Closed Conduit Flashcards
(29 cards)
What is the continuity equation for incompressible flow?
Q = A × V, where Q is flow rate, A is cross-sectional area, and V is velocity.
What does Bernoulli’s equation represent?
The conservation of energy in a flowing fluid: P/γ + V²/2g + z = constant.
What is the hydraulic grade line (HGL)?
The level to which water would rise in a piezometer tube attached to a pipeline.
What is the energy grade line (EGL)?
It represents the total energy (pressure head + velocity head + elevation head) of the flow.
What is the momentum equation used for in hydraulics?
To analyze forces acting on control volumes due to changes in momentum.
When does Bernoulli’s equation apply?
Under steady, incompressible, inviscid flow with no energy added or lost.
How does elevation affect the energy grade line?
Increased elevation adds to the energy head.
What is the Hazen-Williams equation used for?
To estimate head loss due to friction in pressurized water pipes.
Write the Hazen-Williams equation for head loss.
h_f = 10.67 × L × Q^1.85 / (C^1.85 × D^4.87)
What is Darcy-Weisbach equation used for?
To calculate head loss due to friction in a pipe for any fluid.
What is the formula for Darcy-Weisbach head loss?
h_f = f × (L/D) × (V²/2g)
What are major losses in pipe flow?
Head losses due to friction along the length of the pipe.
What are minor losses in pipe flow?
Head losses due to fittings, bends, valves, and other pipe components.
How do you calculate total head loss in a pipe?
Total head loss = Major losses + Minor losses
What factors affect the friction factor in Darcy-Weisbach?
Reynolds number and relative roughness of the pipe.
What is the purpose of a wet well in a lift station?
To collect wastewater before it is pumped to a higher elevation.
Define pump head.
The height to which a pump can raise a fluid, considering friction losses.
What is cavitation in a pump?
The formation and collapse of vapor bubbles, which can damage the pump.
What causes cavitation?
When local pressure drops below the vapor pressure of the fluid.
How do you prevent cavitation in a pump?
By maintaining sufficient Net Positive Suction Head (NPSH).
What is NPSH available?
The absolute pressure at the pump suction minus the fluid’s vapor pressure.
What is the function of a lift station?
To raise wastewater to a higher elevation when gravity flow is not possible.
What is the key assumption in series pipe network analysis?
Flow rate is the same in all pipes; head losses add up.
What is the key assumption in parallel pipe analysis?
Head loss is equal across all branches; flow divides based on resistance.
