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为了研究柴油机喷油器内部的气穴现象,采用一种新的方法建模并进行瞬态两相流动的数值模拟.首先求解针阀开启时刻的稳态流场,然后导入自编的程序进行瞬态流场的计算.自编程序是基于Fluent提供的用户自定义函数,用于控制模型边界条件,分析针阀受力情况和计算其运动速度.初始计算条件来自稳态流场,每一步瞬态计算都依赖之前流场的计算结果.这种建模方法保证了数值模拟的连贯性和真实性,确定喷油器初始条件就可以完整地计算喷油过程,得到每一时刻喷油器内部的压力分布和两相流分布等数据.研究结果表明,这种新的建模方法是可行和有效的,其数值模拟结果和实验结果相吻合,并能揭示出喷油器喷嘴入口处气穴现象的产生、发展和消失过程,是进一步深入开展柴油喷油系统两相流动特性研究的一种新的途径.
In order to study the cavitation phenomenon inside diesel injector, a new method is used to model and simulate the transient two-phase flow.Firstly, the steady-state flow field of the needle valve opening time is solved and then imported into the self-programmed program Transient Flow Field Calculation The self-programming program is based on a user-defined function provided by Fluent for controlling the boundary conditions of the model, analyzing the needle valve force and calculating the velocity of the needle valve. The initial calculation conditions come from the steady-state flow field, Transient calculation depends on the calculation results of the previous flow field.This modeling method ensures the consistency and authenticity of the numerical simulation, and determines the initial conditions of the injector can calculate the fuel injection process, get the fuel injector Internal pressure distribution and two-phase flow distribution data.The results show that this new modeling method is feasible and effective, and its numerical simulation results and experimental results are consistent, and can reveal the injector nozzle gas The emergence, development and disappearance of cavitation phenomena are a new way to further study the two-phase flow characteristics of diesel fuel injection system.