卸荷阀抗气蚀结构的参数协同匹配优化方法

针对矿用乳化液泵站卸荷阀的严重气蚀问题,基于多级节流和高压引流原则提出一种适用于高压大流量工况的卸荷阀抗气蚀新结构。选取阀口半锥角、高压引流孔直径作为优化设计变量,融合最优拉丁超立方设计（Opt LHD）及多岛遗传算法（MIGA）,通过结构参数的变参定量分析获得了各设计变量对阀口空化特性的影响规律,通过参数间的智能优化与匹配,实现以提高阀口抗气蚀性能为目标的参数协同匹配优化。结果表明,优化后的阀口压力梯度显著降低,出口流速下降33.5%,阀套壁面冲击速度下降42.9%,体积平均气相分数下降61.3%。实际应用效果也验证了该优化方法可有效地降低卸荷阀的气蚀损伤程度,对同类型产品的优化设计具有一定的参考价值。     

抗气蚀串联多级节流控制阀设计研究

阀内介质压力合理分配和各级节流额定节流面积的确定,是抗气蚀串联多级节流控制阀的设计难点。以串联多级孔板为模型,本文提出一种介质压力分配方法,以高压差气蚀工况控制阀设计为实例,通过抗气蚀验算和对比分析,证明该方法可以有效抑制气蚀产生,且优于传统压力分配方法。同时,结合本文提出的各级额定节流面积的确定方法,可以精确地计算出各级额定节流面积,从而完成控制阀关键结构参数设计。     

节流槽形式对滑阀空化流场的影响

为了提高采煤工作面液压支架推移拉架准确度,降低空化现象对控制滑阀性能的影响,采用Pumplinx建立了不同节流槽形式下滑阀内部流体域动态模型。仿真分析了不同节流槽形式滑阀在不同开度时,压力场和空化分布以及气体体积分数的变化趋势。结果表明:不同节流槽形式对滑阀内部的压力分布和空化分布具有不同的影响;气体体积分数随着阀口开度的增大,呈现先稳定波动然后陡增最后在阀口完全开放后迅速降低的现象;交错分布形节流槽空化剧烈起始位置为4.5 mm,最大气体体积分数约为0.12,相较于其他槽形明显降低。     

配流盘三角形节流槽抗空化结构改进研究

轴向柱塞泵配流盘三角形节流槽主要是减小柱塞腔及泵出口压力的波动。由于节流槽过流面积小,且槽两端压差大,流体高速流过节流槽的同时压力急剧减小,从而产生空化。为减小配流盘三角形节流槽的空化,提出对配流盘三角形节流槽抗空化的结构改进方案:预卸压阶段,在不改变节流槽通流面积的条件下,减小三角形节流槽倾角可提高其空化抑制性;预升压阶段,在保证三角形节流槽进口过流面积不变时,增大出口的过流面积可有效抑制三角形节流槽的空化。通过仿真分析发现三角形节流槽结构改进后轴向柱塞泵的抗空化性能提高,泵空化程度降低。     

双U形节流槽滑阀多场耦合特性研究

压滑阀在工作过程中阀芯卡滞及磨损现象严重,为了改善阀腔流域特性及液压阀的工作性能,构建了液压滑阀的简化模型,基于计算流体力学对双U形节流槽滑阀阀芯及阀腔内流域动态特性进行了分析。研究了节流槽数量、阀口压差对阀腔内流体速度场、阀芯温度场及阀芯应变场动态特性的影响。研究结果表明,随着阀口压差的增加,流体的最大流速以及阀芯的最高温度和最大变形增大;随节流槽数量的增加,阀芯的最大变形增大,流体流速及阀芯最大温度变化微弱。该研究为阀芯优化设计提供了参考。     

