挖沟机双喷嘴冲击射流的数值研究

Numerical study on double-nozzle impinging jet of trencher

海底射流式挖沟机或疏浚设备的使用过程中涉及到双喷嘴冲击射流问题,揭示射流流场的演化规律有望对工程问题提供理论支持。使用CFD方法对二维双喷嘴淹没条件下射流冲击固体壁面问题进行建模并求解,分析在不同射流靶距、喷嘴间距以及射流流速下流速场、冲击区压力及剪应力的分布特性。验证算例表明,CFD方法可以获得较好的预测结果。计算结果表明,喷嘴间距越小,冲击区压力分布越大;射流靶距减小时,射流压力骤增,且在双喷嘴之间会形成振荡效应,让冲击区压力及剪应力大小和位置发生波动。在实际工程中,应注意这种振荡效应对机械运动稳定性的影响。

Double-nozzle impingingjet is involved in the use of underwater jet trenching machines or dredging equipment.Therefore,theoretical support for engineering problems could be provided if the evolution law of the jet flow field is revealed.In this study,a model was made and solved by the CFD method for the problem of jet impingement on solid walls in the condition of the two-dimensional double nozzle in submergence.This paper analyzed the effect of different impinging distances,nozzle spacing,and jet velocity on the flow velocity field as well as pressure and shear stress distribution in the impact area.The verified result shows that the proposed CFD methodcan achieve good prediction results.The calculation results indicate that pressure distribution in the impact area becomes greater if the nozzle spacing is smaller.When the impinging distance gets closer,the jet pressure suddenly increases.At the same time,an oscillation effect is formed between the two nozzles,causing fluctuations in the magnitude and position of pressure and shear stress in the impact area.In practical engineering,attention should be paid to the impact of this oscillation effect on the stability of mechanical motion.