条件矩封闭模型应用于非预混湍流反应流动

推导了考虑分子和湍流扩散的条件矩封闭方程,并利用其模拟了二维非预混湍流反应流,计算结果与实验结果符合良好.结果表明,有限值的Damkohler数使条件平均变量偏离其平衡状态,且在混合分数η位于化学恰当比下的混合分数附近时偏离最大.Damkohler数的升高还使得条件和无条件平均的反应速率升高,并使条件平均变量向其平衡状态值趋近.本文还观察到以往的简化维数处理会引起一定的偏差.因此,对于一般的椭圆型反应流动,建议采用考虑扩散效应的CMC控制方程. 

Implementation of Elliptic-type Conditional Moment Closure Model to Nonpremixed Turbulent Reacting Flows

The conditional moment closure (CMC) formulation considering both molecular and turbulent diffusions is derived and applied to simulate two dimensional nonpremixed turbulent reacting flows. Calculated results show good agreement with experimental ones. Results show that finite Damkohler number makes conditional averaged variables depart from their equilibrium values and the deviation is the maximum near stoichiometric mass fraction. The increasing Damkohler number increases conditional and unconditional mean reaction rates, and makes the conditional mean variable towards equilibrium limit.It is also shown that the reduction of dimensionality may result in certain deviations. For general elliptic type reaction flow, it is suggested that the CMC formulation accounting for diffusion effect be employed.