Simulation of large plate castings in counter-gravity mould filling process based on single-phase LBM
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摘要: 采用單相格子Boltzmann方法研究大平板的反重力充型過程，該模型不需考慮氣相格子的變化，從而提高了計算效率.針對該方法，本文新提出了一種權重系數重新分配的方法來處理格點中的液相排出及分配問題.首先用該模型計算了單澆口條件下的大平板型腔反重力充填過程，以相同參數下的高速相機成像的水力充填實驗為參照，數值模擬的流場特征及流體形態與實驗結果吻合良好.另外，還采用線速度分布云圖，并提出了自由表面的高度差判據來分析充型過程中的流場區域特征和流體平穩程度.在此基礎上，繼續用該模型研究了雙澆口和圓柱擾流條件下的大平板反重力充型過程.雙澆口條件下由于澆道間的互相影響，流場中形成的漩渦多于單澆口；圓柱擾流條件下的充填方式會降低流體的晃動程度，提高充型的穩定性.
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關鍵詞:
- 反重力充型 /
- 格子Boltzmann方法 /
- 自由表面 /
- 流場 /
- 數值模擬
Abstract: The single-phase free surface lattice Boltzmann model (LBM) was used to investigate the counter-gravity mould filling process of large plate castings. Computational efficiency can be improved by ignoring the variation of the gas lattice. In this paper, a weight coefficient redistribution method was proposed for dealing with the liquid phase discharge problem and distribution in a grid. First, the model was used to calculate the anti-gravity filling process of a large plate cavity with a single gate, with the same parameters, the water filling experiment of high speed camera is taken as a reference, the characteristics of the flow field and the fluid morphology of numerical simulation are in good agreement with the experimental results. Furthermore, the velocity profile of the flow field is used to analyze the characteristics of the flow field, and a criterion called "the altitude difference of free surface" is introduced to evaluate the stability of the fluid. Subsequently, the counter-gravity filling process of a plate with a double gate and the same plate with one gate and a cylindrical obstruction to turbulent flow are investigated. Due to the mutual influence between the two gates, the vortex formed by the double gates is greater than that formed by the single gate. However, the obstacles under the conditions of cylindrical turbulent flow obstruction could reduce the degree of fluid sloshing and improve the stability of the filling. -
參考文獻
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