4/5/2024 0 Comments Tornado simulator v.3 alphaIn recent years, large-scale translating experimental tornado simulators have been built to study tornado wind fields and the interactions with buildings. However, due to various constraints, these simulators cannot facilitate comprehensive study of vortex translation. Following this, extensive studies using analytical models ( Harlow and Stein, 1974 Jischke and Parang, 1974 Baker and Church, 1979 Rotunno 1979 Fiedler and Rotunno, 1986) and physical tornado simulators ( Wan and Chang, 1972 Church et al., 1979 Mitsuta and Monji, 1984 Monji, 1985 Haan et al., 2008 Matsui and Tamura, 2009 Hashemi Tari et al., 2010 Refan et al., 2014 Gillmeier et al., 2017 Refan and Hangan, 2018 Ashton et al., 2019 Gillmeier et al., 2019 Ashrafi et al., 2021) as well as numerical simulators ( Ishihara et al., 2011 Ishihara and Liu, 2014 Eguchi et al., 2018 Yuan et al., 2019 Gairola and Bitsuamlak, 2019 Kashefizadeh et al., 2019 Kawaguchi et al., 2019 Li et al., 2020) had been conducted in order to study the flow fields of tornado-like vortices. The study proposed that the radial momentum flux is one of the primary parameters sustaining the vortex flow structure and showed the reproduction of vortex evolution by adjusting the angular momentum. Ward’s vortex simulator utilises an exhaust fan atop the simulator to provide the updraft flow and a number of guide vanes near the ground to generate the required angular momentum for the formation of the vortices. The earliest systematic attempt to experimentally study laboratory-scaled tornado-like vortices is frequently attributed to Ward (1972). As a result, the modelling of tornadoes using analytical models, laboratory-scaled experiments and numerical simulation have been the alternatives to study the flow fields of tornado-like vortices. Therefore, the study on tornadoes has received growing attention in recent years with the desire to reduce the socio-economic losses that would occur in the event of such devastating weather events.ĭue to the violent wind speed, unpredictable tracks and short warning lead time of only 10–15 min ( Savory et al., 2001), direct measurements are not always possible and can be very dangerous. In 2011 alone, tornadoes claimed the lives of more than 500 people and caused $10 billion dollars in damage in the United States, according to the National Oceanic and Atmospheric Administration ( NOAA, 2012). ![]() Each year more than 1,200 tornadoes are reported in the United States causing approximately 80 deaths, 1,500 injuries and more than $800 million worth of damage ( NOAA, 2012). Tornadoes are one of the most devastating weather events due their violent wind speed and unpredictable nature. Finally, the framework using uniform flow to reproduce the flow conditions which are comparable to those generated by a translating vortex simulator is proposed and discussed in detail. Based on the analysis on the database of National Oceanic and Atmospheric Administration (NOAA), the normalised translation speed of the recorded tornadoes across the EF scales, appears to vary from 0.25 to 0.37, with an average of 0.32 (∼18.8 m/s). Additionally, the maximum forces on a body subjected to a moving tornado can be predicted using uniform flow providing that the appropriate range of inflow angles are known. Further comparison with varying airfoil sizes and distance to tornado translating path (Case 3) showed that the relative inflow and outflow angle is the primary factor affecting the lift on the airfoil. However, the overall lift force appeared to be largely insensitive to the tornado translation velocity due gross changes in pressure on either side of the airfoil cancelling each other out. Investigation on the impact of varying airfoil thickness (Case 2) revealed that the location of the tornado has significant effect on the overall lift force. Analysis showed that the maximum overall pressure at a point was found to increase by up to 20% when the normalised translating velocity was 10% of the tangential velocity, but increases up to 60% when the normalised translating velocity is 30% of the tangential velocity. A panel method was used to compute the flow around an airfoil and an idealised tornado is represented using a moving vortex via unsteady potential flow. A thin symmetrical airfoil was used to explore the effects of tornado translation on a body. ![]() This paper investigates the effects of tornado translation on pressure and overall force experienced by an airfoil subjected to tornado loading and presents a framework to reproduce the flow conditions and effects of a moving tornado. 3Department of Engineering, Calvin University, Grand Rapids, MI, United States.2Boundary Layer Wind Tunnel Laboratory, Western University, London, ON, Canada.1School of Engineering, University of Birmingham, Birmingham, United Kingdom.
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