Hydroelectric Power Generation
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Questions and Answers

What is the main function of a turbine?

  • Convert electrical energy into hydraulic energy
  • Convert hydraulic energy into electrical energy
  • Convert hydraulic energy into mechanical energy (correct)
  • Convert mechanical energy into hydraulic energy

    • What is the difference between Gross Head and Net Head in a turbine system?

  • Gross Head accounts for all losses; Net Head considers only friction losses.
  • Net Head is the total head; Gross Head is the available head at the turbine inlet.
  • Net Head is the head when no water is flowing; Gross Head is the available head at the turbine inlet.
  • Gross Head includes friction losses; Net Head is the effective head at the turbine inlet. (correct)

    • Which loss is primarily considered when calculating the Net Head on a turbine?

  • Loss at the entrance of the penstock
  • Head loss due to friction between water and penstocks (correct)
  • Loss due to bends in the penstocks
  • Loss due to pipe fittings

    • What is the formula to calculate the Net Head on a turbine?

    <p>$H = Hg - hf$</p> Signup and view all the answers

    Why is hydroelectric power considered one of the cheapest forms of power generation?

    <p>Because the generation of hydroelectric power has low operational costs</p> Signup and view all the answers

    Which term refers to the hydraulic machines converting hydraulic energy into electrical energy?

    <p>Turbines</p> Signup and view all the answers

    What type of turbine is characterized by the water flowing through the runner along the direction parallel to the axis of rotation?

    <p>Axial flow turbine</p> Signup and view all the answers

    Which part of a Pelton turbine controls the amount of water striking the buckets of the runner?

    <p>Spear in the nozzle</p> Signup and view all the answers

    What is the purpose of the casing in a Pelton turbine?

    <p>Prevent water splashing and discharge water to tail race</p> Signup and view all the answers

    Which type of flow impulse turbine is the Pelton wheel?

    <p>Tangential flow impulse turbine</p> Signup and view all the answers

    What does the breaking jet do in a Pelton turbine?

    <p>Stops the runner in a short time</p> Signup and view all the answers

    How are the buckets of a Pelton wheel shaped?

    <p>Double hemispherical cups</p> Signup and view all the answers

    What happens when the spear in the nozzle of a Pelton turbine is pushed forward?

    <p>Water striking the runner decreases</p> Signup and view all the answers

    Which type of turbine is characterized by water flowing from outwards to inwards, radially?

    <p>'Inward radial flow' turbine</p> Signup and view all the answers

    'Velocity Triangles and Work done for Pelton Wheel' section is associated with what location on the Pelton wheel?

    <p>'Outlet tip'</p> Signup and view all the answers

    'Breaking Jet' is provided in a Pelton turbine to primarily address which issue?

    <p>'Runner inertia' when stopping</p> Signup and view all the answers

    What is the formula for hydraulic efficiency of a turbine?

    <p>Power delivered to the runner / Power supplied at the inlet</p> Signup and view all the answers

    How is mechanical efficiency of a turbine mathematically expressed?

    <p>Power at the shaft / Power delivered to the runner</p> Signup and view all the answers

    What does volumetric efficiency of a turbine represent?

    <p>Volume of water actually striking the runner / Volume of water supplied to the turbine</p> Signup and view all the answers

    What is the formula for overall efficiency of a turbine?

    <p>Power available at the shaft / Power supplied at the inlet</p> Signup and view all the answers

    What classification criterion is used for hydraulic turbines based on energy at inlet?

    <p>Type of energy at inlet</p> Signup and view all the answers

    Which type of turbine has water under pressure and converts pressure energy into kinetic energy as it flows through?

    <p>Impulse turbine</p> Signup and view all the answers

    In a reaction turbine, what happens to pressure energy as water flows through?

    <p>Pressure energy decreases</p> Signup and view all the answers

    What distinguishes tangential flow turbines from other types of hydraulic turbines?

