Question

issues from the tank in shown at Q = 45 f3/h. Assume laminar flow conditions and neglect entrance and exit losses. (a) ...


issues from the tank in shown at Q = 45 f3/h. Assume laminar flow conditions and neglect entrance and exit losses. (a) What is the velocity of flow in the pipe. Ans: 9.167 ft/s (b) Determine the head lost in the pipe. Ans: 7.695 feet - Determine the kinematic viscosity of the paint in ft?/s. Ans:0.0002444
Transcribed: Problem 7 - 77 Paint issues from the tank in shown at Q = 45 ft/h. Assume laminar flow conditions and neglect entrance and exit losses. 9 ft L=6 ft, d 2 in (a) What is the yelocity of flow in the pipe. Ans: 9.167 ft/s (b) Determine the head lost in the pipe. Ans: 7.695 feet (c) Determine the kinematic viscosity of the paint in ft2/s. Ans: 0.0002444

Answer

ASKED: To determine-

(a) Velocity of flow (V)

(b) Head lost in the pipe (HL)

(c) Kinematic viscosity of the plant (ν)

 

Given:

Head over the pipe (H) = 9 ft

Length of the pipe (L) = 6 ft

Diameter of the pipe (D) = 0.5 in

Flow rate through the pipe (Q) = 45 ft3/h

 

NOTE: The flow is mentioned to be laminar and minor losses are to be neglected.

The flow rate through the pipe can be expressed in terms of the velocity of flow and cross-sectional area of the pipe as:

Q=V×π4×D2

V=4×Qπ×D2

V=4×45 ft3/hπ×0.5 in×1 ft12 in2×1 h60 min×1 min60 s

 V=9.167 ft/s 

The head lost in the pipe can be expressed as:

HL=Head over the pipe-Velocity head=H-V22g

here,

g: acceleration due to earth's gravity = 32.2 ft/s2

HL=9 ft-9.167 ft/s2×32.2 ft/s2

 HL=7.695 ft 

Using the Darcy-Weisbach formula, head loss in a pipe can be given as:

HL=f×L×V22×g×D

here,

f: friction factor, for laminar flow f=64Reynolds number Re

Reynolds number Re=V×Dν

 

First let us determine the friction factor using the Darcy-Weisbach formula and the head loss computed above.

7.695 ft=f×6 ft×9.167 ft/s22×32.2 ft/s2×0.5 in×1 ft12 in

f=0.0409

 

Now, using the calculated value of friction factor and the formula for friction factor, we can obtain the kinematic viscosity.

f=64Re=64V×Dν

ν=f×V×D64

ν=0.0409×9.167 ft/s×0.5 in×1 ft12 in64

 ν=0.000244 ft2/s 

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