Upstream influence on the near field of a plane turbulent jet
Upstream influence on the near field of a plane turbulent jet
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上游对平面湍流射流近场的影响
DOI：
10.1063/1.862037
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发表时间：
1977
影响因子：
4.6
通讯作者：
A. R. Clark
中科院分区：
文献类型：
--
作者：
A. K. M. F. Hussain;A. R. Clark
在四种初始条件下，实验研究了上游（初始）边界层的平均和湍流特性对平面射流近场流动演化的影响。射流加宽速率和中心线平均速度衰减速率以及运动学和几何虚原点显示出系统依赖于初始条件的证据。当初始边界层为层流时，纵向湍流强度和质量通量的增长率均高于湍流时。在出口的下游，层流初始边界层情况下的无量纲夹带率达到峰值，大约是完全湍流初始边界层情况下延迟峰值的两倍。在前40个狭缝宽度内，总平均流向动量通量的增加幅度在20% ~ 56%之间，其中层流初始边界层的增加幅度较大；每次增加大约10%是由湍流场引起的。虽然这种增加违反了传统上公认的动量通量不变性，但它们与负平均静压数据一致。
The effects of the mean and turbulence characteristics of the upstream (initial) boundary layer on the evolution of the flow in the near field of a plane jet have been experimentally investigated for four initial conditions. Rates of jet widening and centerline mean velocity decay as well as the kinematic and geometric virtual origins show evidence of systematic dependence on initial conditions. The growth rate of longitudinal turbulence intensity, and the mass flux are higher when the initial boundary layer is laminar than when turbulent. Immediately downstream of the exit, the nondimensional entrainment rates for the laminar initial boundary layer cases reach peak values which are about twice the delayed peak values for the fully turbulent initial boundary layer cases. Within the first 40 slit widths, increases in total average streamwise momentum flux range from 20% to 56%, the larger increases occurring for the laminar initial boundary layers; about 10% of each increase is due to the turbulence field. While such increases violate the traditionally accepted momentum flux invariance, they are consistent with the negative mean static pressure data.