Numerical Simulation and Experimental Study of Heat-fluid-solid Coupling of Double Flapper-nozzle Servo Valve

The double flapper-nozzle servo valve is widely used to launch and guide the equipment. Due to the large instantaneous flow rate of servo valve working under specific operating conditions, the temperature of servo valve would reach 120℃ and the valve core and valve sleeve deform in a short amount of time. So the control precision of servo valve significantly decreases and the clamping stagnation phenomenon of valve core appears. In order to solve the problem of degraded control accuracy and clamping stagnation of servo valve under large temperature difference circumstance, the numerical simulation of heat-fluid-solid coupling by using finite element method is done. The simulation result shows that zero position leakage of servo valve is basically impacted by oil temperature and change of fit clearance. The clamping stagnation is caused by warpage-deformation and fit clearance reduction of the valve core and valve sleeve. The distribution roles of the temperature and thermal-deformation of shell, valve core and valve sleeve and the pressure, velocity and temperature field of flow channel are also analyzed. Zero position leakage and electromagnet＇s current when valve core moves in full-stroke are tested using Electro-hydraulic Servo-valve Characteristic Test-bed of an aerospace sciences and technology corporation. The experimental results show that the change law of experimental current at different oil temperatures is roughly identical to simulation current. The current curve of the electromagnet is smooth when oil temperature is below 80℃, but the amplitude of current significantly increases and the hairy appears when oil temperature is above 80℃. The current becomes smooth again after the warped valve core and valve sleeve are reground. It indicates that clamping stagnation is caused by warpage-deformation and fit clearance reduction of valve core and valve sleeve. This paper simulates and tests the heat-fluid-solid coupling of double flapper-nozzle servo valve, and the obtained results provide the reference value for the design of double flapper-nozzle force feedback servo valve.

Research on valve core’s clamping stagnation of double flapper-nozzle servo valve

Due to great changing of instantaneous temperature of hydraulic oil of double flapper-nozzle servo valve, thermal deformation between valve core and valve sleeve may result in catching phenomenon of valve core, and then the reliability of servo valve could be affected seriously. The work focuses on a particular model of double flapper-nozzle servo valve and establishes three dimension couple models of liquid-solid-thermal under extreme operating condition. The transmission route and dissipative mechanism of heat is revealed and thermal deformation behavior of valve core and valve sleeve is researched. A change law of the key fit clearance under the effect of thermal expansion and warp deformation is explored, the source of catching phenomenon of valve core is identified, and then preventive measure and improvement can be proposed. In order to verify the correctness of theoretical analysis, the moving smoothness of deformed valve core and reground valve core under the circumstance of high-temperature hydraulic oil on electrohydraulic servo valve static characteristics test table is compared and tested. The results show that as oil temperature rises, relative deformations between valve core and valve sleeve in different direction at a same cross-section are not equal, and then the key fit clearance is less than the initial value. Relative deformations in the same direction at different axial position are not equal, the deformations of middle and two ends are maximum and minimum values respectively, and then warp deformation of valve core occurs. When oil temperature is higher, the relative deformations between valve core and valve sleeve is larger, the moving smoothness of valve core gets worse, and the catching phenomenon of valve core occurs. Axial deformation of valve sleeve and valve core at different axial position is different, and the opening coefficient and stability of servo valve could be affected, especially the operation circumstance of small opening. The study can provide some guidance for designing double nozzle flapper servo valves.

