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Mechanisms of distributed and localized excitation of unsteady Görtler modes by free-stream vortices

Mechanisms of distributed and localized excitation of unsteady Görtler modes by free-stream vortices Abstract The present study is devoted to the investigation of several, presumably most efficient, mechanisms of the production of non-stationary Görtler vortices in a laminar boundary layer on a concave wall due to scattering of 2D and 3D free-stream vortices by streamwise localized 3D and 2D surface and flow non-uniformities. The experiments were carried out by means of the method of controllable non-stationary disturbances. The interaction of downstream-propagating 3D free-stream vortices with the growing boundary layer, presenting natural 2D bas-flow non-uniformity, was found to lead to a rather efficient excitation of unsteady Görtler modes. This mechanism of distributed receptivity is able to modify considerably the growth rates of the excited Görtler vortices in comparison with the linear stability laws. In the present paper, definitions of the coefficients of distributed vortical receptivity are given and some estimates of values of these coefficients are reported. In spite of a high measurement accuracy and a rather broad range of examined parameters, no excitation of Görtler vortices due to other examined mechanisms was identified. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Thermophysics and Aeromechanics Springer Journals

Mechanisms of distributed and localized excitation of unsteady Görtler modes by free-stream vortices

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References (23)

Publisher
Springer Journals
Copyright
2014 Pleiades Publishing, Ltd.
ISSN
0869-8643
eISSN
1531-8699
DOI
10.1134/S0869864314060018
Publisher site
See Article on Publisher Site

Abstract

Abstract The present study is devoted to the investigation of several, presumably most efficient, mechanisms of the production of non-stationary Görtler vortices in a laminar boundary layer on a concave wall due to scattering of 2D and 3D free-stream vortices by streamwise localized 3D and 2D surface and flow non-uniformities. The experiments were carried out by means of the method of controllable non-stationary disturbances. The interaction of downstream-propagating 3D free-stream vortices with the growing boundary layer, presenting natural 2D bas-flow non-uniformity, was found to lead to a rather efficient excitation of unsteady Görtler modes. This mechanism of distributed receptivity is able to modify considerably the growth rates of the excited Görtler vortices in comparison with the linear stability laws. In the present paper, definitions of the coefficients of distributed vortical receptivity are given and some estimates of values of these coefficients are reported. In spite of a high measurement accuracy and a rather broad range of examined parameters, no excitation of Görtler vortices due to other examined mechanisms was identified.

Journal

Thermophysics and Aeromechanics – Springer Journals

Published: Dec 1, 2014

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