射流管伺服阀内部流动失稳及其被动抑制研究

The jet-pipe servovalve (JPSV) is widely used in aviation, aerospace, military and other fields because of its high resistance to contamination and high reliability. As a servo element developed based on jet theory, flow instability of high-speed impinging jet and flow-induced vibration of jet pipe are two key factors for the performance deterioration and even failure. But owing to the limitation of current experiments and simulation methods, the above problem has not been fully resolved. .Based on this consideration, this project combines the PIV transient flow field measurement with unsteady flow simulation based on DDES method, the following investigation will be carried out: (1) Characteristics of extremely close impinging jet on flat plane with hydraulic oil medium. (2) Flow instability of high-speed impinging jet with strong wall constrain and fluid-structure interaction dynamics of thin and long tube/bars. (3) Working performance of structure-improved pilot stage of JPSV. .The objective of this project is to clarify the flow instability mechanism in JPSV, reveal the fluid-structure interaction vibration characteristics of the long jet pipe, and propose a passive suppression method based on the variation of mass distribution. This research can enrich the jet mechanics and fluid-structure interaction mechanics theory and promote the technical progress of JPSV, which has important theoretical significance and practical value.

射流管式电液伺服阀因其突出的抗污染能力，在航空、航天、舰船等以高可靠为目标的应用场合备受青睐。射流管阀内高速冲击射流的流动失稳以及射流管流致振动是导致其工作性能下降，甚至发生啸叫等失效行为的关键，但囿于目前实验与仿真手段的限制，对于上述问题还缺乏深入的理解和认识。.基于此，本项目将PIV瞬态流场测量与基于延迟分离涡模拟方法（DDES）的非定常流场仿真相结合，开展以下研究：(1)油液介质超近距离平板冲击射流特性；(2)强壁面约束高速冲击射流的流动失稳与细长管/杆的流固耦合动力学特性；(3)基于射流管-接受器结构改进的射流管阀前置级工作特性。以期阐明射流管阀内流动失稳机理，揭示细长射流管的流固耦合振动规律，给出一种基于变质量分布的被动抑制方法。.通过本项目研究可以深化对射流管阀内流动本质的理解，其成果可以丰富射流力学和流固耦合力学理论，推动射流管式电液伺服技术进步，具有重要的理论和实用价值。

射流管式电液伺服阀因其突出的抗污染能力，在航空、航天、舰船等以高可靠为目标的液压控制中备受青睐。射流管阀内高速冲击射流的流动失稳以及射流管流致振动是导致其工作性能下降，甚至发生啸叫等失效行为的关键，但囿于目前实验与仿真手段的限制，对于上述问题还缺乏深入的理解和认识。基于此，本项目结合PIV瞬态流场测量与计算机流场仿真相结合，开展了以下研究：(1)油液介质超近距离平板冲击射流特性；(2)强壁面约束高速冲击射流的流动失稳与细长管/杆的流固耦合动力学特性；(3)基于射流管-接受器结构改进的射流管阀前置级工作特性。. （1）运用时间分辨粒子成像测速系统(TR-PIV)对近距离下射流冲击平板时的动静态流场进行了直接测量，揭示了冲击距离和雷诺数对射流间隙内流动特征及涡系结构演化规律的影响。结果表明：射流间隙存在三种典型的涡系结构，分别为双涡环模式、单涡环模式和卷吸模式，各流动模式的出现主要与射流流态及壁面约束作用有关。. （2）研究了雷诺数Re和喷嘴端面轮廓（壁面约束）对间隙内旋涡生成的影响，并对试验数据进行了涡量分析与本征正交分解方法（POD）分析。结果表明，雷诺数对直角型喷嘴的双涡环模式流态影响较小；圆角型喷嘴的冲击射流表现为卷吸模式，且随雷诺数的增大出现动态对称涡旋，该对称涡旋逐渐向间隙外迁移呈现出明显的周期性变化特征。. （3）前置级工作特性研究表明：射流管阀内的流动失稳也与其前置级中的不同结构参数有关，小孔径与小流量下的流场较为稳定，端面形状的改变对流场也有一定优化作用。锥形射流管对流动失稳和射流管流致振动的抑制效果较好。. 通过本项目研究可以深化对射流管阀内流动本质的理解，其成果可以丰富射流力学和流固耦合力学理论，推动射流管式电液伺服技术进步，具有重要的理论和实用价值。