Effect of wall transpiration and heat transfer on Görtler vortices in high-speed flows

Adrian Sescu, Radwa Al-aziz, Mohammed Afsar

Research output: Contribution to journalArticle

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Abstract

Görtler vortices in boundary layer flows over concave surfaces are caused by the imbalance between centrifugal effects and radial pressure gradients. Depending on various geometrical and/or freestream flow conditions, vortex breakdown via secondary instabilities leads to early transition to turbulence. It is desirable, therefore, to reduce vortex energy in an attempt to delay the transition from laminar to turbulent flow, and thereby achieve a reduced frictional drag. To this end, we apply a proportional control algorithm aimed at reducing the wall shear stress and the energy of Görtler vortices evolving in high-speed boundary layers. The active control scheme is based on wall transpiration with sensors placed either in the flow or at the wall. In addition, we evaluate the effect of wall cooling and heating on Görtler vortices evolving in high-speed boundary layers, by reducing or increasing the upstream wall temperature.

The numerical results are obtained by solving the full Navier-Stokes equations in generalized curvilinear coordinates, using a high-order numerical algorithm. Our results show that the active control based on wall transpiration reduces both the wall shear stress and the energy of the Görtler vortices; the passive control based on wall cooling or heating reduces the wall shear stress, but slightly increases the energy of the vortices in both supersonic and hypersonic regimes.
Original languageEnglish
Pages (from-to)1159-1171
Number of pages13
JournalAIAA Journal
Volume57
Issue number3
Early online date11 Jan 2019
DOIs
Publication statusPublished - 31 Mar 2019

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Transpiration
Vortex flow
Heat transfer
Shear stress
Boundary layers
Cooling
Heating
Boundary layer flow
Hypersonic aerodynamics
Pressure gradient
Navier Stokes equations
Turbulent flow
Drag
Turbulence
Sensors

Keywords

  • boundary layer transition
  • control theory
  • computational fluid dynamic (CFD)

Cite this

Sescu, Adrian ; Al-aziz, Radwa ; Afsar, Mohammed. / Effect of wall transpiration and heat transfer on Görtler vortices in high-speed flows. In: AIAA Journal. 2019 ; Vol. 57, No. 3. pp. 1159-1171.
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Effect of wall transpiration and heat transfer on Görtler vortices in high-speed flows. / Sescu, Adrian; Al-aziz, Radwa; Afsar, Mohammed.

In: AIAA Journal, Vol. 57, No. 3, 31.03.2019, p. 1159-1171.

Research output: Contribution to journalArticle

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AU - Al-aziz, Radwa

AU - Afsar, Mohammed

N1 - Note the change in article title, altered immediately prior to publication from 'Effect of wall transpiration and heat transfer on nonlinear Görtler vortices in high-speed boundary layers' to 'Effect of wall transpiration and heat transfer on Görtler vortices in high-speed flows'.

PY - 2019/3/31

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N2 - Görtler vortices in boundary layer flows over concave surfaces are caused by the imbalance between centrifugal effects and radial pressure gradients. Depending on various geometrical and/or freestream flow conditions, vortex breakdown via secondary instabilities leads to early transition to turbulence. It is desirable, therefore, to reduce vortex energy in an attempt to delay the transition from laminar to turbulent flow, and thereby achieve a reduced frictional drag. To this end, we apply a proportional control algorithm aimed at reducing the wall shear stress and the energy of Görtler vortices evolving in high-speed boundary layers. The active control scheme is based on wall transpiration with sensors placed either in the flow or at the wall. In addition, we evaluate the effect of wall cooling and heating on Görtler vortices evolving in high-speed boundary layers, by reducing or increasing the upstream wall temperature.The numerical results are obtained by solving the full Navier-Stokes equations in generalized curvilinear coordinates, using a high-order numerical algorithm. Our results show that the active control based on wall transpiration reduces both the wall shear stress and the energy of the Görtler vortices; the passive control based on wall cooling or heating reduces the wall shear stress, but slightly increases the energy of the vortices in both supersonic and hypersonic regimes.

AB - Görtler vortices in boundary layer flows over concave surfaces are caused by the imbalance between centrifugal effects and radial pressure gradients. Depending on various geometrical and/or freestream flow conditions, vortex breakdown via secondary instabilities leads to early transition to turbulence. It is desirable, therefore, to reduce vortex energy in an attempt to delay the transition from laminar to turbulent flow, and thereby achieve a reduced frictional drag. To this end, we apply a proportional control algorithm aimed at reducing the wall shear stress and the energy of Görtler vortices evolving in high-speed boundary layers. The active control scheme is based on wall transpiration with sensors placed either in the flow or at the wall. In addition, we evaluate the effect of wall cooling and heating on Görtler vortices evolving in high-speed boundary layers, by reducing or increasing the upstream wall temperature.The numerical results are obtained by solving the full Navier-Stokes equations in generalized curvilinear coordinates, using a high-order numerical algorithm. Our results show that the active control based on wall transpiration reduces both the wall shear stress and the energy of the Görtler vortices; the passive control based on wall cooling or heating reduces the wall shear stress, but slightly increases the energy of the vortices in both supersonic and hypersonic regimes.

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