DYNAMIC CHARACTERISTICS OF LARGE FLOW RATING ELECTROHYDRAULIC PROPORTIONAL CARTRIDGE VALVE

A kind of cartridge servo proportional valve is discussed, which can be used for controlling large flow rate with high performance. By analyzing the structure principle of the valve, the transfer fimction of the valve is derived. With the transfer function, some structure elements that may affect its performance are investigated. Through the numerical simulation and test study, some principles of optimality and effective methods for improving the dynamic performance of the valve are proposed. The test results conform to the results of the theoretical analysis and simulation, which proves the correctness of the study and simulation works. The paper provides theoretical basis for engineering applications and series expanding design works

Numerical Study on Flow-induced Noise for a Steam Stop-valve Using Large Eddy Simulation

噪音在 250

Properties analysis of a large flow-rate safety valve test device

In order to solve the problem of property test of large flow-rate safety, the property parameter of safety valve test system was analyzed, and a device for property oflarge flow-rate safety valve test was designed.The device used accumulators as power source and a united function cylinder, which can realized the large flow-rate output for the test system.Analyzed the test data and made a particular research on the test device by testing different flow-rate safety valves;it verifies that the test device can be used tode-sign larger flow-rate safety valve test system and can make the flow-rate test and analysis and dynamic characteristics for the large-flow safety valve.

Development of High-Speed On-Of Valves and Their Applications

With the widespread application of the computer and microelectronic technology in the industry,digitization becomes the inevitable developing trend of the hydraulic technology.Digitization of the hydraulic components is critical in the digital hydraulic technology.High-speed on-of valves(HSVs)which convert a train of input pulses into the fast and accurate switching between the on and of states belong to widely used basic digital hydraulic elements.In some ways,the characteristics of the HSVs determine the performance of the digital hydraulic systems.This paper discusses the development of HSVs and their applications.First,the HSVs with innovative structures which is classifed into direct drive valves and pilot operated valves are discussed,with the emphasis on their performance.Then,an overview of HSVs with intelligent materials is presented with considering of the switching frequency and fow capacity.Finally,the applications of the HSVs are reviewed,including digital hydraulic components with the integration of the HSVs and digital hydraulic systems controlled by the HSVs.

Influence of ground effect on flow field structure and aerodynamic noise of high-speed trains

The simulation of the ground effect has always been a technical difficulty in wind tunnel tests of high-speed trains.In this paper,large eddy simulation and the curl acoustic integral equation were used to simulate the flow-acoustic field results of high-speed trains under four ground simulation systems(GSSs):“moving ground+rotating wheel”,“stationary ground+rotating wheel”,“moving ground+stationary wheel”,and“stationary ground+stationary wheel”.By comparing the fluid-acoustic field results of the four GSSs,the influence laws of different GSSs on the flow field structure,aero-acoustic source,and far-field radiation noise characteristics were investigated,providing guidance for the acoustic wind tunnel testing of high-speed trains.The calculation results of the aerodynamic noise of a 350 km/h high-speed train show that the moving ground and rotating wheel affect mainly the aero-acoustic performance under the train bottom.The influence of the rotating wheel on the equivalent sound source power of the whole vehicle was not more than 5%,but that of the moving ground slip was more than 15%.The average influence of the rotating wheel on the sound pressure level radiated by the whole vehicle was 0.3 dBA,while that of the moving ground was 1.8 dBA.

高压超大流量纯水卸荷阀启闭动态压力特性研究

卸荷阀是液压支架系统关键的压力控制元件。提出了一种高压超大流量纯水卸荷阀结构,并对卸荷阀的工作原理进行分析,建立了卸荷阀的数学模型。通过搭建AMESim仿真模型,分析了卸荷阀的动态循环工作过程,以及先导阀、主阀、单向阀的启闭动态压力特性。在调定卸荷压力下,对影响卸荷阀恢复压力的关键因素进行了分析。为了验证仿真模型的准确性,搭建了卸荷阀的试验测试系统。研究表明,仿真与试验的压力参数吻合较好,通过调整顶杆直径、阻尼孔直径、阻尼孔长度及先导阀弹簧刚度,可以优化卸荷阀的恢复压力,研究结果可以为高压超大流量纯水卸荷阀的设计提供理论基础。

