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Topological modifications due to ramped vanes in a flare-induced shock–boundary layer interaction flowfield


Effect of ′ramped vane′-type vortex generators on a shock-induced flow separation in the vicinity of an axisymmetric compression corner was evaluated. Numerical simulations were performed at Mach 2 on a cone–cylinder–flare model with a flare angle of 24°. The undisturbed boundary layer thickness (δ) at the location of the compression corner was 5 mm. A single array of these vortex generators with a device height of 0.28δ (1.4 mm) was placed on the cylinder surface at different streamwise positions, viz. 5δ, 10δ and 15δ upstream of the compression corner, and their ability to manipulate the shock–boundary layer interaction flowfield was compared. The presence of these devices caused substantial changes in the interaction region and the separation bubble structure. The separation bubble transformed into a series of spade-shaped structures with pockets of attached flow in between them. The ramped vanes increased the separation length along the device centreline, but this effect was attenuated considerably, by bringing them closer to the interaction region. Moving the ramped vanes closer also had a collapsing effect on the spade-shaped structures, which simultaneously widened the attached flow zones in between them.

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F1, F2 :

Separation foci


Height of the ramped vane device (1.4 mm)

HU :

Height of the triple point in the uncontrolled interaction


Upstream influence length (mm)

LAvg :

Average upstream influence length in the controlled interactions (mm)

LU :

Upstream influence length for the uncontrolled interaction (mm)


Attachment node


Local mean wall static pressure (kPa)

PInf :

Freestream static pressure (kPa)

PO :

Stagnation pressure (kPa)


Radial coordinate (mm)


Ramped vane


Separation length/thickness (mm)

SU :

Separation length/thickness for the uncontrolled interaction (mm)


Saddle point


Local velocity (m/s)

VInf :

Freestream velocity (m/s)


Axial coordinate (mm)


Axial position of the RV array (mm)


Main shock angle (~ 41°)


Boundary layer thickness (5 mm)


Azimuthal coordinate (deg)


Local density (kg/m3)

ρInf :

Freestream density (kg/m3)

ωx :

Streamwise vorticity (s1)


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The first author wishes to thank DIAT for the institute fellowship. The technical support of Mr. A. Narayana, Mr. M. S. Eshwar and Mr. V. Biju during the wind tunnel testing at CSIR-NAL is gratefully acknowledged. Special thanks to Mr. Bhushan Lokhande, Mr. Mandar Mate, Mr. Vaibhav Gonjari of the Department of Aerospace Engineering, DIAT for their assistance during the procurements and model fabrication process. The support of Mr. Gabriel Joseph during the computations is also recognized.

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Correspondence to T. Nilavarasan.

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Nilavarasan, T., Joshi, G.N., Misra, A. et al. Topological modifications due to ramped vanes in a flare-induced shock–boundary layer interaction flowfield. J Vis 24, 991–1010 (2021).

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  • Compression corner
  • Flare
  • Flow control
  • Vortex generators
  • Flow separation