AMBIENT GAS ENTRAINMENT INTO A TRANSIENT GAS-JET (VISUALIZATION OF SURROUNDING AIR MOTION AND ESTIMATION OF ENTRAINMENT AMOUNT BY PATH LINEMETHOD)

For the study of the combustion in a transient gas jet used in gas die sel engines, it is very important to investigate the entrainment proce ss of the surroundings of the jet. In this study, a path line method u tilizing a CCD random shutter camera with various shutter times was ap plied. Large (40 mu m), lightweight microballoon particles are used fo r scattering the path lines of the surroundings and fine particles (0. 75 mu m) are used for visualizing the approximate shape of the jet. Th e transient gas velocity was also measured with a two-component laser Doppler velocimeter (LDV). Consequently, (1) the jet configuration and the entrainment process could be visualized simultaneously, and (2) t his path line method was found to be very useful for estimating the ai r mass entrained because of the good agreement with the values obtaine d using LDV.