Wing laminar boundary layer in the presence of a propeller slipstream

Miley, S. J.; Howard, Richard M.; Holmes, Bruce J.

doi:10.2514/3.45630

Cited by 22 publications

(10 citation statements)

References 2 publications

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“…(7)(8)(9) and (11), the thrust required for the vertical flight at a speed V 0 can be found from T W 0:5…”

Section: Designing a Vtol Mav Prototypementioning

confidence: 99%

“…It is important to emphasize the fact that the previous studies [6][7][8] were performed for Reynolds numbers and thrust values relevant to large aircraft and high-speed flights. Also, these studies were concerned with a rotational flow behind a single propeller.…”

Section: Introductionmentioning

confidence: 99%

“…The effect of a propeller slipstream on the wing laminar boundary layer was investigated [8] with the help of hot-wire sensors. Measurements in the boundary layer on the wing surface showed the periodic change of the laminar velocity profile to turbulent and back at the same rate as of the propeller rotation.…”

Section: Introductionmentioning

confidence: 99%

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Aerodynamic Design of Micro Air Vehicles for Vertical Flight

Shkarayev

Moschetta

Bataille

2008

Journal of Aircraft

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The research and development efforts outlined in this paper address the aerodynamic design of micro air vehicles with hovering and vertical takeoff and landing capabilities. The tilt-body configuration of the vertical takeoff and landing micro air vehicle is proposed based on a propulsion system consisting of two coaxial contrarotating motors and propellers. Values of thrust, torque, power, and efficiency of this propulsion system were measured in pusher and tractor arrangements of propellers and compared against single motor-propeller propulsion. With comparable efficiency, the developed propulsion system has very little propeller torque. Hot-wire measurements have been conducted to investigate the velocity profile in slipstream. The lower average velocity and significant decrease in velocity in the core of the slipstream found in the tractor arrangement are mostly due to the parasite drag caused by the motors. It causes the decrease of the thrust force observed for the tractor arrangement in comparison with the pusher arrangement. Wind-tunnel testing was conducted for a motor, a wing, and an arrangement of a wing with a motor. The drag force on the wing is produced by two mixing airflows: freestream and propeller-induced pulsating slipstream. The zero-lift drag coefficient increases by about 4 times with propeller-induced speed increased from 0 to 7:5 m=s. The results of this study were realized in the design of a vertical takeoff and landing micro air vehicle prototype that was successfully flight tested. Nomenclature a = distance from propeller disk to the leading edge of the wing C D = drag coefficient C D 0 = zero-lift drag coefficient C D P = zero-lift drag coefficient on the part of the wing submerged into a propeller slipstream C L = lift coefficient c = chord F total = total force measured by a wind-tunnel balance P = electric power input P ind = induced power Q = torque R = propeller radius R m = maximum distance of velocity measurements from the z axis R s = radius of stream tube at distance s r = motor radius Re = mean aerodynamic chord Reynolds number S p = area of a part of the wing covered by propeller slipstream S S = area of the side wall S 0 = wing area T = thrust force T s = thrust force determined from air-velocity data V 0 = freestream velocity W = takeoff weight of an aircraft ws = induced velocity based on propeller momentum theory w e = measured propeller-induced velocity = air density

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“…(7)(8)(9) and (11), the thrust required for the vertical flight at a speed V 0 can be found from T W 0:5…”

Section: Designing a Vtol Mav Prototypementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Aerodynamic Design of Micro Air Vehicles for Vertical Flight

Shkarayev

Moschetta

Bataille

2008

Journal of Aircraft

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“…Additional studies noted interesting slipstream-wing boundary-layer interactions. One paper [6] found that a propellerinduced slipstream does not eliminate laminar separation bubbles, and another paper [7] identified a cyclic change of the velocity profile of a boundary layer, between laminar and turbulent, which occurred at the same frequency as propeller rotation. The studies [5][6][7] were performed at Reynolds numbers greatly exceeding those typical for MAVs.…”

