共轨高压油泵柱塞副的瞬态泄漏机理及特性研究

It is very important to precisely predict and control the leakage of piston pairs for improving the pump pressure of common-rail high-pressure fuel pump. In fact,the leakage of piston pairs is a transient question that involves micro-motion and heat-fluid-solid coupling which includes three steps,such as temperature rise, heat transfer and structure deformation.However,the current studies have not deeply considered these factors, which to some extent affects the calculation accuracy of the leakage in piston pairs.Through comprehensively using theoretical analysis,numerical calculation and experimental verification methods, the proposer will focus on the transient heat generated from the fuel when it is compressed with high speed and in high differential-pressure flow, heat transfer between the fuel and the piston pair, the piston pair's elastic deformation due to high pressure and high temperature,and the piston's micro motion. Based on these studies, the proposer will establish a mathematical physical model of the transient leakage of the piston pairs working in the heat-fluid-solid coupling and micro-motion environment, which can precisely solve the transient leakage in the piston pair. Further,the project will analyses the influence rule of relevant parameters on the transient leakage,which can explain the transient leakage characteristics and mechanism while the piston pairs work under the complicated environment of high speed,high temperature,high pressure and micro-hole.The study achievement will directly support the accurate control of the leakage based of piston pairs in common-rail high-pressure fuel pump.

精确预测并控制柱塞副的泄漏对提高共轨高压油泵的泵油压力至关重要，而柱塞副的泄漏实质上是一个由生热、流-固传热和结构变形够成热-流-固强耦合并伴有微运动的瞬态问题。现阶段的研究尚没有深入考虑这些因素，在一定程度上影响了柱塞副泄漏的计算精度。本课题针对往复运动过程中的高压共轨柱塞副，拟将综合运用理论分析、数值计算和试验验证方法，重点开展高速压差和剪切流动下的瞬态生热、高温高压下的流-固传热和结构热弹变形、高速运动下的结构动力学研究，建立温度场-流场-位移场强耦合及微运动下柱塞副瞬态泄漏的数学物理模型，实现对共轨高压油泵柱塞副泄漏的精确预测，获得相关参数对瞬态泄漏的影响规律，揭示柱塞副在高速、高温、高压及微孔隙复杂动态环境下的瞬态泄漏机理及特性，为共轨高压油泵柱塞副泄漏量的精确控制提供理论支撑。

柱塞副的泄漏实质上是一个由生热、流-固传热和结构变形所形成的的瞬态问题；以往的研究考虑得不够全面，在一定程度上影响了柱塞副泄漏的计算精度。本项目通过一维方式同时考虑柱塞偏移倾斜微运动、结构弹性变形、柱塞副中燃油非等温流动以及燃油在高温高压条件下的粘温粘压特性，建立了能与实验结果较好匹配的柱塞副泄漏模型，进一步完善发展了柱塞副的泄漏理论；同时考虑柱塞腔和共轨管中的流体流动、柱塞副泄漏、泵的容积效率损失的基础上，从理论方面对高压油泵的泵油能力进行了研究。在此基础上，运用自适应动网格技术和gap条件的基础上模拟柱塞的运动和球阀的开关，分析了整个工作循环的柱塞副瞬态密封特性；最后通过三维方式，建立了双向流-固-热耦合下的柱塞副稳态密封特性仿真模型，对改善柱塞副的密封特性提出了新的研究方向，并对更高泵油压力的柱塞副密封特性进行预测分析。