| Popis: |
A shock tube experimental investigation, by the use of a laser sheet diagnostic technique, is undertaken to study the Richtmyer-Meshkov instability of both air/SF6 and air/He interfaces. 2-D initial perturbations (membrane technique) with a relatively high wave number and initial amplitude product (kη0∼2) are considered in order to rapidly reach the non-linear and turbulent regimes. The development of the perturbations is captured at the frequency of 10 Khz after the interface acceleration by a Ms=l.l Mach number shock wave. For the light/heavy (air/SF6) case, we observe a quickly distortion of the initial interface with mushroom-like structures, followed by a relatively lighter vortex development before the reflected shock return, increasing the transition to turbulence. In the heavy/light (air/He) case, after a phase inversion, we found that vortex structures quickly appear and seem to be preponderant at late times after successive re-shock compressions. Finally, the light/heavy case measured perturbation ampli- tudes show good agreements with recent models, despite of the still unpredictable influence of the membrane. |
