雷诺数对跨音速压气机转子性能的影响

为了研究雷诺数对跨音速压气机转子性能的影响,基于NUMECA流场仿真软件对NASA设计压缩机进口级转子37进行气动研究。对比分析了不同进气压力下,Rotor37总体气动性能和内部流动细节。不同入口压力对应不同雷诺数。结果表明,在满足几何不变,压比不变,转速不变,入口总温不变的条件下,雷诺数进入自模化区后,基本可以忽视雷诺数对压气机转子气动性能的影响。在不考虑叶片粗糙度的情况下,雷诺数为设计雷诺数47倍时,绝热效率-流量特性曲线总体效率升高,最大绝热效率升高1.4%;压比-流量特性曲线向压比更高,折合流量更大偏移,最大压比几乎不变;当压力升高雷诺数升高后,压气机转子稳定运行区间宽度基本不变。     

气动边界不确定条件下离心压气机叶轮优化设计

以某小型离心压气机为研究对象,基于非嵌入式概率配置点法和数值分析研究气动边界不确定性对离心压气机气动性能的影响规律,量化转速波动不确定对离心压气机压比的影响程度;提出一种基于不确定分析方法、代理模型、多目标优化算法的离心压气机气动稳健设计方法,为离心压气机及其他叶轮机械设计及应用提供重要参考。研究结果表明,优化后叶轮压比增大4.1%,压比方差降低13.52%,叶轮气动稳健性增强。     

基于有限元法离心风机气动噪声预报研究

针对离心风机噪声试验研究成本大,产品设计生产周期长等问题,探究了离心风机辐射噪声数值模拟的准确性。基于声学有限元方法,采用数值计算与试验相结合的方式,通过FLUENT软件进行非定常计算得到声源信息,采用ACTRAN有限元法计算风机的气动噪声,并与试验值进行对比分析。研究表明,基频噪声仿真值与试验值分别为86.69,89 dB,误差在4%左右,总声压级分别为94.38,93.804 dB,误差为0.6%。因此声压频谱吻合较好,仿真值与试验值一致性较高,可以进行噪声预测。此外,对不同转速下风机对噪声的影响进行讨论,以验证预测分析的实用性。结果表明,叶轮转速升高,对其离散噪声的影响显著,随着叶轮转速提高,其压差变化越来越显著,所引起的旋转噪声越来越大,基频噪声升高了19.29 dB,声压级变化明显。因而,转速对离散噪声的影响较大,合理选择转速来控制噪声是一种简单有效的方法。通过上述研究的数值计算方法,可以一定程度上减小试验模型反复铸造、调试的时间和成本,为进一步优化风机气动噪声,降低噪声提供思路。     

高压比大推力离心压气机流场分析

基于CFD设计了一款转速60000 r/min、压比7、流量1.5 kg/s的大推力压气机,采用spalart-allmaras湍流模型和Navier-Stokes方程组对压气机叶轮内的气体流动及其工作范围进行了数值模拟,分析了60000 r/min转速时最高效率点附近的相对马赫数和流线云图,开展了非设计转速下的流场分析,计算了不同转速下的工况,研究了设计转速下叶轮入口处激波和射流尾迹的流动情况。研究结果表明：设计工况条件下,等熵效率为84.25%,压比为8.167;转速从48000 r/min到54000 r/min时,等熵效率提高,流场改善,气动损失减小;压气机转速从60000 r/min增加到72000 r/min时,压气机等熵效率、气动损失减小、稳定工作范围收窄;高压叶轮的主要气动损失为叶片表面的激波损失、叶尖间隙损失、二次流损失及吸力面尾缘的低能流体。     

打磨修理对跨声速压气机性能的影响研究

为了控制航空发动机压气机叶片损伤继续发展,通常采用孔探打磨进行修理。为研究其带来的影响,选取跨声速压气机Rotor37为研究对象,构建了不同叶高的叶片前缘打磨修理模型,采用数值模拟方法,研究了打磨修理对跨声速压气机气动性能的影响,结果表明:叶片前缘打磨修理使压气机整体性能下降,压比减小,效率降低,使堵塞点流量减小,而对失速流量点基本没有影响;不同叶高的打磨修理中心对压气机气动性能影响趋势一致影响幅度相当,但打磨叶高的不同造成压气机内部流场变化;叶片前缘打磨后,打磨处激波前马赫数增加,激波强度增大,影响效果随着叶高的增加而增加;压气机进口因为叶片打磨而造成相对动能在叶片打磨处附近降低。     

