Tuesday, 19 March 2019

EXAMPLE 4.1.1. ORIFICE WITH PIEZOMETER

The 50mm-diameter orifice is with  and . The diameter of the pipe is 150mm. The liquid is water and stands at a height of 3m in the piezometer. Compute the following:
  1. Velocity head at the orifice
  2. Discharge at the jet
  3. Diameter of the jet at vena contracta

Using Bernoulli's Energy Equation:

                                 

Both elevation heads are zero because the pipe placed horizontally. The pressure head at station 2 is also taken as zero because the jet sprays out the atmosphere. These conditions leave the equation as:



With the piezometer level rising to 3m, station 1's pressure head is 3m.





With the constant Q equation, we know that:








Substituting to the previous equation:








The discharge at the jet is taken as the actual Q (both coefficients are given)




where:








The diameter of the jet at vena contracta will be computed using the coefficient of contraction:







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