Comment les anneaux tourbillonnaires sont-ils affectés par les compressibilités?
This study explores the behaviour of shock-generated compressible vortex rings. A comparison between these results and the behaviour of incompressible rings is made in order to identify the effects of compressibility on the flow. Three aspects of the problem are studied: the first is the production of compressible vortex rings. A comparison is made between the equipment used in incompressible and compressible studies. Then, a way to gain some control over the fluid ejection velocity program of compressible ring generators is presented.This method highlights the similarities that exist between the compressible and incompressible studies. The second part looks at the propagation of compressible vortex rings produced by two distinct generators. We find that neither compressibility, nor viscosity effects have any measurable effects on the observations. However, the ejection velocity program that characterizes the ring generator has an influence on both the propagation and the trajectory of the rings. Finally, the formation process of compressible rings is explored by studying the evolution of the ring's circulation as it propagates. By comparison with results regarding incompressible rings, we find that compressibility stretches the formation time of the rings. And again, the ejection velocity program affects the results as the observed ring circulation levels are different for different velocity programs. These results explain the origin of the embedded shock previously observed at the center of the ring and make it possible to predict its formation.
- Génie – Thèses