离心泵叶片尾部结构优化设计对性能影响的研究

优化离心泵叶片结构是改善其性能参数的有效途径。叶片的尾部结构与泵内液体的流动状况存在一定关系,而泵内的流动状况很大程度上影响着离心泵的压强分布和空化性能。为进一步优化离心泵的空化性能,以一定数量的叶片为前提,优化泵内3种叶片的尾部结构进行泵内的流场计算和空化计算,以期得到抗空化性能更好的叶片结构。     

离心泵作透平流体诱发内场噪声特性及贡献分析

对某离心泵作透平流体诱发的内场噪声特性进行数值计算和试验研究。在典型流量下,采用雷诺时均方法获取壳体壁面偶极子声源,并利用边界元方法(Boundary element method,BEM)求解出壳体偶极子源作用的流动噪声,基于有限元结合边界元的声振耦合法(Finite element method/boundary element method,FEM/BEM)计算出流体激励结构振动产生的内场流激噪声及考虑结构振动的流动噪声,分析不同性质噪声源的频谱特性,同时评估内场声源在各个频段下的贡献量。借助水听器对透平出口进行流体声学试验,获得了噪声的频谱特性。结果表明,离心泵作透平出口流体诱发噪声主要集中在中低频段,小流量工况低频噪声特性增强。壳体声源作用下考虑结构振动流动噪声的计算结果与试验结果在较大流量下吻合较好。壳体偶极子作用的流动噪声对内场噪声的贡献最大,其次是考虑结构振动的流动噪声,流激噪声对内场噪声贡献最小。结构的影响使得二阶叶频处声压增加,其余离散频率及宽频处声压均有所降低。该研究结果为低噪声叶轮机械设计提供了一定的参考。     

离心泵内部流动诱导噪声的研究

介绍离心泵内部流动诱导噪声的国内外研究概况。结合声学分析软件SYSNOISE，阐述了离心泵内部流动诱导噪声的一些数值模拟方法，如有限元方法、边界元方法及有限元和边界元耦合分析法等，并探讨了离心泵内部流动诱导噪声的一种数值模拟方法。此外，还详细介绍了离心泵内部流动诱导噪声的两种测试方法：双传声器传递函数法和四端网络法。     

基于CFD的离心泵三维流场模拟研究

通过FLUENT软件对离心泵进行三维流场数值模拟.利用模拟计算结果分析了离心泵的内部流动规律;蜗壳菲对称结构对流场分布的影响;隔舌对流动的影响,其分析研究为离心泵的优化设计提供了基础信息.     

不同叶片冲角离心泵内流诱导振动噪声研究

基于离心泵流动诱导振动噪声的试验测试系统,测量了不同叶片进口冲角模型泵在全流量范围内的振动和噪声信号并对其进行了处理和分析。研究结果表明:叶片进口冲角存在一个最优值,使离心泵的性能最佳;模型泵内部流动诱导的振动对泵体的影响最大,随着叶片进口冲角的增加,在各流量下模型泵噪声信号的轴频和叶频能量峰值均没有明显变化规律,但当叶片进口冲角为9°时,在1750～2250Hz频段内的噪声信号消失。     

离心泵内部流场测量系统设计及测量方法研究

离心泵是工业生产过程中的重要设备.离心泵内部流场的测量对优化泵的结构,提高泵的效率,减小泵工作时产生的噪声具有重要的意义.设计、构建了一套多功能离心泵性能试验台,该试验台能够满足泵内非定常流动非接触测量和离心泵外特性测量的需要.介绍了离心泵特性测定的方法和步骤,探讨了应用PIV(Particle Image Velocimetry)测量离心泵内部流场的关键技术及其主要试验参数的确定方法.     

离心泵蜗壳对叶轮内部流动的影响研究

本文基于三维雷诺时均的Navier—Stokes方程和标准的k—ε湍流模型,采用三维无结构网格及压强连接的隐式修正SIMPLEC算法,利用Fluent中提供的多重参考系（MRF）模型,分别对IB型离心泵的叶轮与整机流道进行内部流动的数值模拟,根据计算结果分析离心泵蜗壳对叶轮内部流动的影响,揭示离心泵内的流动规律。对离心泵性能的预测值与实验值作了比较以验证计算结果的正确性。     

