Natural convection heat transfer from three isothermally heated horizontal cylinders submerged in water in a triangular arrangement is investigated. Two configurations, named here as one over two and two over one, are characterised for three cylinder spacings ($S$ = 2, 3 and 4 cylinder diameters) and Rayleigh number conditions ($Ra$ = 2$\times 10^6$, 4 × 10⁶ and 6 × 10⁶). Combined local heat flux measurements and flow velocity measurements using particle image velocimetry are employed to examine the governing heat transfer mechanisms. For many cases of the one over two configuration, substantial differences from the single cylinder case are noted. The buoyant plumes generated from the two lower cylinders interact with the flow field and heat transfer around the upper cylinder, altering the local fluid velocities and temperature fields. This effect is dependent on both the inter-cylinder spacing and the Rayleigh number condition. For the two over one setup, both upper cylinders for all cases, except $S=4D$ and $Ra$ = 6 × 10⁶, behave in the same manner as a single cylinder. This is due to the competing effects of the buoyant plume rising from the lower cylinder and the restriction of flow through the gap between the two upper cylinders.

研究了三个等温加热的水平圆柱体的自然对流传热，这些圆柱体以三角形布置浸入水中。两种配置，这里分别称为“一比二”和“二比一”，其特征是具有三个气缸间距（$\mathrm{小号}$ = 2、3和4的圆柱直径）和瑞利数条件（$\mathrm{[R}\mathrm{一种}$ = 2$\times \mathrm{1个}{0}^6$，4×10 ⁶和6×10 ⁶）。结合使用局部热通量测量和使用粒子图像测速仪的流速测量来检查控制传热的机理。对于“一拖二”配置的许多情况，都注意到与单缸壳体的实质性区别。从两个下部圆柱体产生的浮羽与流场相互作用，并在上部圆柱体周围传热，从而改变了局部流体的速度和温度场。该效果取决于缸间距和瑞利数条件。对于“二合一”设置，所有情况下都为两个上部气缸，除了$\mathrm{小号}=4d$ 和 $\mathrm{[R}\mathrm{一种}$= 6×10 ⁶，其行为与单个圆柱体相同。这是由于浮羽从下圆柱升起而产生的竞争效应，以及通过两个上圆柱之间的间隙的流量受到限制。