环形燃烧室两相喷雾燃烧的大涡模拟

Large-eddy simulation of turbulent spray combustion in an annular combustor

在三维任意曲线坐标系下采用欧拉-拉格朗日两相大涡模拟方法对环形燃烧室火焰筒气液两相紊流瞬态反应流进行数值模拟。采用椭圆偏微分方程生成三维贴体网格,计算中所采用的数学度模型有:k方程亚网格尺度模型估算亚网格紊流粘性;亚网格EBU燃烧模型估算化学反应速率;热通量辐射模型估算辐射换热。并在非交错网格体系下气相采用SIMPLE算法和混合差分格式求解,液相采用随机离散模型(Stachastic Separated Flow,简称SSF),在拉格朗日坐标系下追踪各油珠群沿各自轨道运动、质量损失及能量变化。通过计算结果与实验数据相比较,表明在三维贴体坐标系下对燃烧室火焰筒两相紊流油雾燃烧流场进行大涡模拟,采用欧拉-拉格朗日两相大涡模拟方法能反映两相紊流化学反应流流动及实际燃烧过程。

In three-dimensional arbitrary curvilinear coordinate system, an Eulerian-Lagrangian two phase large-eddy simulation （LES） approach was employed to predict instantaneous gas-liquid two-phase turbulent combustion flows in an annular combustor. Three dimensional body-fitted grid was generated by using an elliptical grid generation procedure. The k-equation sub-grid scale model was used to simulate the sub-grid eddy viscosity, the EBU combustion sub-grid scale model was used to determine the chemical reaction rate, the six-heat flux model was applied to predict the radiant heat transfer. The gas phase was solved with SIMPLE algorithm and hybrid scheme in non-staggered grid system. A Stochastic Separated Flow formulation was used to track the droplet trajectories velocities, size and temperature history by using Lagrangian equations of motion and thermal balance. To avoid the need for detailed calculations in the near wall regions, wall functions was extended to the body-fitted coordinate system. The calculated and measured temperature profiles at outlet plane were in reasonable agreement. It shows that system, in arbitrary curvilinear coordinate system, and an Eulerian-Lagrangian two phase LES formulation may be used to investigate turbulent two-phase reacting flows and combustion process in combustors.