Three-dimensional numerical simulation method for downstream scouring process of flood discharge gate of hydropower station

Abstract

The invention belongs to the technical field of hydropower station flood discharge, and discloses a three-dimensional numerical simulation method for a downstream scouring process of a flood dischargegate of a hydropower station when a hydropower station is stuck, which comprises the following steps: establishing a bed load sediment transport rate formula based on water flow randomness and bed sand distribution randomness based on riverbed sediment particle motion basic characteristics; based on the UDF macro function, conducting secondary development on Fluent software, extracting the bed surface node water flow shearing force, and calculating the bed surface sediment transport rate; and according to a riverbed scouring and silting balance principle, converting the change of the sedimenttransport rate between the nodes into the change of the node elevation along with time, so that the moving boundary grid nodes are controlled to move, and three-dimensional numerical simulation in the scouring process of the scouring pit is realized. According to model actual measurement data verification, a simulation result is basically matched with an actual measurement value; in the forming process of the scouring pit, the shear stress distribution of the bed surface is continuously changed along with the scouring deformation of the bed surface, namely the shear stress of the bottom wallsurface of the scouring pit at the initial scouring stage is larger, and the shear stress of the upstream slope wall surface in the scouring pit at the middle and later scouring stages is larger.

Description

technical field [0001] The invention belongs to the technical field of flood discharge of hydropower stations, and in particular relates to a three-dimensional numerical simulation method for the scouring process downstream of a flood discharge sluice of a Dangka hydropower station. Background technique [0002] The high flow velocity and strong turbulence in the downstream of the gate and dam of the water conservancy and hydropower project will easily cause serious local scour and scour along the downstream channel, posing a serious threat to the safety of hydraulic structures and the banks of the river. Accurately predicting the flow field information of the downstream channel of the hydropower station, the maximum scour depth and the scour range of the scour pit is of great significance for the development and design of the hydropower station and ensuring the safe and stable operation of the hydropower station. [0003] In the early analysis, scholars usually established ...

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Problems solved by technology

[0006] 1) The research on sediment start-up law is currently based on the condition of flat riverbed and uniform water flow. The start-up and retention of sediment on relatively steep slopes (front slope, reverse slope and side slope) in local scour pits are non-uniform flows. conditions, and the water flow is violently mixed, which has strong three-dimensionality and randomness. Therefore, the study of the sediment starting law in the scour pit is very challenging.

[0007] 2) At present, the prediction and prediction of scour pits are mainly based on the physical model test, but the physical model test cycle is long, the cost is high, and the impact of water flow conditions on the scour pit cannot be accurately analyzed.

[0010] Difficulties of the problem: 1) The law of sediment start-up and transport under the condition of non-uniform water flow on the front slope, reverse slope and side slope in the scour pit; 2) Accurate numerical simulation of the scour pit shape and scour process

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