Abstract
A rotary slit valve of 20 x 1mm has been designed to produce a transient flat liquid sheet. It operates with the same fuel delivery pressures as GDI injectors with the long term vie w of conducting a detailed comparison between transient flat and conical liquid sheets. The current work has focused on the pressure range from 10-50 bar. First generation pressure swirl GDI injectors typically operate at a fuel pressure of 50 bar. This study describes the liquid sheet break up phenomena of the transient two dimensional liquid sheet using CCD macro-imaging, Particle Image Velocimetry, PIV, and Laser Doppler Anemometry, LDA. The transient liquid sheet break up behaviour has been assessed from a detailed analysis of the CCD images. The propagation of surface waves and structures downstream from the nozzle as a function of time have been measured by a modified PIV technique. The local velocities of the intact liquid sheet, the remnants of the sheet after break up and droplets due to atomization at various axial positions downstream from the nozzle slit have been measured using LDA to provide the time averaged histories of the liquid velocity.
