BCE Hydraulics & Fluid Mechanics 2 ā Questions and Answers
Question 1: What is the condition for critical flow in an open channel?
- Fr = 0
- Fr = 1 (Correct answer)
- Fr > 1
- Re = 2300
Correct answer: Fr = 1
Critical flow occurs when the Froude number equals 1, at which point specific energy is at its minimum for a given discharge.
Question 2: In a pipe network, the Hardy-Cross method is used to solve for which unknown?
- Pipe diameters
- Flow distribution and head losses (Correct answer)
- Pump head required
- Water quality parameters
Correct answer: Flow distribution and head losses
The Hardy-Cross method is an iterative technique for finding the distribution of flows and head losses that satisfy continuity and energy equations in a pipe network.
Question 3: Which pump type is most commonly used for water supply in civil engineering applications?
- Reciprocating pump
- Centrifugal pump (Correct answer)
- Gear pump
- Axial flow pump
Correct answer: Centrifugal pump
Centrifugal pumps are the most widely used in water supply systems due to their simplicity, reliability, and ability to handle large volumes.
Question 4: What phenomenon occurs when pressure in a flowing liquid drops below its vapor pressure?
- Water hammer
- Cavitation (Correct answer)
- Surge
- Turbulence
Correct answer: Cavitation
Cavitation occurs when local pressure falls below the vapor pressure of the liquid, causing formation and collapse of vapor bubbles that can damage pump impellers.
Question 5: The Darcy-Weisbach equation calculates which quantity in pipe flow?
- Flow velocity
- Head loss due to friction (Correct answer)
- Pump power
- Discharge coefficient
Correct answer: Head loss due to friction
The Darcy-Weisbach equation (hf = fĀ·L/DĀ·VĀ²/2g) calculates the head loss due to friction along a length of pipe.
Question 6: Which spillway type is designed to automatically maintain a fixed reservoir level by allowing overflow?
- Ogee spillway (Correct answer)
- Side channel spillway
- Shaft (glory hole) spillway
- Free overfall spillway
Correct answer: Ogee spillway
An ogee spillway is an overflow weir with an S-shaped profile that follows the natural trajectory of flow and automatically passes excess water when the reservoir reaches design level.
BCE Hydraulics & Fluid Mechanics 2
What is the condition for critical flow in an open channel?