基于AMESim与MATLAB的矢量喷管电液伺服系统建模与仿真研究

为了研究矢量喷管电液伺服系统的性能,设计了AMESim/MATLAB联合仿真方案。根据双喷嘴挡板电液伺服阀的工作原理和结构特点,建立了电液伺服阀的物理模型,并在此基础上搭建了喷管电液伺服系统的AMESim仿真模型,设计了PID控制器和模糊PID控制器。结果表明:建立的系统模型能够根据信号进行正确动作,模糊PID控制器在此系统中具有响应速度快和稳态性能好等优点。

单级双喷嘴挡板电液伺服阀的特性研究

介绍了单级双喷嘴挡板电液伺服阀的结构组成、工作原理和性能特点,通过数学建模获得了该阀的静、动态特性方程,并通过实验测得了其静、动态特性曲线。理论分析和实验结果表明:该阀的流量、压力特性实验曲线与特性方程基本吻合,且具有良好的静态流量(压力)-电流比例特性和小负载流量的控制能力,其动态响应较快,性能稳定可靠。

磁流体对双喷嘴挡板伺服阀工作性能的影响

通过分析伺服阀的工作原理及力矩马达工作间隙中磁流体的作用机理,运用键合图理论以规范的方式统一描述系统中的机液能量耦合、流体磁化以及电磁转换等多种能量作用;考虑磁流体作用力等非线性因素,采用集中参数建立电液伺服阀的通用仿真数学模型,模拟添加磁流体前后及力矩马达工作气隙参数变化对伺服阀工作性能的影响规律,通过试验证明该模型的有效性。研究结果表明:添加磁流体可增加伺服阀力矩马达的阻尼比,提高系统的稳定性和抗干扰能力;增大工作气隙高度或减小导磁体有效工作面积均有利于提高系统的稳定性,但降低了系统的流量增益。

双喷嘴挡板电液伺服阀流量特性的研究

介绍了以双喷嘴挡板阀为功率级的电液伺服阀的结构组成、工作原理和性能特点,通过数学建模获得了静态负载流量特性方程,实验测得了该阀流量特性曲线。理论分析和实验结果表明:双喷嘴挡板电液伺服阀具有良好的流量-电流比例特性和小负载流量的控制能力。

双喷嘴挡板伺服阀工作过程的数值模拟

为从理论上研究双喷嘴挡板伺服阀的工作性能,需对其建立较为精确的数学模型。针对电液伺服阀工作过程固有的机电液耦合特性,选择可统一处理多能域复杂系统的键合图法作为建模工具。根据衔铁、挡板组件和阀芯的运动规律,考虑喷嘴射流液动力等非线性因素,采用集中参数构建了系统的键合图模型,并推导出描述伺服阀工作过程内部能量供给、传递、转化和消耗的状态方程。结合某型伺服阀的相关参数,采用四阶Runge-Kutta法进行数值求解。数值模拟结果表明:伺服阀输入阶跃电流后,预测的负载流量阶跃响应的变化趋势能与试验结果较好吻合,并且模型能预测伺服阀系统内部状态变量的动态特性,为伺服阀结构参数优化研究和动态性能分析提供了理论依据。

双喷嘴挡板电液伺服阀建模与仿真研究

介绍了QDY型双喷嘴挡板电液伺服阀的结构组成、工作原理和性能特点,通过数学建模获得了静、动态流量特性方程,并利用Matlab分析出该阀的动态性能。理论分析和仿真结果表明:双喷嘴挡板电液伺服阀具有良好的流量—电流比例特性,动态性能好。

双喷嘴挡板伺服阀前置放大器的流场分析

运用FLUENT软件对伺服阀双喷嘴挡板级进行了三维流场分析,获得了不同喷嘴挡板距的控制压力和恢复流量,运用二次函数拟合得到控制压力与恢复流量的数学模型,并分析了喷嘴挡板内部流道对伺服阀性能的影响。

双喷嘴挡板电液伺服阀力矩马达电磁特性研究

针对双喷嘴挡板电液伺服阀力矩马达电磁特性对衔铁受力响应影响问题,采用有限元技术,利用CST软件建立了力矩马达电磁特性仿真模型.设置不同线圈匝数和不同磁流体层厚度等边界条件,分别研究了力矩马达在基本结构组件条件下和对力矩马达内加入磁流体条件下的电磁特性.结果表明:在相同电流条件下在力矩马达内引入磁流体或增大线圈匝数都可增大衔铁所受电磁力,提高力矩马达电磁性能.