Oil-based emulsions are been widely used to apply agricultural sprays and they are often delivered through flat-fan spray nozzles mounted on booms. Perforations are one of the typical structures of found during the atomisation of oil-based emulsions, and they are investigated here using visualisation. The generation, development and coalescence of perforations in an expanding liquid sheet are comprehensively studied. The results support the existence of two perforation-generation mechanisms, namely puncture and tear mechanisms. The tear mechanism depends on the thickness modulation of spray sheet caused by surface disturbances. The perforations that are produced by the tear mechanism are widely distributed and are large in number compared with those associated with the puncture mechanism. The increase of the area of perforation exhibits firstly an acceleration followed by a deceleration. The former is ascribed to the effects of surface tension and the expansion of the spray sheet in a spanwise direction, whilst the latter is related to the interaction between perforations. After perforations are formed, the evolution of the area of the perforation is insensitive to the generation mechanism. Generally, the coalescence of two perforations gives rise to one ligament; however, it is demonstrated that multiple ligaments can be produced if the momentums of the perforations are great enough.

油基乳液被广泛用于农业喷雾剂，它们通常通过安装在动臂上的平扇形喷嘴进行输送。穿孔是在油基乳液雾化过程中发现的典型结构之一，在此使用可视化方法对其进行研究。全面研究了膨胀液片中孔眼的产生，发展和合并。结果支持了两种穿孔产生机制的存在，即穿刺和撕裂机制。撕裂机理取决于表面扰动引起的喷漆板厚度调节。由撕裂机构产生的穿孔与与穿刺机构相关的穿孔相比分布广泛并且数量众多。射孔面积的增加首先表现为加速，然后是减速。前者归因于表面张力和喷涂片在翼展方向上的膨胀的影响，而后者则与穿孔之间的相互作用有关。形成孔眼后，孔眼区域的演变对生成机制不敏感。通常，两个穿孔的合并会产生一条韧带；另一条韧带会形成一条韧带。然而，事实证明，如果穿孔的动量足够大，则可以产生多个韧带。形成孔眼后，孔眼区域的演变对生成机制不敏感。通常，两个穿孔的合并会产生一条韧带；另一条韧带会形成一条韧带。然而，事实证明，如果穿孔的动量足够大，则可以产生多个韧带。形成孔眼后，孔眼区域的演变对生成机制不敏感。通常，两个穿孔的合并会产生一条韧带；另一条韧带会形成一条韧带。然而，事实证明，如果穿孔的动量足够大，则可以产生多个韧带。