不同工况下旋流液雾燃烧的直接数值模拟

Direct Numerical Simulations of Swirling Spray Combustion Under Different Conditions

采用有限差分方法对不同工况下三维旋流液雾燃烧进行了直接数值模拟,其中液滴的跟踪在拉格朗日框架中进行,液滴的蒸发相变采用无限热传导蒸发模型描述,气相燃烧采用自适应单步反应机理,模拟中采用的模型燃烧器尽可能逼近真实的燃气轮机旋流燃烧器。结果发现,旋流液雾燃烧流动和火焰结构受到旋流方式和当量比的影响,流场中出现了反平行排列的涡管结构,且各种工况下液雾燃烧火焰都是由贫燃预混火焰、富燃预混火焰、扩散火焰构成。这些给液雾燃烧的模型模拟带来了新的挑战。

Three-dimensional swirling spray combustion flames under different conditions were studied by means of Direct Numerical Simulations（DNS） based on finite difference method.The model combustor was designed to match the realistic gas turbine combustor as most as possible. The droplets were tracked in the Lagrangian framework and the evaporation was described by an infinite heat conduction model.The gas combustion was modelled by an adaptive one-step reaction mechanism.It was found that the turbulent flow and flame structures of the swirling spray combustion are influenced by swirling direction and equivalence ratio.Anti-parallel structures of the vortex tubes were observed in the flow field,and the spray flame was composed of lean premixed flame,rich premixed flame,and diffusion flames under all conditions,which brings tremendous challenge to the spray combustion modelling and simulation.