【作者】 张颖；

【导师】 袁朝辉；

【作者基本信息】 西北工业大学 ， 检测技术与自动化装置， 2015， 博士

【摘要】 射流管式电液伺服阀因其前置级为射流管式放大器而得名,由于其具有优异的抗污染性能,国内外航空及舰船已大量采用射流管伺服阀代替传统的喷嘴挡板伺服阀。由于射流流场十分复杂,目前对射流管伺服阀的理论分析并不成熟,主要依靠大量的试验来设计或改进其结构,但因其加工焊接工艺难度大,装配调试技术要求高,试验的方法往往需要耗费大量的人力物力,因此采用准确、高效的仿真技术对其各方面性能进行深入研究,对于射流管伺服阀相关技术的改进具有重要的意义。随着计算机软硬件技术的迅猛发展,产生了数值模拟技术,它主要结合有限元或有限体积等数值求解方法,通过数值计算和图像显示达到对实际工程问题进行研究的目的。该技术通过数值计算方法逼近问题的真实解,解决了复杂问题通常无法得到其解析解的难题。本文将理论推导及数值模拟技术相结合,对射流管电液伺服阀进行部分及整体分析,主要贡献如下:[1]在对射流管伺服阀结构及工作原理进行分析的基础上,对力矩马达、射流放大器以及衔铁-反馈杆组件这三个部分分别进行理论模型的推导。在传统的集中参数建模过程中,对于射流放大器通常采用压力-流量线性化方程来简化其流场部分的计算,本文通过推导接收器的面积分配公式,并采用能量守恒及冲量定理两种方法完成对射流流场模型的建立;在对较为成熟的喷嘴挡板伺服阀模型进行分析的基础上,完成对衔铁-反馈杆组件数学模型的建立。进一步利用AMESim软件的二次开发工具AMESet编写了射流放大器及衔铁-反馈杆组件模块,并在AMESim中搭建整阀模型并完成仿真分析。[2]采用数值模拟技术对射流管伺服阀的力矩马达、射流放大器以及衔铁-反馈杆组件分别进行三维建模及仿真分析。以电磁场理论为基础,采用有限元方法对衔铁偏转过程中力矩马达的瞬态磁场进行分析,考虑了漏磁现象及各种电磁效应;以结构静力学为基础采用有限元法对衔铁-反馈杆组件进行结构静力分析;以流体力学理论为基础采用有限体积法对射流放大器的流场及阀芯阀套中油液的流场进行分析,对于射流放大器中的流场,在多相流模型的基础上,通过用户自定义函数UDF进行编程,考虑了油液中溶解气体的析出对流场计算的影响,对于阀芯阀套中的流场,利用FLUENT的动网格技术,分析了随着滑阀的移动阀的输出流量。[3]在对射流管伺服阀各组件进行数值计算的基础上,提出两种方法对整阀进行数值模拟,一是将各场的数值计算结果通过插值的方法拟合得到各变量间的关系式,在MATLAB软件中完成系统模型的搭建并仿真;二是结合结构动力学理论,利用ANSYS的参数化语言APDL编程,将力矩马达磁场及射流放大器流场部分的数值分析结果作为可变边界条件施加在衔铁-反馈杆组件结构上完成瞬态动力学仿真。进一步分析了射流管伺服阀的一些相关特性,包括对射流管伺服阀关键部位的刚度进行计算,给出了反馈杆刚度的设计方法并对其结构进行优化;对衔铁-弹簧管组件进行模态及谐响应分析,并分析了弹簧管的材料及厚度对组件共振频率的影响;逐个分析了射流放大器的结构参数对其放大效率的影响,包括油液的入口及出口压强、射流喷嘴与接收器的距离、接收器上两接收孔的直径、距离及夹角。[4]将优化算法引入射流放大器的结构设计,并提出了两种优化流程。一种是基于集中参数模型推导的方法,将得到的压差函数作为优化的目标函数,利用智能算法编程从而完成多个参数的迭代优化。该方法能够方便快捷地对射流放大器的多个结构参数同时进行优化,但由于射流流场十分复杂,包括壁面射流及二次回流等复杂流动现象,对其进行精确的建模十分困难,简化的过程往往会丢失某些结构参数对流场的影响;另一种是基于三维模型的数值优化方法,该方法以模型参数化为前提,通过多软件的集成实现建模、数值计算、参数优化、模型更新等过程的自动循环,有效避开了对射流流场进行准确数学建模的难题,为复杂流场的设计提供了一个准确、全自动的优化平台。[5]射流放大器中油液对接收器的冲蚀磨损会影响整阀的性能。以射流放大器为研究对象,将计算流体动力学理论与冲蚀理论相结合,应用雷诺平均方程,标准k-ε两方程模型(液相),离散相流动模型DPM(固相)和塑性材料冲蚀磨损模型,采用流体动力学软件FLUENT对射流放大器壁面的冲蚀磨损率进行数值计算,并通过分析得到了壁面上冲蚀磨损率的分布规律,最后利用所得结果对射流放大器的寿命进行预测。该研究方法及结果对于射流管式伺服阀故障的定性分析具有一定的参考价值。更多还原

