一种新的湍流修正模型及其在同轴旋流燃烧器空气动力场模拟中的应用(英文)

A NOVEL MODIFIED TURBULENCE MODEL AND ITS APPLICATION FOR SIMULATION ON AERODYNAMIC FIELD IN OUTLET OF COAXIAL SWIRLING BURNER

由于离心力与湍流脉动的相互作用,强旋流动中能量由湍流脉动向平均运动的逆向传输得到了加强。当径向脉动随半径增大时,离心力对湍流微团作正功,湍流微团的脉 动动能增加,反之亦然。基于对离心力作用的分析,该文提出了一种考虑离心力作功的新的k-e 湍流修正模型(k-e-cf模型),其特征参数由大涡与小涡相关参数的几何平均得到,其中涡的频率与实验一致。采用k-e-cf模型对一同轴旋转分层流燃烧器出口空气动力场进行了数值模拟,结果与实验吻合良好,精度比k-e 模型高。当切向速度满足一定分布时,离心力作功可以忽略,一般情况下,应考虑离心力作功以反映强旋流动的各向异性。

In strongly swirling flow, due to interaction between centrifugal force and turbulent pulsation, adverse transfer of energy from turbulent pulsation to average motion is greatly increased. When radial pulsation occurring in the direction of radius increases, centrifugal force does positive work to fluid micro mass of turbulent flow, making its pulsation kinetic energy increase, vice versa. Based on the analyses of effect of centrifugal force, k-e-cf model , a novel modified k- e turbulence model considering work done by centrifugal force in turbulent pulsation, is proposed in the present paper. The characteristic parameters in k-e-cf model are obtained by geometrical average of relevant parameters of big vortex and small eddy, of which frequency of eddy agrees with the experimental data. Aerodynamic field in outlet zone of a coaxial swirling stratified flow burner is numerically simulated. The simulated results with k-e-cf model agree well with the experimental data and have higher precision than those with standard k-e model. When tangential velocity meets with certain distribution, work done by centrifugal force can be ignored, but in general cases, it should be taken into account to reflect anisotropy of strongly swirling flow.