Consider a wind turbine with a 90 m blade span subjected to steady wind is used to generate electric power. The combined turbine generator efficiency of the wind turbine is 30 percent. If the horizontal force exerted by the wind on the supporting mast is 100 + 64  KN.  Determine (a) the wind velocity and (b) the power generated by the turbine. Take the density of air to be 1.25 kg/m3, and disregard frictional effects.

The blades of a wind turbine turn a large shaft at a relatively slow speed. The rotational speed is increased by a gearbox that has an efficiency of 0.93. In turn, the gearbox output shaft drives an electric generator with an efficiency of 0.95. The cylindrical nacelle, which houses the gearbox, generator, and associated equipment, is of length L = 6 m and diameter D = 3 m. If the turbine produces P = 2.5 MW of electrical power, and the air and surroundings temperatures are T = 25 oC and Tsur = 20 oC, respectively, determine the minimum possible operating temperature inside the nacelle. The emissivity of the nacelle is 0.83, and the convective heat transfer coefficient is h = 35 W/m2 .K. The surface of the nacelle that is adjacent to the blade hub can be considered to be adiabatic, and solar irradiation may be neglected.           Use Fin or N number of fins to reduce the Ts of the nacelle less than 143 oC

Large wind turbines with a power capacity of 8 MW and blade span diameters of over 160 m are available for electric power generation. Consider a wind turbine with a blade span diameter of 100 m installed at a site subjected to steady winds at 8 m/s. Taking the overall efficiency of the wind turbine to be 39 percent and the air density to be 1.25 kg/m³, determine the electric power generated by this wind turbine. Also, assuming steady winds of 8 m/s during a 24 hour period, determine the amount of electric energy and the revenue generated per day for a unit price of $0.09/kWh for electricity. The density of air is given to be p = 1.25 kg/m³. The electric power generated by the wind turbine is The amount of electric energy generated is The revenue generated per day is $ kWh. kW. K

A site is being considered for wind power generation. At this site, the wind blows steadily at 9 m/s for 2,579 hours per year. Assuming the wind velocity is negligible at other times for simplicity, determine the kWh/year that can be produced at the site for a turbine with a mechanical efficiency of 100% and an effective flow area of 5 m2. Use a value of 1.25 kg/m3 for the density of the air. Give your answer in killowatt-hours per year (kWh/year). Hint: I reccomend starting by finding the kinetic energy (kJ/kg) of the wind. Hint 2: Multiply the power generation (kW) by the number of hours of wind per year (h/year) to get kWh/year.

An airport escalator is designed to move 40 people, 75 kg each, upward at a constant speed of 0.6 m/s at 45o slope. Determine the minimum power input needed to drive this escalator. Neglect friction and drag. Please give your answer in kW.

Consider a river flowing toward a lake at an average velocity of 3 m/s at a rate of 500 m3 /s at a location 90 m above the lake surface. Determine the total mechanical energy of the river water per unit mass and the power generation potential of the entire river at that location.

An air compressor draws air from the atmosphere and discharges it at 500 kPa through a 100 mm-diameter outlet at 100 m/s. Determine the minimum power required to drive the insulated compressor. Assume atmospheric conditions of 25 C and 80 kPa.

Consider a fan located in a 1m x 1m square duct. Velocities at various points at the outlet are measured, and the average flow velocity is determined to be 7 m/s. Taking the air density to be 1.2 kg/m³, estimate the minimum electric power consumption of the fan motor.

Consider a turbojet powered airplane flying at a standard altitude of 8.5 km at a velocity of 108  m/s. The turbojet engine itself has inlet and exit areas of 2.8 m2 and 1.2 m2, respectively. The  velocity and pressure of the exhaust gas at the exit are 186 m/s and 75000 Pa, respectively.  Calculate the thrust of the turbojet.

A 2.0-kg rock is dropped from a height of 9.0 m. At what height is the rocks kinetic energy twice it's potential energy?