Mikaeel Minaei - Mechanical Engineering Department, Islamic Azad University Science and Research Branch, Tehran, Iran.
Sajad Eshaghi - Mechanical Engineering Department, Islamic Azad University Science and Research Branch, Tehran, Iran.

In the present study, the penetration depth of air bubbles is analyzed using imaging techniques and image processing. Two-phase flows include the flows generated by a water jet oscillated parallel to the free surface and the air bubbles entering the water tank with a constant surface. Three waterjet heights of ۵, ۱۲, and ۱۸ (cm) and four different flow rates ۱۴.۱۷, ۲۳.۶۳, ۲۹.۱۳, and ۳۳.۴۱(l/min) were used for five nozzles with the length/diameter ratio of ۳۲ cm. The smartphone was used for consecutive imaging from the two-phase and the images were evaluated and analyzed. The penetration depth of air entrainment was calculated by the creation of an average image. The obtained values for the penetration depth of air entrainment were compared with the previous studies. According to the figures and compared with prior studies, the maximum penetration depth was decreased with increasing distance from the water surface. Also, with the constant jet length and increasing flow rate, the maximum penetration depth of air bubbles was incremented. Comparing the theoretical (using the formula of scientists) and the experimental values shows the value of ۱۵% error on average.

Two-phase flow, Image analysis, Penetration depth, Air entrainment, Plunging jet