缩放型喷嘴产生的空化射流流场数值分析.doc

缩放型喷嘴产生的空化射流流场数值分析 卢义玉(李晓红康勇(重庆大学,重庆 400030)针对，湍流模型最适合用以数值模拟缩放型喷嘴内部的湍流流场。RNG湍流模型数值模拟结果表明缩放型喷嘴收缩角使喷嘴喉管部产生了低压场，压差的产生使水射流的空化效果得到提高。该分析结果也为缩放型喷嘴空泡形成的机理研究以及喷嘴结构对射流流场参数的影响提供了重要依据。 关键词：空化水射流；缩放型喷嘴；流场；数值模拟；流动特性 中图分类号：TH 137 Numerical Simulation for Cavitation Water Jet Flow through a Convergent-divergent Nozzle LU Yi-yu,WANG Xiao-chuan,LI Xiao-hong,KANG Yong,CHEN YU-long (College of Resources and Environmental Science, Chongqing University, Chongqing 400030, China) Abstract：To study how the convergent-divergent reduction angle influences the dynamic characteristic parameters in high pressure flow field, meanwhile, according to complication of turbulence’s mechanism and law as well as the jet pressure in nozzle is diffcult to test by experiment, applying different turbulent models to numerically simulate the turbulent field in nozzle. Combining the theory analysis and comparaiton with the experiments of mass flow rates, it can be concluded that the RNG is the most suitable model. Applying RNG to numerically simulate and the result shows that the convergent-divergent reduction angle has significantly influence on the parameters of jet flow field. It can form low pressure field in nozzle throat; the pressure difference can improve the cavatition effect of high pressure water jet. Also the result provides improtant basis of mechanism sduty on the formation of cavatition bubble in convergent-divergent nozzle. Key words：cavitation water jet; Convergent-divergent nozzle; Flow field; Numerical simulation; Flow property 1 引言 在相同水力参数条件下，水射流的空化效果取决于喷嘴结构。大量的试验研究已经证实缩放型喷嘴产生的空化射流的冲蚀效果明显比收缩型喷嘴强。但对喷嘴的几何形状与水射流的空化效果之间的关系还缺乏认识，需要对喷嘴内部流场进行全面和准确的实验研究。而直接通过实验测试喷嘴内射流的压力分布状态非常困难，传统的分析方法也不能计算内部截面积有变化的喷嘴中的射流压力分布。因此,探索合适的数值模拟方法进行喷嘴内部射流流场的数值模拟,对弄清喷嘴结构与空化效果间的关系具有重大现实意义[1~5]。本文拟选用适应性强的Standard模型、RNG模型Standard模型 控制方程 FLUENT软件采用SIMPLE算法（求解压力耦合方程的半隐方法）对控制方程进行数值求解，通过“预测—校正”程序来计算交错网格上的压力。非定常的连续方程和Navier-Stokes方程如下： (1) (2) (3)