    <p>Flow direction along runner's tangent</p> Signup and view all the answers

    What occurs in a mixed flow turbine?

    <p>Water flows in multiple directions through vanes</p> Signup and view all the answers

    Which head category does a low head turbine belong to?

    <p>Low head turbine</p> Signup and view all the answers

    What happens to the turbine speed when the load on the generator decreases?

    <p>The turbine speed increases</p> Signup and view all the answers

    How does the control valve respond when the centrifugal governor rotates at an increased speed?

    <p>Valve V opens and valve V closes</p> Signup and view all the answers

    What effect does the movement of the fly-balls have on the sleeve?

    <p>The sleeve moves upward</p> Signup and view all the answers

    How does the control valve react when the sleeve moves upward?

    <p>Piston rod of the control valve moves downward</p> Signup and view all the answers

    Which direction does the piston move when oil under pressure is exerted on face A?

    <p>Towards right</p> Signup and view all the answers

    What is the result of increasing the area of flow of water at the outlet of the nozzle?

    <p>Increases turbine speed</p> Signup and view all the answers

    What is the purpose of the draft tube in a turbine?

    <p>Discharge water from the exit of the runner to the tail race</p> Signup and view all the answers

    In a Francis Turbine, what is the flow ratio defined as?

    <p>The ratio of flow velocity at inlet to the square root of 2gH</p> Signup and view all the answers

    What type of turbine is suitable for a large quantity of water at low head?

    <p>Kaplan Turbine</p> Signup and view all the answers

    What is the significance of the hub in an axial flow reaction turbine?

    <p>It acts as the runner for the turbine</p> Signup and view all the answers

    What characteristic distinguishes a Kaplan Turbine from a Propeller Turbine?

    <p>Adjustability of vanes on the hub</p> Signup and view all the answers

    What does the design of a Pelton Wheel involve determining?

    <p>Diameter of jet, wheel, bucket width, bucket depth</p> Signup and view all the answers

    What type of turbine has water entering and leaving in the axial direction?

    <p>Francis Turbine</p> Signup and view all the answers

    What is the name given to an inward flow reaction turbine with radial discharge at outlet?

    <p>Pelton Turbine</p> Signup and view all the answers

    What is one purpose served by establishing a negative head at the outlet of the runner using a draft tube?

    <p>To increase the net head on the turbine</p> Signup and view all the answers

    What parameter does the speed ratio represent for Francis Turbines?

    <p>Ratio of speed at inlet to speed at outlet</p> Signup and view all the answers

    What is the purpose of a draft-tube in a turbine?

    <p>Convert kinetic energy into pressure energy</p> Signup and view all the answers

    Why is governing of a turbine necessary?

    <p>To regulate the rate of flow through the turbine according to changing load conditions</p> Signup and view all the answers

    What happens to the pressure at the outlet of a runner if a reaction turbine is not fitted with a draft-tube?

    <p>It becomes equal to atmospheric pressure</p> Signup and view all the answers

    What is the primary role of a governor in governing a turbine?

    <p>To adjust the rate of water flow through the turbine</p> Signup and view all the answers

    Which type of draft-tube requires less space compared to others?

    <p>Simple elbow tubes</p> Signup and view all the answers

    What drives the gear pump in an oil pressure governor for Pelton turbines?

    <p>Power obtained from turbine shaft</p> Signup and view all the answers

    What does a spear rod or needle do in an oil pressure governor for Pelton turbines?

    <p>Regulate the flow of oil within the system</p> Signup and view all the answers

    How does a draft-tube impact the net head on a turbine?

    <p>Increases it by converting kinetic energy into pressure energy</p> Signup and view all the answers

    What term is used to describe keeping the speed of a turbine constant under all conditions of working?

    <p>Governing</p> Signup and view all the answers

    Why is it important for an electric generator to run at a constant speed under all fluctuating load conditions?

    <p>To ensure consistent power output frequency</p> Signup and view all the answers

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