护风圈对发动机冷却风扇气动性能影响的CFD分析

本文采用Realizable k-ε湍流模型对发动机冷却风扇进行CFD模拟,计算了转速2000r/min时的风扇流量,研究护风圈对其气动性能的影响。在此基础上,利用宽带声源模型中的Curle噪声源模型对风扇流场中的噪声源分布进行了分析,并通过瞬态仿真分析护风圈对风扇噪声频率特性的影响。分析结果表明:安装护风圈可以提高风扇11.6%的流量,同时可以降低气动噪声。     

某型十级高压压气机进口总压周向畸变试验研究

以某型高压压气机为试验对象,研究了进口总压180°周向畸变对该压气机性能的影响。开展进口均匀进气和总压周向畸变条件下的压气机特性录取试验,并对试验结果进行了对比分析。结果表明:进气周向畸变导致压气机性能恶化,流量、效率均有一定程度的下降;周向畸变对高转速影响较大,随着转速降低影响逐渐减弱。     

叶轮扭振引发离散气动噪声理论计算模型研究

对叶轮振动模态进行分析 ,表明由于叶片刚度远小于轮毂的刚度 ,叶轮振动以叶片振动为主 ,而叶片振动低频表现为扭摆振动 ,高频表现为表面弯曲波振动。低频振动对叶轮气动噪声影响很大 ,本文基于Lowson离散噪声模型对叶片扭振引发离散气动噪声声压的估算公式进行了推导 ,为工程应用提供了方便     

带加强盘的交错叶片型风机结构及流动特性

为提高大流量离心风机的气动性能,运用计算流体动力学研究了加强盘位置及叶轮型式对叶轮结构强度、风机性能及压力脉动的影响。结果表明：加强盘居中时风机设计点效率与原型机相比提升3.9%,叶轮最大总变形量减小56.5%,蜗壳流域压力脉动降低5.4%;表面加强盘居中有利于增强叶轮结构强度,提升风机气动性能并降低蜗壳流域压力脉动;采用交错叶片能降低70%以上蜗壳流域压力脉动,有利于风机离散噪声控制;受高低能流体掺混产生的湍动能耗散影响,交错叶片型风机气动损失增加,且叶道内压力脉动幅值增大。加强盘居中和采用交错叶片是提高大流量离心风机气动性能和降低离散噪声的有效方法,但需注意其对气动损失的影响。研究结果可为大流量风机加强盘设计提供理论依据。     

变流量工况下小型离心压气机多目标优化设计

为提高离心压气机变流量工况下的性能,基于三维流场分析研究了离心压气机叶片几何参数对其变工况气动性能的影响规律;基于相关性分析建立了降阶的优化设 计变量空间,采用拉丁超立方试验设计、Kriging模型和NSGA-Ⅱ算法进行了离心压气机叶轮变流量工况多目标优化。优化后,叶轮设计流量的压比提高6.43%,效率提高3.99%;小流量时压比提高5.62%,效率提高3.52%;内部流动损失减少,喘振流量减小2.7%,阻塞流量增加6.85%,稳定工作范围得到扩宽。     

Analysis and measurement of the impact of diffuser width on rotating stall in centrifugal compressors

In compression systems, instability has long been an important issue. However, compared to axial machines, relatively little work has been done on the stability of centrifugal machines. Especially, many analytical models of stabilities have been developed to predict and control rotating stall, using compressor characteristic. However, stability models for centrifugal compressors are not scarce. Much research on compressor stability has focused on stalling flow coefficient and rotating stall phenomenon at the stalling flow coefficient. Given this situation, this paper presents a stability analysis of centrifugal compressors to predict rotating stall inception as well as the speed and number of cells. This analysis involves the use of compressor geometries, a steady compressor characteristic, and threedimensional flow analysis in the diffuser. The flow field perturbations at the axial inlet duct, impeller, and radial exit duct are determined via an eigenvalue analysis. The predictions are validated against experimental results from compressors with three different diffuser widths. The model accurately predicts the rotating stall inception flow coefficient. As the compressor characteristic becomes less steep with increasing diffuser width, the stalling flow coefficient increases. Also, experiment validates the model prediction that, depending on the dominant mode of flow perturbation, the number of rotating stall cells can be changed from three to two cells in the tested configurations. Furthermore, the cell speed increases as the flow coefficient decreases for a given number of stall cells. However, when the stall cell number is reduced, the cell speed decreases.     

