Large-eddy simulation of fluid flow and heat transfer in a mixing tee junction
Large-eddy simulation of fluid flow and heat transfer in a mixing tee junction
复制标题
混合三通接头中流体流动和传热的大涡模拟
DOI：
10.3901/cjme.2012.06.1144
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发表时间：
2012
影响因子：
4.2
通讯作者：
Kuisheng Wang
中科院分区：
文献类型：
--
作者：
T. Lu;Yong;Kuisheng Wang
冷热流体混合的热条纹现象引起的温度波动导致管壁周期性热应力疲劳破坏。以往的热疲劳失效分析多采用冷热流体的平均温差作为热载荷，而忽略了温度波动幅度和频率对热疲劳失效的影响。基于引起热疲劳的流动和传热机理，采用大涡模拟（LES）湍流模型和Smagorinsky-Lilly（SL）亚网格尺度（SGS）模型，在FLUENT平台上模拟冷热水在T型接头处的湍流混合，捕捉温度波动的幅度和频率。模拟工况中，温度为343.48 K、流速为0.15 m/s的热水进入边长为100 mm的水平主管道，温度为296.78 K、流速为0.3 m/s的冷水进入边长为50 mm的垂直支管道。数值结果表明，平均温度和脉动温度与前期实验数据吻合较好，说明数值模拟具有较高的可靠性和准确性；顶壁的功率谱密度（PSD）高于底壁（频率小于1 Hz），而底壁的PSD相对高于顶壁（频率为1~10 Hz）。 LES可以准确捕捉T形结全混合区域的温度波动，为热应力和热疲劳分析提供理论依据。
The temperature fluctuation caused by thermal striping phenomena of hot and cold fluids mixing results in cyclical thermal stress fatigue failure of the pipe wall. Mean temperature difference between hot and cold fluids was often used as thermal load in previous analysis of thermal fatigue failure, thereby the influences of the amplitude and frequency of temperature fluctuation on thermal fatigue failure were neglected. Based on the mechanism of flow and heat transfer which induces thermal fatigue, the turbulent mixing of hot and cold water in a tee junction is simulated with FLUENT platform by using the Large-eddy simulation(LES) turbulent flow model with the sub-grid scale(SGS) model of Smagorinsky-Lilly(SL) to capture the amplitude and frequency of temperature fluctuation. In a simulation case, hot water with temperature of 343.48 K and velocity of 0.15 m/s enters the horizontal main duct with the side length of 100 mm, while cold water with temperature of 296.78 K and velocity of 0.3 m/s enters the vertical branch duct with the side length of 50 mm. The numerical results show that the mean and fluctuating temperatures are in good agreement with the previous experimental data, which describes numerical simulation with high reliability and accuracy; the power spectrum density(PSD) on top wall is higher than that on bottom wall(as the frequency less than 1 Hz), while the PSD on bottom wall is relatively higher than that on top wall (as the frequency of 1–10Hz). The temperature fluctuations in full mixing region of the tee junction can be accurately captured by LES and can provide the theoretical basis for the thermal stress and thermal fatigue analyses.