Large eddy simulation of hot and cold fluids mixing in a T-junction for predicting thermal fluctuations

Temperature fluctuations in a mixing T-junction have been simulated on the FLUENT platform using the large eddy simulation （LES） turbulent flow model and a sub-grid scale Smagorinsky-Lilly model. The normalized mean and root mean square temperatures for describing time-averaged temperature and temperature fluctuation intensity, and the velocity are obtained. The power spectrum densities of temperature fluctuations, which are key parameters for thermal fatigue analysis and lifetime evaluation, are analyzed. Simulation results are consistent with experimental data published in the literature, showing that the LES is reliable. Several mixing processes under different conditions are simulated in order to analyze the effects of varying Reynolds number and Richardson number on the mixing course and thermal fluctuations.     

填充烧结铜球的T型管中流体混合的大涡模拟

在FLUENT软件平台上,运用大涡模拟湍流模型及Smagorinsky-Lilly亚格子尺度模型,对填充有烧结铜球多孔介质的T型管道内冷热流体混合过程的流动与传热情况进行了数值计算,与未填充多孔介质时混合区域内的平均温度和温度波动、平均速度和速度波动等数据进行了对比,并对温度波动进行了功率谱密度分析．数值结果表明,多孔介质可有效削弱T型通道流体混合区域内的温度和速度波动,有效降低1 Hz至10 Hz频域中的温度波动的功率谱密度．     

高含水原油对油管和抽油杆摩擦磨损性能的影响研究

在实验室考察了油井产出液含水量对抽油杆和油管摩擦磨损性能的影响,采用扫描电子显微镜观察了抽油杆和油管试样磨损表面形貌.结果表明:当油井产出液含水量处于70%～85%之间时,抽油杆和油管摩擦副的摩擦系数和磨损率随含水量增加呈增大趋势;当油井产出液含水量小于70%或大于85%时,摩擦系数和磨损率变化较小;油井产出液含水量对抽油杆和油管试样磨损表面形貌亦具有明显影响,当含水量较低(55%)时,抽油杆和油管磨损表面较光滑,存在少量犁沟;而当含水量较高(95%)时,磨损表面出现宽而深的犁沟,呈现严重粘着和擦伤迹象.     

T型管中冷热流体混合过程热波动大涡模拟

在FLUENT平台上,运用大涡模拟湍流模型及Smagorinsky-Lilly亚格子模型,对T型混合结构中的温度波动进行了模拟.获得了分别用于描述时均温度和温度波动强度的无量纲时均温度和无量纲均方根温度.分析了用于热疲劳分析和生命周期评价关键参数,即温度波动的功率谱密度函数.对不同条件下的混合过程进行了模拟,分析不同Reynolds数Re和Richardson数Ri对混合过程和热波动的影响.     

Large-eddy simulation of fluid mixing in tee with sintered porous medium

Mixing processes of hot and cold fluids in a tee with and without sintered copper spheres are simulated by FLUENT using the large-eddy simulation (LES) turbulent flow model and the sub-grid scale (SGS) Smagorinsky-Lilly (SL) model with buoyancy. Comparisons of numerical results of the two cases with and without sintered copper spheres show that the porous medium significantly reduces velocity and temperature fluctuations because the porous medium can effectively restrict the fluid flow and enhance heat transfer. The porous medium obviously increases the pressure drop in the main duct. The porous medium reduces the power spectrum density (PSD) of temperature fluctuations in the frequency range from 1 Hz to 10 Hz.