T3.2

• Northeast Monsoon (Amihan) originates from northern Asiatic land mass and reaches Philippines in late October to April
• Southwest Monsoon (Habagat) originates from Indian ocean starting mid-June to September
• Monsoon is from the Arabic word "Mawsim" which means "season"
• The kinetic energy of the wind in a unit time increases with the cube of the wind speed
• Doubling the wind speed increases the power output by eight times
• Doubling the rotor diameter will increase the available power by four times
• Wind machines can only extract about 59% of the wind kinetic energy (Betz coefficient)
• Actual performance of the wind machine varies from 10 to 50% depending on the rotor
• Slow running multi-bladed rotor has lower efficiency compared to fast running two or three-bladed rotor
• Multi-bladed rotor are slow speed high torque wind machines and are suitable for mechanical water pumping and grain milling
• Few bladed rotor are fast running and produce low torque and are suitable for power generation and running electric motors
• Wind energy applications include pumping water, power generation, compressed air generation, and driving mechanical machines
• Global wind circulation is driven by solar radiation and the rotation of the Earth and the atmosphere
• Seasonal variations in wind are due to the tilt of the Earth's axis relative to the plane of the Earth's movement around the Sun
• Wind is best described as "a fickle servant" and its characteristics are important in determining the economic feasibility of a wind turbine at a given site
• The theoretical power in a wind stream is determined by P = 0.5 * 𝛒 * A * V^3
• The maximum power coefficient is 0.59, as determined by the Betz limit, and a good efficient rotor would average 0.30
• The power coefficient Cp depends on the specific design of the wind turbine, especially the particular aerodynamic structure of the blades
• Tip-speed ratio (λ) varies based on the number of blades in a wind turbine
• Performance Coefficient (Cp) for different types of wind turbines: Horizontal Axis - Two-bladed 0.47, Farm 0.30, Modern Propeller 0.47, Dutch Four Arm type 0.17; Vertical Axis - Darrieus 0.35, Savonius 0.23
• Air Foil is the surface of the blade over which air flows, and the lower the ratio of drag to lift, the better the airfoil
• Solidity is the ratio of the projected area to the swept area of the rotor
• Overall system efficiency is the ratio of the power output of the machine to the power input
• Power Output is the power delivered by lifting water or generated by the generator
• Cut-In Wind Speed is the speed required to start the rotor, Cut-Out wind speed is the speed required to stop the rotor, and Rated speed is the speed recommended by the manufacturer to optimally operate the wind machine
• Rayleigh wind-speed distribution provides a simple approximation of wind-speed characteristics and predicts wind characteristics with less than a 10% error
• Prevailing wind direction varies by season and location, and wind-direction determinations are important for selecting a wind turbine site
• Accurate wind-speed measurements are needed for wind-turbine siting and predicting energy capture, commonly done using an anemometer
• The most popular type of anemometer is the cup type, consisting of small cups mounted on a rotating shaft
• Anemometers used to measure wind-speeds near evaporation pans have usually been at a height of 0.5 m and have been of the wind totalizing type
• Wind measurements for predicting evapotranspiration have usually been taken at 2 m, with few measurements made above 3m
• Standard anemometer heights for nuclear and coal-fired electrical generating plants are 10 and 40 m, respectively
• Before using reported wind-speed data for predicting energy capture, a determination of how the data were collected is needed along with the height of the anemometer
• Wind shear is the extent to which wind speed is decreased near the Earth’s surface due to roughness caused by trees, buildings, and crops
• Meteorologists have suggested several equations for adjusting wind speed measured at one height to represent wind speed at another height
• The most important decision concerning the use of a wind–energy conversion system is the selection of the site
• Determining the effect of surface terrain in hilly or complex terrain requires much work and analysis
• When evaluating a potential wind turbine site, it is useful to observe the vegetation for deformities caused by high average winds
• Buildings and trees hinder wind flow and create turbulence, affecting the power that can be produced by a wind generator
• A machine should be located away from a building by a distance of 2H upwind and 10H downwind to avoid disturbed wind flow around an obstruction