GATE XE concept:friction-factor PYQs & Answers

Questions 1–7 of 7. Imported answers require independent review unless marked reviewed.

Air flows through a pipe of diameter

with an average velocity of 3 m.s

. The Darcy friction factor of the pipe is 0.02. Assume acceleration due to gravity as 10 m.s

. If the head loss per meter is 0.05, the diameter (in m) of the pipe is __________. (rounded off to two decimal places)

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For incompressible, laminar, fully-developed flow through a circular pipe, Darcy friction factor and Fanning friction factor are represented as

and

, respectively. Which one of the following options is correct?

Your answerChoose one option.

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Consider the fully-developed flow of a Newtonian fluid (density

; viscosity

) through a smooth pipe of diameter

and length

. The average velocity of the flow is

. If the length of the pipe is doubled, keeping

constant, the friction factor

Your answerChoose one option.

increases by two times

remains the same

decreases by two times

increases by four times

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Water discharges steadily from a large reservoir through a long pipe, as shown in the figure. The Darcy friction factor in the pipe is 0.02. The pipe diameter is 20 cm and the discharge of water is 360 m

/h. Water level in the reservoir is 10 m and acceleration due to gravity

m/s

. If minor losses are negligible, the length

(in meters, up to one decimal place) of the pipe is ______.

Diagram for Engineering Sciences question 21

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Water flows at an average velocity,

of 10 m/s through a horizontal smooth tube of diameter,

5 cm. The friction factor,

is 0.02. Head loss is obtained using Darcy-Weisbach relation

. The fluid pressure,

measured at various stations are reported in the table below. The length of the pipe,

between station 0 and station 6 is 6 m.

Station	0	1	2	3	4	5	6
, kPa	304	273	255	240	226	213	-

If acceleration due to gravity, g = 10 m/s

and density of water =1000 kg/m

, then the fluid pressure at station 6 is ______ kPa (rounded off to one decimal place)

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Water is flowing in two different tubes of diameters D and 2D, with the same velocity. The ratio of laminar friction factors for the larger diameter tube to the smaller diameter tube is

Your answerChoose one option.

0.5

1.0

2.0

4.0

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Water is flowing at a rate of 0.5 m³/s in a horizontal pipeline of inside diameter 0.5 m. The density and kinematic viscosity of water is 1000 kg/m³ and 10⁻⁶ m²/s, respectively. Assume Darcy-Weisbach friction factor value to be 0.0093 and acceleration due to gravity as 9.81 m/s². To maintain constant flow rate, the required power per unit length of the pipeline (in W/m, rounded off to the first decimal place) would be ________.

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GATE XE concept:friction-factor PYQs

How to practice concept:friction-factor

Question 43

Question 28

Question 4

Question 21

Question 16

Question 7

Question 30