Author(s): Yiyi Ma; David Z. Zhu; N. Rajaratnam
Linked Author(s):
Keywords: Air pressure; Dropshaft; Drop size distribution; Drop velocity
Abstract: Dropshafts are widely used in urban drainage systems to transfer stormwater or wastewater from a high elevation to a low one. The present paper studies the flow inside a physical model of a tall plunging dropshaft. Visual observations of the flow inside the dropshaft at several flow rates were obtained using a high-speed camera. The size distributions and velocities of water drops were measured. Besides, the air pressure variations along the dropshaft were measured. The water flow inside the dropshaft was found to disintegrate with the majority of the water breaking up into drops of about 2mm. The drop velocities were also found similar in all tests at a velocity between 4-10 m/s. The air pressure was found to be negative at the top of the dropshaft and increase towards the bottom of the dropshaft. The results of this study will aid in the future design of large dropshafts.
Year: 2015