How do you calculate flow over weir?
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 weir equation?
The Weir formula is a formula used in indirect calorimetry, relating metabolic rate to oxygen consumption and carbon dioxide production. According to original source, it says: Metabolic rate (kcal per day) = 1440 (3.94 VO2 + 1.11 VCO2)
What is the coefficient of discharge for a weir?
The flat-topped low weirs generally include broad-crested weir and short-crested weir. Under the same inflow condition, the discharge coefficient of short-crested weir is approximately 0.33–0.46, while that of broad-crested weir is 0.32–0.385, hence the former is stronger than the latter in terms of discharge capacity.
What is Francis formula?
The Francis (1883) equation is convenient for weirs operating under favorable prescribed conditions. The Francis equation is: Q = 3.33h13/2(L-0.2h1) (7-4)
How is weir coefficient calculated?
The Equation used to determine the flow rate of a Rectangular Contracted Weir is: = Height of the upstream water above the weir crest in feet.
What is weir flow?
A flow measuring weir is simply a structure over which water flows in such a way that volumetric flow rate can be calculated…. it lets you know how much water is flowing. Many times a flow measuring weir is simply a thin plate across a flow stream, but weirs can also be broad, thick structures.
How do you calculate weir discharge coefficient?
The generalized weir equation can be written as Q = C D C V C S C P C b l g b h 1.5 where CD is a discharge coefficient, Cv is the velocity coefficient, both as defined before, Cs is a shape coefficient depending on the lateral shape of the crest (e.g. shallow ‘Vee’), Cp is a coefficient to take into account the height …
What is end contraction of weir?
An end contraction is when the length of the weir (L) is less than the width of the Channel and a nappe contracts either one or both sides of the weir.
How do you calculate flow through AV notch weir?
That equation is: Q = 4.28 Ce Tan(θ/2)(H + k)5/2, where Q and H are as previously defined, θ is the angle of the v notch, Ce is the effective discharge coefficient, and k is a head correction factor.
How do you calculate V notch?
The formula for the fully contracted V-notch weir is restricted to the following conditions:
- Head H < 1.25 ft (38 cm).
- Width B > 3 ft (91 cm).
- Height P > 1.5 ft (46 cm).
- Ratio b/H ≥ 2.0.
- Head/width ratio H/B ≤ 0.2.
What is weir calibration?
through the submergence, the weir must be calibrated. The calibration process entails establishing. the discharge coefficient, Cd, which adjusts the theoretical discharge equation to obtain the actual discharge. The weirs used on the hydraulics bench for this experiment are known as sharp edge notches.
What is a weir contraction?
A contracted weir means that the ditch or canal leading up to the weir is wider than the weir opening itself. The water before the weir should be held in a relatively calm and smooth pool.
How to calculate critical flow of a weir?
If there is critical flow, then the equation to use is Q = 1.6 L H 3/2, where Q is the open channel flow rate in cfs, L is the weir length (channel width) in ft, and H is the head over the weir in ft, as shown in the diagram below.
How is the length of a contracted Weir determined?
Rectangular Contracted Weir. A contracted weir means that the ditch leading up to the weir is wider than the weir opening itself. The length is found by measuring the bottom width of the weir and the height is determined from measuring the water height above the bottom of the weir.
How to calculate weir height for open channel?
The four following equations, based on fundamental open channel flow principles, can be used to calculate the minimum weir height, P (see the diagram), needed to ensure critical flow over the weir crest. The four equations are: y1 + V12/2g = y2 + P + V22/2g, an expression of the energy equation, using variables shown in the diagram.
How to calculate the flow rate of critical flow?
If there is critical flow, then the equation to use is Q = 1.6 L H3/2, where Q is the open channel flow rate in cfs, L is the weir length (channel width) in ft, and H is the head over the weir in ft, as shown in the diagram below.