Simulation of Vortex Ring Formation and the Effect of Piston VelocityProgram on the Formation Number
Department of Mechanical Engineering, University of Alaska Anchorage, Anchorage, AK 99508, USA
- *Corresponding Author:
- Peng J
Department of Mechanical Engineering
University of Alaska Anchorage
Anchorage, AK, USA
Tel: +1 907-786-1800
E-mail: [email protected]
Received Date: September 01, 2015 Accepted Date: September 19, 2015 Published Date: September 28, 2015
Citation: Peng J (2015) Simulation of Vortex Ring Formation and the Effect of Piston Velocity Program on the Formation Number. J Vortex Sci Technol 2:120. doi:10.4172/2090-8369.1000120
Copyright: © 2015 Peng J. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Vortex ring formation is a limited growth process. Upon reaching a non-dimensional formation number, the vortex ring pinches off and secondary vortices form in the trailing jet. However, since a larger vortex ring is associated with higher propulsive efficiency, it is desired to delay vortex ring pinch-off. In this study, a numerical model based on vortex sheet method was used to study vortex ring formation from a piston-cylinder apparatus, with the focus on the vortex ring pinch-off at formation number F. Studies on the various piston velocity programs showed that piston acceleration is able to delay the vortex ring pinch-off and the formation of secondary vortices. The delay is more significant when the vortex ring pinch-off occurs while the piston is accelerating. Acceleration of piston before a constant velocity period would still delay the vortex ring pinch-off, but to a much smaller extent.