What is the broad crested weir?
What is the broad crested weir?
A broad-crested weir is an overflow structure with a horizontal crest above which the deviation from a hydrostatic pressure distribution because of centripetal acce- leration may be neglected. In other words, the streamlines are practically straight and parallel.
Does the height of the weir affect the discharge coefficient?
Results revealed that the discharge coefficient of the weir increases with the increase in inclination of the weir plane.
How is weir coefficient calculated?
The equation recommended by the Bureau of Reclamation in their Water Measurement Manual, for use with a suppressed rectangular weir is: Q = 3.33 B H3/2, where Q is the water flow rate in ft3/sec, B is the length of the weir (and the channel width) in ft, and H is the head over the weir in ft.
What is the discharge coefficient of an orifice?
The discharge coefficient is a dimensionless number used to characterise the flow and pressure loss behaviour of nozzles and orifices in fluid systems. Orifices and nozzles are typically used to deliberately reduce pressure, restrict flow or to measure flow rate.
What are the advantage disadvantage and use of a broad crested weir?
Broad crested weir: They are used to measure the discharge of rivers hence they have comparatively sharp sharps. Additionally, the advantage of a wider crested weir having a critical depth meter, is that it operates more effectively with a higher drifted water level than sharp-crested weirs.
How do you calculate the coefficient of discharge?
The discharge coefficient of an orifice or nozzle is defined as the ratio of the actual to theoretical flow rate:
- Cd=Measured Flow RateTheoretical Flow Rate (1)
- η=σΔp12ρ¯V2 (6)
- ξ=σΔp¯Δp (7)
What are the advantages and disadvantages of broad crested?
The disadvantages are that the upstream water depth will be higher than it would have withoutthe structure and for water supplies with sediment there will be deposition upstream of the structure. The main advantage of the Parshall flume vs. the broad-crested weir is its relatively low loss of head.
What are the different types of weirs?
Types of Weirs:
- Types of Weirs based on Shape of the Opening. Rectangular weir. Triangular weir. Trapezoidal weir.
- Types of Weirs based on Shape of the Crest. Sharp-crested weir. Broad- crested weir. Narrow-crested weir. Ogee-shaped weir.
- Types of weirs based on Effect of the sides on the emerging nappe.
Is the discharge coefficient of a broad crested weir constant?
If the coefficient is relatively constant, nothing is gained by using the (more complex) broad-crested weir technique. To determine the potential variation in the discharge coefficient, consult the table of weir coefficients in Appendix D2 of the HydroCAD Reference Manual .
What is the discharge coefficient of a spillway?
C = Discharge coefficient, accounts for energy losses as water enters the spillway, flows through the spillway, and eventually exits the spillway. Typical values will range from 2.6 to 4.0 depending upon the shape of the spillway crest. L = Length of the spillway crest.
How does the broad crested spillway in HEC-HMS work?
HEC-HMS uses the same approach, with some simplifications. The broad-crested spillway allows for uncontrolled flow over the top of the reservoir according to the weir flow assumptions. The discharge coefficient C accounts for energy losses as water enters the spillway, flows through the spillway, and eventually exits the spillway.
When do you use a broad crested weir?
In general, the broad-crested weir capability is useful only in cases where the discharge coefficient varies with head . If the coefficient is relatively constant, nothing is gained by using the (more complex) broad-crested weir technique.