基于试验数据的轴流压气机喘振边界经验预估方法

从压气机特性计算统计法的基本思想出发,对多台轴流压气机喘振试验数据进行了整理分析,总结了同类型压气机喘振边界上参数变化的一般规律,在此基础上,将压气机设计转速下的喘振参数与其非设计转速下的喘振参数进行相互关联,提出了一种基于试验数据的轴流压气机喘振边界经验预估方法.通过与试验结果的详细对比.表明本文所建立的经验方法能够...     

叶片后弯角对车用离心压气机性能的影响

对比分析了6种不同转速下压气机性能的试验与仿真结果.在验证了ANSYS CFX软件用于压气机性能模拟分析中的可靠性后,采用数值模拟方法对3种不同叶片后弯角的叶轮进行了性能计算,得到了相关转速下的压气机特性曲线.仿真结果表明:在不改变压气机出口静压时,在一定的叶片出口角范围内,叶片后弯角的增加使两条特性曲线均向小流量方向偏移,但近喘振点边界得到了拓展,使得压气机的流量范围变得更宽;在小流量区域内,叶片后弯角的增大能够改善压气机内部流动状况,提高叶轮工作效率;而在大流量区域内,较大的叶片后弯角会使叶轮的流通特性降低,叶轮的工作效率反而会降低;适当增加叶片后弯角可以增大压气机工作范围,使压气机效率和流道内的流动均得到提高和改善.     

两区模型离心压气机性能预测方法研究

为获得有效的压气机性能预测方法,基于车用涡轮增压器压气机性能试验数据,重点研究了两区模型离心压气机性能预测及标定方法.研究结果表明:该预测方法仔细考虑了压气机内部扩散和损失过程,综合考虑逆压梯度黏性流动过程影响,标定方法简单实用,能方便地应用于工程设计;该性能预测方法也能有效预测涡轮增压器离心压气机流量特性及喘振、堵塞边界特性,能够反映出压气机的全工况性能;与试验结果相比,预测压比与试验压比差值小于3 %,预测绝热效率差值小于5 %,在高转速跨音速工况下预测喘振堵塞流量差值小于0.06.     

压气机动态模型的建立及喘振过程分析

在SIMULINK环境中,建立了压气机动态数学模型。为了模拟压气机喘振和旋转失速现象,压气机特性图被延伸到负流量区域,还考虑到了气体通过压气机的延迟。模拟了压气机的喘振过程,并对压气机压力信号进行FFT变换,检测了压气机喘振。仿真结果表明:模型能预测压气机喘振过程中压力、流量和转速的振荡频率和振幅;压缩系统的转动惯量、稳压室容积等结构参数影响喘振特性;模型动态调节特性好,可用于压气机控制系统模型,具有广泛实用性。     

多级轴流压气机全工况特性预测

使用三维粘性流动计算软件Fine／Numeca,研究了多级轴流压气机在设计工况及非设计工况的性能预估问题。对某七级轴流压气机进行了全工况特性数值计算。重点分析了低转速下近失速点、设计转速下近最高效率点、高转速下近堵塞点、进口导叶关小时设计转速下近失速点等四个典型工况点的流场特性。计算工作在自主开发的20节点集群计算机系统上进行。计算结果表明现有的软件和硬件平台能比较准确地预测压气机多叶片排的全工况特性。     

贫燃催化燃烧燃气轮机压气机的设计及其性能分析

分析了贫燃催化燃烧燃气轮机系统中压气机的结构特点,设计了低出口宽径比、高比转速的压气机叶轮,并采用数值计算和试验2种方法预测了其工作性能.结果表明:数值计算与试验结果基本吻合,该压气机在全工况下达到设计要求,且2种结果的高压比区域、高效率区域均远离喘振线;低宽径比、高比转速压气机的设计点在高效区;随着转速的提高,此压气机的压比特性曲线在小流量区增长的趋势明显;采用低宽径比、高比转速设计的负面作用是增大了叶尖相对马赫数.     

