调压阀流体空化特性仿真及影响因素分析

针对船用二级调压阀空化问题,建立流域瞬态仿真模型,结合Singhal空化模型和标准k-ε湍流模型对调压阀流体空化现象进行数值模拟,通过流场气体体积分数分析,得出了流体空化强度及分布形态的演变规律,通过流体速度场和压力场分析,阐明了空化演变过程调压阀流场特性,进而研究了开度、流量和背压对调压阀流体空化现象的影响规律.结果...     

抑制调节阀流场空化的响应面结构优化

调节阀流场空化现象会产生空化振动和噪声等不良影响。优化阀内件的结构,抑制流场空化是设计高端调节阀的重要环节。为了实现调节阀内流场的逐级降压,减小空化现象的产生,设计了一种多级降压调节阀的外层套筒和笼式阀座。采用Fluent软件对阀内流场的流动特性进行数值模拟,得到流场压力、流量和气体体积分数的分布规律。采用循环式并联流量测试装置,对阀进行流量实验,验证了数值模拟的可靠性。通过Box-Behnken响应面优化方法探讨外层套筒和笼式阀座节流孔孔径、孔数及其交互作用对流场空化的影响,得出最优设计方案。结果表明,在不影响调节阀流量特性的条件下,70%开度时,优化阀内件参数后,最大气体体积分数从0.88下降到0.19,有效地抑制调节阀内流场空化现象。     

油田用往复式注聚泵锥阀工作特性仿真分析

建立了往复式注聚泵锥阀简化后的二维轴对称流场几何模型,给定进口阀的边界条件,利用Fluent软件对不同高粘度介质、不同最大开启高度下的锥阀内流场进行了数值模拟,获得了介质粘度、最大开启高度与阀进出口压差、阀隙流速、流量系数之间的定量关系.结果表明:随着介质粘度的增大,阀进出口压差增大,流量系数减小,而阀隙流速基本不变;随着最大开启高度的增大,进出口压差减小,阀隙流速减小,流量系数增大.该研究可为往复式注聚泵锥阀的设计计算提供参考.     

液压锥阀空化特性的计算与分析

针对四种不同阀口形状的液压锥阀,采用CFD软件STAR-CCM+中的高雷诺数k-ε模型,结合空化模型,对阀腔内流场进行数值模拟,分析不同阀口形状的锥阀产生空化的位置和强度,并定性分析入口压力对空化强度的影响.同时,对四种形状锥阀进行入口阶跃压力作用下的CFD动态计算,以验证其动态特性,结果表明:空化强度弱的结构,其动态特性较差;空化现象较为强烈的锥阀,其动态特性较好.     

基于CFD的液压锥阀动态和静态性能研究

对液压锥阀的内部流场采用CFD(Computational Fluid Dynamics)方法进行数值模拟,通过移动网格技术,研究锥角大小和阀芯圆周直径以及同一调定压力下不同额定流量对锥阀芯静态和动态性能的影响,其次计算了阀口倒角对锥阀性能的影响.结果表明:阀芯圆周直径B值对锥阀动、静态特性有较大影响,当B=15mm时,锥阀的动、静态性能都较好,且对于同一种阀芯结构,随着额定流量的增加,锥阀的静态调压偏差增大,即开启比降低,而合适的阀口倒角长度可以有效提高锥阀的开启比5%左右.     

水压锥阀流场的CFD计算与分析

建立了水压锥阀的几何模型和数学模型,利用Fluent软件对其内部运动流场进行了CFD解析,解析结果以可视的速度场和压力场分布给出,并对计算结果进行了分析。由分析结果可知：随着锥阀开度的增大,入口速度逐渐增大,流量相应增加。出口压力不变,随着入口压力变大,阀腔负压增大,增大出口压力有助于减小负压．消除气蚀和不稳定。     

液压破碎锤内锥阀中流道流场的数值分析

通过对液压破碎锤内锥阀内流道流场进行数值计算和模拟，探讨了不同情况下液压锥阀内流场包括流道速度场、压力场、流线和涡量线等的分布情况，分析了产生涡旋的位置和强度，找出了造成能耗的主要原因。结果表明，通过对锥阀阀座的优化设计，减少了流线的疏密程度和涡旋的大小，降低了能量损失，负压区也随之改变，减少了噪声，提高了能量利用率。     

液压阀非定常流场数值模拟及分析

为深入研究阀体内部流场结构,采用非定常数值模拟方法对某液压锥阀3种不同开度下的流场进行数值模拟,并对其进行对比分析。成功地捕捉到液压锥阀的非定常流场,液压锥阀中等开度下的流场呈周期性变化;保持进口流速不变,随着开度增大,阀芯所受压力逐渐减小,主流区宽度逐渐增大,角区漩涡面积增大,阀芯上部漩涡区逐渐减小。     

