Elliptic ducts, friction factor

Presented in this section are the friction factors and Nusselt numbers for laminar flow in elliptical ducts. 

Hydrodynamically Developing Flow. Bhatti [181] has analyzed hydrodynamically developing flow in elliptic ducts. The apparent friction factors and incremental pressure drop numbers can be expressed as ... 

The friction factors for fully developed turbulent flow have been measured by Barrow and Roberts [186] in elliptical ducts with a = 0.316 and 0.415 in the range of 103 < Re < 3.105 and by Cain and Duffy [187] in elliptical ducts with a = 0.5 and 0.667 in the range 2 x 104 < Re < 1.3 x 105. Based on the data presented by Barrow and Roberts [186] and Cain and Duffy [187], Bhatti and Shah [45] have derived the following correlation to calculate the friction factor ... 

Dong and Ebadian [234] numerically obtained the friction factor for laminar flow in curved elliptic ducts. The friction factor ratio fjfs is represented by the following expression ... 

An elliptical duct with four internal longitudinal fins mounted on the major and minor axes, as shown in Fig. 5.48, has been analyzed by Dong and Ebadian [275] for fully developed laminar flow and heat transfer. In this analysis, the fins are considered to have zero thickness. The thermal boundary condition is applied to the duct wall, and / is defined as a ratio of Ha a = Hbib. The friction factors and Nusselt numbers for fully developed laminar flow are given in Table 5.52. 

TABLE 5.52 Friction Factors and Nusselt Numbers for Fully Developed Flow in an Elliptical Duct With Internal Fins [275]... 

A confocal elliptical duct is shown in Fig. 5.64. According to the analysis by Topakoglu and Arnas [295], the friction factor for fully developed laminar flow in confocal elliptical ducts can be computed by... 

TABLE 5.66 Fully Developed Friction Factors for Elliptical Ducts With Centered Circular Cores [300]... 

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