An Investigation of the Surface Pressure Fields beneath Simulated Tornado Cyclones

Abstract

The wall static pressure fields beneath tornado-like vortices have been investigated using a large vortex generator especially designed to model tornado cyclone airflow. Presented in nondimensional form, the data include both a series of radial profiles across the mean pressure field under a variety of flow conditions, and a detailed investigation of the magnitude of the central pressure as a function of swirl. The profiles clearly show the development of the intense vortical core from the no-swirl state, and the evolution of the core from a one-celled into a two-celled flow. For the experimental range examined, it is found that the greatest pressure deficits and largest pressure gradients (in the mean field) are associated with single-celled vortices. Strong evidence is found for the existence of a dynamically induced downdraft in the two-celled vortex.