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利用热质比拟原理及萘升华技术对空气横掠半轴比为 1 .6/1 .0椭圆管的局部及平均换热特性以及流阻进行了实验研究。实验雷诺数范围为 70 0 0 - 5 0 0 0 0。实验结果表明 :该椭圆管表面上的局部换热系数分布规律与圆管相似 ,但分离点位置不同 ;其最大值在前驻点 ,之后 ,随着边界层的发展逐渐降低 ,在分离点达到最小值 ,而在尾部区域又有所回升 ;其平均换热系数高于圆管 ,而阻力低于圆管。最后 ,给出了平均对流换热系数和阻力实验关联式。
The local and average heat transfer characteristics and flow resistance of elliptical tubes with air-swept half-axial ratio of 1.6 / 1.0 were experimentally studied by means of the principle of heat and mass transfer and naphthalene sublimation. The experimental Reynolds number range is 70 0 0 - 5 0 0 0 0. The experimental results show that the local heat transfer coefficients on the surface of the oval tube are similar to those of the circular tube, but the positions of the separation points are different. The maximum value is at the pre-stationary point, and then gradually decreases with the development of the boundary layer. Minimum, while in the tail area has picked up again; its average heat transfer coefficient is higher than the tube, while the resistance is lower than the tube. Finally, the experimental correlation of average convection heat transfer coefficient and resistance is given.