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Feng Liu - One of the best experts on this subject based on the ideXlab platform.

  • stability of symmetric and asymmetric vortex pairs over slender Conical wings and bodies
    Physics of Fluids, 2004
    Co-Authors: Jinsheng Cai, Shijun Luo, Feng Liu
    Abstract:

    Theoretical analyses are presented for the stability of symmetric and asymmetric vortex pairs over slender Conical wings and bodies under small perturbations in an inviscid incompressible Flow at high angles of attack and sideslip. The three-dimensional problem of a pair of vortices over slender Conical wings and bodies is reduced to a problem in two dimensions by using the Conical Flow assumption and classical slender-body theory. The stability of symmetric and asymmetric vortex pairs over flat-plate delta wings, slender circular cones, and elliptic cones of various thickness ratios are examined. Results are compared with available experimental data.

  • Stability of symmetric vortices in two dimensions and over three-dimensional slender Conical bodies
    Journal of Fluid Mechanics, 2003
    Co-Authors: Jinsheng Cai, Feng Liu, Shijun Luo
    Abstract:

    Ag eneral stability condition for vortices in a two-dimensional incompressible inviscid Flow field is presented. This condition is first applied to analyse the stability of symmetric vortices behind elliptic cylinders and circular cylinders with a splitter plate at the rear stagnation point. The effect of the size of the splitter plate on the stability of the vortices is studied. It is also shown that no stable symmetric vortices exist behind two-dimensional bodies based on the stability condition. The two-dimensional stability condition is then extended to analyse the absolute (temporal) stability of as ymmetric vortex pair over three-dimensional slender Conical bodies. The threedimensional problem is reduced to a vortex stability problem for a pair of vortices in tw od imensions by using the Conical Flow assumption, classical slender-body theory, and postulated separation positions. The bodies considered include circular cones and highly swept flat-plate wings with and without vertical fins, and elliptic cones of various eccentricities. There exists an intermediate cone with a finite thickness ratio between the circular cone and the flat-plate delta wing for which the symmetric vortices change from being unstable to being stable at a given angle of attack. The effects of the fin height and the separation position on the stability of the vortices are studied. Results agree well with known experimental observations.

Shijun Luo - One of the best experts on this subject based on the ideXlab platform.

  • stability of symmetric and asymmetric vortex pairs over slender Conical wings and bodies
    Physics of Fluids, 2004
    Co-Authors: Jinsheng Cai, Shijun Luo, Feng Liu
    Abstract:

    Theoretical analyses are presented for the stability of symmetric and asymmetric vortex pairs over slender Conical wings and bodies under small perturbations in an inviscid incompressible Flow at high angles of attack and sideslip. The three-dimensional problem of a pair of vortices over slender Conical wings and bodies is reduced to a problem in two dimensions by using the Conical Flow assumption and classical slender-body theory. The stability of symmetric and asymmetric vortex pairs over flat-plate delta wings, slender circular cones, and elliptic cones of various thickness ratios are examined. Results are compared with available experimental data.

  • Stability of symmetric vortices in two dimensions and over three-dimensional slender Conical bodies
    Journal of Fluid Mechanics, 2003
    Co-Authors: Jinsheng Cai, Feng Liu, Shijun Luo
    Abstract:

    Ag eneral stability condition for vortices in a two-dimensional incompressible inviscid Flow field is presented. This condition is first applied to analyse the stability of symmetric vortices behind elliptic cylinders and circular cylinders with a splitter plate at the rear stagnation point. The effect of the size of the splitter plate on the stability of the vortices is studied. It is also shown that no stable symmetric vortices exist behind two-dimensional bodies based on the stability condition. The two-dimensional stability condition is then extended to analyse the absolute (temporal) stability of as ymmetric vortex pair over three-dimensional slender Conical bodies. The threedimensional problem is reduced to a vortex stability problem for a pair of vortices in tw od imensions by using the Conical Flow assumption, classical slender-body theory, and postulated separation positions. The bodies considered include circular cones and highly swept flat-plate wings with and without vertical fins, and elliptic cones of various eccentricities. There exists an intermediate cone with a finite thickness ratio between the circular cone and the flat-plate delta wing for which the symmetric vortices change from being unstable to being stable at a given angle of attack. The effects of the fin height and the separation position on the stability of the vortices are studied. Results agree well with known experimental observations.

