Briefly identify the advantages and disadvantages of wind power in urban environments. (4 marks)
b. Wind approaches a wind turbine at 17m/s and leaves at 8.5 m/s. If the turbine has a
blade diameter of 25m, determine the turbine power and the coefficient of
3 performance. Air density 1.2 kg/m .
(7 marks)
c. The wind approaching and passing through a turbine takes a tubular form. Explain why the wind tube expands on the downstream side of the turbine blades. If a turbine has a blade diameter of 20m and has approaching and leaving velocities of 15m/s and 8m/s, what will be the cross sectional area of the expanded downstream wind tube?
( 3 marks)
d. The tip speed of a horizontal axis turbine is 70m/s and the blade swept area has a circumference of 78.5m. Determine :
i. Blade diameter
ii. Rotational speed of turbine blades in rpm (revolutions/minute)
iii. Volume flow of air approaching the turbine if the tip speed ratio is 8
iv. The turbine power delivered if the interference factor is 1/3 and the overall
efficiency of the system is 0.4
(6 marks)