Conical Euler Analysis And Active Roll Suppression For Unsteady Vortical Flows About Rolling Delta Wings

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Conical Euler Analysis and Active Roll Suppression for Unsteady Vortical Flows about Rolling Delta Wings

National Aeronautics and Space Administration (NASA)
Conical Euler Analysis and Active Roll Suppression for Unsteady Vortical Flows about Rolling Delta Wings Book PDF

Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
Page : 30 pages
File Size : 42,9 Mb
Release : 2018-07-02
Category : Electronic
ISBN : 1722125993

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Conical Euler Analysis and Active Roll Suppression for Unsteady Vortical Flows about Rolling Delta Wings by National Aeronautics and Space Administration (NASA) Pdf

A conical Euler code was developed to study unsteady vortex-dominated flows about rolling, highly swept delta wings undergoing either forced motions or free-to-roll motions that include active roll suppression. The flow solver of the code involves a multistage, Runge-Kutta time-stepping scheme that uses a cell-centered, finite-volume, spatial discretization of the Euler equations on an unstructured grid of triangles. The code allows for the additional analysis of the free to-roll case by simultaneously integrating in time the rigid-body equation of motion with the governing flow equations. Results are presented for a delta wing with a 75 deg swept, sharp leading edge at a free-stream Mach number of 1.2 and at 10 deg, 20 deg, and 30 deg angle of attack alpha. At the lower angles of attack (10 and 20 deg), forced-harmonic analyses indicate that the rolling-moment coefficients provide a positive damping, which is verified by free-to-roll calculations. In contrast, at the higher angle of attack (30 deg), a forced-harmonic analysis indicates that the rolling-moment coefficient provides negative damping at the small roll amplitudes. A free-to-roll calculation for this case produces an initially divergent response, but as the amplitude of motion grows with time, the response transitions to a wing-rock type of limit cycle oscillation, which is characteristic of highly swept delta wings. This limit cycle oscillation may be actively suppressed through the use of a rate-feedback control law and antisymmetrically deflected leading-edge flaps. Descriptions of the conical Euler flow solver and the free-to roll analysis are included in this report. Results are presented that demonstrate how the systematic analysis of the forced response of the delta wing can be used to predict the stable, neutrally stable, and unstable free response of the delta wing. These results also give insight into the flow physics associated with unsteady vortical flows about delta wings undergoing forced m...

Conical Euler Simulation and Active Suppression of Delta Wing Rocking Motion

National Aeronautics and Space Administration (NASA)
Conical Euler Simulation and Active Suppression of Delta Wing Rocking Motion Book PDF

Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
Page : 36 pages
File Size : 40,8 Mb
Release : 2018-07
Category : Electronic
ISBN : 1722126051

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Conical Euler Simulation and Active Suppression of Delta Wing Rocking Motion by National Aeronautics and Space Administration (NASA) Pdf

A conical Euler code was developed to study unsteady vortex-dominated flows about rolling highly-swept delta wings, undergoing either forced or free-to-roll motions including active roll suppression. The flow solver of the code involves a multistage Runge-Kutta time-stepping scheme which uses a finite volume spatial discretization of the Euler equations on an unstructured grid of triangles. The code allows for the additional analysis of the free-to-roll case, by including the rigid-body equation of motion for its simultaneous time integration with the governing flow equations. Results are presented for a 75 deg swept sharp leading edge delta wing at a freestream Mach number of 1.2 and at alpha equal to 10 and 30 deg angle of attack. A forced harmonic analysis indicates that the rolling moment coefficient provides: (1) a positive damping at the lower angle of attack equal to 10 deg, which is verified in a free-to-roll calculation; (2) a negative damping at the higher angle of attack equal to 30 deg at the small roll amplitudes. A free-to-roll calculation for the latter case produces an initially divergent response, but as the amplitude of motion grows with time, the response transitions to a wing-rock type of limit cycle oscillation. The wing rocking motion may be actively suppressed, however, through the use of a rate-feedback control law and antisymmetrically deflected leading edge flaps. The descriptions of the conical Euler flow solver and the free-to-roll analysis are presented. Results are also presented which give insight into the flow physics associated with unsteady vortical flows about forced and free-to-roll delta wings, including the active roll suppression of this wing-rock phenomenon. Lee, Elizabeth M. and Batina, John T. Langley Research Center RTOP 505-63-21-01...

Aeronautical Engineering

Anonim
Aeronautical Engineering Book PDF

Author : Anonim
Publisher : Unknown
Page : 538 pages
File Size : 44,7 Mb
Release : 1991
Category : Aeronautics
ISBN : UOM:39015023295143

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Aeronautical Engineering by Anonim Pdf

Government Reports Annual Index

Anonim
Government Reports Annual Index Book PDF

Author : Anonim
Publisher : Unknown
Page : 1296 pages
File Size : 54,6 Mb
Release : 1993
Category : Government reports announcements & index
ISBN : MINN:30000003749334

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Government Reports Annual Index by Anonim Pdf

NASA SP.

Anonim
NASA SP Book PDF

Author : Anonim
Publisher : Unknown
Page : 654 pages
File Size : 41,5 Mb
Release : 1992
Category : Aeronautics
ISBN : MINN:31951P00163367D

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NASA SP. by Anonim Pdf