轴流式压气机喘振特性的某些规律

综合了几型压气机的试验结果,总结出喘振边界的某些规律。利用这些规律不仅可以减少试验的次数。还可以计算出喘振边界上有关的参数。     

涡轮增压器压气机内部流场的CFD分析

本文采用三维扫描技术与实体造型软件建立了YJP60系列增压器压气机总成内部流道模型和压气机总成耦合流场网格模型,运用CFD软件FLUENT模拟了增压器压气机总成三维粘性定常流动特性,分析了压气机的内部流动情况,并分别对长短叶片的凹凸面进行了速度场和压力场的计算分析,为该系列增压器的优化设计提供理论依据。     

小型离心压气机结构参数优化与流量特性的仿真分析

压气机的流量特性（图）是压气机使用的主要参考依据,但是目前仍主要依靠试验方法得到。笔者探讨利用稳态可压缩粘性流体微分方程和k-ε两方程紊流模型,采用有限体积法对离心压气机的工作状况进行三维仿真计算。对某型压气机,通过改变扩压器和k-ε蜗壳结构参数,得到优化模型。根据优化模型在每一转速不同出口静压工况下的计算结果,得到压气机的流量特性图。结果表明,CFD方法可以得到压气机的流量特性图,并且可以方便地分析压气机各部分的流动损失,是压气机设计及性能前期预测的一种有效方法。     

多级轴流压气机喘振特性分析

基于求解三维雷诺平均N-S方程,采用混合平面法并应用微机网络并行计算技术,结合Spalart-Allamaras一方程湍流模型,对某型多级轴流压气机非设计工况进行了数值计算,分析了近喘振工况下的流场特性。结果表明:在近喘振点时气流流量减小,在叶片吸力面尾缘处容易出现分离,而且叶根附近分离最强。数值模拟结果与实验数据吻合较好,可为压气机的设计和优化提供参考。     

带可调进口导叶的多级轴流压气机非设计点性能计算

多级轴流压气机为保证非设计转速下的性能,通常采用进口导叶(IGV)以及静叶可调的扩稳方法。为获得可靠的进口导叶性能以用于压气机初步设计和扩稳方案的初步筛选,基于Banjac和Petrovic等提出的IGV损失和落后角模型与平均中径计算相结合,开发了带有IGV的多级轴流压气机性能分析工具。选用E3压气机作为算例进行计算分析,结果表明,所选用的IGV模型在较大开度内具有较好的精度和有效性。研究结果可以为多级轴流压气机初步设计和扩稳方案确定提供参考。     

双离心压气机共用单一进气歧管致进口流场畸变的仿真分析

针对V型发动机的共用单一管路对置离心压气机进口流场畸变特性进行了研究,通过台架试验测试了初始压气机性能,完成了仿真模型的标定。在此基础上分析了压气机进口流场的变化特征,分析结果表明:共用单一管路对压气机特性影响明显,造成了两侧压气机堵塞流量的降低,在大流量工况区域效率明显下降,右侧压气机恶化程度要明显高于左侧。原因在于受安装位置空间限制,喉口处畸变扩展与进口周向畸变叠加效应使得右侧压气机在周向和叶高方向的畸变程度均高于左侧压气机。进口的畸变效应会一直持续至压气机叶轮内部,使压气机性能变差。     

Performance improvement of centrifugal compressors for fuel cell vehicles using the aerodynamic optimization and data mining methods

Centrifugal compressors are one of the most important auxiliary components in polymer electrolyte membrane fuel cell vehicles, which tend to operate at a narrow area with low specific speed. Here, the optimal design goals of centrifugal compressors are investigated on the basis of a lumped model for fuel cell systems. A three-dimensional multi-objective and multi-point aerodynamic optimization and data mining method for centrifugal compressors named ODM is presented via integrating a multi-island genetic algorithm, Reynolds-Average Navier-Stokes solver technique and self-organization map based data mining technique. Data mining indicates that compressor geometry would move to a small inlet diameter ratio and a narrow region of the outlet width ratio. Based on the optimization results, a centrifugal compressor for 100 kW fuel cell stack is manufactured. The experimental results show that the improvement of isentropic efficiency near low mass flow has been achieved, which indicates that the proposed ODM is effective in the performance improvement of centrifugal compressors for fuel cell vehicles.     

Three dimensional channel effect on the flow characteristics and the performance of hydrogen Knudsen compressors

As a new type of the micro fluidic device, Knudsen compressor can provide the potential utilizations on the hydrogen transport in the micro systems. Considering actual structure of the compressor is three-dimensional, flow characteristic studies are the key issue for the performance predictions. Firstly, the model of three-dimensional Knudsen compressor is built, and the validity of the model is proved by comparison with the experimental result. Secondly, the flow behaviors in the three-dimensional model is investigated, and the distributions of pressure and velocity are investigated. Also, the performance of the hydrogen Knudsen compressor in two-dimensional structure and three-dimensional structure are compared and discussed. Thirdly, the three-dimensional hydrogen Knudsen compressors with different width are analyzed, and the pressure increase in different cases of the hydrogen Knudsen compressors are studied.     

