高设计点气动性能的前提下推迟失稳,但会牺牲堵塞流量。压气机的失稳和堵塞流量分别与叶片前缘及叶片扩压器中的堵塞程度相关。小流量侧自循环机匣通过抽吸叶轮叶顶附近低能流体,缓解堵塞,推迟失稳。但在大流量侧自循环机匣的喷射效应会增大扩压器进口攻角,加剧扩压器叶片流动分离,减小堵塞流量。抽吸效应与喷射效应强度均取决于抽吸槽的位置和宽度,压气机稳定性和堵塞流量与抽吸槽参数的变化基本呈负相关。自循环机匣对气动性能的影响包含两方面：在抽吸槽前,经回流槽流出的流体与主流的掺混及其产生的进口畸变将带来额外的效率和压比损失,适当减小回流槽角度可以降低该损失;在抽吸槽下游,得益于抽吸效应对叶顶流动状态的改善,压气机抽吸槽附近及下游高熵区减小,做功能力增强,气动损失大幅降低。在上述两方面共同影响下,压气机设计点气动性能最终得以提高。     

一级半轴流式透平级内部若干非定常流动现象的试验研究

设计研制了具有亚音速透平高压级气动特性的一级半轴流式试验透平,采用试验方法对时序效应、叶栅壁面非定常静压幅频特性以及动叶出口非定常速度场进行了研究。结果表明:时序效应具有改善轴流式透平气动性能的潜力;动、静叶排压力有势场干涉引发的基频信号和上游静叶尾迹片段引发的两阶倍频信号,构成了第二列静叶壁面静压非定常分量的基本频率特征,其间还伴随高达六阶的倍频信号,主要由动叶尾缘高频脱落的涡街扰动产生;尚未完成掺混的第一列静叶尾迹片段出现在动叶出口,由其引发的负射流显著改变了动叶出口局部位置处的气流偏转角。     

压气机1.5跨音级内部流动分析

对某轴流式压气机1.5跨音级进行了CFD数值模拟,分析了激波的结构、形状以及激波位置随运行工况变化的规律.研究发现在近失速工况下,动叶通道中出现强激渡,同时在静叶吸力面出现大分离.在近堵塞工况下,静叶根部通道喉部产生了激波,导致流动堵塞,静叶尾缘吸力面出现很强的二次流,使得压气机近堵塞工况损失很大,效率很低.     

离心压气机叶片式机匣拓稳流动特性

内燃机功率提高以及高原、高空功率恢复的要求，推动着内燃机增压比不断提高，高增压技术成为先进内燃机发展的核心关键技术之一．提高压比将导致离心压气机稳定工作范围和效率急剧降低，高压比离心压气机的气动稳定性与扩稳成为高增压技术研究的核心和难点．为拓宽跨声速离心压气机的稳定工作范围，对一种离心压气机叶片式机匣处理结构开展了研究，利用数值模拟研究了叶片式机匣内部流动特性与拓稳机理，并对导叶形式进行了优化，最后通过试验进行验证，结果表明：采用优化的导叶机匣处理结构，能够有效拓宽离心压气机高压比流动范围，喘振流量可拓宽6%～8%.     

多级轴流压气机失速特性分析

为了对某九级低压压气机的低工况性能进行改进和优化,分析压气机在低工况下的特性是必要的。采用三维黏性数值模拟方法对非设计工况进行了计算,根据压气机在近失速状态下的级特性,详细分析了第一级、第二级和末级的流场特性。结果表明:第一级转子扩压负荷过大,顶部发生了突尖波失速,是造成压气机不稳定运行的主要原因,且使下游的进气条件变差,导致第二级叶片顶部发生流动分离;末级静子扩压负荷较大,静子通道涡造成的漩涡耗散损失使末级的绝热效率低下。     

