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  • 1985-1989  (4)
  • 1
    Publication Date: 2011-08-19
    Description: Field tests on a horizontal axis wind turbine (HAWT) have shown that Vortex Generators (VGs) can increase the efficiency of large propeller type (horizontal axis) wind turbines. VGs are devices which are attached to the surfaces of an aerodynamic body to influence the boundary layer behavior. It is pointed out that VGs were originally developed for delaying stall on aircraft wings. An investigation was conducted regarding the possibility to employ VGs also for the improvement of the performance of an intermediate size HAWT with a diameter in the range from 24 to 46 meters. This investigation included wind tunnel tests involving a rotor blade tip section, and field tests. The wind tunnel tests showed that VGs can improve the peak lift capabilities of the section while only slightly increasing the drag. The field tests showed that VGs can increase the rotor power in winds above 6 m/s.
    Keywords: AERODYNAMICS
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  • 2
    Publication Date: 2019-06-28
    Description: Projected NASA, Civil, Commercial, and Military missions will require space power systems of increased versatility and power levels. The Advanced Solar Dynamic (ASD) Power systems offer the potential for efficient, lightweight, survivable, relatively compact, long-lived space power systems applicable to a wide range of power levels (3 to 300 kWe), and a wide variety of orbits. The successful development of these systems could satisfy the power needs for a wide variety of these projected missions. Thus, the NASA Lewis Research Center has embarked upon an aggressive ASD reserach project under the direction of NASA's Office of Aeronautics and Space Technology (DAST). The project is being implemented through a combination of in-house and contracted efforts. Key elements of this project are missions analysis to determine the power systems requirements, systems analysis to identify the most attractive ASD power systems to meet these requirements, and to guide the technology development efforts, and technology development of key components.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-TM-88884 , E-3292 , NAS 1.15:88884
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  • 3
    Publication Date: 2019-06-28
    Description: Tests were conducted in the NASA Langley 30 by 60 foot Wind Tunnel on a full scale 7.31 m (24 ft) long tip section of a wind turbine rotor blade. The blade tip section was built with ailerons on the trailing edge. The ailerons, which spanned a length of 6.1 m (20 ft), were designed so that two types could be evaluated: the plain and the balanced. The ailerons were hinged on the suction surface at the 0.62 X chord station behind the leading edge. The purpose of the tests was to measure the aerodynamic characteristics of the blade section for: an angle of attack range from 0 deg to 90 deg aileron deflections from 0 deg to -90 deg, and Reynolds numbers of 0.79 and 1.5 x 10 to the 6th power. These data were then used to determine which aileron configuration had the most desirable rotor control and aerodynamic braking characteristics. Tests were also run to determine the effects of vortex generators, leading edge roughness, and the gaps between the aileron sections on the lift, drag, and chordwise force coefficients of the blade tip section.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA-TM-87018 , E-2564 , DOE/NASA/20320-65 , NAS 1.15:87018
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  • 4
    Publication Date: 2019-07-13
    Description: Towers for large horizontal axis wind turbines, machines with a rotor axis height above 30 meters and rated at more than 500 kW, have varied in configuration, materials of construction, type of construction, height, and stiffness. For example, the U.S. large HAWTs have utilized steel truss type towers and free-standing steel cylindrical towers. In Europe, the trend has been to use only free-standing and guyed cylindrical towers, but both steel and reinforced concrete have been used as materials of construction. These variations in materials of construction and type of construction reflect different engineering approaches to the design of cost effective towers for large HAWTs. Tower designs are the NASA/DOE Mod-5B presently being fabricated. Design goals and requirements that influence tower configuration, height and materials are discussed. In particular, experiences with United States large wind turbine towers are elucidated. Finally, current trends in tower designs for large HAWTs are highlighted.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: NASA-TM-87166 , E-2803 , DOE/NASA/20320-68 , NAS 1.15:87166 , Energy-Source Technology Conference and Exhibition; Feb 23, 1986 - Feb 27, 1986; New Orleans, LA; United States
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