伺服阀前置级射流流场的流动特性研究

发布时间：2018-05-14 23:32

本文选题：喷嘴挡板伺服阀 + 射流流场　；参考：《哈尔滨工业大学》2011年硕士论文

【摘要】：由喷嘴挡板结构作为前置级驱动的电液伺服阀,其射流流场具有流速快、气穴多、剪切流动强等特征。前置级射流流场的不稳定性往往会导致伺服阀工作时产生高频噪声,严重影响其正常工作特性甚至使用寿命。因此为了改善喷嘴挡板伺服阀的工作性能,建立前置级射流流场的数学模型并研究其分布规律是十分必要的。本文针对喷嘴挡板型伺服阀前置级的射流流场,利用连续性方程、动量方程、改进型k ?ω湍流模型以及近壁区计算模型建立了射流流场的数学模型。利用CAD软件对喷嘴挡板处的射流流场进行了二维建模,用GAMBIT软件对模型进行了网格划分、设置边界条件等前处理操作,用FLUENT软件对不同截面、不同尾流区长度和不同挡板位置的射流流场分别进行了仿真研究,给出了不同条件下速度场和压力场的分布规律,总结了不同流场中出现压力脉动的条件及其变化关系。搭建了伺服阀前置级射流流场流动特性测试实验台,使用数字显微镜和高速摄像机对射流流场进行了可视化实验,观察了不同入口压力下流场的分布情况,使用不同的拍摄速度对流场进行了拍摄,通过观察射流轨迹的振荡规律估算了射流振荡的周期。本文在综述了射流流场流动特性及其压力脉动研究现状的基础上,结合流体力学基本理论,建立了喷嘴挡板之间射流流场的数学模型;通过仿真和实验研究了伺服阀射流流场的流动特性,给出了射流压力脉动与前置级结构参数和伺服阀工作条件之间的变化规律,为进一步研究喷嘴挡板伺服阀前置级射流流场特性以及伺服阀高频噪声产生机理提供了一定的理论依据。
[Abstract]:The jet flow field of the electro-hydraulic servo valve driven by the nozzle baffle structure is characterized by fast velocity, large cavitation and strong shear flow. The instability of the flow field of the front stage jet often leads to high frequency noise when the servo valve works, which seriously affects its normal working characteristics and even its service life. Therefore, in order to improve the performance of the nozzle baffle servo valve, it is necessary to establish the mathematical model of the front stage jet flow field and study its distribution law. In this paper, the mathematical model of jet flow field in front stage of nozzle baffle servo valve is established by using continuity equation, momentum equation, improved k? 蠅 turbulence model and calculation model of near wall region. The jet flow field at the nozzle baffle is modeled by using CAD software. The model is meshed with GAMBIT software, and the pre-processing operation such as setting boundary conditions is carried out. The different sections of the jet flow field are analyzed by FLUENT software. The jet flow field with different wake region length and different baffle position is simulated, the distribution of velocity field and pressure field under different conditions is given, and the conditions of pressure pulsation in different flow field and its variation relationship are summarized. An experimental platform for testing the flow field characteristics of the front stage jet with servo valve is set up. The flow field is visualized by digital microscope and high speed camera, and the distribution of the flow field under different inlet pressure is observed. The jet oscillation period was estimated by observing the oscillation law of the jet trajectory. On the basis of summarizing the current research situation of jet flow field and pressure fluctuation, the mathematical model of jet flow field between nozzle baffles is established based on the basic theory of hydrodynamics. The flow characteristics of the servo valve jet flow field are studied by simulation and experiment. The variation of the jet pressure pulsation, the structural parameters of the front stage and the working conditions of the servo valve are given. It provides a theoretical basis for further studying the characteristics of the jet flow field in the front stage of the nozzle baffle servo valve and the mechanism of the high frequency noise generated by the servo valve.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2011
【分类号】：TH134

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