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On the effect of different step geometries on disturbance growth in 3D boundary layers

Placidi, Marco and Atkin, Chris J. (2016) On the effect of different step geometries on disturbance growth in 3D boundary layers In: The 2016 RAeS Applied Aerodynamics Conference, 19-21 Jul 2016, Bristol, UK.

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Abstract

Experiments on the stability of a 3D boundary layer were performed in a very low turbulence wind tunnel (Tu ͌ 0:006%U¥). The effect of different shapes of surface steps (of h = 200 mm) located at 20% chord were investigated by looking into the crossflow modes evolution and growth. Stable crossflow vortices were generated by the means of discrete roughness elements (DREs) positioned upstream of the steps. Preliminary results seem to suggest that the different step geometries have a severe influence on both the maximum disturbance growth and the excitation of the primary mode and its harmonics. These different surface imperfections also seem to play a critical role on the appearance of the non-linear phase of the instability. Finally, the different step geometries are shown to influence the transition front location by up to 9%, which results in performance degradation. The softer and more gradual geometrical disturbance (i.e. Pyramid-type step) was found to minimise the performance loss, providing that each step comprising the complex geometry is designed to be conservatively subcritical.

Item Type: Conference or Workshop Item (Conference Paper)
Divisions : Faculty of Engineering and Physical Sciences > Mechanical Engineering Sciences
Authors :
NameEmailORCID
Placidi, Marcom.placidi@surrey.ac.uk
Atkin, Chris J.
Date : 19 July 2016
Copyright Disclaimer : © 2016 The Authors.
Related URLs :
Depositing User : Clive Harris
Date Deposited : 17 Oct 2018 13:48
Last Modified : 18 Oct 2018 09:28
URI: http://epubs.surrey.ac.uk/id/eprint/849717

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