油田用往复式注聚泵锥阀流场的CFD计算与分析

针对输送高粘度介质往复式注聚泵,应用CFD方法对液力端锥阀内部流场进行了可视化计算和分析研究。按照实际锥阀的结构,建立了简化后的二维轴对称流场几何模型。根据泵速、柱塞行程和柱塞直径等工作参数,给定进口阀的边界条件,利用Fluent软件对不同高粘度介质的锥阀内部流场进行了数值模拟,获得了介质粘度与锥阀进出口边压差、流量系数、稳态液动力之间的定量关系,可为往复式注聚泵锥阀的设计计算提供参考。     

基于浸入固体法的湿式离合器调压阀流场数值仿真

以船用湿式摩擦离合器调压阀内流道流场为研究对象,运用浸入固体方法模拟接脱排过程中调压阀阀芯的运动状态,建立了椭球形调压阀流体域和固体域的三维计算模型,借助CFX软件分析离合器接脱排过程中调压阀内润滑油的压力和速度分布情况。结果表明:油液流经阀口后,压力明显下降,并在阀口右侧形成低压区;流速迅速上升,并伴有涡流和回流现象;仿真结果与试验得到的调压阀压力试验曲线吻合良好。     

插装型液压锥阀流场与气穴仿真研究

以插装型液压锥阀为研究对象,研究了几何结构参数及边界条件对锥阀流场及气穴现象的影响。按照实际使用中的插装型液压锥阀的参数,建立了锥阀的几何仿真模型,利用FLUENT软件多相流模型对插装型液压锥阀内的流场及气相分布情况进行了仿真计算,并与修改阀芯几何结构进行对比。研究表明:增大阀口开度,增大出口压力,并对阀芯结构进行修改后,插装型液压锥阀阀口气穴现象均可有效减弱。     

高压氢气减压器内部流场仿真分析

氢气减压器是氢燃料电池汽车的关键部位,随着氢燃料电池汽车续航里程要求的提高,氢气减压器的工作压力相应增大,传统的减压器难以满足使用要求.针对上述问题,研究了一种适用于70 MPa氢气压力的两级减压器,利用Fluent软件对其内部流场进行三维仿真模拟,通过研究不同阀门开口量大小来分析流体压力场、速度场、温度场的分布以及流...     

动态压差控制阀流场及流量控制特性研究

针对变流量加热及冷却系统水力和热力失调的问题,设计一种动态压差控制阀.基于计算流体力学(CFD)方法,建立不同阀芯开度下动态压差控制阀三维流道模型.对比研究了不同阀芯开度下阀内流场分布以及流量变化,得出了动态压差控制阀在不同阀芯开度下阀内压降曲线的变化规律、阀芯节流口处速度曲线及湍动能曲线的分布规律,拟合了阀门出口流量...     

Experimental and CFD investigation of 100 mm size cone flow elements

This paper presents performance characteristics of 100 mm line size cone flow elements having beta ratios of 0.4, 0.5, 0.6, 0.7 and 0.8. A magnetic flow meter is used as a reference standard for flow measurement in vertical test section. A series of experiments have been conducted using water at in-house Flow Calibration Facility (FCF) to cover the Reynolds number ranging from 20,000 to 200,000. The performance characteristics of 100 mm line size cone flow elements with different beta values have been evaluated experimentally. It is found that the discharge coefficient of the cone flow element is nearly independent of the specified range of Reynolds number. Testing of the cone flow element in accordance with new API 5.7 is carried out at flow calibration facility. The testing requirements in the standard explain the conditioning effect of the cone flow element having gate valve disturbance upstream of the cone at various locations. The effect of the upstream velocity profile has been investigated by placing a gate valve upstream of the cone flow element at a distance of 0D and 28D and performing experiments at 25%, 50% and 100% opening of gate valve. The value of the discharge coefficient is not affected when the cone is placed at a distance of 0D and for 100% opening of gate valve. The uncertainty results of the cone testing are discussed. For studying pressure and velocity distributions, cone elements are modeled using computational fluid dynamics (CFD) code PHOENICS. Pressure and velocity profiles for different sizes of cone elements are plotted. From the pressure profile, it can be seen that the pressure recovery downstream of the cone is within a distance of 3D. The velocity profile downstream of the cone signifies the use of flow element as a signal conditioner. For measurement of flow through a 100 mm line, differential pressure across the cone is measured using a Differential Pressure Transmitter (DPT). Experiments were repeated by replacing the cone element for obtaining different β values.     