矿用液压支架大流量安全阀卸荷性能分析

针对液压支架大流量安全阀在冲击载荷作用下不稳定的问题,以矿用液压支架上的FAD500/50型大流量安全阀作为研究对象,依据其结构和工作原理,利用AMESim软件对安全阀过载时的卸荷性能进行仿真分析,得到安全阀溢流时压力与流量动态输出特性以及阀芯运动规律特性。结果表明:在冲击载荷下,安全阀压力超调量和压力超调率分别为5.9 MPa和15%;安全阀开启瞬间阀芯会产生震荡,突变载荷是阀芯产生震荡的主要因素。最后通过试验证明了安全阀回路压力损失随着乳化液流量的增大而增大,但在0~320 L/min公称流量下,安全阀的压力损失低于7 MPa,系统整体运行稳定。

基于大流量止回阀实验系统的快速预测模型

针对传感器在数据获取中的局限性和无法用于对实验系统进行全面的数据收集问题,对大流量止回阀实验系统的快速预测模型技术进行了研究,建立了实验系统的快速预测模型,进行了快速预测模型的结果分析。首先,搭建了实体模型,根据大流量止回阀实验系统的结构,结合实验系统的工作原理对其进行了简化,并进行了有限元分析;然后,利用快速预测模型的关键技术构建了实验系统数据库,进行了实验系统的样本采集;通过比对不同机器学习算法的预测准确率,选择了随机森林算法,并建立了实验系统内压与应力应变的关系;最后,进行了快速预测模型的结果分析,并完成了实验系统整体预测实验和实验系统部件单独预测实验。研究结果表明:采用随机森林(RF)算法建立的快速预测模型,拟合优度(R 2)达到了0.99,相较于深度神经网络(DNN)算法和梯度提升树(GBDT)算法,拟合优度(R 2)提高了68.97%和51.47%。实验系统整体预测与实验系统部件单独预测的对比试验结果表明:整体预测模型的预测速度更快,且精度可以达到97.43%。

大排量直井段随钻测斜工具的研制与应用

为解决深井、超深井上部大尺寸直井段因钻井排量高导致的随钻测斜工具冲蚀严重、故障率及成本高等问题,综合采用扩大过流面积、流场仿真优化及冲蚀剧烈区局部硬质合金保护方法,研制了大流道耐冲蚀旋转阀组;采用加速度计柔性悬浮固定、电路板有机硅灌封胶等多级复合减振方法,提高了随钻测斜工具电子电路的抗振能力;通过设计快速传输编码、低功耗电子电路及节能运行模式,提高了测斜效率与测斜工具的续航能力。通过研制关键部件大流道耐冲蚀旋转阀组,采用不同技术方法提高测斜工具的抗振能力、测斜效率和续航能力,研制了系列尺寸的大排量直井段随钻测斜工具。川渝、新疆等地区的12口井应用该工具随钻监测井斜角,该工具表现出耐大排量冲蚀的能力,最高适用排量达120 L/s,运行稳定可靠,故障率低于0.5次/月,续航可达30 d以上。现场应用结果表明,大排量直井段随钻测斜工具能满足深井、超深井大尺寸直井段随钻测斜的要求,可为深井、超深井获得高质量直井段提供支持。

Moldflow软件在汽车大型注塑模设计中的应用

针对大型注塑模的结构特点,以某汽车仪表板注塑件为例,应用Moldflow软件,模拟分析阀式控制的流动过程,优化浇注系统设计和成型工艺参数,为注塑模具设计和试模时工艺参数的设定提供了依据,并获得了高质量的产品。

高压大流量纯水液控单向阀冲击特性与气蚀损伤的关联性

针对高压大流量工况下纯水液控单向阀的气蚀损伤问题,研究其冲击空化特性与气蚀损伤的关联性,通过冲击实验、扫描电镜、电化学等方法对高压大流量纯水冲击后的液控单向阀阀芯表面进行分析。结果表明:随着冲击特性的增强,空化指数显著增强,气蚀损伤越剧烈,说明空化溃灭的动力学作用与冲击特性呈正相关。空化溃灭时能够在短时间内释放高温传递至不锈钢表面,并经过纯水介质的快速冷却,导致出现马氏体结构。经空泡溃灭作用后不锈钢表面钝化膜出现早期裂纹及气孔,其包含区域的电流密度较高,从而电离产生更多H+,致使纯水pH值降低,产生酸性的腐蚀溶液,加速钝化膜的破坏,早期气孔逐渐扩大发展为明显气蚀坑。

