PHEP CH10 Hydraulic Turbines 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 give 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 or 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 100 cu. 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