空心阀杆节流槽设计及多路阀上的应用

介绍了一种空心滑阀阀杆节流槽开口形式,利用阀杆圆周开圆型孔的方式实现弓形节流口,采用多组弓形口不同的组合方式,通过合理的排列组合,在阀杆整个运动区间内获得所需的阀口面积曲线,满足液压执行机构在不同工况下对运动速度的要求。介绍了该节流槽已在多路阀上的应用实例,可为液压阀设计人员提供参考。     

V型液压阀口节流特性多目标优化

提出了用来衡量V型节流阀口节流特性指标:等效水力直径曲线Dh2的斜率dV2、阀口压降分配系数k、节流空化指数曲线σ2-X的值σ2A1in、σ2A1out。利用正交试验设计结构参数样本,运用模糊隶属度分析方法得到了节流特性较优的节流阀口结构参数组合。与初始的节流阀口结构相比较,其中dv2相对初始结构提高了177.19%;阀口压降分配系数k增加了149.98%,使阀口压降过分集中得到了缓解;空化集中截面A2附近的空化指数σ2A1in,σ2A1out分别下降了0.31%和14.99%,在一定程度上减轻了V型节流阀口的空化现象。     

基于Fluent的电磁卸荷阀主阀流场数值仿真分析

利用流体仿真软件Fluent建立了乳化液泵站电磁卸荷阀主阀的二维网格仿真模型,并利用建立的模型对主阀内的流体运动流场进行了仿真,得出在开口度不同以及压差不同时,主阀腔内流体的速度分布云图以及压力分布云图。通过分析得出：在一定条件下,主阀开口度越大,阀口拐角处的压力损失越少,流体流经阀口的流速越慢;流体的最大流速均出现在阀口处,主阀入口压力越大,流体流经阀口的流速越快。增加节流口,可减少工作介质对阀口产生的瞬间冲击、阀芯的振动、气蚀损害,可提高电磁阀的使用寿命。     

节流口结构对超高压插装阀液流特性的影响

超高压是液压系统未来发展的方向之一,因此分析超高压液压元件的性能非常重要。针对DN25超高压插装阀3种不同阀芯节流口结构的液流特性进行了分析。以Fluent软件为平台,建立了3种不同节流口结构的DN25超高压插装阀流场有限元模型,结合阀口的节流特性分析了流体的速度场和压力场,得到了不同阀口开度下的流量以及阀芯所受液压力,为超高压插装阀结构设计提供了理论基础。     

组合型节流槽对多路阀内流场特性影响的仿真研究

针对工程机械用多路阀阀口压损大、流速高,极易出现阀芯冲蚀磨损的问题,以某型号工程机械多路阀为例,设计不同组合形式的节流槽,研究多路阀阀口节流槽结构形式对阀口流阻损失及多路阀内部流场特征的影响。采用数值分析的方法研究了不同阀口节流槽形式在阀芯开启过程中阀口前后压差、流量、流速等流场特征。结果表明:阀芯采用不同组合型节流槽的流场特征明显不同,VU形节流槽较其他阀口出流线性特性更好,且具有良好的预升压效果,可进一步降低液流对阀芯的冲蚀,减小噪声、振动,保证多路阀工作的稳定性。对高压、大流量多路阀阀芯节流槽口的设计及提升多路阀综合性能具有一定的参考意义。     

滑阀非典型阀口过流面积计算与仿真分析

针对三角形和斜三角形两种非全周开口滑阀,结合阀口结构特征和等效阀口面积理论,推导了阀口过流面积计算公式;利用计算流体动力学(CFD)仿真方法,分析了滑阀内部的流场压力和速度分布情况;根据斜三角形滑阀样本的流量特性,对理论与仿真结果进行了验证。理论、仿真和样本实验结果吻合良好,验证了采用的解析和仿真方法,在阀口流量特性计算方面的准确性和有效性,同时为其他非典型阀口多路阀的性能预测提供了依据。     

Numerical analysis of 3-D flow through LNG marine control valves for their advanced design

A numerical analysis of three dimensional incompressible turbulent flows through high pressure drop control valves was carried out by using a CFD-ACE code to develop anti-cavitation control valve used in LNG marine system. For this, numerical simulation was performed on several models of control valve that have different orifice diameters of anti-trim and the size of valve discharge. In this study, flow characteristics of control valves with complex flow fields including pressure drop, cavitation effect and variation of flow coefficient as well as correlation of discharge coefficient were investigated and analyzed. Comparing with conventional control valves, newly designed valves by using the CFD analysis showed an improved flow pattern with reduced cavitation and an anticipated performance characteristic. This paper was presented at the 9^th Asian International Conference on Fluid Machinery (AICFM9), Jeju, Korea, October 16–19, 2007.     

