Flow through Rectangular Ducts

Figure 1: Flow through Rectangular Ducts
(Source: Book-Babcock-Wilcox)

Flow through rectangular ducts is important to be learned. Rectangular duct system will generate pressure loss which is caused by change in direction just like cylindrical pipe. Nevertheless, an additional aspect, the design of the duct in terms of the bend direction, should be considered into consideration. This can be known as the factor ratio, and that is understood to be the duct proportion of actual width (b) to the actual depth (d) dimension namely b/d ratio as shown in Figure 1.

The loss of bend pertaining to the similar ratio of radius reduces when the factor ratio raises, due to the lesser in proportion impact of this flows within the steady stream. The mixed impact of radius and also factor ratios on bends 1.57 rad (90 deg) in the duct is presented with regards to velocity heads as shown in Figure 1.

The loss variables found in Figure 1 are common values of experiment final results upon the ducts. Pertaining to the provided variety of factor ratios, the losses are reasonably separate of the Reynolds number. Other this variety, the variance along with Reynolds number is irregular. It's thus suggested in which the values of Nb intended for b/d = ½ be applied with regard to all factor ratios a smaller amount compared to b/d = ½, and also values pertaining to b/d = 2 be applied for ratios higher in comparison with b/d = 2. The bend loss pertaining to other angle of 1.57 rad (90 deg) is usually regarded for being proportionate to the angle of bend in the process of fluid flow through rectangular ducts.

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