摘要
采用高精度高分辨率格式进行直接数值模拟,既得到了对流马赫数为1.2的混合层中线性发展之后的λ涡、发卡涡和涡的破碎,还得到了破碎后发展的多模态主导下的分层涡结构,以及对应动量厚度饱和下的涡结构。其流动结构的发展显示了混合层在自由空间充分发展能力的有限性。此外捕捉和显示了混合层中自然发展起来的外缘激波、对旋激波和单涡激波,激波主要是由于涡结构的高速旋转造成的相对超声速、低压区和逆压梯度区而产生的。激波的存在抑制了混合层从主流吸取质量和动量,也抑制了混合层内部流质混合的均匀性。
Using the high-order high-resolution scheme, three-dimensional direct numerical simulations are performed for the spatially developing compressible plane mixing layer at convective Maeh number 1.2. The full developing process of instability, formation of λ vortices and hairpin vortices, break down of large vortex structures, the appearance of colayer structures and finally the structures of the saturation state in the sense of momentum thickness are produced in the simulations. Additionally, shocks are generated in the mix- ing layer. Based on their different generation mechanisms shocks are categorized into three types： flee-stream shocks, counter-rotating-vortex shocks and single-vortex shocks. The shocks are mainly generated by the strong swirl motion of the vortices, which produce the relative supersonic domain with low pressure and also the domain with reverse pressure gradient. The appearance of shocks inhibits the mixing layer from drawing mass and momentum from the free stream. It also prevents the fluids from mixing uniformly in the interior of the mixing layer.
出处
《空气动力学学报》
EI
CSCD
北大核心
2010年第3期245-249,共5页
Acta Aerodynamica Sinica
基金
国家自然科学基金(90305014)
关键词
高精度高分辨率格式
可压缩混合层
大尺度结构
小激波
分层涡结构
high-order high-resolution scheme
compressible mixing layer
large-scale structure
shocklets
colayer structure
