Aerodynamics of a Tilting Ducted Fan Configuration PDF Download
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Author: Paul F. Yaggy
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 20
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Author: Paul F. Yaggy
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 20
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Book Description
Author: Paul F. Yaggy
Publisher:
ISBN:
Category :
Languages : en
Pages : 15
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Author: Demo J. Giullianetti
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 34
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Author: Kenneth W. Goodson
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 52
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"An investigation of the aerodynamic characteristics of a powered semispan tilting-shrouded-propeller configuration has been conducted in the 17-foot test section of the Langley 300-MPH 7- by 10-foot tunnel. The wing had an aspect ratio of 2.67 (based on wing span of 60 inches), a taper ratio of 0.67, and an NACA 2418 airfoil section with a 15-inch-diameter shrouded propeller mounted on the tip. The test results show that large nose-up pitching moments are obtained at transitional speeds of about 40 knots and duct angle of about 70°. Decelerating flight procedures further increases in the nose-up moment. Ground proximity reduces the nose-up pitching moments. The large nose-up moments can be trimmed by use of duct-exit control vanes. The results show that unloading the duct (shroud) by flying at a wing angle of attack of 15° reduces the power required by about 30 percent at 50 knots. Duct-lip stall produces large increases in power required. The results in general show that full-scale aerodynamic simulation can be made with small-scale wind-tunnel models if duct-lip separation at low Reynolds numbers is avoided."--Summary.
Author: Kenneth W. Mort
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 38
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Power, free-stream velocity, and duct angle of attack were varied at several wing angles of attack to define the aerodynamic characteristics of the ducted fan, wing, and of the ducted fan wing together. At large duct angles of attack, the inside of the upstream duct lip stalled causing a rapid change in the duct pitching moments and an accompanying increase in the power required. At low horizontal velocities, this lip stall would probably limit the rate of descent of a vehicle with a wing-tip-mounted ducted fan. During low-speed, level, unaccelerated flight (30 to 80 knots) it appeared that a vehicle, with a configuration similar to that examined, would require less power if it were supported by a wing and ducted fans than if it were supported only by ducted fans. (Author).
Author: Kalman J. Grunwald
Publisher:
ISBN:
Category : Aerodynamic load
Languages : en
Pages : 64
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Author: Leighton Montgomery Myers
Publisher:
ISBN:
Category :
Languages : en
Pages : 275
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Book Description
Ducted fans and ducted rotors have been integrated into a wide range of aerospace vehicles, including manned and unmanned systems. Ducted fans offer many potential advantages, the most important of which is an ability to operate safely in confined spaces. There is also the potential for lower environmental noise and increased safety in shipboard operations (due to the shrouded blades). However, ducted lift fans in edgewise forward flight are extremely complicated devices and are not well understood. Future development of air vehicles that use ducted fans for lift (and some portion of forward propulsion) is currently handicapped by some fundamental aerodynamic issues. These issues influence the thrust performance, the unsteadiness leading to vehicle instabilities and control, and aerodynamically generated noise. Less than optimum performance in any of these areas can result in the vehicle using the ducted fan remaining a research idea instead of one in active service. The Penn State Department of Aerospace Engineering initiated an experimental program two years ago to study the aerodynamics of ducted lift fans. The focus of this program from its initiation was to study a single lift fan subject to an edgewise mean flow. Of particular concern was the transitional flow regime from hover to a relatively high forward speed in which a major portion of the vehicle lift is produced by the aerodynamic forces on the body. We refer to this as ducted fan edgewise flow. There are four obvious consequences of operating a ducted lift fan in edgewise (forward) flow. First, separations off the leading portion of the duct can reduce the inflow and thus the thrust of the fan. Second, the separated flow will lead to unsteadiness which will undoubtedly decrease the control authority of the vehicle. Thirdly, the outer surface of the fan shroud is likely to be fairly blunt. This body shape, together with the strong momentum drag of the lift fan outflow, produce excessive drag forces that increase the requirements of the propulsion devices. Finally, increased turbulence of the inflow will also result in increased production of aerodynamic noise. The goals of this project are to conduct detailed experiments on several configurations of ducted lift fans in hover and edgewise flow. Single ducted lift fan configurations involve different shrouded duct shapes and rotor shapes. Rotors are tested with a range of solidities and tip clearances. Including inlet duct vents over the forward portion of the duct shroud, has the potential of reducing the problem of separated flow over the forward portion of the duct inlet, and potentially reducing the drag of the vehicle in forward flight.
Author: Marc de Piolenc
Publisher: Lulu.com
ISBN: 0359104908
Category :
Languages : en
Pages : 182
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 436
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Author: Kenneth W. Mort
Publisher:
ISBN:
Category : Ducted fans
Languages : en
Pages : 38
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Book Description
