The development of coherent structures within the laminar separation bubble that forms on a NACA 0018 airfoil at an angle of attack of 8 deg and a chord-based Reynolds number of 100,000 is investigated experimentally. A combination of high-speed flow visualizations and time-resolved surface pressure measurements is used to enable quantitative analysis of vortex dynamics. The amplification of disturbances in the separated shear layer leads to the formation of rollup vortices that are shed upstream of the mean reattachment location. The experimental results show that these structures produce distinct, periodic surface pressure fluctuations that can be used to detect, track, and characterize the rollup vortices. A vortex tracking technique is developed and validated in the present investigation. The developed methodology is used to investigate temporal and spatial variation in vortex shedding parameters and to study attendant vortex interactions, which involve merging of two or more consecutive vortices. The results provide new insight into vortex dynamics in laminar separation bubbles, and the developed technique can serve as an efficient tool for future studies and active flow control implementation.
Characterization of Vortex Dynamics in a Laminar Separation Bubble
2017
Aufsatz (Zeitschrift)
Englisch
Characterization of Vortex Dynamics in a Laminar Separation Bubble
Online Contents | 2017
|