Turbulent flow past a radiator contributes to noise emission when interacting with a downstream cooling fan. This study examines turbulent flow characteristics downstream of a radiator, focusing on turbulence production, dissipation, non-homogeneity, and anisotropy. We assess turbulence models based on isotropy and homogeneity for noise prediction in real applications. Results show significant non-homogeneity due to the radiator grid’s wakes, extending downstream to a region where the fan would be located. Flow in this region trends toward isotropy, especially when considering a downstream circularly-holed wood panel mimicking the flow contraction caused by a fan casing. The radiator core’s fins and louvers break down vortical structures more than generating large eddies, as reported in studies involving heat exchangers with larger gaps between cooling pipes. The von Kármán turbulence model approximates the experimental spectrum, but caution is needed with rapid flow acceleration. This investigation enhances our understanding of turbulence characteristics in the vicinity of radiators with implications for noise spectrum prediction and modeling in such systems.

中文翻译：

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通过百叶窗翅片管汽车热交换器的湍流的空气动力学研究

当与下游冷却风扇相互作用时，经过散热器的湍流会导致噪音排放。本研究研究了散热器下游的湍流特性，重点关注湍流的产生、耗散、非均匀性和各向异性。我们评估基于各向同性和均匀性的湍流模型，以进行实际应用中的噪声预测。结果显示，由于散热器网格的尾流向下游延伸到风扇所在的区域，因此存在显着的不均匀性。该区域的流动趋于各向同性，特别是当考虑下游圆孔木板模仿风扇外壳引起的流动收缩时。正如涉及冷却管之间间隙较大的热交换器的研究报告所述，散热器芯的翅片和百叶窗对涡流结构的破坏作用大于产生大涡流的作用。冯·卡门湍流模型近似于实验谱，但需要谨慎对待快速流动加速。这项研究增强了我们对散热器附近湍流特性的理解，对此类系统中的噪声谱预测和建模具有重要意义。