基于CFD/CA声比拟分析的两级离心泵流动诱导噪声数值模拟

针对两级离心泵的流体诱发噪声产生的复杂机理,基于Lighthill声比拟理论,采用了计算流体力学(CFD)与计算声学(CA)结合的数值模拟分析方法,研究了两级离心泵变工况下的流场特性及诱发的辐射噪声。采用SST k-ω模型计算分析了不同工况下两级离心泵内部非稳态流场及关键区域压力脉动特性,进而采用声学有限元法(AFEM)计算离心泵内场辐射噪声的声压级变化。研究结果表明,两级离心泵压力脉动幅值从吸水室进口到叶轮出口逐渐增大,叶轮出口处的压力脉动强度最大、声压级最高,且不同工况下压力脉动的主频保持为叶频及其倍频,叶轮和蜗壳之间的动静干涉是流动诱导噪声产生的主要原因;总体声压级在低流量工况下较高,随流量增大逐渐减小,在设计工况处最小;越接近压力脉动主频,声压级的分布越离散,宽频特性越明显,压力脉动强度为流动诱导噪声产生的主要影响因素。研究结果对两级离心泵的低噪设计和水力性能改善提供理论依据和参考。     

6-U式离心泵内流场的数值模拟

为了分析离心泵内三维不可压缩流体相关特性,以便更好地利用其结果对离心泵进行设计与修正.运用CFDesign流体分析软件,对离心泵内三维不可压缩斋流流动进行了数值模拟.分析了离心泵吸入室、涡室内流体不同截面处的压力及速度特性;并得到了泵的流量及扬程值其结果与实验值达到了很好的吻合.     

叶片数对螺旋离心泵内部流场影响研究

利用工程上普遍采用的k-ε两方程模型和SIMPLE算法,对单叶片和双叶片螺旋离心泵的内部流场进行了数值模拟.得出了叶轮与蜗壳内的速度分布和压力分布等流场信息,比较了单叶片和双叶片螺旋离心泵的特性曲线,单叶片和双叶片螺旋离心泵内部流场的区别与联系,分析了叶片数对螺旋离心泵内部流动规律的影响.     

离心泵水动力噪声测试系统的研制

阐述了水泵水动力噪声测试试验系统的组成及其所依据的试验原理，重点介绍了基于四端网络的测量分析方法。该试验系统能同时检测被测系统的水力学参数及水下噪声、振动和空气噪声，并可对它们进行实时或非实时同步分析。同时还可方便控制压头、流量及阀门大小等水力学参数，以研究这些参数的变化对水泵水动力噪声的影响。该系统能够对离心水泵水下噪声机理进行深入的研究，同时可以检验各种降噪措施的实际效果。     

一种新型球塞液压油泵的研制

介绍了一种新型径向球塞液压油泵及其试验装置，该球塞液压泵的工作原理是由主轴带动转子旋转，使其球塞、球塞孔和配流轴之间形成的工作腔体体积发生周期性变化，从而实现吸排液压油。简要说明了该泵在设计加工制造过程中的关键技术，对该泵的流量、压力、噪声进行了全面的性能试验检测，根据其性能曲线进行性能分析，该泵在转速1000 r/min时其流量可达理论流量的88%，压力可达5.8 MPa，噪声65 dB，为液压泵的后续研究提供必要的参考。该泵具体性能指标为最大转速1300 r/min，输出流量范围0~130.6 L/min，输出压力范围0~6.7 MPa，运转噪声最大66 dB，重量33 kg，工作介质为液压油。     

Experimental investigation on the flow-induced noise under variable conditions for centrifugal pumps

With extensively using of centrifugal pumps,noise generation in these pumps is increasingly receiving research attention in recent years.The noise sources in centrifugal pumps are mainly composed of mechanical noise and flow-induced noise.And the study of flow-induced noise has become a hotspot and important domain in the field.The flow-induced noise closely related to the inner pressure pulses and vibration of volute in pumps,therefore,it is necessary to research the interaction and mechanism among them.To investigate the relationships,a test system is designed which includes a test loop and a measurement system.The hydrophones and pressure sensors are installed on the outlet of the pump and vibration acceleration sensors are disposed on the pump body.Via these instruments,the signals of noise,pressure pulses and vibration are collected and analyzed.The results show that the level of flow-induced noise becomes smaller as the flow increment during low flow rate operations,and it is steadily close to the design point,then it increases with the growing of flow rate in high flow rate conditions.Furthermore,there are some similar peak points in the power spectrum charts of noise,pressure pulses and vibration.The broadband noise at low flow rate is mostly focused on the region of 0-40 times shaft frequency,which is mostly made by rotating stall and vortex;while the noise at high flow rate conditions is focused on the region of 60-100 times shaft frequency,which may be mostly made by cavitations.The proposed research is of practical and academic significance to the study of noise reduction for centrifugal pumps.     

