Turbines PHEP Flashcards
Which of the following would not be used with a Pelton Wheel?
Wicket Gates
Pelton wheels:
May use two or more jets per wheel to obtain increased power
Power available at the nozzle varies:
Directly with the head and quantity of water
Water hammer:
Can damage a penstock if not kept within reasonable limits
The purpose of an auxiliary needle is to:
Provide a means for reducing flow to an impulse wheel rapidly while reducing the flow more slowly through the penstock
To deliver the same amount of power, a smaller diameter runner is required for a reaction turbine than for an impulse wheel because:
The entire circumference of the runner of the reaction turbine is being acted on by the water stream
Which of the following would not be found on a reaction turbine?
Stripper
For most reaction turbines, greatest efficiency is obtained when the wicket gates are:
80-90 percent open
A draft tube:
Increases the effective head of the turbine
Readings from a pressure gauge on the crown plate of a reaction turbine gives a good indication of the:
Seal ring effectiveness
A Kaplan turbine:
Propeller blades adjust automatically to maintain best efficiency for gate position and variations in head
Net head most nearly means:
Gross or static head less the frictional losses in feet
Which of the below factors would not generally contribute to cavitation damage?
Little to no variation in effective head
How much head would be required to develop 10,000 horsepower from a turbine operating at 80% efficiency from a stream with a flow of 100cu. Ft/sec?
1100 feet
What is the best speed of rotation in rpm for a Pelton wheel 54 inches in diameter, on which the net head is 625 feet?
360
