分离涡方法模拟浓淡气固射流两相非稳态流动特性研究

利用分离涡模拟(Detached eddy simulation，DES)这一新型湍流模拟技术对撞击式浓淡燃烧器内部和出口射流的气固两相流动结构进行了模拟，获得了浓淡燃烧器出口射流的旋涡拟序结构，模拟了射流出口旋涡生成、发展和脱落的规律。对于颗粒场，应用了Lagrangian方法跟踪颗粒运动，获得了浓淡燃烧器出口射流中不同Stokes数颗粒在射流流场旋涡拟序结构作用下的运动扩散规律。结果表明，射流外边界处的大涡是引起浓淡侧小颗粒相互混合的主要因素，而煤粉气流中Stokes数大于1的颗粒在射流中基本不会发生浓淡混合现象，燃烧器下游的浓淡分离效果可以在较长的距离内得到保持。

THE NUMERICAL INVESTIGATION ON THE TRANSIENT CHARACTERISTICS OF THE GAS-SOLID TWO-PHASE FUEL RICH-LEAN BURNER FLOW

The detached-eddy-simulation (DES) approach was employed to study the turbulent flow in the fuel rich-lean separator and the gas-solid multiphase jet from the exit of a fuel rich-lean burner. The vortex shedding process was simulated and its effect on the fuel rich-lean separate performance was evaluated. Combined with the stochastic particle tracking method, the motion characteristics of the coal particle with various Stokes number in the gas-solid fuel rich-lean jet was tracked, which show the large vortex structure at the jet outer boundary is the main factor which make the small particle to mix together. The coal particles with large Stokes number (St>1) diffuse very slowly in the jet flow, which makes the fuel rich-lean combustion be kept in a rather long distance downstream the exit of the nozzle.