基于微米敏感颗粒运移与热形变调控的无滞卡滑阀基础研究

Spool clamping is the main reason for performance degradation and defunctionalization in fluid control of hydraulic valve, which can also be the main source for reliability declined in hydraulic system. Take into consideration comprehensively, such as, irregular surface topography in micro gap wall, micro particle motion in valve chamber and sliding gap, geometry change in sliding gap caused by thermal deformation. The conclusion will reveal the flow characteristics of micro particle in valve chamber and sliding gap under real working conditions and the mechanical mechanism of spool valve clamping. In aspect of experiment, work will be started from the following three parts, deformation measurement of spool valve throttle and sliding mating surface in typical working condition, research about the micro scale visualization experimental methods and devices, and trace display the micro particle trajectory, accumulation and retention. In aspect of theory and numerical, the research will be launched from the following parts, high precision numerical simulation method of trans-scale (mm to μm) fluid flow in valve chamber and sliding gap, research about the particle motion and accumulation based on Euler - Lagrange method, research about the micro particle motion and migration in sliding gap based on immersed boundary method, and the establishment of mechanical model about spool clamping. The basic theory and surface design technology of the clamping-free spool valve based on the regulation to the deformation due to throttling heat and the control of micro particle motion in sliding gap will be proposed, which can provide basic theory support and experimental data for the development of high reliability proportional valve and servo valve.

阀芯滞卡是引起液压阀流体控制性能劣化、功能丧失的主要原因，也是液压系统可靠性下降的重要根源。综合考虑微米级间隙壁面的不规则表面形貌、微米敏感颗粒在阀腔与间隙流道内的运移、热形变引起间隙流道的几何改变等微观因素，揭示真实工况下滑阀阀腔与间隙内敏感颗粒的流动特征与阀芯滞卡的力学机理。实验方面，主要开展滑阀节流边、滑动配合面在典型工况中的热形变特征测量，微米尺度可视化实验方法及装置研究，敏感颗粒运动轨迹和集聚、滞留现象的追踪显示。理论与数值方面，研究阀腔-间隙（毫米-微米）跨尺度流域流动的高精度数值模拟方法，基于欧拉-拉格朗日方法研究颗粒物在阀腔内的运移与集聚，基于浸入边界法研究敏感颗粒在间隙内运移及间隙内的流动，建立阀芯滞卡的力学模型。由此，形成基于热形变调控与敏感颗粒运移控制的无滞卡滑阀的基础理论和表面设计技术，为高可靠性比例阀、伺服阀的发展提供基础理论支撑和实验数据。

本项目中滑阀是指带有滑阀配合间隙结构的所有液压控制阀，滑阀在液压系统中无处不在，决定着液压驱动装备的运动规律、品质和可靠性。据统计75%以上液压故障与油液污染有关；在工程实践中，军工装备、工程机械等会不同程度显现出液压可靠性相关问题，甚至某些国产比例阀在使用中呈现高达40%故障率的情况。揭示液压滑阀可靠性的本质、为高性能液压控制阀设计制造提供理论指导是本项目的目标。. 液压系统可靠性问题，一定程度上就是滑阀滞卡问题。项目以实验研究为主，研制出了阀口热形变测量、阀内颗粒物运动可视化、滑阀阀芯滞卡力测量等装置，基于高速摄像机、光学显微镜、嵌入式微小传感器等，取得重要数据；深化了油液污染统计学认知，根据敏感颗粒物的非规则外形特征，将球形颗粒模型推进为方形颗粒模型，将敏感颗粒物的浓度度量推进为有限个数颗粒物，实现了敏感颗粒物运动规律的精确定量研究；发现了颗粒物在阀腔、滑阀间隙中的自旋转现象，敏感颗粒物在阀腔流场的驱动下侵入滑阀间隙，在滑阀间隙内旋转、进动、驻留；发现滑阀小开口热形变大梯度现象；由于节流温升热形变、滑动副制造误差、阀芯移动等导致滑阀间隙边界变化，使得敏感颗粒物对滑阀运动呈现微弱、明显、强烈等不同程度的脉动性滞卡作用；基于大量实验数据分析，提出了“滑阀阀芯径向微动”概念，揭示了滑阀滞卡机制，阀芯滞卡是由敏感颗粒物在阀芯周向分布引起阀芯径向微动量减小所致。采用Fluent-Abaqus/Workbench热流固耦合，COMSOL Multiphysics流固耦合模块的ALE移动网格法等数值方法，与实验数据联合揭示了滑阀滞卡机理和机制。. 基于基础研究，提出了几种无滞卡滑阀的调控方法，包括滑阀变间隙设计、内嵌磁环吸附颗粒结构、纯净液体密封圈等。本项目构建了滑阀滞卡机理与机制的基本理论体系，为高可靠性液压滑阀的设计制造及创新提供了指导。