【Abstract】 Jet pipe electro-hydraulic servo valve is named for its pre-stage is a jet pipe amplifier. Because of its excellent anti-pollution performance, jet pipe servo valve has been extensive used on foreign aircrafts and ships instead of traditional flapper-nozzle servo valve. For the jet flow field is very complicated, the theoretical analysis of it is not mature, and currently, the optimal design of its structure parameters is relied on a large number of experiments. In consideration of the difficulty of its processing and welding, and the requirement of high technology during the assembly and debugging, this method requires lots of manpower and resources, therefore, accurate and efficient simulation technology would be of great importance to the in-depth study on the performance and related technology of jet pipe servo valve.The numerical simulation technology has been produced with the rapid development of computer technology, which uses the numerical methods of finite element and finite volume to conduct research on the practical engineering problems. Usually, it is difficult to get analytic solution of complicated issues, but we can adopt the numerical method to solve this problem by using high accuracy approximation.In this paper, part and whole analysis of the jet pipe servo valve has been done using the theoretical analysis combined with the numerical simulation technology. The main contributions are as follows.[1] The theoretical model of the torque motor, jet pipe amplifier and armature assembly have been established on the basis of analyzing the structure and working principle of the jet pipe servo valve. In the traditional lumped parameter model, the linear equation of pressure-flow is used to simplify the modeling of flow field of the jet pipe amplifier, in this paper, conservation of energy and theorem of impulse are used to establish the model of the amplifier which are on the premise of the formula derivation of the receivers’ area distribution. The armature assembly’s mathematical model is established on the basis of analyzing the mature model of flapper-nozzle servo valve. Furthermore, used the AMESim developing tool to design the submodels of the jet pipe amplifier and the armature assembly, finally accomplished the system modeling and simulation in AMESim.[2] Used the numerical simulation technology to accomplish the 3-D modeling and simulation of the torque motor, jet pipe amplifier and armature assembly of the jet pipe servo valve. Used the finite element method to carry on the dynamic analysis of the torque motor on the bases of electromagnetic field theory, in the process of calculation, magnetic flux leakage and various electromagnetic effects are taken into consideration; Used the finite element method to carry on the static structure analysis of the armature assembly based on structural mechanics; Used the finite volume method to carry out the analysis of the flow field in the jet pipe amplifier and between the spool and sleeve on the basis of fluid mechanics. For the cavitation which can be caused by some reasons may influence the flow field, in this paper, this phenomenon has been considered by programming using UDF(user defined function) combined with multiphase flow model.[3] On the basis of above analysis, the system modeling and simulation has been carried out by two ways: one is to obtained the interpolated functions on the basis of the numerical analysis’ s results by fitting, and utilized these functions to establish model and accomplish the simulation in MATLAB; another is to use the results of the numerical analysis of magnetic field and flow field as the variable boundary conditions, and applied them on the armature assembly to carry out the dynamics simulation by programming using APDL. Furthermore some correlate characteristics of this valve are analyzed. Some key parts’ stiffness are computated, the design method of the feedback lever’s stiffness has been derived and the optimization of its structure has been carried out by numerical simulation; Modal and harmonic analysis of the armature assembly have been done to study its vibration performance; Based on the material mechanics theory, the structures of jet pipe servo valve and flapper-nozzle servo valve have been compared and analyzed; The effects of the oil pressure and the structural parameters of the jet pipe amplifier on the amplification efficiency have been studied in this paper, including the inlet and outlet pressure of the oil, the distance between the jet nozzle and receiver, the diameter of the hole, the angle and distance between the two holes.[4] In this paper the optimization algorithm is introduced for the structural design of jet pipe amplifier, two methods are designed as follow. One is based on the lumped-parameter model, the pressure differential function derived before has been used as the objective function, and the iterative optimization of multiple parameters has been accomplished by programming using proper intelligent algorithm. This method can optimize multiple structural parameters at the same time efficiently, however, due to the complexity of the jet flow field which includes some complex phenomena such as the wall jet and backflow, it is difficult to build the mathematical model accurately, and some simplifications may lead to erroneous results. Another method is the numerical optimization methods which is based on the 3-D model, the parametric model has been used to realize the automatic optimization process which includes modeling, numerical computation, optimization and updating by using the multi-software integration technology, this method effectively avoids the difficult problem of modeling the jet flow field, and this method can be used as an optimization platform for any complex flow field.[5] The erosion wear of the jet pipe amplifier may affect the performance of the whole valve. According to the computational fluid dynamics(CFD) theory and the theory of erosion, Adopted the k-ε two-equation model for the fluid and the discrete phase model(DPM) for the solid particle and used the Navier-Stokes equations combined with the plastic material erosion model to carry out the numerical simulation of the erosion rate using FLUENT, and analysed the regularities of the erosion rate’s distribution, finally used the results of the numerical analysis to estimate the service life of the valve. This research method and results has certain reference value for the fault qualitative analysis of jet pipe servo valve.更多还原