壁面冷却的三股混合气流的数值计算

对双层壁扩压器与波瓣喷管组合的三股气流的引射混合进行了流场温度场的数值计算。计算域划分为各子域 ,通过求解拉普拉斯方程 ,分别生成三维贴体曲线坐标网格 ,边界网格加密且波瓣处正交 ,各子域组合成整个网格。为避免因波瓣造成的网格强烈的非正交而引起解的发散 ,本文采用了同位网格 SIMPLEC计算方法和Chen-Kim修正的 k-ε湍流模型。固体区域采用大粘性解决流固耦合 ,还结合了线性欠松弛和拟瞬态欠松弛。结果证明 :双层壁间有外界冷气流被引射进入 ,形成壁面的冷却气流 ,相对单层壁扩压器 ,双层壁扩压器的壁面温度明显降低。对于小扩压角 ( 0～ 5°) ,随着扩压角的增大 ,壁面平均温度降低 ;但当扩压角较大时 ( 5～ 1 0°) ,壁面平均温度则增加

NUMERICAL CALCULATION OF THREE-STREAM MIXING FLOW WITH WALL COOLING

The flow and the temperature in the three-stream mixing flow of the lobed nozzle mixer-ejector with double-wall diffuser are numerically investigated. The domain of computation is divided into sub-domains according to the shapes of the double-plate and lobed nozzle. The three-dimensional body-fitted coordinated grids are generated respectively in these sub-domains by solving Lapalace′s equations. Grids are dense on the boundaries and orthogonal at the lobe. The grids of all sub-domains compose the whole grid of the domain. In order to avoid the divergence of the computation as the serious non-orthogonality of the grid from the lobe, the co-located grid,SIMPLEC and Chen-Kim modified k-ε turbulence model are applied. The great viscosity, the linear and simultaneous cooperation under-relaxation factors are used to solve the coupling of the fluid and solid. Results show that the air is ejected into the double wall section to form the cooling flow. The wall temperature of the double-wall diffuser is lower than that of the single-wall diffuser. The average wall temperature goes down as the diffuser angle increases at the range of 0～5°,otherwise, the result at the range of 5～10° is opposite.