Water flows at a rate of 10 gallons per minute in a new horizontal 0.75?in. diameter galvanized iron pipe. Determine the pressure gradient, ?P/L, along the pipe.

Respuesta :

Answer:

[tex]\frac{\delta p }{l} = 30.4 lb/ft^3[/tex]

Explanation:

Given data:

flow rate = 10 gallon per  minute = 0.0223 ft^3/sec

diameter = 0.75 inch

we know discharge is given as

Q =  VA

solve for velocity V = \frac{Q}{A}[/tex]

[tex] V = \frac{0.223}{\frac{\pi}{4} \frac{0.75}{12}}[/tex]

V = 7.27 ft/sec

we know that Reynold number

[tex]Re = \frac{VD}{\nu}[/tex]

[tex]Re = \frac{7.27 \times \frac{0.75}{12}}{1.21\times 10^{-5}}[/tex]

[tex]Re = 3.76 \times 10^4 [/tex]

calculate the [tex]\frac{\epsilon }{D} [/tex]ratio to determine the fanning friction f

[tex]\frac{\epsilon }{D} = \frac{0.0005}{\frac{0.75}{12}} = 0.008[/tex]

from moody diagram f value corresonding to Re and [tex]\frac{\epsilon }{D} [/tex]is 0.037

for horizontal pipe

[tex]\delta p = \frac{f l \rho v^2}{2D}[/tex]

[tex]\frac{\delta p }{l} = \frac{1 \times 0.037 \times 1.94 \times 7.27}{\frac{0.75}{12}}[/tex]

where 1.94 slug/ft^3is density of  water

[tex]\frac{\delta p }{l} = 30.4 lb/ft^3[/tex]