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The objective of this investigation is to characterize the influence of injection parameters and spray-wall interaction on atomization and gas entrainment processes of high-pressure non-evaporative sprays injected into a high-pressure vessel using several imaging techniques. The effects of injection pressure on the droplet distribution, size and velocity were quantified using single and double nano second exposure photography techniques. A laser-sheet imaging method was employed to measure the two-dimensional gas velocity around the spray and to clarify the effects of the above parameters on the gas entrainment into the impinging sprays. It was found that increasing the injection pressure causes an increase in droplet number in both free and wall-jet regions of the sprays. Spray-wall impingement creates a large-scale gas vortex around the spray, which promotes the gas entrainment into sprays typically at the impinging zone, and it also affects the spatial distribution of droplets.

A single nano-spark back light photography method has been developed to record the image of non-evaporating diesel sprays injected into high pressure nitrogen gas. Relatively clear image of fine droplets and spray was obtained. An image analysis method has been developed to quantify the droplet characteristics which are in focus, such as droplet size and shape. Spatial and temporal distribution of droplets has been clarified. It was observed that the number of droplets around the nozzle tip region decreases by time, however a large number of droplets were observed at X=13∼25 mm from nozzle tip at t=300∼700 μs from injection start. Double-nano spark photography of diesel sprays was carried out and relatively clear double exposure images of droplets were obtained on the same film. Two dimensional size and velocity measurement of droplets were simultaneously carried out based on these photographs.