Jinsheng Cai - One of the best experts on this subject based on the ideXlab platform.

  • stability of symmetric and asymmetric vortex pairs over slender Conical wings and bodies
    Physics of Fluids, 2004
    Co-Authors: Jinsheng Cai, Shijun Luo, Feng Liu
    Abstract:

    Theoretical analyses are presented for the stability of symmetric and asymmetric vortex pairs over slender Conical wings and bodies under small perturbations in an inviscid incompressible Flow at high angles of attack and sideslip. The three-dimensional problem of a pair of vortices over slender Conical wings and bodies is reduced to a problem in two dimensions by using the Conical Flow assumption and classical slender-body theory. The stability of symmetric and asymmetric vortex pairs over flat-plate delta wings, slender circular cones, and elliptic cones of various thickness ratios are examined. Results are compared with available experimental data.

  • Stability of symmetric vortices in two dimensions and over three-dimensional slender Conical bodies
    Journal of Fluid Mechanics, 2003
    Co-Authors: Jinsheng Cai, Feng Liu, Shijun Luo
    Abstract:

    Ag eneral stability condition for vortices in a two-dimensional incompressible inviscid Flow field is presented. This condition is first applied to analyse the stability of symmetric vortices behind elliptic cylinders and circular cylinders with a splitter plate at the rear stagnation point. The effect of the size of the splitter plate on the stability of the vortices is studied. It is also shown that no stable symmetric vortices exist behind two-dimensional bodies based on the stability condition. The two-dimensional stability condition is then extended to analyse the absolute (temporal) stability of as ymmetric vortex pair over three-dimensional slender Conical bodies. The threedimensional problem is reduced to a vortex stability problem for a pair of vortices in tw od imensions by using the Conical Flow assumption, classical slender-body theory, and postulated separation positions. The bodies considered include circular cones and highly swept flat-plate wings with and without vertical fins, and elliptic cones of various eccentricities. There exists an intermediate cone with a finite thickness ratio between the circular cone and the flat-plate delta wing for which the symmetric vortices change from being unstable to being stable at a given angle of attack. The effects of the fin height and the separation position on the stability of the vortices are studied. Results agree well with known experimental observations.

Roberto Da Cunha Follador - One of the best experts on this subject based on the ideXlab platform.

  • experimental results of a mach 10 Conical Flow derived waverider to 14 x hypersonic aerospace vehicle
    Journal of Aerospace Technology and Management, 2011
    Co-Authors: Tiago Rolim, Marco Antonio Sala Minucci, Paulo Toro, Antonio Carlos De Oliveira, Roberto Da Cunha Follador
    Abstract:

    Resumen en: This paper presents a research in the development of the 14-X hypersonic airspace vehicle at Institute for Advanced Studies (IEAv) from Department of Sci...

  • Experimental results of a Mach 10 Conical-Flow derived waverider to 14-X hypersonic aerospace vehicle
    Departamento de Ciência e Tecnologia Aeroespacial, 2011
    Co-Authors: Tiago Cavalcanti Rolim, Marco Antonio Sala Minucci, Paulo Gilberto De Paula Toro, Antônio De Carlos De Oliveira, Roberto Da Cunha Follador
    Abstract:

