Richtmyer-Meshkov Instability Shock Tube Experiments

About the Experiment:

   Richtmyer-Meshkov instability occurs whenever a shock wave passes over a nearly planar interface separating two fluids of unequal density. It is one of the most fundamental fluid instabilities and is of importance to applications ranging from astrophysics to supersonic combustion. Previous experimental studies have been hampered by the difficulty in generating a well defined interface between two gases. We have overcome this difficulty in our experiments by utilizing a flow system in which a light gas (Air) and a heavy gas (SF6) flow from opposite ends of the driven section of a vertical shock tube. The gases meet and are allowed to exit the tube through slots in the shock tube wall thus forming a stagnation point flow at the interface location. A sinusoidal perturbation can then be given to this interface by gently oscillating the shock tube in the horizontal direction to produce standing waves. A weak shock wave is then generated by puncturing a diaphragm which travels down the tube where it impacts the interface to produce the instability.

   Planar Laser Induced Fluorescence (PLIF) is utilized to visualize the flow in these experiments by seeding the air with acetone vapor and illuminating it with a sheet of laser light produced by a pulsed Nd:YAG laser. The fluorescent images are then captured by a cooled CCD camera. Pictures below shows a sequence of images illustrating the evolution of the instability in these experiments. The incident shock wave causes the initially sinusoidal perturbation to grow and develop into the characteristic mushroom structures. However the interface is reaccelerated in the opposite direction by an expansion wave which ultimately produces a much more complex turbulent flow.

Pictures:

Click on the image to see larger view



Publications:

Jones M.A. and Jacobs J.W. (1997) "A membraneless experiment for the study of Richtmyer-Meshkov instability of a shock-accelerated gas interface" Phys. Fluids , 9, 3078-3085. [paper6.pdf, 2539 KB]

Jacobs, J.W. and Collins, B.D. (1999) "Experimental study of the Richtmyer-Meshkov instability of a diffuse interface," Proceedings of the 22rd International Symposium on Shock Waves.[paper1.pdf, 290 KB][paper1.ps,5742 KB]