1-7,10-14 PROBLEMS 1) What is the Reynold\'s number for water flowing in a 24-in

Question

1-7,10-14

PROBLEMS 1) What is the Reynold's number for water flowing in a 24-inch circular pipe at (2 Water is flowing in a 2V-inch pipe with a discharge of 0.150 cfs. Find the ? water is flowing in a 4-inch pipe with a discharge of 4.0×10 3 cfs. Find the (4) Water is flowing in a 300-mm circular pipe with a discharge of 0.250 m/s. a velocity of 6.21 tls? Is the flow laminar or turbulent? Reynold's number for this flow. Is the flow laminar or turbulent? Reynolds number for this flow. Is the flow laminar or turbulent? Find the Reynold's numher for this flow. Is the flow laminar or turbulent? 5.) What is the velocity head of the flow in problem 1? 6) Water in a pipe has a pressure of 2211b/h2, what is the pressure head? 7 Water in a pipe has a velocity of 4.25 fus. What is the velocity head 8. Water is flowing in an S-inch-diameter new cast iton pipe with a velocity of 7.49 ft/s. The friction factor is 0.0215. What is the friction head loss over a length of 115 feet? 9. Water is flowing in a 36-inch conerete pipe (finished surface) with a velocity of 12.5 ft/s. What is the friction head loss over a length of 225 feet? 10 Water is flowing in 2-inch tubing with a velocity of 1.35 fl/s. What is the fric- tion head loss over a length of 25 ft? A reservoir of water is connected to an 8-inch-diameter pipe 50 feet long and discharging freely. The water surface elevation of the reservoir is 410.0, and the elevation of the center of the pipe at its discharge end is 372.5. Neglecting friction, determine the velocity, v, and discharge, Q. at the end of the pipe. 12) Find the velocity, v, and discharge, Q, for the pipe in problem 9 if the pipe is composed of new cast iron and friction is considered.

Explanation / Answer

Reynolds number for pipe flow

Re = ( Density × Velocity × Diameter )/Viscosity

Density : Density of flowing fluid. Here flowing fluid is water

Density of water = 1000 Kg/m3

Viscosity: Viscosity of flowing fluid. Here flowing fluid is water.

Viscosity of water at 25? = 8.90 × 10-4 N/m2

A)If Reynolds number < 2000 ?Flow will be laminar.

B)If Reynolds number > 4000 ?Flow wil be turbulent.

C)In between flow will be transition.

Note:

1. 1 inch = 0.0254 m

2. 1feet = 0.3048 m

Solution of question (1)?

Given:

Diameter = 24 in = 24 × 0.0254 m =0.6096 m

Velocity = 6.21 feet/s = 6.21× 0.3048 m/s = 1.892 m/s

Re =( 1000×1.892×0.6096)/(8.90 × 10-4)=1295913.708 > 4000

Hence the flow will be turbulent.

Question 2 solution:

Diameter = 2.50 inch = 2.50 × 0.0254 m= 0.0635 m

Discharge = 0.15 cfs =0.15×0.30483 m3/s.= 4.247×10-3 m3/s.

Velocity = Discharge / Area of flow = 4.247×10-3/(3.166×10-3)=1.341 m/s

Area of flow =?/4×Diameter2 =?/4×0.06352= 3.166×10-3 m2.

Re = 1000×1.341×0.0635/(8.90×10-4) =95678.089 > 4000

Hence flow is turbulent.

Question 3 solution

Diameter = 4 inch = 4×0.0254 m = 0.1016 m

Discharge=4×10-3 cfs= 4×10-3 × 0.30483 =1.132×10-4 m3 /s

Area of flow = ? / 4 × 0.10162= 8.107×10-3 m2

Velocity = Discharge/ Area =0.1132/8.107 =0.0139 m/s

Re = 1000×0.0139×0.1016/(8.90×10-4)=1586.786 < 2000

Hence flow is laminar.

Question 4 solution

Diameter = 300 mm = 0.3 m

Discharge = 0.250 m3/s

Area of flow = ? / 4 × 0.32=0.0706 m2

Velocity = Dischare / Area =0.250/0.0706=3.54 m /s

Re = 1000×3.54×0.3/(8.90×10-4)=1193258.43 >4000

Hence the flow is turbulent.

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