The three-dimensional turbulent wall jet has a lateral half-width that is 5 to 8 times greater than its vertical half-height. This has been previously attributed to strong turbulence generated secondary flow caused by the passage of coherent vortex-ring structures formed at the nozzle exit. In order to assess whether the large lateral growth of the jet is tied to these structures, a grid was placed at the nozzle exit to disrupt the shear-layer that produces the vortex rings at the outlet. Here, the jet was formed using a 0.038m round contoured nozzle with an exit Reynolds number of 108,000. The grid has a mesh wire size of 0.2mm with an opening of 1 mm giving it a solidity ratio of 0.4. Measurements of the jet with and without the grid were taken using hot-wire anemometry and stereoscopic Particle Image Velocimetry (PIV). The results indicate that the grid delays the lateral growth of the jet and increases its vertical growth. By x/D=40 though, these differences were minimal. The presence of the grid also decreased the mass entrainment and mixing associated with the jet at each downstream location investigated.
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机译：三维湍流壁射流具有比其垂直半高的横向半宽度为5至8倍。这前这一直归因于由在喷嘴出口处形成的相干涡旋结构的通过引起的强烈湍流产生的二次流动。为了评估射流的大的横向生长是否与这些结构相关联，将栅格放置在喷嘴出口处，以破坏在出口处产生涡旋环的剪切层。这里，使用0.038M圆形轮廓喷嘴形成射流，其出口雷诺数为108,000。该网格具有0.2mm的网格线尺寸，开口为1mm，使其具有0.4的韧度。采用热线风化术和立体粒子图像速度（PIV）拍摄具有和不具有栅格的喷射的测量。结果表明，网格延迟了射流的横向生长并增加了其垂直生长。通过X / D = 40，但这些差异很小。网格的存在还降低了在每个下游位置的与射流相关的质量夹带和混合。
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