不同湍流模型在90°弯管数值模拟中的应用

Application of different turbulent models to numerically simulating 90° duct bends

为了揭示不同湍流模型对弯管内部流动模拟的影响因素,在90°弯管PIV(粒子成像测速仪)试验研究的基础之上,采用6种湍流模式模拟了方形截面90°弯管内的三维湍流流动,与试验数据进行了比较,并根据试验与数值计算的比较结果,选择较优的湍流模型模拟了半径r=164mm的速度分布曲线以及各个截面内的流动情况.结果表明:LES(大涡模拟)模型的计算结果在流体运动的整个过程中与试验值符合较好;其他湍流模型模拟弯管直线段时,计算误差较小,而一旦流体进入弯曲段后,计算值与试验值存在一定差异.相对于RNG(重正化群)k-ε(湍动能-耗散率)湍流模型,LES模型计算半径r=164mm上速度分布与试验值更为接近.此外,LES模型能够较好地模拟出弯管各个断面上的二次流动情况.

To study internal flow variation of 90° duct bends with square-section by different turbulent models,the tree-dimensional turbulent flow within 90° bending ducts based on PIV（particle image velocimetry） were simulated numerically by six turbulent models.The simulated numerical results were given and compared with the experimental data.Meanwhile,the best turbulent model was selected and velocity distribution curve for r=164 mm and internal flow in each section according to comparing between the experimental data and calculated data.The results show that the result of large eddy simulation is in good agreement with test results.Other turbulent models gave small errors when the fluid in the straightway.However,there is some differences between the experimental data and calculated data when the fluid in the bending.The large eddy simulation（LES） results is more close to the testing data than renormalization group（RNG） turbulent kinetic energy-dissipation rate（k-ε） turbulent model for velocity distribution at r=164 mm.Furthermore,the large eddy results can simulate secondary flow streamline in each section.