1. Increasing the diameter of turbine blade 3 times, power of turbine will A) In
ID: 290149 • Letter: 1
Question
1. Increasing the diameter of turbine blade 3 times, power of turbine will A) Increase 2 times B) decrease 4 times C) increase 8 times D) Increase 9 times Ans: 2. Maxi imum possible efficiency of a wind turbine is A) 39% B) 49% C) 59% D) 90% Ans: 3. A taller wind turbine gives higher power because at higher altitude A) Density of air is higher B) air velocity of higher C) air pressure is higher D) air temperature is higher Ans: 4. Wind energy reduces global warming (True /False) Ans: 5. The ratio of the actual area of the blades to the circular area they sweep out is called A) Solidarity B) Solid C) Solidity D) Saltity Ans: 6. HAWT is more common than VAWT (T/F) Ans: 7. In a wind turbine with pitch control if the wind velocity goes beyond rated speed, the power will A) Increases B) decreases C) remains constant at rated power D) shut down Ans: 8. "Tip-speed ratio is A) Blade tip speed/wind speed B) wind speed/blade speed C) wind speed/sound speed D) blade speed/wind speed Ans: 9. Power from a wind turbine is proportional to A) density of air B) (Velocity of wind) 2 C circular area swept by blades D) Height of the turbine Answer(s): 10. For a given wind turbine if wind speed doubles, its power will A) Increase 2 times B) increase 4 times C) increase 8 times D) decrease 8 times Ans 11. Calculate the power produced from a wind turbine having blade diameter 150 meters. Assume Cp-0.5 and wind speed 12 m/sec. Assume air density as 1.1 kg/m (10) 12. Calculate the required blade diameter of a 5 MW turbine. Assume air density 1.2 kg/m, Cp-0.4 and wind speed 1 1 msec. (10) Ans:Explanation / Answer
1. d) increase 9 times
power is proportional to square of blade diameter
so increase in 3 times blade diameter will give 32 times increase in the power ,i.e. 9 times
2. c) 59%
Albert Betz concluded that betz limit,i.e. maximum efficiency of turbine to convert kinetic energy is not more than 59.3%.
3. b) air velocity is higher
at more height the wind blows at steady rate and increases the turbine capacity factor.
4. True
Wind energy creates low pressure upon non renewables for energy demand which reduces emmision of harmful gases.Even in the countries like USA the wind power is on rise.It provide clean and fossil fuel free energy.
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