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Flow regimes associated with yawed rectangular cavities

Published online by Cambridge University Press:  04 July 2016

M. Czech ,
E. Savory ,
N. Toy  and
T. Mavrides
M. Czech
Affiliation:
Fluid Mechanics Research Group, Department of Civil Engineering, University of Surrey Guildford, UK
E. Savory
Affiliation:
Fluid Mechanics Research Group, Department of Civil Engineering, University of Surrey Guildford, UK
N. Toy
Affiliation:
Fluid Mechanics Research Group, Department of Civil Engineering, University of Surrey Guildford, UK
T. Mavrides
Affiliation:
Fluid Mechanics Research Group, Department of Civil Engineering, University of Surrey Guildford, UK
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Abstract

The present work is concerned with the aerodynamics of the turbulent boundary-layer flow over yawed rectangular cavities with the focus on the steady and unsteady pressures generated by the interaction. Cavities with a planform aspect ratio of 4-85 and streamwise length to depth ratios from 1 to 3 were studied experimentally in a low-speed wind tunnel.

The results indicated three main types of cavity flows. The shear layer bridges the cavity for small angles between mean flow direction and minor cavity axis. The flow field remains almost two-dimensional with little change in drag coefficient. Strong instabilities, associated with a rise in drag coefficient, are found when the cavity is yawed to greater angles. An aerodynamic feedback mechanism depending on interactions between the separated shear layer and the cavity fluid is suggested as the mechanism responsible for the generated oscillations. The influence of the cavity depth is, hereby, found to be fundamental as it determines the degree to which interactions between the separated shear layer and the cavity base occur. As a result both the magnitude and the frequency of the instabilities are a function of the cavity depth. When rotating to higher angles a greater portion of the shear layer reattaches to the cavity base which leads to a loss of flow organisation and a significant increase in drag.

Type
Research Article
Information
The Aeronautical Journal , Volume 105 , Issue 1045 , March 2001 , pp. 125 - 134
Copyright
Copyright © Royal Aeronautical Society 2001 

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