Abstract In the current work, the turbulent flow and heat transfer in divergent swirl cooling tubes is studied numerically by using the open source CFD code OpenFOAM. The k-ω SST turbulence model with curvature correction, i.e., the k-ω SSTCC model, is used to compute the strong turbulent swirling flow. The unsteady solver “rhoPimpleFoam” is adopted in the computation and a time-averaging operation is implemented for the pressure, velocity and temperature fields to cover the effect of large-scale, low-frequency deterministic fluctuations of the vortex breakdown phenomenon. To generate high-quality grids, different parts of the swirl tubes are meshed with different block structures in ICEM and the Arbitrarily Coupled Mesh Interface (ACMI) boundary condition is used to couple the neighboring segments with non-conformal grids. The current model is validated by comparing the numerical results of a swirl tube with constant diameter to experimental data and numerical results from literature. In this study we investigated the turbulent heat transfer enhancement in a divergent swirl tube that features two 180°-displaced tangential inlets and a divergence angle of 0.596°. Moreover, the influence of axially multiple tangential inlets is studied for the same divergence angle. The current work demonstrates that the computationally cheap k-ω SSTCC model can predict the flow and heat transfer performances in a swirl tube with reasonable accuracy. Additionally, it is found that the Nu number of the divergent swirl tube with 180°-displaced inlets (S2D), is about 3.57 times higher than the one in a smooth tube with axial flow, and it is slightly lower (by 13%) than that of constant-diameter swirl tube (S2C), while its decrement of pressure drop is notable (by40%) compared with S2C. Axially-displaced multiple inlets can result in a tremendous reduction of pressure drop for swirl tubes by over 90% at the cost of a limited decrease in the Nu number (by ˜10%) compared to the swirl tube S2D.

中文翻译：

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使用带有曲率校正的 k-ω SST 湍流模型的发散涡流管中湍流和传热的 URANS

摘要 在目前的工作中，使用开源CFD代码OpenFOAM对发散涡流冷却管中的湍流和传热进行了数值研究。具有曲率修正的k-ω SST湍流模型，即k-ω SSTCC模型，用于计算强湍流涡流。计算中采用非定常求解器“rhoPimpleFoam”，并对压力、速度和温度场进行时间平均运算，以覆盖涡流击穿现象的大尺度、低频确定性波动的影响。为了生成高质量的网格，旋流管的不同部分在 ICEM 中用不同的块结构进行网格划分，并使用任意耦合网格接口 (ACMI) 边界条件将相邻段与非共形网格耦合。通过将具有恒定直径的涡流管的数值结果与实验数据和文献中的数值结果进行比较来验证当前模型。在这项研究中，我们研究了具有两个 180° 位移切向入口和 0.596° 发散角的发散涡流管中的湍流传热增强。此外，对于相同的发散角，研究了轴向多个切向入口的影响。目前的工作表明，计算成本低的 k-ω SSTCC 模型可以以合理的精度预测涡流管中的流动和传热性能。此外，发现具有 180°位移入口（S2D）的发散旋流管的 Nu 数比具有轴流的光滑管中的 Nu 数高约 3.57 倍，比定径旋流管（S2C）略低（13%），而压降比S2C显着（40%）。与旋流管 S2D 相比，轴向位移的多个入口可以使旋流管的压降大幅降低 90% 以上，但代价是 Nu 数有限地降低（约 10%）。