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 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 angle of V notch?
. The plate edges of an angle of at least 45° or 60° are highly recommended for a V-notch, Bos .
What is V notch?
Triangular weirs are sharp crested thin plates with V-shaped opening (or notch). These plates are installed at the exit of a channel, tank, or basin in order to measure the real-time flow of water. A typical application for these plates consists in measuring the flow of water on the downstream side of a dam.
What is the purpose of V notch?
These notches are used to measure discharge of open channel flows, by passing or placing or constructing them across the stream. Notches are generally used for measuring discharge in small open channels or laboratory flumes.
What is the minimum distance is case of V notch?
The bottom of the “V” should be at least 1.5 ft.
How is weir 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 function of V notch?
A v notch weir is simply a ‘v notch’ in a plate that is placed so that it obstructs an open channel flow, causing the water to flow over the v notch. It is used to meter flow of water in the channel, by measuring the head of water over the v notch crest.
Why is V notch used?
What is calibration of V notch?
As water approaches the notch, its surface becomes curved. Therefore, the head over the notch is to be measured at the upstream of the notch where the effect of curvature is minimum. Also, it should be close to the notch so that the loss of energy between head measuring section and notch is neglegible.
Why is V notch used in Charpy?
Charpy also found that the use of a notch in the test specimen was crucial in increasing the sensitivity and reproducibility of the measurement. This impact test shows the relationship of ductile to brittle transition in absorbed energy at a series of temperatures.
How to calculate flow rate of V notch weir?
For a V notch weir with a notch angle other than 90 degrees, the equation for calculation of the flow rate over the weir is given by the equation: Q = 4.28 Ce Tan (θ/2) (H + k)5/2, where the effective discharge coefficient, Ce, and the head correction factor, k, are both functions of the notch angle, θ.
What’s the correct angle for a notch weir?
“Angle out of range”. The notch angle must be between 20 o and 100 o (0.35 and 1.75 radians) for the equations to be valid.
What is the effective Coefficient of a V notch?
Figure 7-7 — Effective coefficient, Ce, for partially contracted 90-degree V-notches (courtesy of National Bureau of Standards, Kulin et al. ).. Bos (1989) and International Organization for Standardization (1983) explain and define limits basic to the use of these figures.
What happens if the notch angle is not 90o?
If the notch angle is not 90o, then the V-notch weir equation and calculations become somewhat more complicated and the use of Excel spreadsheet formulas can be quite useful.