Flow control in a multichamber settling basin by sluice gates driven by a CFD and an ancillary analytical model

Abstract

Unequal flow distribution between the chambers of a three-chamber settling basin causes its malfunction and endangers the turbines of a small hydropower plant. To equalize the flows, sluice gates are used. To find their positions, the following methodologies are considered: (1) measurements combined with trial-and-error method (TAE), (2) measurements with regression analysis (RA), (3) CFD model combined with TAE, (4) CFD model with RA, (5) CFD model supported by a one-dimensional flow model, and (6) CFD model with an analytical model. The additional models and RA are intended to speed up the solution finding. From the previous list, only the sixth methodology is applicable. The first four are not because of the weir design, and the fifth because of the three-dimensional flow character. Initially, the CFD model of the side-weir intake was developed and validated. Afterward, the analytical model, which consists of a system of three pressure drop equations for three parallel and partly imaginary streams, is formed. The local flow resistances in the analytical model are determined by the CFD model combined with RA. To equalize the flows, three solutions with (i) fix, (ii) fix in a range of flows, and (iii) variable positions of the sluice gates are analyzed. HIGHLIGHTS Unequal flow distribution among the chambers of a settling basin causes its malfunctioning.; For the equalization of flows, sluice gates are used.; A 3D CFD model of a side-weir intake is developed and validated by measurements.; To speed up solution finding with the CFD model, an ancillary analytical model is developed.; From three types of flow control (two with fix and one with variable gate positions), the optimal is chosen.;

Keywords

• ancillary model
• cfd modeling
• settling basin
• side water intake
• sluice gate
• small hydropower plant