超高压水射流冲击应力分布规律的数值分析

由于高压水射流破岩涉及的因素较多,且水射流作用过程复杂,致使水射流冲击下介质内部的应力分布一直未能被准确揭示,从而制约着水射流技术的应用和发展。运用全解耦的流固耦合理论,建立了超高压水射流冲击弹性非孔隙介质的应力分布计算的数值模型,其中水射流采用标准K-ε双方程模型和控制体积法,介质采用固体有限元法,给出了水射流与介质耦合的数值算法。根据建立的理论模型,计算了介质在不同水射流速度冲击下流场压力和介质内部的应力分布规律。计算结果表明,在超高压水射流冲击作用下,固体介质受力局部效应明显,冲击区内介质基本处于受压状态,最大拉应力值位于介质表面,最大剪切应力位于冲击中心下部约0.5倍喷嘴直径的位置。控制好水射流喷射速度与喷距,可以提高水射流清洗、切割、破碎和表面处理效率。

Numerical Analysis on the Stress Distribution of Super High Pressure Water Jet-Flow Impinging Solid

The stress distribution in the media under high pressure water jet-flow remains unknown and this restricts the application and development of the water jetting technology. A numerical analyzing model of stress distribution about interaction of super high water jets impinging no porous elastic solid is established according to fluid-structure interaction theory. Standard K-epsilon dual-equation model and controlled volume method for the water jets, and elastic orthotropic continuum and finite element method for the solid are adopted. Also, the numerical method for both material interactions is given. The stress distributions in the fluid field and the media with different water jetting velocity are computed using the model and method. Numerical results show that the stress distributes obviously on the part solid under water jets impingement. The impinging area is subjected to compression stress, and the maximum tensile stress is located on impacting surface and the maximum shear stress being under impacting center about half nozzle diameter away. It concludes that by controlling the jet velocity and distance, jet cutting, breaking, washing, surface processing efficiencies could be improved.