Exam 4 Flashcards
What is routing
A process used to predict the temporal and spatial of a flood hydrograph as it moves through a river, reservoir or basin
IMPORTANT
AS the hydrograph travels it Blank
2 items
Attenuate (peak flow rate is reduced)
Gets delayed (base time increase)
Types of flow routing (2)
- Lumped/Hydrologic - flow is calculated as a function of time alone at a location (Q=Q)
- Distributed/hydraulic-Flow is calculated as a function of time and space (Q=Q and momentum)
Level pool routing
Its a procedure for calculating outflow hydrograph from a reservoir with a horizontal water surface.
Its giving its inflow hydrograph I(t) and storage outflow relationship
Pipes in series
Q = Q
Hl total = Hl1+hl2…
Pipes in parallel
Q not = Q
Hl1=hl2=hl3…
What is static head
Difference in elevation
What is dynamic head
The sum of headloss = Hl minor + Hl friction
What pump is used for civil engineering applications and why
Centrifugal
cheap, reliable, simple
What is cavitation and what can it cause
Water vaporizes when the pressure is at or below vapor pressure, this creates pockets of air,
These pockets collapse and can cause a high increase in pressure, vibration, and sound
It will remove material in pump impellers or casings
Factor of safety for vapor pressure
negative pressure cannot be more than 2/3 atmospheric pressure
2 pump operations to consider
- System conditions -
physical conditions of pipe network
energy losses
cavitation potential - Pump capacity
impeller diameter/speed
capacity to deliver flow rates based as a function of resistance head
Static suction lift
The vertical distance from source (inlet) water level to the centerline of the pump
Static discharge lift
The vertical distance from centerline of pump to water at outlet
Total static head
Vertical distance from source water (inlet) to water level at outlet
= Static suction lift + Static discharge lift
Rated capacity
where the pump is operating at most efficient level
BEP
best efficiency point
min loads on impellor
min cavitation problems
Shutoff head
the amount of head where the pump cannot deliver flow
