Technical noteInvestigation of fine droplet generation from hot engine oil by impinging gas jets onto liquid surface

•Impinging gas jet on liquid surface in penetrating mode as a new mechanism of fine and reliable droplet atomization is proposed.•The mechanism is analyzed by high speed imaging.•The fine drops atomization is justified by a proposed semi-empirical method.•The drops size measured by the light scattering method.•The proposed atomizer is proper to produce drops in size distribution that is similar to one in the engine crankcase ventilation system.

The generation of fine oil droplets by impinging an air jet on an engine oil surface represents a new mechanism of atomization. The process was studied using high-speed imaging and laser light scattering. The gas that penetrates the surface leads to the formation of liquid ligaments that enter the high-velocity region of the gas jet where they are atomized to produce droplets with diameters smaller than 5 µm with a Sauter mean diameter of 1.21 µm.The measured Sauter mean diameter was compared with a proposed semi-empirical analysis, and good agreement was found. The atomizer, based on this impinging air-jet mechanism, can be used to simulate the size distribution of oil droplets in engine crankcase ventilation and, therefore, is suitable for implementation in a laboratory test rig.