基于CFD仿真和正交试验的喷油嘴针阀公差分析∗

摘要

为了降低柴油机喷油嘴的流量分散度,找出影响喷油嘴出口流量的主要形位公差。首先利用计算流体力学软件FLUENT,建立了喷油嘴三维流场模型,得到了公称模型下喷油嘴出口流量值；然后选取针阀外圆柱工作面的圆度、轴线的直线度和密封圆锥的圆锥度为主要因素,采用正交设计的方法,通过极差分析,得到了各形位公差影响喷油嘴出口流量的规律,并得到了优化后的公差组合；最后根据其优化方案进行了CFD仿真,通过和实验结果对比表明,该形位公差方案降低了喷油嘴流量分散度,证明了正交试验的可行性,对喷油嘴针阀的形位公差设计提供了一种参考。%In order to reduce diesel engine nozzle flow dispersity, find out the main form tolerances which influences nozzle outlet flow. Firstly,establishingthe three-dimensional flow field model of nozzle by using computational fluid dynamics software FLUENT, getting the nozzle outlet flowunder nominal model; And then select the needle valve outer cylinder roundness,axis straightness and taper error as the main factors, through the analysis of rangeby using the orthogonal test, got the influence lawsofform tolerance on nozzle outlet flow, and get the optimized combination of tolerance;Comparing the optimizationis carried out by the CFD simulation and experiment,results show that the form tolerance scheme reduces the nozzle flow disper-sity, prove the feasibility of the orthogonal test, provides a referenceof the nozzle needle valve form toler-ance design.