小轴向间隙下直_弯静叶Clocking效应的实验研究

实验研究了采用直、弯静叶的某低速重复级压气机的Clocking效应在小轴向间隙下的变化情况,探讨了Clocking效应在小轴向间隙下影响压气机内部流动状况的机理.结果表明,当动、静叶间轴向间隙减小到原型间隙的67%时,压气机整体效率较原型有所提高,且采用正弯静叶时压气机效率提高的幅度要大于采用直静叶时.综合不同叶型和Clocking 效应带来的效率收益,在设计工况下最多提高1.8%～1.9%,最大流量工况下则可达到2.8%.设计工况下最高效率点发生在一级静叶尾迹与二级静叶尾迹相重合时,最低效率则对应于一级静叶尾迹位于二级静叶流道中央时.     

自循环机匣处理对某型离心压气机性能的影响

采用数值模拟的方法对比带/不带自循环机匣处理结构对某型离心压气机性能的影响进行研究。结果表明,自循环机匣处理结构基本不影响设计点压气机效率,可以增加压气机堵塞状态的流量,减小失速状态的流量。同时,文章展示了带/不带自循环机匣处理结构时压气机内部的流场情况,从流场流动的角度分析了自循环机匣结构引起压气机特性变化的原因。带机匣处理结构的压气机,在设计状态下,气流攻角不变,压气机效率基本不变;失速状态下,气流攻角改善,流动更加稳定;堵塞状态下,气流由机匣处理结构流入叶轮喉部下游,增加了叶轮排气流量,拓宽了堵塞流量。     

Application of high-turning bowed compressor stator to redesign of highly loaded fan stage

A redesign of a highly loaded fan stage by using high-turning bowed compressor stator was conducted. The original tandem stator was replaced by the highly loaded bowed stator which was applicable to highly subsonic flow conditions. 3D contouring technique and local modification of blade were applied to the design of the bowed blade in order to improve the aerodynamic performance and the matching of the rotor and stator blade rows. Performance curves at different rotating speeds and performances at different operating points for both the original fan stage and redesigned fan stage were obtained by numerical simulations. The results show that the highly loaded bowed stator can be used not only to improve the structure and the aerodynamic performances at various operating points of the compressor stage but also to provide high performances at off-design conditions. It is believed that the highly loaded bowed stator can advance the design of high-performance compressor.     

Impact of clocking on the aero-thermodynamics of a second stator tested in a one and a half stage HP turbine

This paper focuses on the experimental investigation of the time-averaged and time-accurate aero- thermodynamics of a second stator tested in a 1.5 stage high-pressure turbine. The effect of clocking on aerodynamic and heat transfer are investigated. Tests are performed under engine representative conditions in the VKI compression tube CT3. The test program includes four different clocking positions, i.e. relative pitch-wise positions between the fh-st and the second stator. Probes located upstream and downstream of the second stator provide the thermodynamic conditions of the flow field. On the second stator airfoil, measurements are taken around the blade profile at 15, 50 and 85% span with pressure sensors and thin-film gauges. Both time-averaged and time-resolved aspects of the flow field are addressed. Regarding the time-averaged results, clocking effects are mainly observed within the leading edge region of the second stator, the largest effects being observed at 15% span. The surface static pressure distribution is changed locally, hence affecting the overall airfoil performance. For one clocking position, the thermal load of the airfoil is noticeably reduced. Pressure fluctuations are attributed to the passage of the up- stream transonic rotor and its associated pressure gradients. The pattern of these fluctuations changes noticeably as a function of docking. The time-resolved variations of heat flux and static pressure are analyzed together showing that the major effect is due to a potential interaction. The time-resolved pressure distribution integrated along the second stator surface yields the unsteady forces on the vane. The magnitude of the unsteady force is very dependent on the clocking position.     

