We present recent experimental results on the dynamics of atomization of a liquid column by a coaxial turbulent gas jet, under varying air angular momentum (swirl) conditions and densities. We compare between atomization under atmospheric conditions and in a pressurized environment where the atomizing and ambient air density is 5 times the atmospheric level. For both conditions, the parameter space includes a gas-to-liquid momentum ratio in the range of and swirl ratios of . High-speed shadowgraphy images in the spray near-field are used to quantify the spatial and temporal evolution of the liquid–gas interface. In the mid-field, Phase Doppler Interferometry, collected radially across the spray, quantify droplet size, velocity, and number density distributions. At high pressure and with increasing M, we observe a decrease in spray angle when but a spray angle increase when (critical swirl). We reconcile these observations with the crown de-wetting mechanism, first observed in X-ray shadowgraphs of the spray. Crown de-wetting depends on gas inertia relative to the liquid, which increases linearly with atomization environment pressure, leading to this switch in behavior. This mechanism also explains the modified droplet radial distribution in the mid-field, with critical transition from concave to convex-shaped trends in the mean droplet size profile. Finally, we reconstruct the full spray droplet population from radial measurements, showing that swirl not only modifies the transport of droplets in the spray cross-section, but also enhances break-up and reduces the Sauter Mean Diameter globally, for all momentum ratios and pressure conditions tested.

中文翻译：

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高压环境下旋流气液同轴雾化

我们提出了在不同的空气角动量（涡流）条件和密度下，通过同轴湍流气体射流对液柱进行雾化动力学的最新实验结果。我们比较了大气条件下的雾化和雾化和环境空气密度为大气水平 5 倍的加压环境下的雾化。对于这两种情况，参数空间包括 范围内的气液动量比和 范围内的涡流比。喷雾近场中的高速阴影图像用于量化液-气界面的空间和时间演变。在中场，相位多普勒干涉测量法沿喷雾径向收集，量化液滴尺寸、速度和数量密度分布。在高压下，随着 M 的增加，我们观察到喷雾角度减小，但喷雾角度增加（临界涡流）。我们将这些观察结果与冠部去湿机制进行了协调，该机制首先是在喷雾的 X 射线阴影图中观察到的。冠部去湿取决于气体相对于液体的惯性，其随着雾化环境压力线性增加，从而导致这种行为的转变。该机制还解释了中场中液滴径向分布的变化，以及平均液滴尺寸轮廓中从凹形到凸形趋势的关键转变。最后，我们从径向测量中重建了完整的喷雾液滴群，表明对于所有动量比和压力，旋流不仅改变了喷雾横截面中液滴的传输，而且还增强了破碎并减小了全局的索特平均直径测试的条件。