A PERFORMANCE OVERVIEW OF DRAG-TYPE WIND TURBINESFOR ROOF MOUNTING IN URBAN AREAS

摘要

The objective of this paper is to promote the idea of using wind energy in the urban areas and inrnparticular in high-rise buildings. On the roof of tall buildings wind speed is higher and the roofrnis appropriate for installation of a class of wind turbine that is safer and quieter than the propellerrnturbine. The generated energy can be used for boosting up the power to a building, as well as forrncontinuous lighting of special areas like the staircases and for emergency systems.rnPropeller turbines have been successfully used in wind farms in the past 20 years for powerrngeneration. They are the most efficient and the most appropriate type of turbine for productionrnpower plants. Drag-type turbines have lower efficiency and, as a result, have been left aside.rnAlthough drag-type wind turbines are less efficient than propeller turbines, they have severalrnadvantages. Since they operate at lower speed and have a good starting torque, they are able tornself start in low wind velocities and can withstand high speed winds where the propeller turbinernmust be stopped for safety reasons. Thus they can generate useful energy at a larger range ofrnwind speeds. Also they make less noise and their operation is safer, because of the lower speedrnand the form of their structure. These turbines are normally used with a vertical axis, thusrnhaving the advantage of insensitive to wind direction. Moreover, a recent study has shown thatrnvertical axis turbine have a better efficiency in skew winds (which is the case in the built areas).rnThe above advantages can compensate for the lower efficiency if we are concerned about issuesrnsuch as safety of operation, noise, structural stability, building vibration and the appearance. Allrnof these issues come into picture when considering wind turbines in the urban areas.rnThe paper summarizes the previous work on Savonius rotor and introduces a modified Savoniusrnturbine that can be used efficiently for its objective.