Application of high-turning bowed compressor stator to redesign of highly loaded fan stage

A redesign of a highly loaded fan stage by using high-turning bowed compressor stator was conducted. The original tandem stator was replaced by the highly loaded bowed stator which was applicable to highly subsonic flow conditions. 3D contouring technique and local modification of blade were applied to the design of the bowed blade in order to improve the aerodynamic performance and the matching of the rotor and stator blade rows. Performance curves at different rotating speeds and performances at different operating points for both the original fan stage and redesigned fan stage were obtained by numerical simulations. The results show that the highly loaded bowed stator can be used not only to improve the structure and the aerodynamic performances at various operating points of the compressor stage but also to provide high performances at off-design conditions. It is believed that the highly loaded bowed stator can advance the design of high-performance compressor. __________ Translated from Journal of Propulsion Technology, 2007, 28(1): 26–31 [译自: 推进技术]     

船用燃气轮机压气机多级可调静叶优化匹配方法研究

作为防止燃气轮机喘振的有效手段之一,可调静叶技术的应用能够提升压气机在非设计工况下的效率和运行范围,从而提高燃气轮机变工况下的经济性和稳定性.以某型船用三轴燃气轮机为研究对象,建立压气机一维性能分析模型与燃气轮机零维仿真模型耦合的变维度燃气轮机仿真模型,以经济性和稳定性为优化目标,通过多目标遗传算法对低压压气机多级可调...     

Aerodynamic performance of bowed compressor cascades with different camber angles

The effects of a positively bowed blade on the aerodynamic performance of annular compressor cascades with different camber angles were experimentally investigated. The distributions of the exit total pressure loss and secondary flow vectors of the compressor cascades were analyzed. The static pressure was measured by tapping on the cascade surfaces, and the ink-trace flow visualizations were conducted. The results show that the value of the optimum bowed angle and optimum bowed height decrease because of the increased losses at the mid-span with the increase of the camber angle. The C-shape static pressure distribution along the radial direction exists on the suction surface of the straight cascade with larger camber angles. When bowed blade is applied, the larger bowed angle and larger bowed height will further enhance the accumulation of the low-energy fluid at the mid-span, thus causing the flow behavior to deteriorate. Under 60° camber angle, flow behavior near the end-wall region of some bowed cascades even deteriorates instead of improving because the blockage of the separated flow near the mid-span keeps the low-energy fluid near the end-walls from moving towards the mid-span region. As a result, a rapid augmentation of the total loss can easily take place under a large bowed angle.     

增压器压气机叶片结构/振动一体化优化设计

以废气涡轮增压器压气机叶轮为研究对象,创建了压气机叶片的三维参数化模型,通过全三维流场仿真分析,得到压气机的气动性能及叶片表面的压力分布.在不改变叶片形状、保证压气机气动性能的情况下,对叶片的静强度及振动特性进行了一体化优化设计.以叶片4个关键截面的叶顶、叶根厚度为设计变量,以离心力及气动压力作用下叶片的最大Mises应力、叶片的一阶动频为约束,以叶片体积为目标函数,在iSIGHT优化平台上集成了I-DEAS、ANSYS软件,采用混合整型优化和自适应模拟退火算法的组合优化方法,在满足叶片静强度小于屈服强度和一阶动频大于3倍工作频率的条件下,叶片体积(质量)减小了14.7%.     

进口畸变下涡流发生器对压气机流场的影响

为研究进口总压畸变条件下涡流发生器对压气机流场的影响,建立单级轴流压气机模型,计算和分析了不同工况下的压气机内部流场.计算结果显示:在进口畸变条件下,压气机流场恶化,性能降低;使用涡流发生器后,可以有效改善静叶叶根附近的流场,控制叶片尾缘分离,降低沿叶高方向的压力波动,从而削弱进口畸变对效率的负面影响,改善出口压力场,...     

