Effect of Small Bluntness on Formation of Görtler Vortices in a Supersonic Compression Corner Flow

Chuvakhov, P. V.; Borovoy, V. Ya.; Егоров, И. В.; Radchenko, Vladimir; Olivier, H.; Roghelia, Amit

doi:10.1134/s0021894417060037

Cited by 54 publications

(44 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, the appearance of the temperature streaks near reattachment is triggered by the growth of streamwise velocity and vorticity as well as by the amplification of upstream temperature perturbations by the reattachment shock. In contrast to previous studies (Chuvakhov et al 2017;Roghelia et al 2017a;Navarro-Martinez & Tutty 2005), our analysis demonstrates the importance of baroclinic terms in cold wall hypersonic boundary layers and shows that the centrifugal effects play only a minor role in the emergence of steady reattachment streaks. We also show that the spanwise scale selection results from the interplay between the presence of flow perturbations in the separation bubble and in the reattaching shear layer.…”

Section: Introductioncontrasting

confidence: 99%

“…The spanwise wavelength of the global instability scales with the recirculation length (Sidharth et al 2017). This is in contrast to the spanwise wavelength observed for reattachment streaks (Chuvakhov et al 2017;Roghelia et al 2017a;Navarro-Martinez & Tutty 2005), which scale with the separated boundary layer thickness, indicating that the global instability is not responsible for their formation. To characterize the role of external perturbations in the formation of these streaks, we consider compression ramp flows that do not exhibit 3D global instability.…”

Section: Introductionmentioning

confidence: 57%

“…These techniques were employed to study the formation of streamwise streaks and reattachment heat flux patterns. Previous studies (Inger 1977;Simeonides & Haase 1995;Chuvakhov et al 2017) attribute the observed structures to Görtler-like vortices which develop from upstream perturbations (Hall 1983) and can be amplified by centrifugal effects in the regions of concave streamline curvature near reattachment. However, in most compression ramp studies, the comparison with the theory of Görtler instability on curved walls is only qualitative.…”

Section: Introductionmentioning

confidence: 89%

“…Herein, we employ the I/O framework to study the amplification of infinitesimal spanwise periodic upstream disturbances in hypersonic compression ramp flow and explain origin of the heat streaks at reattachment. Recently, Roghelia et al (2017a) and Chuvakhov et al (2017) reported multiple hypersonic compression ramp experiments in two different facilities with matched freestream Mach and Reynolds numbers. Temperature sensitive paint (TSP) and infrared thermography measurements of reattachment heat-flux wall patterns revealed quantitatively similar streaks.…”

Section: Input-output Analysis Of Hypersonic Compression Ramp Flowmentioning

confidence: 99%

“…Recently, Roghelia et al (2017a) and Chuvakhov et al (2017) investigated hypersonic compression ramp flows using temperature sensitive paint (TSP) and infrared (IR) imaging. These techniques were employed to study the formation of streamwise streaks and reattachment heat flux patterns.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Reattachment streaks in hypersonic compression ramp flow: an input–output analysis

Dwivedi¹,

Sidharth

Nichols³

et al. 2019

J. Fluid Mech.

View full text Add to dashboard Cite

We employ global input-output analysis to quantify amplification of exogenous disturbances in compressible boundary layer flows. Using the spatial structure of the dominant response to time-periodic inputs, we explain the origin of steady reattachment streaks in a hypersonic flow over a compression ramp. Our analysis of the laminar shock/boundary layer interaction reveals that the streaks arise from a preferential amplification of upstream counter-rotating vortical perturbations with a specific spanwise wavelength. These streaks are associated with heat flux striations at the wall near flow reattachment and they can trigger transition to turbulence. The streak wavelength predicted by our analysis compares favorably with observations from two different hypersonic compression ramp experiments. Furthermore, our analysis of inviscid transport equations demonstrates that base flow deceleration contributes to the amplification of streamwise velocity and that the baroclinic effects are responsible for the production of streamwise vorticity. Finally, the appearance of the temperature streaks near reattachment is triggered by the growth of streamwise velocity and streamwise vorticity perturbations as well as by the amplification of upstream temperature perturbations by the reattachment shock.

show abstract

Section: Introductioncontrasting

confidence: 99%

Section: Introductionmentioning

confidence: 57%