基于IPC的高压阀类产品性能参数采集与处理系统

采用基于IPC和工业组态软件的控制方案，解决了高压阀类产品性能参数的高速采集和存储问题，完成了对采集数据的显示和曲线分析；通过PLC高速计数功能对流量计进行高精度的实时测频，完成实时流量测量；对系统中使用的高压手动调节阀进行了创新型的改造，实现了高压下其行程的自动调节；设计出了通用的阀类产品测试平台。该系统已应用于某军品高压阀类产品性能参数的测试线中，采集速度最高达到了20次／秒，精度达到了0．3％以上。     

调节阀介质流向对不平衡力的影响

以快速更换式单座调节阀为例,利用Solidworks软件对调节阀内部流场进行三维实体建模,用CFX软件对流场进行流体动力学分析,得到各开度下不平衡力的可视化结果。用等效阀瓣截面积的变化表示不同开度下压力的变化,用五阶泰勒展开式表示等效截面积与行程h的关系。结果表明,流开型调节阀不平衡力较大,冲刷作用区域较宽,但不平衡力作用方向始终为正,并且比流关型调节阀稳定。因此,一般直通单座调节阀设计成流开型。     

High GVF and low pressure gas–liquid two-phase flow measurement based on dual-cone flowmeter

Parameter measurement of gas–liquid two-phase flows with a high gas volume fraction (GVF) has received great attention in the research field of multiphase flow. The cone meter, as a new proposed differential pressure (DP) meter, is increasingly being applied in flowrate measurement of gas–liquid two-phase flow. A dual-parameter measurement method of gas–liquid two-phase flow based on a dual-cone meter is proposed. The two-phase flow is investigated in a horizontal pipeline with high GVF and low pressure, and exists in the form of annular flow. By adding a second cone meter, both gas mass fraction (GMF) and mass flowrate are measured. The pressure drop performances of five different sized cones have been discussed to make a cooperating cone selection and efficiently position the dual-cone in the pipe. Dual-cone flowmeter experiments of 0.45 and 0.65 equivalent diameter ratio combination, and 0.65 and 0.85 equivalent diameter ratio combination are respectively carried out to analyze the linearity of two-phase flow multiplier with Lockhart–Martinelli parameter and obtain the dual-parameter measurement results. The relative experiment error of GMF, gas mass flowrate and total mass flowrate are respectively within ±7%, ±5% and ±10%. The relative error of the liquid phase is within ±10% when the liquid mass fraction is beyond 40%. The experimental results show that it is efficient to utilize this dual-cone method for high GVF and low pressure gas–liquid two-phase flow measurement.     

掘进机用螺纹插装式平衡阀流场特性研究

针对掘进机用螺纹插装式平衡阀易产生低频抖动、气穴、漩涡、噪声等现象,对螺纹插装式平衡阀的内部流场特性进行了模拟仿真。主要分析了螺纹插装式平衡阀的工作原理和主阀芯的受力情况,建立了主阀芯的数学模型;建立了螺纹插装式平衡阀的主阀二维几何模型,利用FLUENT软件模拟其内部流场特性,寻找出低压区、高速区和漩涡区。结果表明:较大的锥角角度,可以减小节流口出口的低压区域,可以减少气蚀现象的发生,也会使阀芯侧面的漩涡区域变大,易使阀芯产生抖动;较小的开口度,会减小节流口出口处的负压区域,增大节流口出口漩涡区域,减小阀芯侧面的漩涡区域,减少和避免气蚀和低频抖动现象发生,也会加大油液对阀芯锥面的冲击。     

2种锥段结构的轴流式旋流器内的流场模拟

采用Fluent软件对实体锥段轴流式旋流器和多孔介质锥段轴流式旋流器进行单相和液固两相的模拟研究,着重分析了旋流器内速度场与压力场的分布和液固分离效率,得到以下结论:速度场方面,多孔介质锥段旋流器,切向速度峰值较大,向下轴向速度较大向上轴向速度较小,有利于固体颗粒的分离;压力场方面,在边壁附近形成一个环带状的低压区,有利于固体颗粒的分离;相同截面,多孔介质锥段旋流器的压力明显较低,能耗较低;多孔介质锥段旋流器的液固分离效率较实体锥段旋流器高5%～10%,具有广阔的应用前景。     

Numerical and experimental studies on hydrodynamic characteristics of sleeve regulating valves

The sleeve regulating valve is a kind of control valve, which widely used in natural gas transportation. Jet flow generated in valve throats will impact on the surface of the valve body and the valve clack, and then cause the destruction of the valve. In this work, two regulators were designed to reduce the hydraulic impacts, and the effects of regulators on the hydraulic performance of the sleeve regulating valve are investigated in detail. Numerical and experimental studies were applied. Results indicate that the introduction of a regulator reduces the value of flow coefficient (K_V), and the reduction is greater with larger valve opening. Meanwhile, the flow coefficients for the valve with regulator I is a bit larger than that with regulator II. The results also demonstrate that the employment of regulator decreases the entropy production rate (EPR) of high EPR regions, reduces the pressure drop of valve throats, and slows down the velocity in the valve throats. Thus the impacts of the fluid on the throat walls are weakened by regulators. It is noted that the reduction of impact forces with regulator I (has small round holes) is larger than that with regulator II (with two rows of oval holes).