Prediction of Heat Transfer in a Ribbed Channel: Evaluation of Unsteady RANS Methodology
Prediction of Heat Transfer in a Ribbed Channel: Evaluation of Unsteady RANS Methodology
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DOI：
10.1115/gt2005-68821
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发表时间：
2005
影响因子：
6.2
通讯作者：
W. York;D. Holloway;J. Leylek
中科院分区：
文献类型：
--
作者：
W. York;D. Holloway;J. Leylek
使用非稳态雷诺平均纳维斯托克斯 (URANS) 方法对一壁上带有肋状湍流器的直通道中的传热进行数值预测，并与文献中的代码验证质量实验数据进行比较。此外，为了进行比较，使用两种流行的湍流闭合模型（可实现的 k-e 模型和微分雷诺应力模型）对问题进行了稳定模拟。 URANS 模拟中的闭合是由克莱姆森大学高级计算研究实验室开发的基于涡粘性的新模型提供的。这个新模型由三个输运方程组成，专门设计用于促进流动的自然不稳定性，而不需要人工强迫。在所有情况下，基于水力直径的雷诺数都等于 24,000。通道底壁上等距分布有八个与流动方向正交的方形肋。对于 URANS 模拟，当流动在流向方向充分发展后，肋壁上的预测努塞尔数遵循建模实验研究的测量数据的趋势。然而，非稳态模拟稍微高估了每个肋骨尾部到峰值传热的距离。此外，传热预测很大程度上取决于肋板尾部的网格分辨率。因此，讨论了非结构化网格的有效细化和网格无关问题。两种稳态模拟的结果表明，整个肋壁上的努塞尔数明显低估，雷诺应力模型给出了两种稳态闭合模型的更好结果。这项研究的结果清楚地表明，肋片上的非稳态涡流脱落在该问题的物理过程中非常重要，并且需要一种系统的非定常方法来准确预测肋状通道的传热。版权所有 © 2005 ASME
Heat transfer in a straight channel with rib turbulators on one wall is predicted numerically with an unsteady Reynolds-averaged Navier-Stokes (URANS) methodology and compared to code-validation quality experimental data from the literature. Additionally, for comparison, steady simulations of the problem are conducted using two popular turbulence closure models, a Realizable k-e model and a differential Reynolds-stress model. Closure in the URANS simulation is provided by a new eddy-viscosity-based model that was developed in the Advanced Computational Research Laboratory at Clemson University. This new model consists of three transport equations, and it is designed specifically to promote natural unsteadiness in the flow without the need for artificial forcing. In all cases, the Reynolds number, based on hydraulic diameter, is equal to 24,000. Eight square ribs, orthogonal to the flow direction, are equally spaced on the bottom wall of the channel. For the URANS simulation, after the flow becomes fully-developed in the streamwise direction, the predicted Nusselt number on the ribbed wall follows the trend of measured data from the modeled experimental study. However, the unsteady simulation slightly overpredicts the distance to the peak heat transfer aft of each rib. Also, the heat transfer prediction is very dependent on the grid resolution aft of the ribs. Therefore, efficient refinement of the unstructured mesh and grid-independence issues are discussed. Results of both steady simulations show a significant underprediction of Nusselt number over the entire ribbed wall, with the Reynolds-stress model giving the better result of the two steady closure models. The results of this study clearly show that unsteady vortex shedding off of the ribs is important in the physics of this problem, and a systematic, unsteady methodology is necessary to accurately predict ribbed-channel heat transfer.Copyright © 2005 by ASME