Investigation of scalar dissipation rate fluctuations in non-premixed turbulent combustion using a stochastic approach
Investigation of scalar dissipation rate fluctuations in non-premixed turbulent combustion using a stochastic approach
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DOI：
10.1088/1364-7830/5/1/303
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发表时间：
2001-03
影响因子：
1.3
通讯作者：
H. Pitsch;S. Fedotov
中科院分区：
文献类型：
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作者：
H. Pitsch;S. Fedotov
在非预混燃烧中，标量耗散率的湍流波动对着火和熄灭有很大的影响。本文研究了标量耗散率的随机波动对火焰方程解的影响。假设是一步不可逆反应。因此，系统可以用温度方程的解来描述。通过对火焰方程中的扩散项进行建模，可以将其写成普通随机微分方程。此外，还推导了标量耗散率的SDE。由这两个方程可以得到描述温度和标量耗散率联合概率的Fokker-Planck方程。采用四阶龙格-库塔格式对方程进行了分析和数值积分。讨论了Damköhler数、Zeldovich数、放热参数和标量耗散率波动方差等主要参数的影响。
Turbulent fluctuations of the scalar dissipation rate are well known to have a strong impact on ignition and extinction in non-premixed combustion. In the present study the influence of stochastic fluctuations of the scalar dissipation rate on the solution of the flamelet equations is investigated. A one-step irreversible reaction is assumed. The system can thereby be described by the solution of the temperature equation. By modelling the diffusion terms in the flamelet equation this can be written as an ordinary stochastic differential equation (SDE). In addition, an SDE is derived for the scalar dissipation rate. From these two equations, a Fokker-Planck equation can be obtained describing the joint probability of temperature and the scalar dissipation rate. The equation is analysed and integrated numerically using a fourth-order Runge-Kutta scheme. The influence of the main parameters, which are the Damköhler number, the Zeldovich number, the heat release parameter and the variance of the scalar dissipation rate fluctuations, are discussed.