The present work reports an experimental investigation on pulsed water spray impingement into cross-stream air flow in an optically accessible channel with circular cross section. Such flow configuration refers to a complex fluid dynamics system due to interaction of polydispersed droplets with the channel wall. The current study aims at gaining some insight into post-impact droplet characteristics and the in-channel mixing process following spray interaction. The spatial distribution of spray droplets across the channel cross section was visualized by application of the laser sheet imaging (LSI) technique at different axial locations. A uniformity index parameter was measured to quantify the degree of mixing. Measurement of spray droplet size distribution post-impingement and at the channel exit was achieved by the interferometric laser imaging for droplet sizing (ILIDS) technique. The impingement of the spray droplets on the channel wall was visualized by high-speed shadowgraphic imaging technique. The effect of introducing a swirler-type mixer in the channel was examined. Experiments were performed by varying the flow and injection parameters. It was found that efficient mixing of droplets after impingement is not very sensitive to moderate variations in the injection parameters though careful swirler design is important.

中文翻译：

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横流喷射喷射、壁面相互作用和通道气流混合的光学表征

目前的工作报告了在具有圆形横截面的光学可访问通道中脉冲水喷雾撞击横流气流的实验研究。这种流动配置是指由于多分散液滴与通道壁的相互作用而产生的复杂流体动力学系统。目前的研究旨在深入了解冲击后液滴特性和喷雾相互作用后的通道内混合过程。通过在不同轴向位置应用激光片材成像 (LSI) 技术，可以观察到喷雾液滴在通道横截面上的空间分布。测量均匀性指数参数以量化混合程度。通过液滴尺寸干涉激光成像 (ILIDS) 技术测量撞击后和通道出口处的喷雾液滴尺寸分布。通过高速阴影成像技术可视化喷射液滴在通道壁上的撞击。研究了在通道中引入旋流式混合器的效果。通过改变流量和注射参数进行实验。研究发现，尽管仔细的旋流器设计很重要，但撞击后液滴的有效混合对喷射参数的适度变化不是很敏感。通过改变流量和注射参数进行实验。研究发现，尽管仔细的旋流器设计很重要，但撞击后液滴的有效混合对喷射参数的适度变化不是很敏感。通过改变流量和注射参数进行实验。研究发现，尽管仔细的旋流器设计很重要，但撞击后液滴的有效混合对喷射参数的适度变化不是很敏感。