Study on control mechanism and vortex suppression law of air-entraining vortices in side intake structures

Abstract

[Objective] Vortex issues in hydraulic engineering cannot be ignored, as they reduce the discharge capacity of the hub, deteriorate the flow pattern, increase head loss, and pose risks to the safe operation of structures. To mitigate the potential risks of vortices in side intake structures and to propose a reasonable vortex suppression scheme, [Methods]vortex suppression characteristics and mechanisms of single-layer and double-layer vortex suppression beams were investigated through physical model experiments, focusing on side intake structures and air-entraining vortices. [Results] The result showed that the vortex suppression beams mainly reduce the tangential velocity V_θ and radial velocity V_r in the vortex region. This reduction weakens the circulation on the water surface in front of the intake, ultimately leading to the elimination of air-entraining vortices. For single-layer vortex suppression beams, reducing the relative spacing∑Δ l/l or increasing the installation height h_e/D enhances the vortex suppression effect. Compared to the scheme without vortex suppression beams(∑Δ l/l=1.000), when ∑Δ l/l=0.357, the intensity of the lower vortex is reduced by about 80.0%. Compared to the scheme where the beam is installed at the top of the intake(h_e/D=0.00), when h_e/D=0.40, the vortex intensity is reduced by about 78.8%. For double-layer vortex suppression beams, when using both transverse and longitudinal beams and ∑Δ L/L_z being reduced from 0.710 to 0.310, the vortex intensity is reduced by about 70.0%. The cross-arranged configuration achieves the best vortex dissipation effect compared to the V-shaped and stepped vertical configurations. [Conclusion] The spacing, installation height, and arrangement of vortex suppression beams significantly impact their suppression characteristics. A deeper understanding of vortex suppression laws is gained, providing a reference for future solutions to vortex problems in side intake structures.

Keywords

side intake structure / air-entraining vortex / vortex suppression beam / vortex suppression mechanism / model experiment