Three-dimensional transition studies at ONERA/CERT

Arnal, D.; Juillen, J. C.

doi:10.2514/6.1987-1335

Cited by 30 publications

(10 citation statements)

References 1 publication

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“…The alternating high-and low-shear regions are evident. As in the experiment of Dagenhart (1992), no vortex merging or adjustment of vortex spacing is observed, in contrast to the experimental results of Arnal and Juillen (1987). The vortex adjustment in the numerical simulations could be restricted to some extent by the spanwise periodicity.…”

Section: Flow Visualizationcontrasting

confidence: 48%

Large-eddy simulation of laminar-turbulent transition in a swept-wing boundary layer

Xiaoli

Joslin

Piomelli

1997

35th Aerospace Sciences Meeting and Exhibit

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The spatial development of laminar-turbulent transition in a 45 swept-wing boundary layer is investigated using the large-eddy simulation approach. Both stationary and traveling disturbances are initiated by steady and random forcings. The numerical simulations reproduce the surface shear streaks typical of the crossow instability observed in experiments. Downstream of the transition location the wall shear stress is found to turn towards the streak direction. The strength of the stationary vortices grows exponentially, initially independent of the unsteady forcing amplitude and saturates at dierent levels during the later development, depending on the magnitude of the traveling vortices. Streamwise velocity contours show the evolution from a wave-like structure to the \half-mushroom" structure for the lower-amplitude, traveling-wave case, leading to double inection points in the wallnormal velocity proles prior to transition; the nonlinear interactions involving the stationary vortices are also much stronger, as indicated by the amplication of higher harmonics of the primary mode. The frequency spectrum of the traveling waves show a high frequency secondary instability prior to transition that, however, is not prominent in the higheramplitude traveling-wave case.

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Section: Flow Visualizationcontrasting

confidence: 48%

Large-eddy simulation of laminar-turbulent transition in a swept-wing boundary layer

Xiaoli

Joslin

Piomelli

1997

35th Aerospace Sciences Meeting and Exhibit

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“…The alternating high-and low-shear regions associated with the crossflow vortices are evident. As in the experiment of Dagenhart (1992), no adjustment of vortex spacing is observed, in contrast to the experimental results of Arnal & Juillen (1987); however, as the vortices evolve and spread with chordwise distance, merging of the vortices occurs due to this natural spreading, as discussed by Joslin & Streett (1994).…”

Section: Global Characteristics Of the Flow Fieldmentioning

confidence: 67%

Large-eddy simulation of boundary-layer transition on a swept wedge

1999

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The spatial evolution of the disturbances that lead to boundary-layer transition on a swept wedge is computed by large-eddy simulations (LES). Stationary and travelling crossflow-vortex disturbances are generated using steady and random-amplitude suction and blowing on the wedge. For a fixed initial amplitude of the stationary vortex and low-amplitude unsteady disturbances, the LES show the evolution of stationary-dominated crossflow disturbances similar to previous simulations and experiments: linear amplification is followed by vortex roll-over and doubly inflectional velocity profiles just prior to transition. A high-frequency secondary instability is associated with the double inflection points in the velocity profiles. The harmonic modes of the primary disturbance were found to be amplified, while no energy was found in any subharmonic mode. The physical phenomena were significantly different when the stationary and travelling vortices have comparable initial amplitudes: in this case, the vortex roll-over does not occur and transition is dominated by the travelling-wave component.

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“…A larger body of experimental work on the nature of the cross-flow instability exists for swept wings. These include the work by by groups at DLR (Müller & Bippes 1988;Bippes 1991), at Arizona State University (Dagenhart et al 1989;Kohama, Saric & Hoos 1991;Radeztsky et al 1993) and at ONERA/CERT (Arnal & Juillen 1987). The experiment of Müller & Bippes (1988) is somewhat singular because it was one of the few to show both stationary and travelling cross-flow modes.…”

Section: Introductionmentioning

confidence: 99%

Stationary travelling cross-flow mode interactions on a rotating disk

Corke

Knasiak

1998

J. Fluid Mech.

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This work involves the study of the development of Type 1 stationary and travelling cross-flow modes in the three-dimensional boundary layer over a rotating disk. In order to control the characteristics of the stationary modes, we utilized organized patterns of roughness which were applied to the disk surface. These consisted of ink dots which were equally spaced in the azimuthal direction at a fixed radius in order to enhance particular azimuthal wavenumbers. Logarithmic spiral patterns of dots were also used to enhance azimuthal wave angles. Velocity fluctuation time series were decomposed into the components corresponding to the stationary and travelling modes using the instantaneous disk position as a reference. Their development was documented through the linear and nonlinear stages leading to turbulence. The linear stage agreed well with linear stability predictions for both modes. In the nonlinear stage we documented a triad coupling between pairs of travelling modes and a stationary mode. The strongest of these was a difference interaction which led to the growth of a low-azimuthal-number, stationary mode. This mode had the largest amplitude and appeared to dominate transition. In retrospect, we can observe the signs of this mechanism in past flow visualization (Kobayashi, Kohama & Takamadate 1980), and it can account for the ‘jagged’ front normally associated with cross-flow-dominated transition on swept wings.

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Three-dimensional transition studies at ONERA/CERT

Cited by 30 publications

References 1 publication

Large-eddy simulation of laminar-turbulent transition in a swept-wing boundary layer

Large-eddy simulation of laminar-turbulent transition in a swept-wing boundary layer

Large-eddy simulation of boundary-layer transition on a swept wedge

Stationary travelling cross-flow mode interactions on a rotating disk

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