Two phases flow regime assignment based on Wavelet features of pressure signal in the airlift pump-bubble generator

Abstract

Airlift pump-bubble generator is a development of the conventional airlift pump in the injector design. It uses a bubble generator to supply the bubble in the riser pipe. This method can be used to lift water and solid particles. In the current study, the airlift pump-bubble generator was operated only to lift water using a transparent acrylic riser pipe with 56 mm diameter and 2550 mm length. Water and air were the working fluid with the water level in the riser pipe was setted-up for a submergence ratio of 0.74, and the injected air flow rate was varied from 0.3 m3/h to 3 m3/h with the flow rate of injected water to the bubble generator being kept constant at 7.5 m3/h. Two bubble generator units with an angle of 45° to the horizontal and opposite directions were attached to the mouth bell-shaped suction head to form a swirl flow. A high-speed camera and a pressure tap were used to recording the video of flow pattern and pressure signals in the test section, respectively. The flow pattern was objectively classified by using wavelet analysis. As a result, it was found that the flow regimes were assigned into clustered bubbles, homogenous bubbles, cap bubbles, bubbly-stable slugs, bubbly-unstable slugs, and slug churn when the air flow rate was increased. The distribution of energy fluctuation will have a peak in the signal approximation section of the large scale when the bubble regime flows in the test section, while the peak of the energy fluctuation distribution will occur in the detailed signal when the slug regime is flowing.