Hydraulic 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 circumfrence 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 percent efficiency from a stream with a flow of 100 ct. 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