    This paper presents a research in the development of the 14-X hypersonic airspace vehicle at Institute for Advanced Studies (IEAv) from Department of Science and Aerospace Technology (DCTA) of the Brazilian Air Force (FAB). The 14-X project objective is to develop a higher efficient satellite launch alternative, using a Supersonic Combustion Ramjet (SCRAMJET) engine and waverider aerodynamics. For this development, the waverider technology is under investigation in Prof. Henry T. Nagamatsu Aerothermodynamics and Hypersonics Laboratory (LHTN), in IEAv/DCTA. The investigation has been conducted through ground test campaigns in Hypersonic Shock Tunnel T3. The 14-X Waverider Vehicle characteristic was verified in shock tunnel T3 where surface static pressures and pitot pressure for Mach number 10 were measured and, using Schlieren photographs Diagnostic Method, it was possible to identify a leading-edge attached shock wave in 14-X lower surface

Verhamme Anne - One of the best experts on this subject based on the ideXlab platform.

  • MusE GAs Flow and Wind (MEGAFlow) IV: A two sightline tomography of a galactic wind
    HAL CCSD, 2020
    Co-Authors: Zabl Johannes, Bouché, Nicolas F., Schroetter Ilane, Wendt Martin, Contini Thierry, Schaye Joop, Marino, Raffaella A., Muzahid Sowgat, Pezzulli Gabriele, Verhamme Anne
    Abstract:

    Galactic outFlows are thought to eject baryons back out to the circum-galactic medium (CGM). Studies based on metal absorption lines (MgII in particular) in the spectra of background quasars indicate that the gas is ejected anisotropically, with galactic winds likely leaving the host in a bi-Conical Flow perpendicular to the galaxy disk. In this paper, we present a detailed analysis of an outFlow from a z = 0.7 "green-valley" galaxy (log($M_*$/$\mathrm{M}_\odot$) = 9.9; SFR = 0.5 $\mathrm{M}_\odot\,\mathrm{yr}^{-1}$) probed by two background sources part of the MUSE Gas Flow and Wind (MEGAFlow) survey. Thanks to a fortuitous configuration with a background quasar (SDSSJ1358+1145) and a bright background galaxy at $z = 1.4$, both at impact parameters of $\approx 15\,\mathrm{kpc}$, we can - for the first time - probe both the receding and approaching components of a putative galactic outFlow around a distant galaxy. We measure a significant velocity shift between the MgII absorption from the two sightlines ($84\pm17\,\mathrm{km}\,\mathrm{s}^{-1}$), which is consistent with the expectation from our simple fiducial wind model, possibly combined with an extended disk contribution

  • MusE GAs Flow and Wind (MEGAFlow) IV: A two sightline tomography of a galactic wind
    'Oxford University Press (OUP)', 2020
    Co-Authors: Zabl Johannes, Bouché, Nicolas F., Schroetter Ilane, Wendt Martin, Contini Thierry, Schaye Joop, Marino, Raffaella A., Muzahid Sowgat, Pezzulli Gabriele, Verhamme Anne
    Abstract:

    International audienceGalactic outFlows are thought to eject baryons back out to the circumgalactic medium. Studies based on metal absorption lines (Mg ii in particular) in the spectra of background quasars indicate that the gas is ejected anisotropically, with galactic winds likely leaving the host in a bi-Conical Flow perpendicular to the galaxy disc. In this paper, we present a detailed analysis of an outFlow from a z = 0.7 ‘green-valley’ galaxy [log (M_*/M_⊙) = 9.8; |$\mbox{SFR}=0.5\, \mathrm{M}_{\odot }\, \mathrm{yr}^{-1}$|] probed by two background sources from the MusE GAs Flow and Wind (MEGAFlow) survey. Thanks to a fortuitous configuration with a background quasar (SDSSJ1358 + 1145) and a bright background galaxy at z = 1.4, both at impact parameters of |$\approx\! 15\, \hbox{kpc}$|⁠, we can – for the first time – probe both the receding and approaching components of a putative galactic outFlow around a distant galaxy. We measure a significant velocity shift between the Mg ii absorption from the two sightlines (⁠|$84\pm 17\, \hbox{km~s$^{-1}$}$|⁠), which is consistent with the expectation from our simple fiducial wind model, possibly combined with an extended disc contribution