Dispersion of spray droplets near diesel fuel injector nozzle

Abstract

A laser 2-focus velocimeter (L2F) was used for measurements of velocity, size and number density of droplets in diesel sprays injected into the atmosphere by using 8-hole injector nozzle. The diameter of the nozzle orifice was 0.112mm. The injection pressure was set at 65MPa. The droplets dispersion model which can estimate the number density by using the spray width and the droplet velocity was proposed. It was shown that the velocity of droplets at the spray center region was higher than the one at spray periphery region in the middle period of injection duration. The size of droplets at the spray center region was larger than the one at the spray periphery region. The number density of droplets was high at the region between the spray center and the spray periphery. The number density estimated by the droplets dispersion model was nearly same as the one evaluated by L2F measurement at the spray center region in the middle period of injection duration. It is understood that the number density was decided by the dispersion due to the changes of the spray width and the spray velocity at the center region in the middle period of injection duration.