Individual Submissions

Read carefully the Reference section and the Competition Rules for the Wind Turbine Project and answer the following.

1. The 20-inch box fan used in Project 1 consumes about 85 watts of electricity (on high setting) and delivers a useful stream of air moving with the maximum velocity of about 15 feet per second. Estimate the mechanical power of wind (or the kinetic power of the moving air) from equation P_wind = 1/2ρAV³_wind (in watts). Assume that the fan generates a 'tube' of wind 20 inches in diameter and with uniform wind speed of 15 ft/s. What is the efficiency of the power conversion in the fan (in percent)? Convert all non-SI units to SI units.

2. In real wind turbines mechanical power of wind P_wind is first converted to shaft power of the turbine rotor P_rotor, then the a gear box converts it to shaft power of an electric generator P_generator finally the generator converts it into electric power P_electric. If the efficiency of the three power conversion steps are η_blades = 30%, η_gearbox = 88% and η_generator = 95%, respectively, what is the overall power conversion efficiency of the whole wind turbine? Draw a block schematic showing the flow of power into and out of each power conversion stage.