Part 9: Pipe Flow

Question 1

A general expression for head loss in a pipe can be given by which equation

Answer 1

Darcy-Weisbach

Question 2

This person studied the friction factor of commercial pipes

Answer 2

Moody

Question 3

T or F: In the region immediately adjacent to the pipe wall, the fluid behaves as though it is highly viscous.

Answer 3

True

Question 4

The layer immediately adjacent to the pipe wall that behaves as though it was highly viscous is called…

Answer 4

the laminar sub-layer (also called viscous sub-layer)

Question 5

When is a pipe considered to be smooth?

Answer 5

When the roughness elements of the pipe are submerged within the laminar sub-layer

Question 6

As the Reynolds number of the flow increases, the laminar sub-layer becomes thinner or wider?

Answer 6

Thinner

Question 7

What does the Reynolds number characterize and what are these levels?

Answer 7

The flow regime of the pipe, the three levels are:
Re<2100 Laminar
Re: 2100-4000 Transitional
Re>4000 Turbulent

Question 8

What is wholly rough and when does it occur?

Answer 8

it is when all the roughness elements project through the laminar sub-layer, this occurs when the Reynolds number is very high.

Question 9

Name four persons that created friction factor equations

Answer 9

• Colebrook or (Colebrook-White)
• Haaland
• Swamee and Jain
• Moody

Question 10

What is Major loss and Minor Loss

Answer 10

Major Loss: headless in a pipe due to friction

Minor Loss: headloss ina pipe due to fittings

Question 11

What are three causes of minor loss

Answer 11

• Expansion and contraction of the flow
• Increased Shear Stress
• Turbulent Mixing

Question 12

Another name for abrupt expansion is

Answer 12

Borda-Carnot Loss

Question 13

The vertical distance between the EGL and HGL is equal to

Answer 13

the Velocity Head of the flow

Question 14

Can a pipe lay above the HGL?

Answer 14

Yes, this section of the pipe will have a negative pressure