Release of suspension particles from a prismatic tank by multiple jet arrangements

The performance of circular and linear jet arrangements on the release of suspended sediment out of a prismatic tank has been investigated. Experiments conducted are (1) without any forced jet stirring (reference case), (2) four jets arranged in a horizontal circle and (3) aligned jets; they were all in a tank containing water with a known homogeneous initial suspended sediment concentration. The concentration of the suspended sediment inside the tank and released through the outlet is monitored over time, and the evacuated sediment ratio (ESR) is defined, computed, and used as a metric for comparison between the various configurations. The idealized suspended sediment release is also calculated and compared to measured quantity. In order to explain the significant differences in evacuated sediment ratio, the induced circulation is analyzed by measuring the flow field on two vertical planes using the ultrasonic Doppler method. The geometrical parameters of the jet arrangement, the outlet elevation as well as the discharge of the jets are varied. Thus, the optimal parameter combination regarding sediment release can be identified. Finally, recommendations regarding jet arrangement and jet discharge practice in conditions of high sediment release are given. (C) 2016 Elsevier Ltd. All rights reserved.