Experimental Investigations of Annular Liquid Curtains

Experiments have been performed to study the dynamics of vertical annular liquid curtains. Using a high and a low speed photographic recording technique, different modes of curtain formation have been visualized: (a) nonpressurized curtain, (b) pressurized steady curtain, (c) pressurized oscillating curtain, and (d) punctured curtain. The velocity of the liquid was measured by an argon-ion laser Doppler velocimeter, and results were compared with free falling motion. The convergence length of the curtain was measured as a function of the pressure differential for different Froude and Weber numbers, and for different nozzle gap widths. The experimental data agree well with existing theoretical predictions for steady curtains. For harmonically oscillating curtains, the average values of minimum and maximum convergence lengths show fairly good agreement with the theory.