Chapt10

1 3 and 18 a weir of which the ordinary dam is an

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Unformatted text preview: ad-crested, assumed to be very wide. In both cases the flow upstream is subcritical, accelerates to critical near the top of the weir, and spills over into a supercritical nappe. For both weirs the | v v Some Illustrative Composite-Flow Profiles | e-Text Main Menu | Textbook Table of Contents | Study Guide 688 Chapter 10 Open-Channel Flow discharge q per unit width is proportional to g1/2H3/2 but with somewhat different coefficients. The short-crested (or thin-plate) weir nappe should be ventilated to the atmosphere; i.e., it should spring clear of the weir crest. Unventilated or drowned nappes are more difficult to correlate and depend upon tailwater conditions. (The spillway of Fig. 10.11 is a sort of unventilated weir.) M–2 yn1 Critical flow S–2 yc yn2 Mild (a) Steep yn1 M–1 (b) yn2 yc Mild Milder yn1 yc yn2 S–3 (c) Steep Less steep S–1 yn1 yn, high Jump M–3 yn, low yc Steep (d) Mild yn M–2 yc (e) v v Fig. 10.15 Some examples of composite-flow profiles. | Critical flow | e-Text Main Menu Free overfall...
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This note was uploaded on 10/27/2009 for the course MAE 101a taught by Professor Sakar during the Spring '08 term at UCSD.

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