Thursday, April 3, 2014

HHM - Assignment 2



Unit 5: Hydraulic Turbines - I

1.     a) How are turbines classified? Explain
b) What is a draft tube? Why is it used in a reaction turbine? Explain with the help of sketches two different types of draft tubes

2.    A Pelton wheel is required to develop 12000 kW when working under a head of 300m. It rotates at a speed of 540 rpm. Assuming the jet ratio as 10 and overall efficiency as 84%, calculate the diameter of the wheel, the quantities of water required and the number of jets.

3.    A Kaplan turbine works under a head of 22m and runs at 150 rpm. The diameters of the runner and boss are 4.50m and 2.0m respectively. The flow ratio is 0.43. The inlet vane angle at the extreme edge of the runner is 200. If the turbine discharges radially at outlet, determine the discharge and hydraulic efficiency. And also draw the inlet and outlet velocity triangles.

4.    An inward flow reaction turbine has inner and outer diameter of the wheel as 350mm and 750mm respectively. The vanes radial at inlet and the discharge is radial of outlet. The water enters the vane at an angle of 150. Assuming the velocity of flow to be constant and equal to 3.5m/sec, Find the speed of the wheel and the vane angle at outlet.

Unit 6: Hydraulic Turbines - II

5.    A Francis turbine working under a head of 5 m at a speed of 210 rpm develops 75 KW when the rate of flow of water is 1.8 m3/ sec. If the head is increased to 16 m, determine the speed, discharge and power.

6.    A turbine is to operate under a head of 30m and a speed of 300 rpm. The discharge is 10 cumecs. If the efficiency of the turbine is 90%, determine the specific speed of the turbine, Power generated and Type of turbine

7.    A hydraulic turbine develops 120 KW under a head of 10 m at a speed of 1200 rpm and gives an efficiency of 92%. Find the water consumption and the specific speed. If a model of scale 1: 30 is constructed to operate under a head of 8m what must be its speed, power and water consumption to run under the conditions similar to prototype.

8.    a) What are the physical indicators for the presence of cavitations in turbines?
     b)  What do you understand by unit speed of a turbine? What is its use?

Unit 7: Centrifugal Pumps

9.    Centrifugal pump discharges 1200 lit/minute against a head of 16.5 m when the speed is 1500 rpm. The diameter of the impeller is 35 cm and the power required is 6 H.P. A geometrically similar pump of 45 cm is to run at 1750 rpm. Assuming equal efficiency, Find i) the head developed ii) the discharge and iii) power developed by the 45 cm pump.

10. How are pumps classified? Quote the approximate values of specific speed for different types.

11. The impeller of a centrifugal pump has 1.2 m outside diameter. It is used to lift 1.8 m3/s of water to a height of 6m. Its blades make an angle of 1500 with the direction of motion at outlet and runs at 200 rpm. If the radial velocity of flow at outlet is 2.5m/s, find the useful H.P and efficiency

12. A centrifugal pump 20 cm diameter running at 1450 rpm delivers 0.1 m3/s against a head of 40 m with an efficiency of 90%. Determine its specific speed.

Unit 8: Hydropower Engineering

13. Draw the typical layout of hydroelectric power plant and explain its components.

14. Where is the location of surge tank in hydro power installation? Explain with a neat sketch.

15. Write down the advantages and disadvantages of hydroelectric power plants.

16. Explain different measures to be taken for safe operation of hydroelectric power plants

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