阀芯旋转式大功率电液激振基础理论和技术

Frequency, power and waveform determine the technological level of all kinds of vibration exciters. It was found in previous research that the relationship between the vibration waveform and the structure of valve core, the accurate calculation on the hydrodynamic force are the key problems restricting the rotation-spool-type vibration exciter for further development. Supposing the rotate speed as stable, this project presents a preliminary mathematical models under ideal conditions based on the law of continuous flow of fluid, and then obtains an accurate calculation method through modifying by the simulation results of computational fluid dynamics ( CFD ) and the experimental results. On the basis of it, this project will: ①reveal that the nonlinear factors of hydrodynamic force, viscous friction etc. affect on the rotate speed of the valve core interactionally, and propose a compensation method; ②establish a mathematical model of relationship between the core structure and vibration wave, and found a valve design method based on the vibration waveform; ③demonstrate the internal flow regularity in the vibration exciter, and put forward optimization methods and constraint conditions of vibration exciter system; ④overcome the key technology of detection of the hydrodynamic force and observation of the flow field, put forward experiment methods on the external characteristics of vibration frequency, waveform etc. and the internal characteristics of flow field, pressure distribution etc., and develop a high-power rotation-spool-type vibration exciter and an experimental system. Expected outcomes can be a breakthrough in the current excitation technique on the limit of frequency, power and waveform distortion. It is of great theoretical and practical significance to meet the needs of high-quality vibration for vibration simulating and vibration mechanical in various industry fields.

频宽、功率和波形决定着各类激振技术的水平，前期研究中发现阀芯旋转式激振器振动波形与阀芯结构、阀芯液动力与阀芯转速的准确解算等问题是制约这类激振技术进一步发展的瓶颈。本项目假设阀芯转速稳定，依据流体连续流动定律获得理想条件下的初步计算模型，继而根据计算流体动力学（CFD）数值模拟和实验结果修正，获得准确的计算方法。在此基础上，揭示液动力等非线性因素对阀芯转速的相互影响规律，提出补偿方法；建立阀芯结构和振动波形的数学模型，提出基于振动波形的阀芯设计方法；揭示激振器内部流体流动规律，提出激振系统优化方法和约束条件；攻克液动力检测和流场观测分析等关键技术，提出振动频率、波形等外部特性和流场、压力分布等内部流动特征的实验方法，研制阀芯旋转式大功率激振器及实验系统。预期成果可突破现有激振技术在频宽、功率和波形失真方面的限制，满足各领域对于振动模拟和振动机械的高品质激振要求，具有重要理论和现实意义。

阀芯旋转式电液激振器通过电机驱动阀芯旋转实现高速换向，可以突破阀芯往复式结构存在的局限，其振动波形与阀芯结构、阀芯液动力与阀芯转速的准确解算等问题是制约这类激振技术进一步发展的瓶颈。. 建立了阀芯旋转式高速换向阀的压力－流量特性方程和阀芯的受力平衡方程，获得了不同阀口形状下高速换向阀的静、动态特性，揭示了阻尼系数和转动惯量对动态特性的影响规律。研究结果表明：增大阻尼系数，可以增大阻尼比，从而有效抑制阀的振荡和超调，降低调整时间，提高阀的工作稳定性，但阀的响应速度变慢，不利于阀的快速控制；降低转动惯量，可以提高阀的固有频率和阻尼比，从而抑制阀的振荡和超调，提高阀的响应速度。. 建立了阀芯旋转式高速换向阀液动力矩的理论计算模型，研究了结构和运动参数对液动力矩的影响，提出了以阀芯转速稳定为目标的液动力矩补偿方法。研究结果表明：液动力矩是阀芯转速的非线性干扰因素；采用提出的液动力矩理论计算公式对阀芯旋转式高速换向阀液动力矩进行计算是可行的；提出的液动力矩补偿方法可有效降低阀芯旋转式高速换向阀液动力矩。. 建立了阀口过流面积与振动波形之间的映射关系，研究了结构参数对振动波形的影响，提出了基于振动波形的阀口设计方法。研究结果表明：谐波共振是引起振动波形失真的原因，与三角形阀口和半圆形阀口相比，矩形阀口下的振动波形失真度最低；提出的阀口设计方法可有效提高振动波形的准确性。. 对阀芯旋转式高速换向阀内流场进行分析。研究结果表明：随着阀口开度的增大，低压区的范围和位置也发生变化，低压区范围不断缩小，并逐渐从阀口中间向阀口壁面转移；阀口最低压力值随着供油压力的增大而降低，甚至会出现负压区，从而诱发气穴和噪声。. 研制了阀芯旋转式激振阀实验台，分别开展了静态特性、液动力矩和振动波形实验。进一步研究了进油方向和回油方向单向通油和双向通油时稳态液动力矩的耦合，验证和完善了所提出的液动力矩理论计算模型、补偿方法以及基于振动波形的阀口设计方法。. 基础研究成果为研制各类高频激振阀打下了基础，可满足各领域对于振动模拟和振动机械的高品质激振要求，具有重要理论意义和工程应用价值。