Chapt10

55 where b is the crest width and cd is a

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Unformatted text preview: ly to higher Re, such as large dams on rivers. The broad-crested weir of Fig. 10.16b is considerably more sensitive to geometric parameters, including the surface roughness of the crest. If the leading-edge nose is rounded, R/L 0.05, available data [19, chap. 7] may be correlated as follows: | v v Round-nosed broad-crested weir: Cd | e-Text Main Menu | 0.544 1 */L H/L Textbook Table of Contents 3/2 (10.57) | Study Guide 10.7 Flow Measurement and Control by Weirs * L where 0.001 0.2 691 /L The chief effect is due to turbulent boundary-layer displacement-thickness growth * on the crest as compared to upstream head H. The formula is limited to H/L 0.7, /L 0.002, and V1H/ 3 E5. If the nose is round, there is no significant effect of weir height Y, at least if H/Y 2.4. If the broad-crested weir has a sharp leading edge, thus commonly called a rectangular weir, the discharge may depend upon the weir height Y. However, in a certain range of weir height and length, Cd is nearly constant: Sharp-nosed broad-crested weir: Cd 0.462 for H L 0.22 0...
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