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[Fluid Mechanics] Water Flow in a Hose

  • Thread starter Aprileo
  • Start date
  • #1
3
0

Homework Statement



Given:
Water flows through a 15.24m long, 1.6cm diameter hose.

pressure at the outdoor tap = 275.8kPa

volumetric flowrate, Q = 7.5e-4 m^3/s (i.e. 7.5L for 10 seconds)

viscosity of water, μ = 0.001 Pa*s
density of water, ρ = 1000 kg/m^3

Look for: the roughness of the hose

Homework Equations



Renolds number:
23032e25451927df6094806dcd3ba4dd.png


Darcy equation:
d507bcd5f5091fb94dabf55d828f59a3.png


Moody chart:
800px-Moody_diagram.jpg


The Attempt at a Solution



I have calculated Renolds number = 7958 ==> turbulent flow

I used Darcy equation and found out the friction factor, f, is great than 1.
I am confused and stuck here.
I must have used the wrong formula or missed some important steps.

Please help me by providing some advice, double checking my work or giving some steps would be greatly appreciated!

Homework Statement





Homework Equations





The Attempt at a Solution

 

Answers and Replies

  • #3
3
0
volumetric flowrate = Q = 7.5e-4 m^3/s
D = diameter = 0.016m
velocity = V =volumetric flow rate/cross sectional area = Q/(pi*D^2*0.25) = 0.497 m/s

density = ρ = 1000kg/m^3
viscosity = μ = 0.001 Pa*s
Renolds number = Re = (density*velocity*diameter)/viscosity = 7958 > 2100 ==> turbulent flow

L = length of the hose = 15.24m
pressure at outdoor tap = ΔP = 275.8kPa
friction factor = f = (2*ΔP*D) / (L*ρ*V^2) = 2.34 ==> doesn't make sense and I'm stuck here.
 
  • #5
3
0
Thank you very much, Chestermiller!

you are correct, V = 3.73 m/s,
problem solved.
 

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