Near surface experimental exploration of tornado vortices

作者：Refan Maryam^*; Hangan Horia

来源：Journal of Wind Engineering and Industrial Aerodynamics, 2018, 175: 120-135.

DOI：10.1016/j.jweia.2018.01.042

• Tornado-like vortex
• Swirl ratio
• Laboratory simulations
• Surface pressure measurements
• Particle Image Velocimetry
• Reynolds number dependency
• Surface layer

Large scale and high-resolution surface pressure and Particle Image Velocimetry measurements were carried out in a new testing chamber, the WindEEE Dome, to investigate the structure of stationary tornado-like vortices and their surface layer over a broad range of swirl ratios and at the highest radial Reynolds numbers ever achieved in laboratory simulations of tornadoes. The large size of vortices simulated in this facility allows for the laboratory resolution needed for near surface exploration.
It is shown that at low swirls, tornado vortices are unstable and highly characterized by wandering. A qualitative investigation of the vortex wandering and a preliminary estimation of the effect of vortex wandering on time-averaged pressures are performed. Also, surface pressure data are used to examine the Reynolds number dependency of the flow. A clear demarcation of the surface layer behavior inside versus outside of the vortex core is observed. Normalizing axial profiles of core radii and tangential velocities in the region outside of the vortex core with the core radius and height of the maximum tangential velocity suggests self-similarity of the flow with future implications for empirical modeling. Axial profiles of the radial velocity are used to determine the vortex structure at various swirl ratios.

• 出版日期2018-4