Section: Introductionmentioning

confidence: 99%

Longitudinal Aerodynamics of a Vertical Takeoff and Landing Micro Air Vehicle

Randall

Hoffmann

Shkarayev

2011

Journal of Aircraft

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The research and development efforts outlined in this paper address the aerodynamic design of micro air vehicles that are capable of vertical takeoff and landing, as well as hovering. The effect of a propulsive slipstream on a wing's quasi-steady aerodynamics is investigated as an early step toward improving existing vertical takeoff and landing designs and control algorithms. Wind-tunnel testing was conducted on a propulsion system with contrarotating propellers, a wing, and the combined wing and propulsion system. Aerodynamic coefficient definitions are discussed with regard to vertical takeoff and landing micro air vehicles, and modified definitions are presented.

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“…It is however not fair to assume trailing wing's boundary layers to be fully turbulent. Catalano himself noticed some extent of laminarity in his results, and other authors have confirmed how laminar flow design principles should be applied in such configurations as well [18].…”

Section: Viscous Effectsmentioning

confidence: 63%

A Surrogate-Based Multi-Disciplinary Design Optimization Framework Exploiting Wing-Propeller Interaction

Alba

Elham

German

et al. 2017

18th AIAA/ISSMO Multidisciplinary Analysis and Optimization Conference

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The adoption of propellers is the oldest propulsive solution in aviation, and remains nowadays the preferred one in several segments of the market, being the greenest and most fuel-efficient choice for low-to-mid subsonic speeds. New paradigms of mobility envision the use of propeller powered aircrafts to provide an answer to the issue of future mass transportation in and between major cities.Common aircraft design procedures determine optimal wing design parameters pursuing low drag and weight solutions, but neglecting the influence that propellers' slipstreams have on lift and drag distributions, especially when mounted in tractor configurations.Considering such strong interest in propeller propulsion, and the apparent lack of insightful research in the multi-disciplinary design optimization (MDO) opportunities that propeller-wing integration brings along, the present Thesis was designed with the objective of building a surrogate-based MDO framework for a general aviation aircraft featuring wing mounted tractor propellers. Such objective was achieved by developing appropriate analysis tools to model the most relevant effects of wing-propellers interaction, and by integrating them in suitable optimization architectures enhanced by the adoption of surrogate models. Two research hypotheses underlay such approach, the first claiming that accounting for wing-propeller interaction effects could lead to better designs, and the second claiming that the adoption of surrogate modeling techniques could greatly improve overall optimization performances. The successful accomplishment of the described objective was demonstrated by applying the optimization on an existing aircraft and achieving sensitive fuel savings. The mentioned hypotheses were instead proven under several aspects through the multiple surrogate-based optimization frameworks adopted and the obtained optimal designs. The work proposed as well innovative solutions to perform a full interaction wing-propellers analysis, such as routines to assess and model the propeller streamtube deflection and the wing swirl recovery effects. It also provided guidance for the implementation of surrogate-based optimizations in problems featuring high numbers of design variables and multiple complex non-linear constraints, testing different surrogate models, as well as different frameworks, to achieve local and global optimal designs.iii ACKNOWLEDGEMENTSThe path leading to the achievement of my Master in Aerospace Engineering has been a challenging and rewarding one, along which all my professors and colleagues at TU Delft have been a huge source of motivation and improvement.This Thesis is the culmination of such journey, and would not have been possible without the support of the people I have been working with over the past year. I would first like to thank my supervisor Dr. Elham of TU Delft for his availability and precious contribution in several aspects of the work. A great thanks is due as well to Professor Brian German who hosted me at the Georgia Institute o...

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Wing laminar boundary layer in the presence of a propeller slipstream

Cited by 22 publications

References 2 publications

Aerodynamic Design of Micro Air Vehicles for Vertical Flight

Aerodynamic Design of Micro Air Vehicles for Vertical Flight

Longitudinal Aerodynamics of a Vertical Takeoff and Landing Micro Air Vehicle

A Surrogate-Based Multi-Disciplinary Design Optimization Framework Exploiting Wing-Propeller Interaction

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