Affiliations: The University of Manchester, School of MACE, George
Begg Building, Manchester M60 1QD, UK. E-mail: [email protected]
Abstract: The physics of compressible vortex loops generated due to the
rolling up of the shear layer upon the diffraction of a shock wave from a shock
tube is far from being understood, especially when shock-vortex interactions
are involved. This is mainly due to the lack of global quantitative data
available which characterizes the flow. The present study involves the usage of
the PIV technique to characterize the velocity and vorticity of compressible
vortex loops formed at incident shock Mach numbers of M = 1.54 and 1.66. Another
perk of the PIV technique over purely qualitative methods, which has been
demonstrated in the current study, is that at the same time the results also
provide a clear image of the various flow features. Techniques such as
schlieren and shadowgraph rely on density gradients present in the flow and
fail to capture regions of the flow influenced by the primary flow structure
which would have relatively lower pressure and density. Various vortex loops,
namely, square, elliptic and circular, were generated using different shape
adaptors fitted to the end of the shock tube. The formation of a coaxial vortex
loop with opposite circulation along with the generation of a third stronger
vortex loop ahead of the primary with same circulation direction are of the
interesting findings of the current study.