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Flow of water in a venturimeter

  • Thread starter Karol
  • Start date
  • #1
1,380
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Homework Statement


Water flows in a horizontal venturimeter. the diameter is 100 mm, and the throat is 50 mm.
The pressure at the entrance is 0.65[bar].
What is the maximum throughput that is allowed so that the absolute pressure in the throat will not drop under 0.3[bar]

Homework Equations


Bernoully equation:
[tex]H_1+\frac{V_1^2}{2g}+\frac{P_1}{\gamma}+H_P=H_2+ \frac{V_2^2}{2g} +\frac{P_2}{\gamma}[/tex]

The Attempt at a Solution


The velocity V2 in the throat:
[tex]V_2=V_1 \frac{0.1^2}{0.005^2}=4V_1[/tex]
Bernoully equation:
[tex]\frac{0.65E5}{1E5}+\frac{V_1^2}{20}=\frac{0.3E5}{1E5}+\frac{16V_1^2}{20}[/tex]
Which produces negative velocity.
Even if i use absolute pressures, the same. i use 1.65 instead of 0.65.
 

Answers and Replies

  • #2
TSny
Homework Helper
Gold Member
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[tex]\frac{0.65E5}{1E5}+\frac{V_1^2}{20}=\frac{0.3E5}{1E5}+\frac{16V_1^2}{20}[/tex]
Which produces negative velocity.
Hi, Karol.

I don't see how you're getting a negative velocity here.

Also, are you sure that your value of [itex]\gamma[/itex] is correct?
 
  • #3
1,380
22
you are right!
Thanks...
 

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