Hydraulics and Turbines
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Questions and Answers

What is the hydraulic efficiency of a turbine defined as?

  • The ratio of power available at the shaft to the power delivered to the runner
  • The ratio of power supplied by water to the power available at the shaft
  • The ratio of power delivered to the runner to the power supplied by water at the inlet (correct)
  • The ratio of power supplied by water to the power delivered to the runner

    • What is the main cause of power decrease from the inlet to the outlet of a turbine?

  • Hydraulic losses (correct)
  • Electrical losses
  • Volumetric losses
  • Mechanical losses

    • What is the mechanical efficiency of a turbine defined as?

  • The ratio of power delivered to the runner to the power supplied by water at the inlet
  • The ratio of power supplied by water to the power available at the shaft
  • The ratio of power at the shaft to the power delivered to the runner (correct)
  • The ratio of power available at the shaft to the power supplied by water at the inlet

    • What is the volumetric efficiency of a turbine defined as?

    <p>The ratio of volume of water actually striking the runner to the volume of water supplied</p> Signup and view all the answers

    What is the overall efficiency of a turbine defined as?

    <p>The ratio of power available at the shaft to the power supplied by water at the inlet</p> Signup and view all the answers

    How are hydraulic turbines classified according to the type of energy available at the inlet?

    <p>Impulse and reaction turbines</p> Signup and view all the answers

    What is the characteristic of a tangential flow turbine?

    <p>The water flows along the tangent of the runner</p> Signup and view all the answers

    What is the purpose of the air-tight casing in a reaction turbine?

    <p>To keep the runner and casing completely full of water</p> Signup and view all the answers

    What is the result of hydraulic losses in a turbine?

    <p>Decrease in power delivered to the runner</p> Signup and view all the answers

    What is the factor that affects the classification of hydraulic turbines according to the specific speed?

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

    What is the width of the buckets of a Pelton wheel in relation to the diameter of the jet?

    <p>5 times</p> Signup and view all the answers

    What is the direction of water flow at the outlet of a Francis turbine?

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

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

    <p>To permit a negative head to be established</p> Signup and view all the answers

    What type of turbine is characterized by radial discharge at the outlet?

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

    What is the name of the Austrian engineer who designed the Kaplan turbine?

    <p>V. Kaplan</p> Signup and view all the answers

    What is the term for the ratio of the width of the wheel to its diameter in a Francis turbine?

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

    What is the direction of water flow in an axial flow reaction turbine?

    <p>Parallel to the axis of rotation</p> Signup and view all the answers

    What is the purpose of the guide vanes mechanism in a Kaplan turbine?

    <p>To adjust the angle of the vanes</p> Signup and view all the answers

    What is the term for the velocity of whirl at the outlet of a Francis turbine?

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

    What is the name of the turbine that is suitable for a large quantity of water at low head?

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

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

    <p>It increases</p> Signup and view all the answers

    What is the effect of the increased centrifugal force on the fly-balls?

    <p>They move upward</p> Signup and view all the answers

    What happens to the valve V when the sleeve moves upward?

    <p>It closes</p> Signup and view all the answers

    What is the effect of the decrease in the area of flow of water at the outlet of the nozzle?

    <p>The rate of flow of water to the turbine decreases</p> Signup and view all the answers

    What happens to the piston rod of the control valve when the sleeve moves downward?

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

    What is the effect of the increase in the area of flow of water at the outlet of the nozzle?

    <p>The rate of flow of water to the turbine increases</p> Signup and view all the answers

    What is the primary function of turbines?

    <p>Convert hydraulic energy into mechanical energy</p> Signup and view all the answers

    Which term defines the head difference between the head race level and tail race level?

    <p>Gross Head</p> Signup and view all the answers

    What is the electric power obtained from hydraulic energy known as?

    <p>Hydroelectric power</p> Signup and view all the answers

    What is the efficiency of a turbine that accounts for losses such as friction, bends, and pipe fittings?

    <p>Overall Efficiency</p> Signup and view all the answers

    Which term represents the head available at the inlet of the turbine?

    <p>Effective Head</p> Signup and view all the answers

    How is the net head on a turbine calculated?

    <p>Net Head = Gross Head - Frictional Head Loss</p> Signup and view all the answers

    What type of turbine is a Pelton wheel?

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

    In which direction does water flow in an inward radial flow turbine?

    <p>Radial direction from inwards to outwards</p> Signup and view all the answers

    What regulates the amount of water striking the buckets of a Pelton wheel?

    <p>Nozzle and flow regulating arrangement</p> Signup and view all the answers

    What part of the Pelton turbine prevents the splashing of water?

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

    What directs the jet of water on the back of the vanes to stop the Pelton wheel in a short time?

    <p>Breaking jet</p> Signup and view all the answers

    What divides the jet of water into two equal parts in a Pelton wheel?

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

    Which material are the buckets of a Pelton wheel typically made of?

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

    Where does the water strike the bucket in a Pelton wheel?

    <p>At the splitter</p> Signup and view all the answers

    What is the primary energy form at the inlet of a Pelton wheel?

    <p>Kinetic energy</p> Signup and view all the answers

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

    <p>Increase the kinetic energy of water</p> Signup and view all the answers

    Why is a draft-tube used in turbines?

    <p>To convert kinetic energy into useful pressure energy</p> Signup and view all the answers

    What happens to the pressure at the outlet of a reaction turbine without a draft-tube?

    <p>Equal to atmospheric pressure</p> Signup and view all the answers

    What is the main purpose of governing a turbine?

    <p>To maintain constant turbine speed</p> Signup and view all the answers

    Which type of draft-tube is considered most efficient?

    <p>Conical draft-tube</p> Signup and view all the answers

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

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

    What purpose does the control valve serve in an oil pressure governor for a Pelton turbine?

    <p>Regulates the rate of flow through the turbine</p> Signup and view all the answers

    Why is governing of a turbine essential when it is coupled to an electric generator?

    <p>To ensure the constant speed of the electric generator</p> Signup and view all the answers

    What happens to the speed of the turbine if there is a decrease in load on the generator?

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

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

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

    What drives the centrifugal governor or pendulum in a Pelton turbine system?

    <p>Belt or gear from the turbine shaft</p> Signup and view all the answers

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