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为了研究过渡流状态下管束传热强化机理,通过基于复合网格的专用程序,本文建立了顺排布置双列管束计算模型。计算结果表明:1)两列圆柱之间的流场结构分为稳定结构(对称死区)和非稳定结构(旋涡),非稳定结构的流场下的下列圆柱传热效率高于稳定结构流场的传热效率。2)由于旋涡的出现,在一定的横向间距内,传热效率升高速率要大于流动阻力升高的速率,大于这个横向间距后,情况相反,这一结果肯定了旋涡不稳定性对下游圆柱壁面传热强化的影响.3)随着纵向间距的缩小,涡脱频率升高,两列圆柱之间流体被加速,加速了旋涡的发展,这能在更小的横向间距内,率先使传热效率升高。
In order to study the heat transfer enhancement mechanism of tube bundle under transitional flow conditions, a dual-row tube bundle calculation model was established in this paper through a special program based on composite grid. The calculation results show that: 1) The flow field structure between two columns is divided into stable structure (symmetrical dead zone) and unsteady structure (vortex). The heat transfer efficiency of the following columns under the flow field of unstable structure is higher than that of steady structure flow Field heat transfer efficiency. 2) Due to the appearance of vortices, the rate of increase of heat transfer efficiency is greater than the rate of increase of flow resistance at a certain lateral spacing, which is opposite to that of this lateral spacing. This result confirms the effect of vortex instability on the downstream cylinder Wall heat transfer enhancement.3) As the longitudinal spacing shrinks, the eddy frequency increases and the fluid between the two columns is accelerated, accelerating the development of the vortices, which can lead the transmission in the smaller lateral spacing Thermal efficiency increases.