Low flow rate spray devices have many diverse engineering applications ranging from low energy burners to medical inhalers. Conventional atomizers are unsuitable for low injection rate applications, owing to inefficient atomization. Coaxial flow-blurring injectors have shown the capability of spray formation at extremely low injection rates, although challenges remain with respect to maintaining a sub-millimeter gap and concentricity between the liquid tube and the orifice. To achieve miniaturization, this work presents a novel cross-flow injector design that atomizes liquid into micron size droplets at extremely low flow rates with small pressure loss. Experiments are conducted at ultra-low liquid flow rate (<0.1 g/s) which is relevant for various small-scale application. The injector exhibit three distinct atomization modes based on primary liquid breakup mechanism. The experiments demonstrate that two phase gas-liquid interaction inside the injector has significant influence on the external liquid breakup. No spray formation was observed for the flow-focusing breakup regimes. Steady, axisymmetric, fully developed spray formation was reported only between 0.06 – 0.1 g/s with flow-blurring mode of liquid breakup. In addition, comparative investigation was performed to highlight the effect of exit orifice geometry on fundamental spray characteristics such as droplet size and droplet velocity. Results show that overall superior atomization quality can be achieved with conical exit.

中文翻译：

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横流式进样器的液体破裂形态和喷雾特性的实验研究

低流量喷雾装置具有从低能燃烧器到医疗吸入器的多种工程应用。由于雾化效率低，传统的雾化器不适合低喷射速率的应用。尽管在保持亚毫米间隙和液体管与孔之间的同心度方面仍然存在挑战，但同轴的流体流动喷射器已经显示出在极低的喷射速率下形成喷雾的能力。为了实现小型化，这项工作提出了一种新颖的错流喷射器设计，该设计以极低的流速将液体雾化成微米大小的液滴，而压力损失却很小。实验是在超低液体流速（<0.1 g / s）下进行的，这与各种小规模应用有关。喷油器基于主要的液体破碎机理展现出三种不同的雾化模式。实验表明，喷射器内部的两相气液相互作用对外部液体的破裂有重大影响。对于流聚焦破裂方案，未观察到喷雾形成。稳定，轴对称，充分形成的喷雾形成仅在0.06 – 0.1 g / s之间发生，并具有液体破碎的流动模糊模式。此外，进行了比较研究，以突出出口孔几何形状对基本喷雾特性（如液滴尺寸和液滴速度）的影响。结果表明，圆锥形出口可以实现总体上优异的雾化质量。实验表明，喷射器内部的两相气液相互作用对外部液体的破裂有重大影响。对于流聚焦破裂方案，未观察到喷雾形成。稳定，轴对称，充分形成的喷雾形成仅在0.06 – 0.1 g / s之间发生，并具有液体破碎的流动模糊模式。此外，进行了比较研究，以突出出口孔几何形状对基本喷雾特性（如液滴尺寸和液滴速度）的影响。结果表明，圆锥形出口可以实现总体上优异的雾化质量。实验表明，喷射器内部的两相气液相互作用对外部液体的破裂有重要影响。对于流聚焦破裂方案，未观察到喷雾形成。稳定，轴对称，充分形成的喷雾形成仅在0.06-0.1 g / s之间发生，并具有液体破碎的流动模糊模式。此外，进行了比较研究，以突出出口孔几何形状对基本喷雾特性（如液滴尺寸和液滴速度）的影响。结果表明，圆锥形出口可以实现总体上优异的雾化质量。1 g / s，带有分流模式的液体破碎功能。此外，进行了比较研究，以突出出口孔几何形状对基本喷雾特性（如液滴尺寸和液滴速度）的影响。结果表明，圆锥形出口可以实现总体上优异的雾化质量。1 g / s，带有分流模式的液体破碎功能。此外，进行了比较研究，以突出出口孔几何形状对基本喷雾特性（如液滴尺寸和液滴速度）的影响。结果表明，圆锥形出口可以实现总体上优异的雾化质量。