Measurement of Air in Flowing Water

Procedures are developed using gamma ray and hot-film anemometer methods for determining void fraction and sizes of air bubbles entrained in flowing water. The hot-film data are analyzed by computer. The gamma ray data are used to determine the duration factor, a term accounting for the additional time that must be added to the time sensed by the hot-film anemometer to arrive at the true bubble duration. The duration factor is found to be a function of velocity. The procedures are developed using a hydraulic jump with Froude number 6. The continuity equation is used in conjunction with void fraction and mean velocity data to compute the location of air entering and leaving the jump.