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研究了基于层流小火焰概念和假定beta-PDF(probability density function)的湍流预混燃烧模型.该模型采用PREMIX程序来计算层流小火焰,将计算结果表示为进程变量的函数,并利用进程变量的be-ta-PDF积分生成了用于RANS(雷诺平均Navier-Stokes)计算的PDF表.以化学当量的甲烷湍流本生火焰为算例对模型进行了计算验证,并与Zimont模型的计算结果和实验结果做了对比.结果表明,平均速度分布与实验符合的较好,温度和湍动能计算结果有待改善.本模型高估了化学反应速率,导致计算火焰比实际瘦,这是因为模型中未能考虑湍流对火焰的拉伸和弯曲效应,考虑湍流拉伸和弯曲效应的预混燃烧模型是今后进一步研究的方向.
A turbulent premixed combustion model based on the concept of laminar small flame and the assumption of a probabilistic beta-PDF is studied. The PREMIX program is used to calculate the laminar flow flames, and the results are expressed as function of process variables. The be-ta-PDF integrals of the variables generate the PDF tables used for the RANS (Reynolds Average Navier-Stokes) calculations.The model was validated with a stochastic methane turbulence Bunsen flame and compared with the Zimont model The results are compared with the experimental results.The results show that the average velocity distribution is in good agreement with the experimental results and the calculation results of temperature and turbulent kinetic energy need to be improved.This model overestimates the chemical reaction rate and leads to the calculation of the flame is thinner than the actual, Can not consider the effect of turbulence on flame stretching and bending, and the premixed combustion model considering the effect of turbulence stretching and bending is the direction for further research.