This preview shows page 1. Sign up to view the full content.
Unformatted text preview: 2 curve and accelerates to critical
flow near the overfall. The falling stream will be supercritical. The overfall “controls”
the water depths upstream and can serve as an initial condition for computation of y(x).
This is the type of flow which occurs in a weir or waterfall, Sec. 10.7.
The examples in Fig. 10.15 show that changing conditions in openchannel flow can
result in complex flow patterns. Many more examples of compositeflow profiles are
given in Refs. 1, 3, and 18. 10.7 Flow Measurement
and Control by Weirs A weir, of which the ordinary dam is an example, is a channel obstruction over which
the flow must deflect. For simple geometries the channel discharge Q correlates with
gravity and with the blockage height H to which the upstream flow is backed up above
the weir elevation (see Fig. 10.16). Thus a weir is a simple but effective openchannel flowmeter. We used a weir as an example of dimensional analysis in Prob. 5.32.
Figure 10.16 shows two common weirs, sharpcrested and bro...
View
Full
Document
This note was uploaded on 10/27/2009 for the course MAE 101a taught by Professor Sakar during the Spring '08 term at UCSD.
 Spring '08
 Sakar

Click to edit the document details