Question

For an offshore wind farm, a tower is built on the sea floor at a depth of 50m and it rises 30m above the still water level (SWL). Sustained wind in that location is 10 m/s. Ocean wave parameters are: T = 7s and H=3m. Consider the tower as cylindrical and its diameter = 0.75m. Consider wave effect and wind driven current for the submerged portion of the tower, and wind alone above SWL. a) Calculate the total force exerted on the tower below and above SWL using Morrison’s equation. Ignore inertia force. Take Cd = 1.0 for both air and water. Given ρa = 1.2 kg/m3 , ρw = 1025 kg/m3 , h = 10m, ua(h) = 15 m/s, n = 7, uw(0) = 0.45 m/s. Assume that wind, wave, and wind driven current are in the same direction. b) If the tower is supporting a turbine rotor of diameter 12m, what is the thrust due to wind. Use momentum theory and take axial induction factor, a = 1/3.

Answer 1