Ambient Gas Entrainment into a Transient Gas Jet. Visualization of Surrounding Air Motion and an Estimation of Entrainment Amount by Path Line Method.

Abstract

For the study of the combustion in a transient gas jet used in gas diesel engines, it is very important to investigate the entrainment process of the surroundings of the jet. In this study, a path line method utilizing a CCD camera with various shutter times was applied. Large (40μm), light weight micro-balloon particles are used for scattering the path lines of the surroundings and fine particles (0.75μm) are used for visualizing the approximate shape of the jet. The transient gas velocity was also measured with a two-component laser Doppler velocimeter. Consequently, (1) the jet shape and the entrainment process could be visualized simultaneously, and (2) this path line method was found to be very useful fot estimating the amount of entrainment air because of the good agreement with the value obtained using LDV data.