Author: Julia Cole
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
A new higher-order free-wake (HOFW) method has been developed to enable conceptual design space explorations of propeller-wing systems. The method uses higher order vorticity elements to represent the wings and propeller blades as lifting surfaces. The higher order elements allow for better force resolution and more intrinsically computationally stable wakes than a comparable vortex-lattice method, while retaining the relative ease of geometric representation inherent to such methods. The propeller and wing surfaces and wakes are modeled within the same flow field, thus accounting for mutual interaction without the need for empirical models. The method was shown to be accurate through comparisons with other methods and experimental data. To ensure the method is capable of capturing an unsteady lift response, it was compared with a Kussner function approximation of the change in two-dimensional lift due to a sharp-edged gust. This study showed excellent agreement with an average error in the HOFW lift response of less than 3% from 0 to 10 semi-chords, but required high time and space resolution. The time-accurate lift response of a propeller-wing system as predicted with the HOFW method was then compared with with fully unsteady CFD. These results showed that the HOFW method can identify the peak frequency and general amplitude of the lift oscillations at high resolution. Due to the high resolution requirements, this mode of analysis is not recommended for use in design studies. Time-averaged results found using the HOFW method were compared with experimental propeller, proprotor, and propeller-wing system data, along with two semi-empirical methods. The method matched experimental propeller efficiencies to within 4% for lightly loaded conditions. Increases in lift coefficient due to interaction with a propeller for a series of wings as analyzed with the HOFW method matched the average of those predicted with two semi-empirical methods with an average of 6.5% error for a lightly loaded propeller case. A comparison of HOFW predictions of lift for a more non-conventional propeller-wing system with experimental results over a range of angles of attack showed an average difference of 0.04 in lift coefficient. For this system, predictions in thrust and torque also matched experimental results within 5% over a small angle of attack range (+/- 5 degrees). The method was less successful at predicting the magnitude of drag in comparison with experimental results, but was capable of qualitatively matching trends in drag, both with changes in angle of attack and for variations in design.Finally, two design studies were conducted to show the practical utility of the method: an investigation of the twist distribution on a large civil tiltrotor wing and an investigation into propeller rotation direction and vertical location on a distributed electric propulsion vehicle. The studies showed that the method is capable, fast, accurate, and robust for performance prediction of propeller-wing systems, and thus appropriate for use in design-space exploration.
A Higher-Order Free-Wake Method for Aerodynamic Performance Prediction of Propeller-Wing Systems
Author: Julia Cole
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
A new higher-order free-wake (HOFW) method has been developed to enable conceptual design space explorations of propeller-wing systems. The method uses higher order vorticity elements to represent the wings and propeller blades as lifting surfaces. The higher order elements allow for better force resolution and more intrinsically computationally stable wakes than a comparable vortex-lattice method, while retaining the relative ease of geometric representation inherent to such methods. The propeller and wing surfaces and wakes are modeled within the same flow field, thus accounting for mutual interaction without the need for empirical models. The method was shown to be accurate through comparisons with other methods and experimental data. To ensure the method is capable of capturing an unsteady lift response, it was compared with a Kussner function approximation of the change in two-dimensional lift due to a sharp-edged gust. This study showed excellent agreement with an average error in the HOFW lift response of less than 3% from 0 to 10 semi-chords, but required high time and space resolution. The time-accurate lift response of a propeller-wing system as predicted with the HOFW method was then compared with with fully unsteady CFD. These results showed that the HOFW method can identify the peak frequency and general amplitude of the lift oscillations at high resolution. Due to the high resolution requirements, this mode of analysis is not recommended for use in design studies. Time-averaged results found using the HOFW method were compared with experimental propeller, proprotor, and propeller-wing system data, along with two semi-empirical methods. The method matched experimental propeller efficiencies to within 4% for lightly loaded conditions. Increases in lift coefficient due to interaction with a propeller for a series of wings as analyzed with the HOFW method matched the average of those predicted with two semi-empirical methods with an average of 6.5% error for a lightly loaded propeller case. A comparison of HOFW predictions of lift for a more non-conventional propeller-wing system with experimental results over a range of angles of attack showed an average difference of 0.04 in lift coefficient. For this system, predictions in thrust and torque also matched experimental results within 5% over a small angle of attack range (+/- 5 degrees). The method was less successful at predicting the magnitude of drag in comparison with experimental results, but was capable of qualitatively matching trends in drag, both with changes in angle of attack and for variations in design.Finally, two design studies were conducted to show the practical utility of the method: an investigation of the twist distribution on a large civil tiltrotor wing and an investigation into propeller rotation direction and vertical location on a distributed electric propulsion vehicle. The studies showed that the method is capable, fast, accurate, and robust for performance prediction of propeller-wing systems, and thus appropriate for use in design-space exploration.
