18 Questions
What is the primary consideration for selecting material for runners and buckets?
Fatigue hazards and erosion due to slit content
What type of alloy steel is used for small units?
High quality alloy steel
What is the composition of stainless steel used for very high head and large size plants?
13% Cr and 4% Ni
Why is the runner, nozzle, and associated components installed above the maximum water level of the tailrace?
To prevent the turbine from being affected by floods
What is the primary material used for manufacturing the bucket?
All of the above
What is the purpose of the dividing wall in the bucket?
To divide the impinging jet into two equal streams
What is the primary purpose of the deflector in the nozzle-spear system?
To deflect the path of the jet emerging from the nozzle
Why is the nozzle-spear system made of stainless steel (13% Cr, 4% Ni alloy)?
For its corrosion-resistant properties
What is the advantage of the monocast system in the runner fabrication?
It is particularly advantageous in high capacity power units
What is the purpose of finishing the nozzle-spear system to a very smooth surface?
To reduce the frictional losses
What is the consequence of rapid closure in the high velocity nozzle?
Water hammer problems in the penstock
What is the shape of the buckets in the runner assembly?
Ellipsoidal
What material are the guide blades usually made of?
Cast steel
What material are the runner blades typically made of?
Stainless steel
Which of the following materials is not commonly used for runner blades?
Copper
What material is used for the crown or hub of the runner?
Cast steel
What type of construction is used to join the blades, crown, and shroud ring of the runner?
Welded
Why is the surface of the vanes made very smooth?
To minimize shock
Learn about the selection of materials for runners and buckets in hydroelectric turbines, considering factors such as strength, fatigue, erosion, and cavitation. Discover the materials used for small and large units, including high-quality alloy steel and stainless steel.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