基于CAE技术的带嵌件汽车前段框架大型注塑模设计

采用CAE技术对含有金属嵌件的汽车前段框架进行注射成型分析,确定了热流道10点浇注方案,并预判了塑件注射过程中可能出现的问题。结合仿真分析结果及塑件的结构特点,设计了一副一模一腔的顺序阀热流道大型注塑模具。采用“斜导柱+滑块+侧型芯”机构和液压抽芯机构解决了因塑件内外侧倒扣多、抽芯面积大而导致的脱模困难问题;通过设计“H形块+拉钩+浮动块”的机械式机构解决了塑件粘大滑块的问题;在位于顶部的侧抽芯结构中设计了防坠落机构,安全可靠;利用“顶辊+氮气弹簧”组合方式驱动和复位顶出机构,效率较高;各机构都有独立冷却回路,模温均匀;利用成型零件、顶杆及强力磁铁固定嵌件,定位简单可靠。模具投产后,运行平稳,塑件质量符合要求,其模具设计思路可为同行借鉴。

自适应大流量安全阀的流固耦合分析与保压实验

为提高自适应大流量安全阀关键零件的可靠性及寿命,利用UG软件建立自适应大流量安全阀关键零件的三维模型,并借助ANSYS Fluent软件对其进行了网格划分,通过单向流固耦合分析得到了一级锥阀、二级差动阀芯等关键零件的应力、应变云图;为进一步研究自适应大流量安全阀的低压密封性,利用ZF-2WG液压支架阀综合实验台对其进行了6、14 MPa 2种不同压力的打压实验。仿真及实验结果表明:一级锥阀的锥面附近区域为应力集中区域,锥尖附近区域为应变集中区域;二级阀芯4个阻尼孔靠差动腔侧的出口处为应力集中区域,二级阀芯外环形差动腔接触流体区域为应变集中区域;通过操作控制P口压力为6、14 MPa,保压时间为120 s,压力值基本保持在设定值,保压效果非常理想。

大口径异构蝶阀流动特性分析及其流量系数研究

为了研究大口径蝶阀阀板加强结构对阀内流动特性的影响,针对板加强型和块加强型2种阀板加强结构的大口径异构蝶阀,分别建立了蝶阀流场CFD仿真模型,对各工况下阀内流场流动特性进行分析,并通过与试验测试数据的对比验证仿真模型的合理性。结果表明,不同开度、压比下2种大口径蝶阀均具有显著的非线性流动特性,相对于块加强型蝶阀,板加强型蝶阀阀后流场漩涡小,对应能量损失低,而流量系数更高。2种大口径异构蝶阀的流量系数均与其管道雷诺数呈现线性关系,且该线性关系的斜率与流通面积成反比,提出了基于管道雷诺数的大口径蝶阀流量系数计算公式,结果显示此流量系数计算公式与CFD仿真误差小于7%,可以统一表征大口径异构蝶阀流量特性。

冷流率对大口径涡流管性能影响分析

为了探究冷流率对大口径涡流管节流降压效果的影响,基于Fluent改变冷流率值,对比模拟计算结果发现:主管段区内外旋气体存在能量损耗,轴向位置出现压力滞止点和速度方向折点,径向位置r=28 mm处出现分界层。冷流率0.1至0.5,外旋气体温度上升趋势平缓,制热效果不明显;冷流率0.6至0.9,外旋气体温度上升趋势明显,制热效果加强;冷流率增大过程中,内旋气体温度下降趋势平缓,制热效果减弱。热端出口气体压力随冷流率增大而增加,大部分气体流至冷端出口,导致冷端压力变化梯度明显;冷流率过大,热端出口节流降压效果降低,无法满足节流需求。冷热端出口压差变大,外旋气体流动受阻,速度减小;内旋气体流动加快,速度增大。综合分析得出:冷流率0.5时,大口径涡流管节流降压效果最佳,节流区间3 MPa左右,冷热端出口气体温降区间均为5 K,忽略传热损失,节流前后气体温降区间几乎为零,满足后续工艺温度要求。

浮式生产储卸油装置放空管路压力安全阀流致噪声特性

针对单相气体流致噪声问题,以某浮式生产储卸油装置(floating production storage offloading,FPSO)大流量天然气处理装置管路系统的压力安全阀为研究对象,采用非定常大涡模拟(large eddy simulation,LES)和Ffowcs Williams-Hawkings(FW-H)声类比模型对其流动特性和流致噪声特性进行研究,得到了压力安全阀(pressure safety valve,PSV)内流场分布,预测了噪声产生位置及其频谱特性,结论可为压力安全阀和天然气管路系统的前期设计提供理论依据和技术支撑。

