Part 5: Flow in Pipes and Pipe Networks

Question 1

A ____________ flow (or flow field) is a flow for which the fluid is contained within the boundaries of a body.

Answer 1

Internal. An example of this is a duct, river Channel, or valve

Question 2

T or F: movement of fluid is in response to a pressure gradient?

Answer 2

True

Question 3

T or F: movement of fluid is in response to a gravity?

Answer 3

False, It is a response to pressure gradient

Question 4

T or F: Open channel flow in liquids is in response to gravity?

Answer 4

True

Question 5

T or F: Open channel flow in liquids is in response to a pressure gradient?

Answer 5

False, a response to gravity

Question 6

What is the Reynolds number for a laminar flow in a pipe?

Answer 6

Re<=2100

Question 7

What is the Reynolds number for a transitional flow in a pipe?

Answer 7

2100<=Re<=4000

Question 8

What is the Reynolds number for a turbulent flow in a pipe?

Answer 8

Re>=4000

Question 9

T or F: The centre core of a fluid as it enters the entrance region from a tank to a pipe acts as a ________ fluid.

Answer 9

Inviscid

Question 10

T or F: Unsteady flow through a pipe represents a balance between pressure and viscous force?

Answer 10

F. a steady flow represents this

Question 11

At entrance into a pipe, a force imbalance results in fluid…

Answer 11

acceleration

Question 12

Pressure differences in a horizontal pipe occur due to ___________

Answer 12

Shear stress resistance

Question 13

T or F: A horizontal pipe experiences some head loss due to gravity?

Answer 13

False, only to shear stress resistance.

Question 14

What is Poiseulle’s law?

Answer 14

Poiseulle’s law gives the discharge for laminar flow in a horizontal pipe

Question 15

_____________ Law gives the discharge for laminar flow in a horizontal pipe

Answer 15

Poiseuille’s

Question 16

T or F: For non-horizontal pipes it is not necessary to consider the effects of gravity in the pressure term?

Answer 16

False. It is necessary

Question 17

for a constant diameter, horizontal pipe, ∆p represents the __________ of the flow in the pipe

Answer 17

energy loss (head loss)

Question 18

Where does the head loss energy go?

Answer 18

internal energy, heat

Question 19

T or F: For flow in a pipe, the onset of turbulence is related to the Reynolds number

Answer 19

True

Question 20

The head loss in the ___________ equation represents the change in piezometric head over a length of pipe

Answer 20

Darcy-Weisbach

Question 21

T or F: The head loss given by the Darcy-Weisbach equation represents the ‘minor’ head loss in a piping system

Answer 21

False, It represents the major

Question 22

Friction factor relationship for uniform roughness represented by _________

Answer 22

Stanton diagram

Question 23

T or F: The moody diagram is used in both steady and unsteady flow?

Answer 23

False, only steady

Question 24

Head loss at an entrance to a pipe from a reservoir is due to all of the following except:  Boundary friction (small)  Gravity  Flow separation  Flow expansion

Answer 24

Gravity

Question 25

Head loss at an exit from a pipe into a reservoir due to:

Answer 25

Flow Expansion

Question 26

Abrupt expansion in a system is also called:

Answer 26

Borda Head Loss

Question 27

T or F: For both laminar and turbulent flow in a rectangular pipe, use Darcy-Weisbach head loss equation with Dh

Answer 27

True

Question 28

_______ head is the head required to overcome the level of difference between a pumphouse and reservoir?

Answer 28

Static

Question 29

_______ head is the head required to overcome the energy losses in the system

Answer 29

Dynamic

Question 30

T or F: For pipes in parallel, head loss between any two points must be the same regardless of the path taken

Answer 30

True

Question 31

What is the NPSH(r)?

Answer 31

Net Positive Suction Head (required). It is the minimum value of the suction head that a particular type or design can tolerate without cavitation occurring

Question 32

T or F: Since the pump has a characteristic H-Q curve and the system has a characteristic H-Q curve, the point at which the system will operate will be at the intersection of the two curves?

Answer 32

True

Question 33

___________ is a pressure eave created when a flowing liquid is suddenly decelerated

Answer 33

Water Hammer

Question 34

The time for the pressure wave to travel to the reservoir and back to the valve is called the _________ of valve closure

Answer 34

critical time