孔盘截断式脉冲射流能够充分利用水锤压力、高速侧向流、循环载荷等效应，破岩效率高，在硬岩破碎中具有较高的开发潜力。本文基于VOF模型和动网格技术，建立与截断式脉冲射流生成装置几何及运动过程一致的两相流瞬态计算模型，结合高速摄像技术，研究了截断式脉冲水射流的流体结构的动态演变动力特征，测试了截断式脉冲水射流的破岩能力，并分别从流畅结构和破岩能力上与常规圆柱水射流进行了对比分析。研究结果表明：截断式脉冲射流有助于在射流末端形成偏转的瓦状尖体结构，可有效减弱或避免激波阻力的影响；截断式脉冲水射流在破岩过程中，岩石靶物冲蚀孔口呈现非轴对称形态，与常规圆柱射流相比，截断式脉冲射流能够大幅度提升破岩速度，增大破岩体积。
Abstract
Disc-slotted pulse water jet is a potential tool to break hard rock due to its special loading styles of water hammer pressure，ultra-speed lateral jetting and pulse dynamic load etc. Aiming to investigate the flow filed of the jet, a two-phase-flow transient computational model, matching with the geometry and motion of interrupted water jet generating device, was established to simulate dynamic evolution and characteristics of a single pulsation within 100 mm standoff based on volume of fluid (VOF) model and dynamic mesh theory. The results show that the head of the pulsed jet forms deflective slug structure which is consistent with the result from high-speed photography experiment. The slug head velocity is lower than jet outlet and the jet turbulence mainly distributes over boundary layers between jet and air and the deflective side. Tile-shaped stereo-Structure is yielded during the pulse formation process. It presents non-axisymmetric flow pattern when impacting target, which consists with the irregular erosion cavity obtained by hard rock fragmentation experiment.
关键词
孔盘截断式脉冲射流 /
流场结构 /
动网格技术 /
硬岩冲蚀
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Key words
Disc-slotted pulse water jet /
flow field structure /
dynamic mesh /
hard rock erosion
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