基于Lighthill声类比法的外啮合齿轮泵流致噪声特性研究

为深入了解外啮合齿轮泵运行中流致噪声规律,基于CFD和Lighthill声类比理论建立其流致噪声数值仿真模型,以研究不同转速工况下外啮合齿轮泵流致噪声特性,并搭建实验测试系统,用水听器对泵的出口2倍管径处流体噪声进行测量,以获得其时域和频域信息。结果表明:流致噪声由离散噪声和宽频带噪声构成,且基频及其倍频为流致噪声的主要频率;泵体辐射噪声的强度随齿轮转速的增加而非线性单调增长,且在1000~2000 r/min转速区间辐射噪声急剧增长(增量约20 dB);流致噪声的主频是由压力脉动的主频以及壳体的固有频率共同决定的。     

水压柱塞泵噪声特性的试验研究

基于阀配流式轴向水压柱塞泵的结构原理,分析了其噪声产生的主要原因,并对不同的配流阀结构型式、主轴动平衡前后、不同转速以及不同排量水压泵的噪声特性进行了对比试验研究。试验结果表明:采用平板型配流阀的水压泵噪声低于蕈阀结构的噪声;主轴动平衡后水压泵的噪声有明显降低;增大排量、降低转速可以降低泵的噪声;配流阀通径对泵的噪声影响较大。研究结果为水压泵的降噪提供了试验依据。     

NOISE IDENTIFICATION FOR HYDRAULIC AXIAL PISTON PUMP BASED ON ARTIFICIAL NEURAL NETWORKS

The noise identification model of the neural networks is established for the 63SCY14-1B hydraulic axial piston pump. Taking four kinds of different port plates as instances, the noise identification is successfully carried out for hydraulic axial piston pump based on experiments with the MATLAB and the toolbox of neural networks. The operating pressure, the flow rate of hydraulic axial piston pump, the temperature of hydraulic oil, and bulk modulus of hydraulic oil are the main parameters having influences on the noise of hydraulic axial piston pump. These four parameters are used as inputs of neural networks, and experimental data of the noise are used as outputs of neural networks. Error of noise identification is less than 1% after the neural networks have been trained. The results show that the noise identification of hydraulic axial piston pump is feasible and reliable by using artificial neural networks. The method of noise identification with neural networks is also creative one of noise theoretical research for hydraulic axial piston pump.     

Flow Ripple of Axial Piston Pump with Computational Fluid Dynamic Simulation Using Compressible Hydraulic Oil

The flow ripple, which is the source of noise in an axial piston pump, is widely studied today with the computational fluid dynamic(CFD) technology development. In the traditional CFD modeling, the fluid compressibility, which strongly influences the accuracy of the flow ripple simulation results, is often neglected. So a compressible sub-model was added with user defined function(UDF) in the CFD model to predict the flow ripple. At the same time, a test rig of flow ripple was built to study the validity of simulation. The flow ripple of pump was tested with different working parameters, including the rotation speed and the working pressure. The comparisons with experimental results show that the validity of the CFD model with compressible hydraulic oil is acceptable in analyzing the flow ripple characteristics. In this paper, the improved CFD model increases the accuracy of flow ripple rate to about one-magnitude order. Therefore, the compressible model of hydraulic oil is necessary in the flow ripple investigation of CFD simulation. The compressibility of hydraulic oil has significant effect on flow ripple, and the compression ripple takes about 88% of the total flow ripple of pump. Leakage ripple has the lowest proportion of about 4%, and geometrical ripple leakage ripple takes the remnant 8%. Besides, the influence of working parameters was investigated through the CFD simulations and experimental measurements. Comparison results show that the amplitude of flow ripple grows with the increasing of rotation speed and working pressure, and the flow ripple rate is independent of the rotation speed. However, flow ripple rate of piston pump grows with the increasing of working pressure, because the leakage ripple will increase with the pressure growing. The investigation on flow ripple of an axial piston pump using compressible hydraulic oil provides a more validity simulation model for the CFD analyzing and is beneficial to further understanding of the flow ripple characteristics in an axial piston pump.     

