液滴碰撞聚合模型及其在喷雾燃烧流场中的应用

Droplet collision and coalescence model and its application in the spray combustion simulation

关键词:  液雾+  液滴  碰撞和聚合+  数学模型  数值计算

Key words:  Liquid sprays~+  Droplet  Collision and coalescence~+  Mathematical simulation  Numerical calculation

摘要:

基于平滑粒子流体动力学方法的思想,建立了新的描述液滴间碰撞和聚合过程的数学模型,将相互碰撞的液滴局限在其周围一定数目的液滴之间,并对液滴间碰撞的概率进行了重新定义。数值计算结果表明:模型从根本上摆脱了O’Rourke模型对计算网格的依赖性,大幅度提高了计算效率和精度。在此基础上考虑液滴的变形、破碎及相变过程,采用Eu ler-Lagrangian方法和有限化学反应速率模型,对RBCC引射模态进行了三维两相喷雾燃烧流场数值模拟,并和实验数据进行了对比。结果表明:在RBCC自由引射模态,二次燃料喷射位置的适当后移会使燃料利用率提高,引射比增加,引射火箭推力增加。

Abstract:

Due to the fact that the droplet collision and coalescence model is very important and the models existed are time-consuming and mesh-dependent.Based on the principal idea of Smooth Particle Hydrodynamics method,a new droplet collision and coalescence model was presented in this paper.The model assumes that a droplet can only collide with a given number of nearest droplets surrounding it.In this way the droplet collision probability was redefined.Numerical simulation shows that the model presented is mesh independent,highly efficient and accurate.Then Euler-Lagrangian method including droplet deformation,breakup and phase change,coupled with finite rate chemical reaction model was used and three dimensional turbulent spray combustion simulation was carried on the eject mode of RBCC.Comparison was made between computatlon and the experimental data and it is shown that in the eject mode of RBCC,the movement of injector downstream to some extent can increase the fuel combustion efficiency and thrust.