低温大口径高压轴流式止回阀研制

针对高压大口径轴流式止回阀超低温工况密封失效,特别是经过高压试验或者高压下开关动作后密封面损坏,阀门无法满足长周期稳定运行问题,设计了一种具有特殊阀内密封结构的高压轴流式止回阀。使用有限元软件对改进后的阀体结构进行强度分析校核;以相关型式试验论证,将阀门置于-196℃试验温度下,进行2 000次的阀门整机低温疲劳寿命试验,试验全过程中最大泄漏率为1 700 m L/min,远远低于标准规定上限值3 600 m L/min;经江苏LNG现场使用,结果表明通过结构优化,低温大口径高压轴流式止回阀性能完全满足LNG装置及超低温工况要求,主要性能和技术指标达到了国际上同类阀门的水平。

大口径轮盘式特种调节阀流动特性分析

大口径轮盘式特种调节阀(简称特种阀)是高空试验台保证进气系统温度和压力及时达到发动机飞行环境所对应温度和压力的主要调节阀之一。为了提高特种阀流量系数控制模型的精度,基于Fluent软件模拟研究特种阀的内部流动特性,探索分析了9个开度(10°、20°、30°、40°、50°、60°、70°、80°、90°(全开))和9个压比(0.1、0.2、0.3、0.4、0.5、0.6、0.7、0.8、0.9)对特种阀内部速度和压力的影响规律。结果表明:特种阀内速度和压力沿无级调节盘呈对称分布,气流速度随着开度的增大而逐渐增加,在阀前压力为200 kPa、压比为0.1时,开度为90°的进口速度为72.92 m/s,约为开度10°的9倍;在开度不变时,进口速度随着压比增大先不变后减小,存在临界压比;开度为10°~50°时临界压比约为0.5,开度在60°~90°范围内临界压比约为0.6;特种阀的流阻系数随着开度和压比的增大而减小,开度为10°~40°时,流阻系数下降速度最显著,其中开度从10°增大到30°时,流阻系数下降了88%。

Development of a novel two-stage proportional valve with a pilot digital flow distribution

Pilot two-stage proportional valves are widely used in high-power hydraulic systems. For the purpose of improving the dynamic performance, reliability, and digitization of the traditional proportional valve, a novel two-stage proportional valve with a pilot digital flow distribution is proposed from the viewpoint of the dual nozzle-flapper valve’s working principle. In particular, the dual nozzle-flapper is decoupled by two high-speed on/off valves (HSVs). First, the working principle and mathematical model of the proposed valve are determined. Then, the influences of the control parameters (duty cycle and switching frequency) and structural parameters (fixed orifice’s diameter and main valve’s spring) on the main valve’s motion are analyzed on the basis of theory, simulation, and experiment. In addition, in optimizing the value of the fixed orifice’s diameter, a new design criterion that considers the maximum pressure sensitivity, flow controllability, and flow linearization is proposed to improve the balance between the effective displacement and the displacement fluctuation of the main valve. The new scheme is verified by simulations and experiments. Experimental results of the closed-loop displacement tracking have demonstrated that the delay time of the main valve is always within 3.5 ms under different working conditions, and the tracking error can be significantly reduced using the higher switching frequency. The amplitude–frequency experiments indicate that a −3 dB-frequency of the proposed valve can reach 9.5 Hz in the case of ±50% full scale and 15 Hz in the case of 0%–50% full scale. The values can be further improved by increasing the flow rate of the pilot HSV.

变刚度弹簧对高压大流量安全阀响应特性的影响规律

随着煤炭综采技术的发展,液压支架受到顶板来压的强度和频率不断增强。为研究高压大流量安全阀在顶板来压时的响应特性,以典型的1000 L/min大流量安全阀为基础研究对象,分别利用Simulink和AMESim建立模型,分析顶板来压时安全阀的弹簧刚度变化对其响应特性和启溢闭时间的影响规律。结果表明:定刚度弹簧刚度减小能有效减小超调量但阀芯震荡加剧,安全阀压力波动较大;刚度增加能使阀芯振幅减小且更快趋于稳定,但安全阀超调量增加,不利于卸荷溢流;变刚度弹簧能有效减小冲击载荷下安全阀的超调量,提高安全阀的压力控制精度,从而提高安全阀的稳定性和可靠性。此外,设计一种以氮气为气体弹簧的新结构安全阀,仿真结果表明:氮气弹簧安全阀的超调量为9.5 MPa,压力稳定时间61.4 ms,安全阀关闭时液压缸内压力为35.61 MPa,关闭延迟时间为78 ms,为高压大流量安全阀的设计提供了理论依据。