52 Questions
What is the hydraulic efficiency of a turbine defined as?
The ratio of power delivered to the runner to the power supplied by water at the inlet
What is the main cause of power decrease from the inlet to the outlet of a turbine?
Hydraulic losses
What is the mechanical efficiency of a turbine defined as?
The ratio of power at the shaft to the power delivered to the runner
What is the volumetric efficiency of a turbine defined as?
The ratio of volume of water actually striking the runner to the volume of water supplied
What is the overall efficiency of a turbine defined as?
The ratio of power available at the shaft to the power supplied by water at the inlet
How are hydraulic turbines classified according to the type of energy available at the inlet?
Impulse and reaction turbines
What is the characteristic of a tangential flow turbine?
The water flows along the tangent of the runner
What is the purpose of the air-tight casing in a reaction turbine?
To keep the runner and casing completely full of water
What is the result of hydraulic losses in a turbine?
Decrease in power delivered to the runner
What is the factor that affects the classification of hydraulic turbines according to the specific speed?
Specific speed of the turbine
What is the width of the buckets of a Pelton wheel in relation to the diameter of the jet?
5 times
What is the direction of water flow at the outlet of a Francis turbine?
Radial
What is the purpose of the draft tube in a Kaplan turbine?
To permit a negative head to be established
What type of turbine is characterized by radial discharge at the outlet?
Francis turbine
What is the name of the Austrian engineer who designed the Kaplan turbine?
V. Kaplan
What is the term for the ratio of the width of the wheel to its diameter in a Francis turbine?
n
What is the direction of water flow in an axial flow reaction turbine?
Parallel to the axis of rotation
What is the purpose of the guide vanes mechanism in a Kaplan turbine?
To adjust the angle of the vanes
What is the term for the velocity of whirl at the outlet of a Francis turbine?
Vi
What is the name of the turbine that is suitable for a large quantity of water at low head?
Kaplan turbine
What happens to the speed of the turbine when the load on the generator decreases?
It increases
What is the effect of the increased centrifugal force on the fly-balls?
They move upward
What happens to the valve V when the sleeve moves upward?
It closes
What is the effect of the decrease in the area of flow of water at the outlet of the nozzle?
The rate of flow of water to the turbine decreases
What happens to the piston rod of the control valve when the sleeve moves downward?
It moves upward
What is the effect of the increase in the area of flow of water at the outlet of the nozzle?
The rate of flow of water to the turbine increases
What is the primary function of turbines?
Convert hydraulic energy into mechanical energy
Which term defines the head difference between the head race level and tail race level?
Gross Head
What is the electric power obtained from hydraulic energy known as?
Hydroelectric power
What is the efficiency of a turbine that accounts for losses such as friction, bends, and pipe fittings?
Overall Efficiency
Which term represents the head available at the inlet of the turbine?
Effective Head
How is the net head on a turbine calculated?
Net Head = Gross Head - Frictional Head Loss
What type of turbine is a Pelton wheel?
Tangential flow impulse turbine
In which direction does water flow in an inward radial flow turbine?
Radial direction from inwards to outwards
What regulates the amount of water striking the buckets of a Pelton wheel?
Nozzle and flow regulating arrangement
What part of the Pelton turbine prevents the splashing of water?
Casing
What directs the jet of water on the back of the vanes to stop the Pelton wheel in a short time?
Breaking jet
What divides the jet of water into two equal parts in a Pelton wheel?
Splitter
Which material are the buckets of a Pelton wheel typically made of?
Bronze
Where does the water strike the bucket in a Pelton wheel?
At the splitter
What is the primary energy form at the inlet of a Pelton wheel?
Kinetic energy
What is the purpose of the nozzle in a Pelton turbine?
Increase the kinetic energy of water
Why is a draft-tube used in turbines?
To convert kinetic energy into useful pressure energy
What happens to the pressure at the outlet of a reaction turbine without a draft-tube?
Equal to atmospheric pressure
What is the main purpose of governing a turbine?
To maintain constant turbine speed
Which type of draft-tube is considered most efficient?
Conical draft-tube
What drives the gear pump in an oil pressure governor for a Pelton turbine?
Power obtained from the turbine shaft
What purpose does the control valve serve in an oil pressure governor for a Pelton turbine?
Regulates the rate of flow through the turbine
Why is governing of a turbine essential when it is coupled to an electric generator?
To ensure the constant speed of the electric generator
What happens to the speed of the turbine if there is a decrease in load on the generator?
Turbine speed increases
Which type of draft-tube requires less space compared to other types?
Simple elbow tubes
What drives the centrifugal governor or pendulum in a Pelton turbine system?
Belt or gear from the turbine shaft
Learn about turbines, which are hydraulic machines that convert hydraulic energy into mechanical energy. This mechanical energy is then used to run an electric generator, producing electrical energy. Discover how hydroelectric power is generated and its cost efficiency.
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