Flow visualisation of leading edge vortices on a Delta Wing by laser sheet technique

Gopinath, PR and Sundaram, S and Madhavan, KT and Siddalingappa, SR and Yajnik, KS (1988) Flow visualisation of leading edge vortices on a Delta Wing by laser sheet technique. Technical Report. National Aeronautical Laboratory, Bangalore, India.

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Abstract

A technique of illuminating a section of the flow which has13; become very popular recently uses a sheet of light obtained by expanding a laser beam by passing it through a cylindrical lens system . This report gives the results of first application of this technique in NAL. A delta wing of aspect ratio 0 .53 was placed in the NAL boundary layer tunnel at various incidences upto 35 0 and sideslip angles upto 20 0 . The freestream speed was 3m/s, the chord Reynolds number being 0 .53 x 105 quot;. Smoke was introduced upstream of the apex of the wing model . Vertical planes at 40% to 75% of chord were illuminated by the laser sheet by traversing the laser . The cross-sections of the flow within the vortices above the delta wing model and also downstream of the trailing edge were photographed . The pictures show sharp vortex cores changing into diffused cores over a relatively small distance . There is a secondary instability of shear layer visible in some photographs especially in the transition region .

Item Type:	Monograph (Technical Report)
Uncontrolled Keywords:	Delta wing;Leading edge vortices;Flow visualisation
Subjects:	ENGINEERING > Fluid Mechanics and Thermodynamics
Depositing User:	Poornima Narayana
Date Deposited:	09 Aug 2006
Last Modified:	24 May 2010 04:15
URI:	http://nal-ir.nal.res.in/id/eprint/2017

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