CHARACTERISTICS OF THE SPEEDS AND PRESSURE DROPS OF PHYSICALLY SIMULATED TORNADOES

Compared with monsoons and typhoons, the tornadoes with the smallest scales and the highest speeds are difficult to measure by meteorological observation instruments. Until now, little wind field information of tornado speeds and pressure drops was obtained by using Doppler radars. The field-measured tornado data are not enough to investigate the wind characteristics. To comprehensively recognize tornados, it is significant to study the wind fields of tornadoes generated by scaled-down physical simulators in the laboratory. Different wind fields of tornadoes with five swirl ratios are produced by the tornado simulator in Beijing Jiaotong University. The spatial distribution characteristics of the tornadoes including the tangential, radial, vertical wind speeds and pressure drops are summarized and analyzed. The simulation results are compared with those recorded in full-scale measurements and determined by theoretical models. The results indicate that the shapes of the simulated tornadoes are similar to those of the actual cases. Furthermore, the distributions of wind speeds and pressure drops generally agree with the actual observed data and theoretical results based on the modified Rankine vortex model. The comparisons prove the validity of the current tornado simulator, which provides a good experimental platform to examine the tornado-induced effects on buildings, bridges, power transmission lines and other infrastructures.