Experimental study of Swirl Microbubble Generator with 1.2 millimeter diameter of gas nozzle and 1 millimeter distance to the outlet.

Swirling Microbubble Generator (MBG) with a 1.2-millimeter diameter of gas nozzle and 1-millimeter distance to the outlet is a tool functioned as an aerator. MBG is capable of producing micrometer bubbles by using swirling flow. The swirling flow originates from the inlet channel with tangential direction leading to a swirling chamber. This experiment was conducted by giving variation toward air debit (QG) and water debit (QL) to figure out the characteristics of MBG. The MBG characteristics are influenced by the combination of air and water flow velocity through MBG. In this research, the range of air and water flow velocity are set 0.1-1.0 lpm and 20.0-50.0 lpm, respectively.MBG installed at a depth of 40 cm below the surface. After that, the bubbles' diameter was measured by capturing the image of bubbles with a high-speed Phantom video camera. This high-speed Phantom video camera has a maximum frame rate of 10.000 frames per second (fps) to observe the behavior of microbubbles produced. A sound lighting system is applied to gain better visualization. The microbubble recorded is then being analyzed by observing the interface behavior in two-phase flow with image processing. The result indicates that in microbubble distribution, the increase of water debit produces smaller bubbles. In contrast, the rise of gas debit results in the production of bigger microbubbles. Meanwhile, in the MBG working system, the increase in water debit causes the rise of pressure drop and hydraulic power. If the gas debit is raised, it results in the raise of pressure drops and hydraulic power. However, the change is not significant. According to PDF chart of microbubble distribution, microbubble diameter with the highest probability of being generated by MBG is 100 µm. [ABSTRACT FROM AUTHOR]