Abstract
This study is to investigate the droplet-air flow characteristics of a multi-hole diesel spray. A multi-hole nozzle has a 2-spring nozzle holder, and its hole number is 5(dn=0.32mm). The droplet diameter and velocity of a spray injected intermittently into still ambient air were simultaneously measured by using a 2-D PDPA(phase Doppler particle analyzer). The intermittent characteristics of fuel droplets(10<D²500mm) and the air flow were examined, but the behavior of small droplets(D²10mm) was regarded as a air flow. In normalized axial and radial droplet-air relative-velocity, comparatively high axial and radial relative-velocity is observed near the half width of the spray and in the leading edge of the spray. The mean axial and radial relative-velocity normalized by centerline velocity shows higher value near the nozzle tip, and it continuously decreases with increasing axial distance until axial distance of 50mm. Overall mean axial and radial droplet-air relative-velocity is evaluated as 0.13 and 0.023 respectively.