The effect of variable stator on performance of a highly loaded tandem axial flow compressor stage

Increasing the aerodynamic load on compressor blades helps to obtain a higher pressure ratio in lower rotational speeds.Considering the high aerodynamic load effects and structural concerns in the design process,it is possible to obtain higher pressure ratios compared to conventional compressors.However,it must be noted that imposing higher aerodynamic loads results in higher loss coefficients and deteriorates the overall performance.To avoid the loss increase,the boundary layer quality must be studied carefully over the blade suction surface.Employment of advanced shaped airfoils (like CDAs),slotted blades or other boundary layer control methods has helped the designers to use higher aerodynamic loads on compressor blades.Tandem cascade is a passive boundary layer control method,which is based on using the flow momentum to control the boundary layer on the suction surface and also to avoid the probable separation caused by higher aerodynamic loads.In fact,the front pressure side flow momentum helps to compensate the positive pressure gradient over the aft blade's suction side.Also,in comparison to the single blade stators,tandem variable stators have more degrees of freedom,and this issue increases the possibility of finding enhanced conditions in the compressor off-design performance.In the current study,a 3D design procedure for an axial flow tandem compressor stage has been applied to design a highly loaded stage.Following,this design is numerically investigated using a CFD code and the stage characteristic map is reported.Also,the effect of various stator stagger angles on the compressor performance and especially on the compressor surge margin has been discussed.To validate the CFD method,another known compressor stage is presented and its performance is numerically investigated and the results are compared with available experimental results.     

Performance improvements of a subsonic axial-flow compressor by means of a non-axisymmetric stator hub end-wall

This paper deals with the application of a non-axisyrmnetric hub end-wall on the stator of a single stage high subsonic axial-flow compressor. In order to obtain a state-of-the-art stator non-axisymmetric hub end-wall con- figuration fulfilling the requirements for higher efficiency and total pressure ratio, an automated multi-objective optimizer was used, in conjunction with 3D-RANS-flow simulations. For the purpose of quantifying the effect of the optimal stator non axis-symmetric hub contouring on the compressor performance and its effects on the sub- sonic axial-flow compressor stator end-wall flow field structure, the coupled flow of the compressor stage with the baseline, axisymmetric and the non-axisynunetric stator hub end-wall was simulated with a state-of-the- art multi-block flow 3D CFD solver. Based on the CFD simulations, the optimal compressor hub end-wall con- figuration is expected to increase the peak efficiency by approximately 2.04 points and a slight increase of the to- tal pressure ratio. Detailed analyses of the numerical flow visualization at the hub have uncovered the different hub flow topologies between the cases with axisymmetric and non-axisymmetric hub end-walls. It was found that that the primary performance enhancement afforded by the non-axisymmelric hub end-wall is a result of the end-wall flow structure modification. Compared to the smooth wall case, the non-axisymmetric hub end-wall can reduce the formation and development of in-passage secondary flow by aerodynamic loading redistribution.     

Experimental analysis of the aerodynamic performance of an innovative low pressure turbine rotor

In the present work the aerodynamic performances of an innovative rotor blade row have been experimentally investigated. Measurements have been carried out in a large scale low speed single stage cold flow facility at a Reynolds number typical of aeroengine cruise, under nominal and off-design conditions. The time-mean blade aerodynamic loadings have been measured at three radial positions along the blade height through a pressure transducer installed inside the hollow shaft, by delivering the signal to the stationary frame with a slip ring. The time mean aerodynamic flow fields upstream and downstream of the rotor have been measured by means of a five-hole probe to investigate the losses associated with the rotor. The investigations in the single stage research turbine allow the reproduction of both wake-boundary layer interaction as well as vortex-vortex interaction. The detail of the present results clearly highlights the strong dissipative effects induced by the blade tip vortex and by the momentum defect as well as the turbulence production, which is generated during the migration of the stator wake in the rotor passage. Phase-locked hot-wire investigations have been also performed to analyze the time-varying flow during the wake passing period. In particular the interaction between stator and rotor structures has been investigated also under off-design conditions to further explain the mechanisms contributing to the loss generation for the different conditions.