Author:
URBAN WILLIAM D.,MUNGAL M. G.
Abstract
In the present study, we use particle image velocimetry (PIV) to obtain planar, two-component velocity fields in two-dimensional, turbulent mixing layers at convective
Mach numbers Mc of 0.25, 0.63, and 0.76. The experiments are performed in a large-scale blowdown wind tunnel, with high-speed free-stream Mach numbers up to 2.25
and shear-layer Reynolds numbers up to 106. Specific issues relating to the application
of PIV to supersonic flows are addressed. The instantaneous data are analysed to
produce maps of derived quantities such as vorticity, and ensemble averaged to
provide turbulence statistics. The results show that compressibility introduces marked
changes in the disposition of instantaneous velocity gradients within the layer, and
hence in the vorticity field. In particular, peak transverse vorticity values are seen
to be confined to thin streamwise sheets under compressible conditions, with little
transverse communication. The location of these sheets near the lab-frame sonic
velocity suggests a sensitivity of the compressible layer to stationary disturbances.
Turbulence statistics derived from the planar velocity measurements confirm previous
observations of strong suppression of transverse velocity fluctuations and primary
Reynolds stress as Mc increases between 0.25 and 0.76.
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics
Cited by
93 articles.
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