自循环机匣处理对离心压气机气动性能影响分析

对比分析了带实壁机匣与带处理机匣的压气机模型在多工况下的气动性能,结果表明,在不同转速下,处理机匣结构都具有不同程度的扩稳作用,但同时也造成绝热效率有所降低,而且峰值效率损失随着转速增大而加剧;处理机匣前后槽口与叶顶通道形成的回流运动可有效地削弱激波与间隙泄漏流的强度以及二者的相互作用,有利于改善叶轮通道的气体流通性。     

磁悬浮压缩机顶隙调压模型与实验

风压紊乱是造成压缩机旋转失速、喘振等故障的直接原因,磁悬浮压缩机具有主动控制磁悬浮转子轴向位移对风压进行调控的优势。通过建立主动磁轴承轴向控制的动力学方程,首先,分析了磁悬浮转子稳定悬浮及轴向位移调整原理;其次,采用对磁悬浮压缩机风压性能有决定性影响的转速、叶轮高度、叶轮顶端间隙等参数,建立了磁悬浮压缩机叶轮顶隙与蜗壳出口风压之间关系的数学模型;最后,以30kW磁悬浮压缩机为实验对象,在叶轮顶隙分别改变0.1mm及0.2mm时,对出口风压及流量进行采集与分析。实验结果表明,磁悬浮压缩机蜗壳出口风压在数值上与所建数学模型的解算值契合度较高,并且叶轮顶隙对其有显著影响。针对压缩机不同故障状态,可依据数学模型选择不同叶轮顶隙进行调节。     

扭曲叶片贯流风机流场及扭曲角对性能的影响研究

研究了电壁炉用贯流风机在扭曲叶片下的三维内部流场,数值比较了不同扭曲角对贯流风机出风口体积流率的影响,从而得到贯流风机叶轮在一定转速下,叶片扭曲角取60°时,风机出风口风量最大,性能最优.通过自建的贯流风机性能参数检测台,实验测试了扭曲叶片贯流风机出风口平均风速和直叶片贯流风机出风口平均风速大小,并且和数值计算结果基本吻合.为贯流风机叶片优化设计提供了重要的理论基础.     

Experimental investigation on aero-acoustic characteristics of a centrifugal compressor for the fuel-cell vehicle

A variety of centrifugal compressors are used in various fields of industry such as aircraft, home appliances, and vehicles. Comfort and quietness are important in these uses. As a result, noise has become an important consideration in compressor design besides the conventional performance parameters such as efficiency and pressure ratio. However, compressor noise has been difficult to understand because of the lack of information. The aim of this paper is to investigate the aero-acoustic characteristics of a centrifugal compressor for the fuelcell vehicle by experiments. The existing compressor system is modified to measure the internal pressure fluctuation at the impeller inlet, the impeller outlet and the diffuser outlet. Four microphone probes are also installed to determine the external noise levels and spectra of the compressor in an airtight room according to the RPM and mass flow rate. The test results show the possibility to tell the relative noise level of a centrifugal compressor with the internal pressure data. The external microphone signals have relation to the internal pressure signals. They have similar patterns and spectra. It is a noteworthy phenomenon because it is easier and inexpensive to predict pressure behaviors than noise characteristics of centrifugal compressors. The dominant noise source is the tonal noise during normal operation. But the broadband noise component due to the turbulent flow in the compressor increases during low flow rate operation. Computational simulations are carried out to describe these phenomena and to identify noise indicators. The turbulence kinetic energy and the pressure distribution obtained from CFD results may be indicative of the relative noise intensity of the compressor. The experimental facility, instrumentation and simulation conditions are described, and the results are presented in this paper.     

多级离心压缩机级间弯道与回流器内流动的数值研究

对某型多级离心压缩机的气动性能进行了CFD数值研究,计算方法基于Jameson格式,湍流模型选择BaldwinLomax模型.对弯道与回流器等多级压缩机级间的静止部件内的气动特点进行研究,旨在揭示气流经弯道与回流器后气动参数的变化特征.结果表明,不同位置的弯道对流动的影响是截然不同的.由于这些静止部件对流体的扰动,使次级动叶的进口来流工况点偏离设计值,易于造成对整机气动性能的下降.因此多级压缩机的动叶设计应对来流的不均匀性加以充分考虑.     