不同开口度下的煤矿水液压安全阀的气蚀特性

针对煤矿水液压安全阀存在的严重气蚀问题,建立双排阀口的CFD模型,分析了不同启动次序和开口度的阀腔气相体积分数和压力分布云图,并得到其影响规律及最佳的阀口开启次序。研究表明:3种开启方式下,开口度为0.8~1.2 mm时气蚀均较为严重;同步开启时,综合抗气蚀效果最差,开口度为0.8~1.2 mm时极易形成涡旋,且对气蚀现象有扩大作用;阀口1,2依次开启时,阀腔内部的气穴气蚀现象也较明显,最大气相体积分数值达98.3%,气穴范围也较大;阀口2,1依次开启时,其阀口1附近尾椎部分高压区域可以补偿压降,从而降低阀芯内部流场最大气相体积分数,且在阀口2开口度为0.8~1.2 mm时,相对其他2种开启方式,最大气相体积分数和面积分别降低了25.7%,18.6%,抗气蚀效果最佳。     

Influence of the flow area around the ball valve on the flow characteristics of the injector control valve

The increase in common rail pressure can lead to increased cavitation inside the injector, resulting in degradation of injector performance and reduced life. The paper investigates the effect of the pressure block structure parameters (initial flow area around the ball valve) on the velocity field, pressure field, fuel gas phase volume fraction and drain rate of the control valve. The relationship between the initial flow area around the ball valve on the cavitation strength and unloading rate inside the valve was revealed. The results show that both the reduction of the flow area around the ball valve and the increase of the cavitation intensity inhibit the rate of oil discharge from the control valve. The reduction of the fuel flow area inhibits the expansion of the low-pressure region (0–1 MPa) within the flow layer, thus limiting the development of cavitation. The reduction of the cavitation area increases the fuel flow rate, however, the increase in flow rate increases the cavitation phenomenon, and these changes form a cycle (Reviewer 5. comment 2). The increase in cavitation inhibits the control valve pressure relief rate more significantly than the decrease in the initial flow area around the ball valve. Based on this, a stepped-pressure block model is proposed. The stepped pressure block model can effectively reduce the cavitation strength near the seal and enhance the oil discharge rate of the control valve. The study can provide a reference for the engineering optimization design of high-pressure common rail injector control valves.     

具有孔道沉槽的滑阀过流面积分析

多路阀以其高集成度被广泛应用于工程机械领域,其中阀口形式对多路阀流量控制特性具有重要影响。对于阀体上开有孔道沉槽、节流面为常见的圆柱面和圆锥面两种滑阀阀口形式的多路阀,根据其结构特征及内部流场压力分布和速度变化情况,利用等效阀口面积理论,推导了圆柱面阀口和圆锥面阀口过流面积计算公式。利用流场仿真对计算结果进行了修正,采用实验手段验证了计算结果的准确性。研究结果对滑阀阀芯的多路阀设计及性能预测具有一定参考价值。     

以水为介质阻尼孔气穴流动理论和试验研究

针对水的汽化压力高、容易发生气穴的特点,应用气穴模型理论对阻尼小孔中以水作为工作介质时的流动特性进行理论分析.在此基础上,用可视化方法对阻尼小孔中的气穴流动特性进行试验,研究阻尼孔中的气穴发生过程,分析阻尼孔内径和长径比对气穴的影响.研究结果表明阻尼孔的气穴首先在进口部位产生,并随着两端压差的增大向出口推移.大长径比的阻尼孔相对小长径比的阻尼孔而言不容易发生气穴.在相同长径比的情况下,孔径大的阻尼孔相对孔径小的阻尼孔更容易发生气穴.研究结果对阻尼小孔的选择设计具有一定的参考意义.     

