Measurement of gas hold‐up in three‐phase systems by ultrasonic technique

It was established by using double impulse method that the transmission time of an ultrasonic wave, which passes near a bubble, is either shorter or longer than that in the liquid system. This is attributed to the fluid vortex originated by the bubble rising ahead of the wave. The longitudinal distribution of gas hold‐up in a three‐phase system, measured by analyzing wave shape and reduction of transmission time is in good agreement with that obtained by using the static pressure method. This indicates the possibility of application of ultrasonic techniques to the simultaneous measurement of phase hold‐ups in the three‐phase system.