柴油喷雾计算时空差分尺度依赖性消减的方法

A Method of Spatial and Temporal Difference Scale Dependent Reduction in Diesel Spray Simulation

柴油喷雾计算流体动力学(CFD)计算具有差分尺度依赖性,对计算精度和计算效率会产生影响.基于KIVA3v程序中现有的喷雾模型,开发了一套减小时间和空间差分尺度依赖性的方法和模型.修正了用于喷雾气/液相对速度计算的gasjet模型和用于液滴碰撞计算的影响半径(ROI)O’Rourke模型,从而减小对网格尺度的依赖性.并在喷雾源项计算中加入了子循环,用于消除时间步长的依赖性.经检验该模型可明显降低差分尺度的选取对喷雾计算贯穿距、粒径及喷雾形态的影响.

The accuracy and efficiency of diesel spray CFD simulation depend on the mesh difference scale. A spatial and temporal difference scale independent spray model was developed based on the KIVA3v code. The gasjet model which is used for liquid-gas relative velocity calculation and the ROI （radius of influence） O＇Rourke collision model which is used for droplet collision calculation were revised so that the mesh scale dependencies are reduced. The time- step dependencies are also reduced by adding the spray sub-cycle into the source term calculation step. Significant reduction on spatial and temporal difference scale dependencies is observed in the model validation, including spray penetration, droplets diameters and spray structure.