APPARENT DENSITY OF AIR-WATER MIXTURES

A dynamic model was developed to estimate the effect of hydraulic pres sure gradient on the variation of air-water mixture density. The resul ts showed that the density increases linearly with depth in the air-wa ter mixture. The density variation was found to be greater at higher a irflow rates. Static and dynamic models to estimate the apparent densi ty of air-water mixtures were developed. The static model estimated th e effect of the force due to bubbles adhering to a submerged body on t he apparent mixture density. The dynamic model estimated the effect of the drag force on the apparent mixture density. The static model coul d only be applied for very low superficial air velocities (volumetric airflow rates divided by the tank cross-section area) or small bubble size. The dynamic model precisely predicted apparent density of an air -water mixture over the range of superficial air velocities studied (0 to 4 cm/s). A relationship between the airflow rate and density of an air-water mixture was established by experiment. It was found that th e density decreased linearly with increasing superficial air velocity in the range of 0 to 4 cm/s, with an air-water mixture density of abou t 0.7 g/cm3 at a superficial air velocity of 4 cm/s. The initial liqui d height in the experimental tank had no effect on the specific gravit y of the air-water mixture.