Longitudinal flow triangular array

The friction factor and Nusselt number for longitudinal laminar flow between a triangular array and a square array are discussed in this section. 

Triangular Array. A triangular array is shown in Fig. 5.38. The fluid longitudinally flows in the virtual channel formed by the triangular array. The friction factor for fully developed laminar flow in this configuration has been proposed by Rehme [237] as follows ... 

FIGURE 5.38 Fully developed / Re and Nusselt numbers for longitudinal laminar flow between cylinders in a triangular array [237]. 

The fully developed Nusselt number for longitudinal flow in a triangular array with uniform cylinder temperature has been analyzed by Ramachandra [238] and is shown in Fig. 5.38. The fully developed Nusselt numbers for the and boundary conditions have been studied by Sparrow et al. [253], Dwyer and Berry [250], Hsu [254], and Ramachandra [238]. The differences for NuHi and NuH2 reported by these investigators are small (1 percent). The fully developed Num and NuH2 are shown in Fig. 5.38. 

In the study of Miyatake and Iwashita [256], the relationship of local Nusselt number and Graetz number is formulated for developing longitudinal flow between a triangular array of cylinders with a uniform heat flux and various pitch-to-diameter ratios. For PID = 1.01-1.1 ... 

Fully developed turbulent flow and heat transfer in triangular and square arrays have been analyzed by Deissler and Taylor [261, 262]. The friction factors for longitudinal flow between the cylinders in a triangular and a square array are given in Fig. 5.40. Correspondingly, the Nusselt numbers, in terms of the Stanton number, defined as Nu/(Re Pr), are given in Fig. 5.41, where the cylinders are considered to be uniformly heated. 

Maresca and Dwyer [264] have analyzed the heat transfer of liquid metal flow in a triangular array with uniform longitudinal heat flux. The Nusselt number resulting from their analysis is given in Fig. 5.42. 

FIGURE 5.40 Fully developed friction factor for longitudinal turbulent flow between a triangular and a rectangular array [261]. 

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