Quantitative Analysis of the Gas Entrainment Process of Intermittent Gas Jets with Laser-Induced Fluorescence of Ambient Gas (LIFA)

Gas entrainment processes of intermittent low-speed gas jets were quantitatively analyzed with the laser-induced fluorescence of ambient gas ( LIFA ) technique. The results showed that mean injectant concentrations decreased with decreased nozzle diameter (D), shorter nozzle hole length, higher kinematic viscosity of jet, and elapsed time after injection (t). Also, the mean injectant concentration could be approximately related with ReD/Ut, where Re is the discharge Reynolds number, and U is the discharge velocity of the jet. When two jets were injected in series, the mean injectant concentration showed a minimum at the end of the first injection. The injectant concentration distribution of intermittent gas jets was similar to that of steady gas jets, except in the umbrella region at the top of the jet.