Effect of the convergence flow conditioner on rectifying eccentric jet flow induced by a ball valve

Installing a flow conditioner is an important method for rectifying irregular and unstable flow to stable flow state within a short flow distance in fluid transportation and control industrial applications. However, classical flow conditioners (such as Laws and Zanker flow conditioners in ISO 5167) with parallel pipeline axial orifices ineffectively rectify the distinct eccentric jet flow caused by valve regulation. The convergence flow conditioner with convergent orifices was innovatively designed for rectifying the eccentric jet flow caused by a ball valve in this study. Three convergent orifice angles (8°, 10°, and 12°) defined as angles between orifice and pipeline axes were considered to compare their effect on eccentric jet flow rectification as well as with the classical Laws flow conditioner (characterized by the convergent orifice angle of 0°) under different valve openings with an experimental setup for monitoring downstream pressures that develop along the pipeline and corresponding numerical simulation used. Pressure loss and throttling effect of installing convergence flow conditioners downstream the ball valve was assessed. Analysis of distributions of the pressure, velocity, and streamline for convergent flow conditioners showed that the flow conditioner with a large convergent orifice angle can effectively improve violent eccentric jet flows, especially under a small valve opening. The axial velocity on various downstream cross sections was extracted to evaluate the velocity uniformity. A dimensionless parameter of velocity eccentric ratio was used to quantify the rectification effect of eccentric jet flow evolving in the downstream pipeline. Results showed that a short pipeline length is needed to obtain additional symmetry and uniform flow field downstream of the flow conditioner with a high convergent orifice angle, that is, the convergence flow conditioner with a high convergent orifice angle demonstrated a strong effect of flow rectification on the valve-induced eccentric jet flow. This work can help understand characteristics of flow rectification on valve-induced eccentric jet flow in scientific research, and provide guidance for the flow conditioner design in fluid engineering.     

Hydrodynamic characteristics and optimization design of a bio-inspired anti-erosion structure for a regulating valve core

Cavitation is the main failure mode of coal liquefaction regulating valve, which seriously limits the service life of the regulating valve. In order to restrain cavitation in the regulating valve, a bio-inspired anti-cavitation structure inspired by the red willow of valve core is proposed. Distributions of pressure, velocity and vapor volume fraction in the bionic valve under different openings (30%, 40%, 50%, and 60%) and inlet pressures (2.0MPa, 3.0MPa, 4.0MPa, and 5.0MPa) are discussed. In addition, the parameters of bionic valve structure are optimized using NSGA-II algorithm, the field synergy principle is applied to evaluate the flow field optimization in the bionic valve. The results show that the cavitation area and cavitation length in these bionic structures are reduced significantly compared with the traditional smooth structure. And the anti-cavitation performance of the trench structure is the best, when the inlet pressure is 3 MPa and the opening is 30%, the vapor volume is 0.10 mm³, the vapor volume is reduced by 98.07% compared with traditional smooth structure. Convex hull structure is the second. When the inlet pressure is 5.0 MPa, the vapor volume of the traditional smooth structure is as high as 148 mm³, and the vapor volume of the convex hull structure is 35 mm³, the vapor volume of the trench structure is 19 mm³. Through the field synergy theory to evaluate the internal flow field, it is found that the effective viscosity coefficient in the traditional smooth structure regulating valve varies from 0.7 to 1.2, that of the bionic trench valve changes from 0.1 to 0.5, both the flow resistance and energy consumption in the trench structure valve are reduced. It is proved that the bionic trench structure of the valve core can effectively improve anti cavitation performance and optimize the internal flow resistance of the flow field, which is of great significance to the optimal design of the control valve.