design : v notch for flow measurement

To design a V notch for measurement of flow, We first will have to build a chamber to install the V notch.

 

The size of the chamber  will depend on the quantity of total discharge to be estimated.

 

After knowing the cross sectinal size of the chamber, the size and thickness of the V notch plate can be determined.

 

 

Installation Guidelines for V notch

 

 

 

 

• Use a 2mm Thick Mild Steel plate to make the V notch. Make a 90^o V

• Water surface downstream of the weir should be at least 6 cm below the bottom of the V to allow a free flowing waterfall.

• The bottom of the "V" only needs to be 10 cm (=P) above the bottom of the upstream channel,
• the approach channel (=B) only needs to be 2 ft. wide,

• Head (h) should be measured at a distance of at least 4h upstream of the weir.

 

Q = 4.28 C tan(θ/2)( h+k)^5/2

 

where

Q = flow rate (cfs)

C= Discharge Coefficient, C=0.578 for 90^o V notch

θ = v-notch angle ( 90^o

h = head on the weir (ft)

k = Head Correction factor(Ft)

• k (ft.) = 0.0144902648 - 0.00033955535 Ø + 3.29819003x10^-6 ز - 1.06215442x10^-8 س
  where Ø is the V notch angle in degrees ( 90^o

 

 

Source: ENVO PROJECTS. NEW DELHI-25 9899300371, 9810004529