Numerical simulation of novel axial impeller patterns to compress water vapor as refrigerant

Through means of 3-D CFD (Computational Fluid Dynamics) method, a novel axial compressor with different impeller shapes compressing water vapor as refrigerant was investigated. The numerical simulation focuses on the fluid flow from compressor impeller inlet to outlet. The overall performance level and range are predicted. Different blade patterns with different hub sizes were compared regarding the aerodynamic performance. Independent of the blade pattern, in this numerical investigation the largest hub diameter shows the highest pressure ratio and efficiency at narrowest operating range.     

单级离心压气机气动性能预测与优化设计

为了提升低转速工况下压气机的气动性能,采用人工神经网络与遗传算法相结合的优化方法对某单级离心压气机离心叶轮的弯特性进行优化计算。利用NUMECA软件对该离心压气机进行了不同转速的数值模拟,得到压气机不同工况下的气动性能。通过设置不同控制参数和曲线形式对离心叶轮叶片进行参数化拟合,以8个改变叶片弯特性的参数为自由参数进行了叶型优化设计,最终得到了优化后的叶轮叶片。结果表明:优化后在低转速的设计工况下离心压气机压比增加了4.69%,稳定裕度拓宽了17.41%。     

The influence of wedge diffuser blade number and divergence angle on the performance of a high pressure ratio centrifugal compressor

Wedge diffuser is widely used in centrifugal compressors due to its high performance and compact size. This paper is aimed to research the influence of wedge diffuser blade number and divergence angle on centrifugal compressor performance. The impact of wedge diffuser blade number on compressor stage performance is investigated, and then the wedge diffusers with different divergence angle are studied by varying diffuser wedge angle and blade number simultaneously. It is found that wedge diffuser with 27 blades could have about 0.8% higher adiabatic efficiency and 0.14 higher total pressure ratio than the wedge diffuser with 19 blades and the best compressor performance is achieved when diffuser divergence angle is 8.3°.These results could give some advices on centrifugal compressor design.     

几何参数变化对离心压气机性能影响的仿真研究

采用离心压气机性能仿真数学模型研究某些几何参数，如叶片顶部间隙，叶轮叶片出口角变化对压气机性能产生的影响，是当今设计高压比、宽工作范围、高效离心压气机的关键步骤。为此，首先建立了离心压气机性能仿真数学模型。为了验证数学模型的有效性，对Krain叶轮性能进行了计算。随后，对不同叶片顶部间隙，不同出口叶片角的压气机性能进行仿真研究。研究结果表明，随顶部间隙的增大，压气机效率及压比下降；后弯叶轮性能优于径向叶轮。     

Effect of helium xenon as working fluid on the compressor of power conversion unit of closed Brayton cycle HTGR power plant

Helium is one of the best coolants in closed Brayton cycle power plants as it has superior transport properties; however, the main shortcoming is its compression, which is very difficult to achieve. It leads to a higher number of compressor stages, means bigger mass and big size of the compressor, which create dynamic issues in a compressor of the power conversion unit. All the helium compressors ever constructed have a very high number of stages such as Oberhausen II type 50 MW and JAEA 300 MW, high and low pressure compressors have 25 and 35 stages respectively. In this paper thermodynamic traits of mixing helium with an inert gas xenon were presented. Helium xenon mixture up to the molecular weight of <40 g/mol not only increases heat transfer coefficient but also significantly increase the loading of the compressor. A 7% higher heat transfer coefficient can be achieved with 15 g/mol helium xenon mixture. Therefore, a 15 g/mol helium xenon mixture compressor was designed and its performance analysis conducted using Ansys CFX. It is found that the use of 15 g/mol helium xenon mixture greatly increases the blade loading, which gives a higher total outlet pressure ratio. The obtained results indicated that only 18.75% stages of helium xenon compressor can generate requisite outlet pressure. Hence, the use of helium xenon over pure helium is advantageous as it reduces size and cost of turbo compressor of HTGR power plant.