Changes in Propeller Performance Due to Ground and Partial Ground Proximity

Changes in Propeller Performance Due to Ground and Partial Ground Proximity PDF Author: Jielong Cai
Publisher:
ISBN:
Category :
Languages : en
Pages : 77

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Book Description
With the increased usage of propeller-driven unmanned-aerial-vehicles (UAV) in closed spaces such as caves, buildings, pipelines, etc. for photography, surveillance, and inspection, understanding the influence of the ground and ceiling on a remote-controlled (R/C) propeller is of the utmost importance. The flying characteristics of drones changes when an object or a ground plane is in its close proximity due to changes in its propeller performance. The changes in performance are due to the changes in the flow field around the propeller that occur due to ground proximity, which is also known as ground effect. Ground effect on lifting rotor performance has been studied theoretically and experimentally for decades. Historically, most investigations focus on helicopter rotors, which have high aspect ratio, lower pitch and rarely have spanwise twist. This research focuses on smaller size rotors, in particular, the thin-electric propeller which is used widely on small UAVs. The research considers parameter variations not broadly available in the literature such as propeller pitch, diameter, solidity, and blockage. In particular, extreme ground effect is considered, where the ratio of ground plane stand-off distance to propeller diameter is 0.1 or less. Moreover, the propeller is reversed, to examine the ceiling effect. Typically, the ground effect investigation is done with a ground plane that is big enough to be considered an infinite plane. In this research, both infinite plane and circular plates of similar diameter (or less) of the propeller are used as ground planes. Various circular plates with different diameter to propeller diameter ratios are used in the research representing different 'blockage ratios'. The investigation gives insight into changes in propeller performance in proximity to fuselages of a given diameter in propeller-driven airplanes under pusher and puller configurations. All experiments were conducted on a thrust-stand built in-house at the University of Dayton Low-Speed Wind Tunnel (UD-LSWT) Laboratory. All propellers used in the experiment are from the "thin electric" APC series, with diameter ranging from 11 inches to 17 inches and pitch from 4.5 inches to 14 inches. The propeller peak Reynolds number varies from 90,000 to 190,000 in the experiment. Circular plates with diameter ratio from 0.5 to 1.0 are used in the blockage effect experiment. Force, torque and RPM propeller data are taken during the experiment from a propeller diameter normalized ground distance of -1.5 to 1.5. Results from the infinite ground experiment are separated into three major sections: thrust coefficient and power coefficient, power required at constant thrust, and effective thrust. A significant increment in the thrust coefficient and decrement in the power coefficient is found in ground proximity among the propellers with a pitch-to-diameter ratio less than 0.7. This results in a decrement of power required at constant thrust in ground effect. Almost identical changes in the power required at constant thrust in the ceiling effect is also found in most of the low pitch to diameter ratio propellers. For the blockage experiment, a less significant reduction in the power required in constant thrust for all propellers is found at lower blockage ratios as expected. Similar trends in the effect on? thrust for different propellers at the same blockage ratio are found. Results for the positive h/D region (the puller configuration), overlap regardless of the propeller pitch to diameter ratio or solidity. A phenomenological expression (an algebraic equation) for power required at constant thrust as a function of propeller parameter is established during the research to predict the changes in the propeller performance in ground effect which will benefit the operation of small UAVs in both open and confined areas.

Changes in Propeller Performance Due to Ground and Partial Ground Proximity

Changes in Propeller Performance Due to Ground and Partial Ground Proximity PDF Author: Jielong Cai
Publisher:
ISBN:
Category :
Languages : en
Pages : 77

