Experimental and Numerical Simulation Study on the Influence of Distance Parameter on Bubble Motion in Shallow Water
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摘要: 当爆炸气泡在浅水中运动时,同时受到自由面和水底壁面的作用而产生极其复杂的水面现象,气泡的运动特性与在自由场中或单一边界附近处爆炸相比会发生很大变化。为探究其规律,通过电火花诱导气泡实验,利用高速摄影技术对气泡与组合多边界的相互作用进行了研究,总结了自由面距离(γf)和壁面距离(γw)对气泡运动和水冢类型的影响。并用OpenFOAM进行了数值模拟,分析了距离参数对射流载荷的影响。结果表明:自由面距离参数较壁面距离参数对水冢类型影响更大;射流速度随自由面距离的增大而减小,在0 < γw < 2时,射流速度随壁面距离的增大先减小后增大;壁面压力与距离呈负相关,射流冲击面积与距离呈正相关。Abstract: When the bubble develops in shallow water between the free surface and the bottom, extremely complex phenomena of the free surface will be caused.The bubble motion characteristics are different from that in the free field.To explore its patterns, spark induced bubble experiments are carried out and high-speed video-photography is employed to study the interaction between bubbles and combined boundaries.The influence of distance parameter on dome type and bubble motion has been summarized.The influence of distance parameter on jet loading is analyzed by numerical simulation using OpenFOAM.The results show that the free surface distance parameter has a greater influence on the type of dome than that of the wall distance parameter.The jet velocity decreases with the increase of the free surface distance.The jet velocity first decreases and then increases with the increase of the wall surface distance.The pressure on the wall decreases with the distance increasing while the jet impact area increases with the distance increasing.
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Key words:
- shallow water explosion /
- bubble motion /
- distance parameter
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表 1 实验工况设计
Table 1. Experimental conditions
Group Number γf γw 1 0.63 Ⅰ 2 1.54 0.31 3 2.26 1 0.75 Ⅱ 2 0.38 1.88 3 3.01 表 2 自由场中气泡脉动模型的CFD边界条件
Table 2. Boundary conditions for CFD of single bubble pulsation in a free field
Boundary α p U T Empty (left) Empty Empty Empty Empty Advective (right & top) Advective Advective Advective Advective Wedge (front & back) Wedge Wedge Wedge Wedge Wall (bottom) zeroGradient fixedValue(0, 0, 0) zeroGradient zeroGradient Charge radius r/cm Charge amount W/g Rm/cm T/ms Empirical Simulation Deviation/% Empirical Simulation Deviation/% 0.2 0.055 6.0 6.3 6.18 11.5 11.2 -2.8 0.3 0.184 8.9 8.3 -6.6 17.2 14.6 -15.3 0.4 0.437 11.9 10.6 -10.1 23.0 18.5 -19.5 -
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