48 Questions
What is the main function of turbines?
Convert hydraulic energy into mechanical energy
What is the term used to describe the electric power obtained from the hydraulic energy?
Hydroelectric power
What is the Gross Head of a turbine?
The head race level minus tail race level when no water is flowing
Which term is used interchangeably with 'effective head' for a turbine?
Net head
What are losses caused by bend, pipe fittings, and entrance of penstock collectively known as?
Frictional losses
In the equation H = Hg - hf, what does 'hf' represent?
Friction head loss between penstocks and water
What is the main difference between an inward radial flow turbine and an outward radial flow turbine?
Direction of water flow
Which type of turbine is a Pelton wheel?
Tangential flow impulse turbine
What is the function of the casing in a Pelton turbine?
Prevent splashing of water
Why is a breaking jet used in a Pelton turbine?
To stop the runner quickly
What is controlled by a spear in the nozzle of a Pelton turbine?
Amount of water striking the runner
How are the buckets of a Pelton wheel shaped to deflect the water jet?
$160^{ ext{o}}$
What part of a Pelton wheel divides the jet into two equal parts before it strikes the buckets?
$90^{ ext{o}}$ splitter
What describes a tangential flow impulse turbine like a Pelton wheel?
$180^{ ext{o}}$ water flow
Which material is NOT typically used for making the buckets of a Pelton wheel?
$180^{ ext{o}}$ splitter
What is the mathematical expression for hydraulic efficiency?
Power at shaft/Power supplied at inlet
Which type of turbine is identified by having only kinetic energy at the inlet?
Impulse turbine
What does volumetric efficiency measure?
Volume of water striking the runner
In a reaction turbine, what happens to the pressure energy as water flows through the runner?
Changes into kinetic energy
Which type of turbine is enclosed in an air-tight casing?
Tangential flow turbine
What is the definition of mechanical efficiency?
Power at shaft of the turbine/Power delivered by water to the runner
'Specific speed' is a classification criterion based on what aspect of hydraulic turbines?
Energy available at inlet
What is the primary reason for a decrease in power as water flows over the vanes of a turbine?
Hydraulic losses
'Overall Efficiency' is defined as the ratio of what variables?
'Power available at shaft' to 'Power supplied at inlet'
'Volumetric Efficiency' measures the ratio of what volumes?
'Water striking the runner' to 'Water supplied to turbine'
What is the purpose of the draft-tube in a turbine system?
To create a negative head at the outlet of the runner
In the design of a Pelton wheel, what is determined as 5 times the diameter of the jet?
Width of the buckets
Who is the modern Francis Turbine named after?
J.B. Francis
What type of turbine is a Francis Turbine?
Mixed flow type turbine
What is the speed ratio for a Francis Turbine?
$u1 / \sqrt{2gH}$
In an inward flow reaction turbine, where does the water enter and leave?
Enters radially, leaves axially
'Hub' or 'boss' in an axial flow reaction turbine serves as what?
Blade attachment point
'Flow ratio' for a Francis Turbine is expressed as?
$Vf1/ \sqrt{2gH}$
What happens to the speed of the turbine when the load on the generator decreases?
The speed of the turbine increases.
How does the centrifugal governor respond when the speed of the generator increases?
It rotates at an increased speed.
What is the role of the fly-balls in the centrifugal governor system?
To respond to changes in centrifugal force.
When the sleeve moves upward, what happens to the piston rod of the control valve?
It moves downward.
What effect does closing valve V have on the rate of flow of water to the turbine?
Decreases it.
How does increasing the area of flow of water at the outlet of the nozzle affect the speed of the turbine?
Increases it.
What is the purpose of a draft-tube in a turbine?
Convert kinetic energy into useful pressure energy
What is the main function of governing in a turbine system?
Regulate the flow rate through the turbines
Which type of draft-tube is known to be most efficient?
Conical draft-tubes
What happens if a reaction turbine is not fitted with a draft-tube?
Water freely discharges into the tail race
Why is it important to keep the speed of a turbine constant?
To ensure constant power generation by the generator
How does governing help in maintaining constant speed of a turbine?
By regulating flow through the turbines based on load conditions
What drives the gear pump in an oil pressure governor for a Pelton turbine?
The power obtained from the turbine shaft
Which element is responsible for driving the centrifugal governor in governing a Pelton turbine?
Centrifugal governor or pendulum
What part of an oil pressure governor receives power from the turbine shaft?
The gear pump also called oil pump, which is driven by the power obtained from turbine shaft
Explore the concept of turbines, which are hydraulic machines that convert hydraulic energy into mechanical energy. Learn how this mechanical energy is transformed into electrical energy for hydroelectric power generation.
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