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Book Description
With the increased usage of propeller-driven unmanned-aerial-vehicles (UAV) in closed spaces such as caves, buildings, pipelines, etc. for photography, surveillance, and inspection, understanding the influence of the ground and ceiling on a remote-controlled (R/C) propeller is of the utmost importance. The flying characteristics of drones changes when an object or a ground plane is in its close proximity due to changes in its propeller performance. The changes in performance are due to the changes in the flow field around the propeller that occur due to ground proximity, which is also known as ground effect. Ground effect on lifting rotor performance has been studied theoretically and experimentally for decades. Historically, most investigations focus on helicopter rotors, which have high aspect ratio, lower pitch and rarely have spanwise twist. This research focuses on smaller size rotors, in particular, the thin-electric propeller which is used widely on small UAVs. The research considers parameter variations not broadly available in the literature such as propeller pitch, diameter, solidity, and blockage. In particular, extreme ground effect is considered, where the ratio of ground plane stand-off distance to propeller diameter is 0.1 or less. Moreover, the propeller is reversed, to examine the ceiling effect. Typically, the ground effect investigation is done with a ground plane that is big enough to be considered an infinite plane. In this research, both infinite plane and circular plates of similar diameter (or less) of the propeller are used as ground planes. Various circular plates with different diameter to propeller diameter ratios are used in the research representing different 'blockage ratios'. The investigation gives insight into changes in propeller performance in proximity to fuselages of a given diameter in propeller-driven airplanes under pusher and puller configurations. All experiments were conducted on a thrust-stand built in-house at the University of Dayton Low-Speed Wind Tunnel (UD-LSWT) Laboratory. All propellers used in the experiment are from the "thin electric" APC series, with diameter ranging from 11 inches to 17 inches and pitch from 4.5 inches to 14 inches. The propeller peak Reynolds number varies from 90,000 to 190,000 in the experiment. Circular plates with diameter ratio from 0.5 to 1.0 are used in the blockage effect experiment. Force, torque and RPM propeller data are taken during the experiment from a propeller diameter normalized ground distance of -1.5 to 1.5. Results from the infinite ground experiment are separated into three major sections: thrust coefficient and power coefficient, power required at constant thrust, and effective thrust. A significant increment in the thrust coefficient and decrement in the power coefficient is found in ground proximity among the propellers with a pitch-to-diameter ratio less than 0.7. This results in a decrement of power required at constant thrust in ground effect. Almost identical changes in the power required at constant thrust in the ceiling effect is also found in most of the low pitch to diameter ratio propellers. For the blockage experiment, a less significant reduction in the power required in constant thrust for all propellers is found at lower blockage ratios as expected. Similar trends in the effect on? thrust for different propellers at the same blockage ratio are found. Results for the positive h/D region (the puller configuration), overlap regardless of the propeller pitch to diameter ratio or solidity. A phenomenological expression (an algebraic equation) for power required at constant thrust as a function of propeller parameter is established during the research to predict the changes in the propeller performance in ground effect which will benefit the operation of small UAVs in both open and confined areas.

Ground Effects on a Four-propeller Tilt-wing Configuration Over a Fixed and a Moving Ground Plane

Ground Effects on a Four-propeller Tilt-wing Configuration Over a Fixed and a Moving Ground Plane PDF Author: Kenneth W. Goodson
Publisher:
ISBN:
Category :
Languages : en
Pages : 100

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NASA Technical Note

NASA Technical Note PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 578

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The Ground Effect on Lifting Propellers

The Ground Effect on Lifting Propellers PDF Author: Albert Betz
Publisher:
ISBN:
Category : Ground-cushion phenomenon
Languages : en
Pages : 544

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Book Description
In what follows an estimate will be made of the magnitude of the ground effect. For the two cases where the distance a of the propeller from the ground is very small, and very large, respectively, in comparison with the propeller radius r(sub o) the relations may be simply expressed. We consider first the effect of the ground, assuming that the thrust is held constant, as may be done by a suitable change in the propeller speed.

Large-scale Wind-tunnel Investigation of an Airplane Model with a Tilt Wing of Aspect Ratio 8.4, and Four Propellers, in the Presence of a Ground Plane

Large-scale Wind-tunnel Investigation of an Airplane Model with a Tilt Wing of Aspect Ratio 8.4, and Four Propellers, in the Presence of a Ground Plane PDF Author: Stanley O. Dickinson
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 82

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Marine Propellers and Propulsion

Marine Propellers and Propulsion PDF Author: John Carlton
Publisher: Butterworth-Heinemann
ISBN: 0080971237
Category : Technology & Engineering
Languages : en
Pages : 539

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Book Description
The early development of the screw propeller. Propeller geometry. The propeller environment. The ship wake field, propeller performance characteristics.

Scientific and Technical Aerospace Reports

Scientific and Technical Aerospace Reports PDF Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 728

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Technical Abstract Bulletin

Technical Abstract Bulletin PDF Author: Defense Documentation Center (U.S.)
Publisher:
ISBN:
Category : Technology
Languages : en
Pages : 1766

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Masters Theses in the Pure and Applied Sciences

Masters Theses in the Pure and Applied Sciences PDF Author: Wade H. Shafer
Publisher: Springer Science & Business Media
ISBN: 1461524539
Category : Science
Languages : en
Pages : 391

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Book Description
Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS)* at Purdue University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dis semination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the though that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all concerned if the printing and distribution of the volumes were handled by an international publishing house to assure improved service and broader dissemi nation. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Corporation of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 37 (thesis year 1992) a total of 12,549 thesis titles from 25 Canadian and 153 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this impor tant annual reference work. While Volume 37 reports theses submitted in 1992, on occasion, certain uni versities do report theses submitted in previous years but not reported at the time.

U.S. Government Research Reports

U.S. Government Research Reports PDF Author:
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 262

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