Hydraulics

Question 1

Minor (local) Losses are caused by?

Answer 1

friction in the pipe walls of the fitting

Question 2

Name 3 things that would help prevent cavitation?

Answer 2

1. Increasing height of fluid source
2. Decreasing flow rate
3. choosing a larger pump

Question 3

Name three types of positive displacement pumps

Answer 3

piston, rotary and reciprocating pumps

Question 4

Is a dynamic pump a positive displacement pump?

Answer 4

No

Question 5

Give an example of a dynamic pump

Answer 5

Centrifugal

Question 6

what causes water hammer?

Answer 6

a sudden increase of water pressure

Question 7

Name 3 ways to decrease the net positive suction head required in a pumping system?

Answer 7

Decrease the motor speed, Trim the pump impeller, remove restrictions in piping

Question 8

Dye flowing straight and uninterrupted/ disturbed in and open channel describes what type of flow?

Answer 8

Laminar

Question 9

What are Roughness rings?

Answer 9

they are concentric rings that used inside the conduit to slow the flow, this is an internal flow dissipater

Question 10

Name 3 external energy flow dissipaters?

Answer 10

Water filled pools
Rip Rap Pads
Complex dissipaters

Question 11

what is the difference between External and Internal Flow dissipaters ?

Answer 11

External are located at the outlet ends of channels and conduits
Internal dissipaters are located within the conduit that slow the flow before it leaves the conduits

Question 12

Discharge for partially full flow versus full flow in a circular channel?

Answer 12

Partically full flow can have a larger dischage than the full flow at certain normal flow depth

Question 13

What shape is the most efficient open channel cross -section?

Answer 13

semi-circle, lowest wetted perimeter

Question 14

When using BErnoulli’s equation, if the friction is assumed to be zero, what can be said about the Pipe and the Fluid?

Answer 14

the Pipe is frictionless and the Fluid is inviscid

Question 15

What is achieved by the trimming the impeller of a centrifugal pump?

Answer 15

Decreases/reduce head - it will reduce the head and flow delivered by the pump

Question 16

How does a hydraulic jump occur?

Answer 16

occurs in an open channel flow when the supercritical flow taking place on a slope that cannot maintain supercritical flow.

Question 17

When can a surface wave produced by a disturbance travel upstream?

Answer 17

When the flow is subcritical

Question 18

Froude number is 12, what type of flow is occuring?

Answer 18

Supercritical flow

Question 19

Supercritical flow happens If the froude number is greater than what number ?

Answer 19

1

Question 20

For a prismatic channel, in the absence of backwater conditions, what three things are equal?

Answer 20

The slope of the energy grade line, water surface and channel bottom

Question 21

A uniform flow has these two characteristics

Answer 21

1. Average velocities in successive cross sections of the channel are the same
2. The friction slope and channel bottom slope of the water surface are the same with that of the channel

Question 22

If the net positive suction head available in the system is BELOW the net positive suction head required by the pump, what may occur?

Answer 22

Cavitation may occur in the pump, which is the pumped liquid flashing between liquid and gas. This causes violent implosions of the gas bubbles which will damage the pump.

Question 23

The head loss of a horizontal pipe of constant diameter is equal to?

Answer 23

the decrease in pressure/ pressure loss/ change in pressure