Spatial Distribution of Droplet Diameter of Wall-impinging-spray for Direct Injection Gasoline Engines

Spray characteristics such as spray shape and spatial distribution of droplet diameter remarkably influences on output and exhaust emissions of direct injection gasoline engines. Especially, spatial distribution of the droplet diameter after impingement of a spray against a piston cavity is one of the most important factors for output and exhaust emissions, but is not revealed sufficiently because of the difficulties of measurement.

In this paper, a new laser holography method that can obtain spatial distribution of droplet diameter over the spray in a short time was developed. And with this method, differences of spatial distribution of Sauter mean diameter (SMD) of droplets between before and after impingement on a flat wall in a high-pressure chamber were revealed using a prototype injector. Effects of impinging angle and distance against the wall on spatial SMD distribution were also investigated.