论文标题
通过周期性凹槽通道的湍流流动的大型涡流模拟
Large Eddy Simulations of turbulent convective flow through a periodic groove channel
论文作者
论文摘要
自最近几十年以来，使用扩展表面可以在传热设备中发现广泛的应用，以实现燃气轮机叶片冷却和核反应堆芯等传热增强。因此，理解潜在的流动物理学和控制传热增强的运输现象是本研究的目的。在本研究中，使用大型涡模拟进行了通过周期性凹槽通道进行湍流强制对流的数值计算。凹槽通道的下壁有恒定的热通量，而上壁绝缘。使用在有限体积的求解器ANSYS Fluent 19.2中实现的LES公式中的WMLES模型进行了计算。在不同比率的凹槽宽度与通道高度（B/h）的不同雷诺数范围内，进行模拟的范围为0.75-1.75。凹槽的螺距比和深度比分别保持恒定2和0.5。系统地进行了传热系数，相关的摩擦损失和热量增强幅度的估计，并将其与使用文献中报道的Rans框架获得的文献中报告的结果进行了比较。使用LES获得的结果表明，与使用RANS配方在上述RE的RANS配方中获得的结果相比，相关的摩擦损失的合理幅度提高了45％，而相关的摩擦损失的平均量降低了40％。此外，使用LES的B/H比为0.75，最大幅度提高了64％的热增强因子。提出了两个相关性，以根据所获得的模拟结果计算给定RE，NU和（B/H）比的摩擦因子和热增强因子，R-squared值分别为0.94和0.96。
The use of extended surfaces find wide range of applications in heat transfer devices for achieving heat transfer augmentation like gas turbine blade cooling and nuclear reactor core since the last few decades. So, understanding the underlying flow physics physics and the transport phenomenon governing the heat transfer enhancement is the goal of the present study. In the present investigation, numerical computations of turbulent forced convection through a periodic groove channel are carried out using large eddy simulations. The lower wall of the grooved channel is provided with constant heat flux while upper wall insulated. Computations were carried out using WMLES model in LES formulation implemented in a finite volume based solver ANSYS Fluent 19.2. The simulations are performed over varying Reynolds numbers range of 3000-30000 at different ratios groove width to channel height (B/H) in the range 0.75-1.75. The groove pitch ratio, and depth ratio kept constant of magnitude 2 and 0.5 respectively. Estimation of coefficient of heat transfer, associated frictional losses, and magnitude of heat enhancement are systematically carried out and compared with reported results in literature obtained using RANS framework reported in literature. The results obtained using LES show improvements in the heat transfer rate by a reasonable magnitude of 45% while the associated frictional losses decreased by an average magnitude of 40% compared to results obtained using RANS formulation in the aforementioned range of Re. Further, a maximum magnitude of 64% improvement in the thermal enhancement factor is achieved using LES for a B/H ratio of 0.75. Two correlations are proposed to calculate the friction factor and thermal enhancement factor for a given Re, Nu and (B/H) ratio, with a R-squared value of 0.94 and 0.96 respectively based on the obtained simulated results.
