可压缩湍流圆孔射流的大涡模拟

Large Eddy Simulation of Compressible Turbulent Round Jet

采用大涡模拟方法研究了可压缩湍流圆孔射流问题,射流的马赫数为0.9,雷诺数为36 000。分析了射流的剪切层不稳定性过程,研究结果表明,沿剪切层的对流马赫数小于0.6,剪切层中的扰动涡在初始阶段沿周向呈管状结构。剪切层的不稳定性过程分为3个阶段,即增长阶段、失稳阶段和混合阶段,剪切层的增长速度在失稳阶段最慢,射流流场的湍动能峰值出现在剪切层混合阶段。

The compressible round jet is investigated by using large eddy simulation.The jet Mach number is 0.9 and the Reynolds number 36 000. The shear layer instability process is analyzed.Results show that the convective Mach number is less than 0.6.It indicates that the shear layer instability process is bi-dimensional with circumferential eddy structures originated from the Kelvin-Helmholtz instability.Three different stages of shear layer instability process are found,i.e.,shear layer growth,instability and mixing,with the shear layer growing slowly in the mixing stage.Moreover,the turbulent kinetic energy in the jet field reaches the peak value in the mixing stage.