绕流椭圆柱管束的流动与传热特性

椭圆柱管束换热器在工业领域中得到广泛的应用。本文采用一种简单合理的自由表面模型深入研究了流体绕流椭圆柱管束的流动与传热问题。通过适体坐标转换方法在非规则流道截面上求解出动量与热量传递控制方程，获得了等壁温条件下的流道内的阻力系数和努塞尔数等准则数，并且和文献值进行了对比。文献值和模拟值之间的最大绝对误差小于3.5%，表明所建立的数学模型是正确的。利用所建立的数学模型分析了流动方向、椭圆柱横截面形状、管束结构参数以及壁面边界条件对绕流椭圆柱管束的流动与传热特性的影响。获得了等壁温和等热流密度条件下的阻力系数和平均努塞尔数。这些准则数为椭圆柱管束的设计和优化提供理论指导。

Fluid flow and heat transfer across an elliptical cylinder tube bank

Heat exchangers based on elliptical cylinder tube bank are widely used in industrial field. A convenient yet reasonable approach, a free surface model, is employed to model the fluid flow and heat transfer processes across the elliptical cylinder tube bank. The equations governing the momentum and heat transports on the irregular channel are solved by using a body-fitted coordinate transform method. The fundamental data such as friction factor and Nusselt number under uniform temperature condition are obtained. The friction factor and Nusselt number are validated by the values in the literature. The error of comparison between literature and simulation is within 3.5%. The effects of the flowing direction, shape of the elliptical cylinder cross-section, structural parameters of the tube bank and the wall boundary conditions on the fluid flow and heat transfer are investigated. The friction factor and Nusselt number are obtained under uniform temperature and heat flux condition. These fundamental data are useful for the future design and structural optimum of the elliptical cylinder tube bank.