The Influence of Inlet Flow Rate on Surface Eddy in Pumping Stations

Abstract

【Background and objective】 The inflow water velocity controls water flow pattern in pumping stations. Turbulence accompanied by the generated vortices not only reduces pump operation but also causes cavitation, vibration, thereby compromising pump operation. The purpose of this paper is to study the influence of inlet water flow rate on flow pattern, generation and development of vortices in a real pump station. 【Method】 The NX UG10.0 software was used to construct the physical model for water intake in the pump; three-dimensional turbulence for the pump station, including the closed intake channel, horizontal intake and open intake pool, vertical intake, were described using the Reynolds’ equation, VOF model and unsteady SST k-ω model. The impact of the distribution of influent flow field and generation, change and distribution of the vortices at different influent velocities was simulated for two influent modes. 【Result】 When the critical submerged depth of the inlet was met, the vortex intensity at the inlet surface under the two inlet modes increased with the increase in the inlet flow rate, and the vortices appeared on the two inlet surfaces and the inlet water. When the horizontal inlet velocity in the closed inlet flow channel was 0.217~0.304, 0.349~0.448, 0.482~0.554, 0.575~0.661 m/s, their associated vortex type was Ⅰ-Ⅱ, Ⅲ-Ⅳ, Ⅴ and Ⅵ, respectively. When the open vertical inlet flow velocity was 0.322~0.402, 0.484, 0.521~0.564 m/s, their associated vortex type was Ⅲ, Ⅳ-Ⅴ and Ⅵ, respectively. Surface vortices were simultaneously generated in the water body of the open inlet pool with vertical water inlet and vortex in the water. The simulation results were consistent with experimental results. 【Conclusion】 For pumping stations with closed inlet channel and horizontal inlet method, the inflow velocity should be less than 0.349 m/s for the open inlet pool. For pumping stations with vertical water intake, the influent flow rate should be less than 0.322 m/s.

Keywords

• pumping station
• inlet water flow rate
• vortex
• numerical calculation
• model test