Abstract: This paper reports a series of model tests on the sand-water separation performance of a vortex setting chamber (VSC) equipped with a flow deflector that is placed in horizontal, downward or upward direction toward the central orifice. The results show that in these three deflector conditions, the removal efficiency of the chamber is nearly the same but its sediment deposition differs. For a deflector tilted upward and downward, the total amount of sediment deposited in the VSC basin and on the deflector surface is less than that of a horizontal deflector. Usually a larger inclination angle results in a smaller deposition volume. The decrease in the amount of deposition in the upward deflector case is greater than that of a downward deflector. For the upward deflector, water consumption is lower than that in the downward or horizontal case and it decreases with an increasing upward angle. Thus, tilting the near-center edge of the deflector upward at a certain angle can effectively avoid sediment deposition on the deflector surface while reducing water consumption and sediment deposition in the VSC basin, which helps better optimize the design of vortex setting chambers.

Key words: vortex settling chamber, deflector, model test, removal efficiency, water consumption