燃烧室污染物生成大涡模拟模型的研究

采用亚网格动力学模型和联合概率密度函数(PDF)亚网格模型对污染物NO的生成进行大涡模拟.计算中采用的数学模型有:k方程亚网格尺度模型来估算亚网格湍流粘性;亚网格EBU燃烧模型估算化学反应速率;在交错网格体系下,采用SIMPLE算法和混合差分格式来求解差分方程.数值分析两种不同亚网格污染物生成模型和两种进口气流温度对NO排放的影响,计算结果与实验数据比较表明:两种亚网格污染物生成模型都能较好的预估燃烧室污染物NO的生成,但亚网格动力学模型的计算工作量要比联合概率密度函数亚网格模型少得多,更适合工程应用.

Study of sub-grid pollutant formation model in combustor

The NO subgrid-scale formation model and the beta PDF subgrid-scale NO formation model were used for Large-Eddy Simulation(LES) of NO emission in model afterburner with V-gutter flame stabilizer.The k-equation sub-grid scale model was used to simulate the sub-grid eddy viscosity,and the EBU combustion sub-grid scale model was employed to determine the chemical reaction rate.Discrete equations were solved with SIMPLE algorithm and hybrid scheme in staggered grid system.The effects of two different subgrid-scale NO formation models and inlet temperatures on NO formation were calculated.The reasonable agreement of simulation results in comparison with experimental data shows two different subgrid-scale pollutant formation models may predict the NO formation in the combustor.The NO subgrid-scale formation model spends much less calculation time than the Beta PDF(subgrid-scale) NO formation model,and it was more appropriate for engineering application.