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Hydraulic Machines Practice Test: Francis Turbine
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Francis Turbine topics include: Francis turbine velocity diagrams, francis turbine work and efficiency. A Francis turbine is a type of reaction turbine invented by James B. Francis around 1855. It is the most common type of turbine used today. Francis turbines are used in about 60% of the world's hydropower capacity.  Here's how a Francis turbine works: Water enters the turbine in a radial direction, flowing towards its axis. The water is deflected 90 degrees in the runner, which sets the runner and the generator in a rotary motion. The energy released in this way can achieve an... Show more
Hydraulic Machines Practice Test: Francis Turbine
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25 Questions

1. Francis turbine is typically used for which of the following values of available heads?
2. The volumetric efficiency of a given turbine is 80%. If volume flow rate of water in given to be 30 m3/s, find the volume of water (m3) NOT flowing over the runner blades per second?
3. In the velocity diagrams for Francis turbine, which of the following velocity directions is along the blade curvature?
4. What is the water flow direction in the runner in a Francis turbine?
5. Power developed by Francis turbine are calculated for a certain set of conditions. Now, the inlet whirl velocity is doubled, the blade velocity at inlet is doubled and the flow velocity is quartered. The power developed:
6. Which of the following efficiencies for Francis Turbine is described as the ratio between the power produced by runner to the power supplied by water at the inlet?
7. The desired hydraulic efficiency of a turbine is 80% at a whirl velocity of 20 m/s and a head of 100 m. What should be the blade velocity of the turbine at inlet in m/s?
8. The available head of a Francis Turbine is 120 m. The blade velocity is given 35 m/s. Find the speed ratio of the turbine.
9. The whirl velocity at inlet of Francis turbine is given to be 20 m/s. The blade velocity is given as 35 m/s. What is the hydraulic efficiency for a head of 100 m?
10. Which of the following efficiencies for Francis Turbine is defined as the ratio between the power available at the shaft of the turbine to the power produced by the runner?
11. Which of the following efficiencies for Francis Turbine is described as the ratio between total quantity of water over runner blades to total quantity of water supplied to turbine?
12. Which of the following terms is considered to be zero while deriving the equation for work done per second for Francis Turbine?
13. Which of the following runner types will have the highest vane angle at inlet (β1 value)?
14. The typical value range of speed ratio for a Francis turbine is:
15. A student performs an experiment with a Francis turbine. He accidently set the RPM of Francis turbine to 1400 rpm instead of 700 rpm. He reported the power to be 1 MW. His teacher asks him to perform the same experiment using the correct RPM. The student performs the same experiment again, but this time the erroneously doubled the flow velocity. What does the student report the power to be?
16. The volume flow rate into a Francis turbine is Q m3/s. 0.25Q m3/s volume of water do not flow over the runner blades. What is the mechanical efficiency of the turbine (in %)?
17. Which of the following profiles are used for guide vanes to ensure smooth flow without separation?
18. Which of the following is true in case of flow of water before it enters the runner of a Francis Turbine?
19. How does the flow ratio (ψ) of a Francis turbine vary with available head (H)?
20. Why does the cross sectional area of the Spiral casing gradually decrease along the circumference of the Francis turbine from the entrance to the tip?
21. In case of a Medium runner, tan (α1) CANNOT be given by (α1 = Guide vane angle at inlet)?
22. The volumetric efficiency of a Francis turbine is given to be 90%. If the volume flow rate through the turbine is 25 m3/s. What is the flow rate of water over the runner blades (in m3/s)?
23. The flow rate of the water flow in a Francis turbine is increased by 50% keeping all the other parameters same. The work done by the turbine changes by?
24. The power output of the shaft is 5 MW. The volume flow rate of water in 10 m3/s at an available head of 60 m. Find the overall efficiency of the turbine in % (g = 10 m/s2)?
25. The available head of a Francis Turbine is 100 m. Velocity of the flow at the runner inlet is 15 m/s. Find the flow ratio.