节气门急速开启过程流动噪声数值分析与研究

研究了节气门运动对流动噪声的影响。采用计算流体力学与计算声学耦合方法,并结合运动网格技术,实现对节气门由关闭向全开位置急速转动过程时空气瞬态流动引起噪声形成的三维数值模拟,分析了节气门处于不同转角时刻,空气流场与流动噪声的变化规律。在节气门转动初期,节气门后侧流动区域有涡流形成,节气门前后两侧的压力发生陡降,在节气门上边缘和下边缘附近产生两个流动噪声区,随后在节气门下游逐渐合并。流动噪声声功率级先增加然后逐渐减小,并接近稳定,节气门开度在40°附近时,声功率级达到最大。随着节气门开度的继续增加,节气门后侧的涡流逐渐减弱,节气门前后两侧的压力降逐渐减小。噪声场时域-频域计算结果发现,节气门噪声属于中低频段宽频噪声,其中大约100Hz以下的低频噪声占主要贡献量,声压级较高,并且声压没有随着测点与节气门的距离增加而明显衰减。控制节气门流动噪声的重点在于减少低频噪声。     

Experimental study of the influence of flow passage subtle variation on mixed-flow pump performance

In the mixed-flow pump design, the shape of the flow passage can directly affect the flow capacity and the internal flow, thus influencing hydraulic performance, cavitation performance and operation stability of the mixed-flow pump. However, there is currently a lack of experimental research on the influence mechanism. Therefore, in order to analyze the effects of subtle variations of the flow passage on the mixed-flow pump performance, the frustum cone surface of the end part of inlet contraction flow passage of the mixed-flow pump is processed into a cylindrical surface and a test rig is built to carry out the hydraulic performance experiment. In this experiment, parameters, such as the head, the efficiency, and the shaft power, are measured, and the pressure fluctuation and the noise signal are also collected. The research results suggest that after processing the inlet flow passage, the head of the mixed-flow pump significantly goes down; the best efficiency of the mixed-flow pump drops by approximately 1.5%, the efficiency decreases more significantly under the large flow rate; the shaft power slightly increases under the large flow rate, slightly decreases under the small flow rate. In addition, the pressure fluctuation amplitudes on both the impeller inlet and the diffuser outlet increase significantly with more drastic pressure fluctuations and significantly lower stability of the internal flow of the mixed-flow pump. At the same time, the noise dramatically increases. Overall speaking, the subtle variation of the inlet flow passage leads to a significant change of the mixed-flow pump performance, thus suggesting a special attention to the optimization of flow passage. This paper investigates the influence of the flow passage variation on the mixed-flow pump performance by experiment, which will benefit the optimal design of the flow passage of the mixed-flow pump.     

Numerical and experimental study on flow-induced noise at blade-passing frequency in centrifugal pumps

With the increasing noise pollution, low noise optimization of centrifugal pimps has become a hot topic. However, experimental study on this problem is unacceptable for industrial applications due to unsustainable cost. A hybrid method that couples computational fluid dynamics （CFD） with computational aeroacoustic software is used to predict the flow-induced noise of pumps in order to minimize the noise of centrifugal pumps in actual projects. Under Langthjem＇s assumption that the blade surface pressure is the main flow-induced acoustic source in centrifugal pumps, the blade surface pressure pulsation is considered in terms of the acoustical sources and simulated using CFX software. The pressure pulsation and noise distribution in the near-cutoff region are examined for the blade-passing frequency （BPF） noise, and the sound pressure level （SPL） reached peaks near the cutoff that corresponded with the pressure pulsation in this region. An experiment is performed to validate this prediction. Four hydrophones are fixed to the inlet and outlet ports of the test pump to measure the flow-induced noise from the four-port model. The simulation results for the noise are analyzed and compared with the experimental results. The variation in the calculated noise with changes in the flow agreed well with the experimental results. When the flow rate was increased, the SPL first decreased and reached the minimum near the best efficient point （BEP）; it then increased when the flow rate was further increased. The numerical and experimental results confirmed that the BPF noise generated by a blade-rotating dipole roughly reflects the acoustic features of centrifugal pumps. The noise simulation method in current study has a good feasibility and suitability, which could be adopted in engineering design to predict and optimize the hydroacoustic behavior of centrifugal pumps.