小型LNG装置混合制冷剂螺杆压缩机工作过程模拟

螺杆压缩机具有结构紧凑、维护方便和工况适应性强等优点,在采用混合制冷剂液化流程工艺(MRC)的小型LNG装置中具有良好的应用前景。在MRC流程中需要两级压缩,级间压力是影响两级螺杆压缩机运行状态的主要参数之一。本文根据混合制冷剂工艺流程参数特点,采用圆弧及圆弧包络线构建了螺杆转子型线,分析了两级压缩机工作腔容积的变化规律,建立了两级螺杆压缩机工作过程的数学模型,研究了压缩机工作过程中工作腔内气体压力、级间压力、等熵效率等参数的变化规律。结果表明:两级螺杆压缩机的级间压力依据各级瞬态质量流量自动形成,压缩机稳定运行时的级间压力能使各级质量流量相等;级间压力随转速的增大而逐渐降低,各级等熵效率均随转速的增大而增大。     

离心压缩机动静干涉信号特征识别方法

离心式压缩机由于内部静、动叶片排的相对运动,气流在压缩机内部流动时会产生动静干涉,从而会产生不定常气流激振力和高振幅压力脉动。这种非定常动静干涉对压缩机的稳定正常运行和实际工作效率有着重要的影响。为了有效研究动静干涉的信号特征,首先,对某模型级压缩机试验台离心叶轮进行运行模态仿真计算从而得到叶轮干涉图;其次,确定进口导叶(inlet guide vanes,简称IGV)和出口扩压器(outlet guide vanes,简称OGV)对叶轮存在干涉的转速;最后,在确定的试验转速工况下进行应变测试和压力脉动测试。通过分析对比,验证了仿真转速工况下干涉特征频率的存在,也证实了应变信号更适用于识别干涉信号特征。通过总结干涉较严重的转速工况干涉特征频率与叶轮固有频率的关系,为离心压缩机进一步改进设计奠定了基础。     

Aeroacoustic characteristics and noise reduction of a centrifugal fan for a vacuum cleaner

The aeroacoustic characteristics of a centrifugal fan for a vacuum cleaner and its noise reduction method are studied in this paper. The major noise source of a vacuum cleaner is the centrifugal fan. The impeller of the fan rotates at over 3000 rpm, and generates very high-level noise. It was revealed that the dominant noise source is the aerodynamic interaction between the rotating impeller and stationary diffuser. The directivity of acoustic pressure showed that most of the noise propagates backward direction of the fan-motor assembly. In order to reduce the high tonal sound generated from the aerodynamic interaction, unevenly pitched impeller and diffuser, and tapered impeller designs were proposed and experiments were performed. Uneven pitch design of the impeller changes the sound quality while the overall sound power level (SPL) and the performance remains similar. The effect of the tapered design of impeller was evaluated. The trailing edge of the tapered fan is inclined. This reduces the flow interaction between the rotating impeller and the stationary diffuser because of some phase shifts. The static efficiency of the new impeller design is slightly lower than the previous design. However, the overall SPL is reduced by about 4 dB(A). The SPL of the fundamental blade passing frequency (BPF) is reduced by about 6 dB(A) and the 2^nd BPF is reduced about 20 dB(A). The vacuum cleaner with the tapered impeller design produces lower noise level than the previous one, and the strong tonal sound was dramatically reduced.     

平动回转式压缩机的泄漏研究

建立了平动回转式压缩机主要泄漏通道的数学模型,通过计算得到各个通道的泄漏量随转角的变化情况,进行了泄漏量的分析,并比较了各个泄漏通道的泄漏量。计算结果表明:各个泄漏通道中,转子外表面与气缸内表面之间的径向间隙的泄漏量最大,占总泄漏量的80.38%,其次是转子端面间隙和滑片端面间隙,其泄漏量各占总泄漏量的9.48%和10.14%;在相同的工作条件下,各个泄漏通道的泄漏量都随转速的升高而增大,但各个通道泄漏量所占的比例基本不变;通过平动回转式压缩机性能试验对制冷量的测试间接验证了泄漏模型的正确性;通过对间隙泄漏的研究,为平动回转式压缩机的设计研究和加工提供了理论依据。