25.2.3. Power Calculations

Try these first

1. 1.

   What does the hydraulic gradient line represent in an open channel?

   Hint

   Think about where the water level is in a channel.

2. 2.

   What role does a pump play in a fluid system?

   Hint

   Consider energy transfer in the context of fluid flow.

3. 3.

   What does the hydraulic gradient line represent in an open channel?

   • The pressure of the gas
   • The elevation of the fluid surface
   • The energy level of the fluid

   Hint

   Consider where the water sits in a channel.

4. 4.

   True or False: A pump extracts energy from the fluid.

   • True
   • False

   Hint

   Think about the function of a pump in fluid mechanics.

5. 5.

   A pipe with a diameter of 10 cm has water flowing through it at 2 m/s, and the outlet pressure is 150 kPa. Calculate the hydraulic gradient and the expected energy gradient line, considering frictional losses.

   Hint

   Use A = π*(d/2)^2 to find cross-sectional area and calculate expected energy.

6. 6.

   Design a system incorporating a pump and a turbine. The pump needs to lift water from a lower reservoir by 5 m against atmospheric pressure. Give the required input power considering efficiency ratings of both devices.

   Hint

   Use the power output formula, and apply efficiency ratings from standard sources.