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
A new higher-order free-wake (HOFW) method has been developed to enable conceptual design space explorations of propeller-wing systems. The method uses higher order vorticity elements to represent the wings and propeller blades as lifting surfaces. The higher order elements allow for better force resolution and more intrinsically computationally stable wakes than a comparable vortex-lattice method, while retaining the relative ease of geometric representation inherent to such methods. The propeller and wing surfaces and wakes are modeled within the same flow field, thus accounting for mutual interaction without the need for empirical models. The method was shown to be accurate through comparisons with other methods and experimental data. To ensure the method is capable of capturing an unsteady lift response, it was compared with a Kussner function approximation of the change in two-dimensional lift due to a sharp-edged gust. This study showed excellent agreement with an average error in the HOFW lift response of less than 3% from 0 to 10 semi-chords, but required high time and space resolution. The time-accurate lift response of a propeller-wing system as predicted with the HOFW method was then compared with with fully unsteady CFD. These results showed that the HOFW method can identify the peak frequency and general amplitude of the lift oscillations at high resolution. Due to the high resolution requirements, this mode of analysis is not recommended for use in design studies. Time-averaged results found using the HOFW method were compared with experimental propeller, proprotor, and propeller-wing system data, along with two semi-empirical methods. The method matched experimental propeller efficiencies to within 4% for lightly loaded conditions. Increases in lift coefficient due to interaction with a propeller for a series of wings as analyzed with the HOFW method matched the average of those predicted with two semi-empirical methods with an average of 6.5% error for a lightly loaded propeller case. A comparison of HOFW predictions of lift for a more non-conventional propeller-wing system with experimental results over a range of angles of attack showed an average difference of 0.04 in lift coefficient. For this system, predictions in thrust and torque also matched experimental results within 5% over a small angle of attack range (+/- 5 degrees). The method was less successful at predicting the magnitude of drag in comparison with experimental results, but was capable of qualitatively matching trends in drag, both with changes in angle of attack and for variations in design.Finally, two design studies were conducted to show the practical utility of the method: an investigation of the twist distribution on a large civil tiltrotor wing and an investigation into propeller rotation direction and vertical location on a distributed electric propulsion vehicle. The studies showed that the method is capable, fast, accurate, and robust for performance prediction of propeller-wing systems, and thus appropriate for use in design-space exploration.
An Analysis for High Speed Propeller-nacelle Aerodynamic Performance Prediction. Volume 1: Theory and Application
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 342
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages : 342
Book Description
An Analysis for High Speed Propeller-nacelle Aerodynamic Performance Prediction: User's manual
Author:
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 312
Book Description
Publisher:
ISBN:
Category : Airplanes
Languages : en
Pages : 312
Book Description
An Analysis for High Speed Propeller-nacelle Aerodynamic Performance Prediction
Author: T. Alan Egolf
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Scientific and Technical Aerospace Reports
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 702
Book Description
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 702
Book Description
Numerical Prediction of Propeller Performance by Vortex Lattice Method
Author: Cheung, Richard Shiu Wing
Publisher:
ISBN:
Category : Propellers, Aerial
Languages : en
Pages : 116
Book Description
Publisher:
ISBN:
Category : Propellers, Aerial
Languages : en
Pages : 116
Book Description
AGARD Advisory Report
Author: North Atlantic Treaty Organization. Advisory Group for Aerospace Research and Development
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 36
Book Description
Publisher:
ISBN:
Category : Aerodynamics
Languages : en
Pages : 36
Book Description
NASA SP.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 654
Book Description
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 654
Book Description
Applied mechanics reviews
Author:
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 400
Book Description
Publisher:
ISBN:
Category : Mechanics, Applied
Languages : en
Pages : 400
Book Description
Aeronautical Engineering
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 580
Book Description
A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA)
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 580
Book Description
A selection of annotated references to unclassified reports and journal articles that were introduced into the NASA scientific and technical information system and announced in Scientific and technical aerospace reports (STAR) and International aerospace abstracts (IAA)