带气环旋喷射流流场特征及喷嘴结构正交优化研究

Numerical Simulation on Flow Field Characteristics of Rotary Jet Grouting with Gas Ring and Orthogonal Optimization of Nozzle Structure

为提高二/三重管法旋喷射流切割土体效率,采用Mixture多相流模型和RNGκ-ε湍流模型,开展了淹没环境下带气环旋喷射流流动模拟研究,获得了射流速度、气液两相体积分布、靶体作用压力等流场特征,并基于L_(16)(4^(5))正交试验设计及误差分析方法,获得了旋喷射流喷嘴关键结构参数对射流速度及其作用靶体压力的影响敏感程度与影响规律。结果表明:带气环旋喷射流能量衰减慢且集中在轴心区域,射流等速核心段长,冲击破坏土体性能好;喷嘴结构参数对射流冲击性能的影响敏感次序为:射流喷嘴出口直径>收敛角>气体喷嘴直径>气液喷嘴间距>射流喷嘴长径比;射流轴心速度及其作用靶体压力随出口直径和气体喷嘴直径的增大呈先快速增加后缓慢增加趋势,随收敛角、长径比、气液喷嘴间距的增大呈先增加后降低趋势。基于此,考虑旋喷射流设备性能,给出了最优结构参数为:射流喷嘴出口直径2.0 mm,收敛角12°或18°,长径比1,气体喷嘴直径0.9 mm,气液喷嘴间距5 mm。

In order to improve the soil-cutting efficiency of rotary jet grouting in double pipe method and triple pipe method,based on Mixture multiphase flow model and RNGκ-εturbulence model,the simulation of flow field characteristics of rotary jet grouting with gas ring in submerged environment is carried out.The flow field characteristics such as jet velocity,gas-liquid two-phase volume distribution,and target action pressure and so on are obtained.Based on L_(16)(4^(5))orthogonal experimental design and error analysis method,the sensitivity and influence laws of key structural parameters of rotary jet grouting nozzle on jet velocity and target action pressure are obtained.The results show that the energy of rotary jet grouting with gas ring decays slowly and concentrates in the axial region,and the constant velocity core section of jet is long and the impact damage performance on soil is nice.The sensitive order of nozzle structural parameters on jet impact performance is as follows:jet nozzle outlet diameter>convergence angle>gas nozzle diameter>spacing between gas nozzle and liquid nozzle>length-diameter ratio.The jet axial velocity and its target pressure increase rapidly at first and then slowly with the increase of outlet diameter and gas nozzle diameter,and increase first and then decrease with the increase of convergence angle,length-diameter ratio and spacing between gas nozzle and liquid nozzle.Based on this,considering the performance of rotary jet grouting flow equipment,the optimal structural parameters are given as follows:2.0 mm of jet nozzle outlet diameter,12°or 18°of convergence angle,1 of length-diameter ratio,0.9 mm of gas nozzle diameter,5 mm of spacing between gas nozzle and liquid nozzle.