On the use of the laser sheet drop-sizing (LSD) technique: droplet size distribution by uncertainty analysis

Abstract

Sprays are used in many combustion systems such as gasoline/diesel engines and gas turbines. In order to meet more stringent emissions regulations, advanced developments of the fuel injection systems are required. For a given type of injector design, representative spray characteristics such as droplet size, size distribution, spray tip penetration and spray angel are largely dependent upon the injection condition. To further development of fuel injection strategies, a clear understanding of the transient nature of the injector spray should be established.A laser sheet drop-sizing (LSD) technique has been applied in transient fuel spray to understand the spray characteristics of an air-assisted, direct fuel injector. Ensemble averaged, planar images of the laser induced fluorescence (LIF) and Mie scattering from the spray have been obtained to measure Sauter mean diameter (SMD). Planar droplet size distribution of the spray from the injector has been investigated by means of uncertainty analysis of the LIF and Mie scattering images. Larger droplets exist in the spray tip and periphery of the spray, and the standard deviation of droplet size distribution are also high in these region. Examining both the droplet size and size distribution images provide more details of the transient spray development.</p