龙卷风风场的试验模拟

Physical Study on Tornado like Flow Based on Tornado Vortex Simulator

摘要:

为试验研究龙卷风气流特性及其作用于结构上的风荷载，建立了新型龙卷风模拟器（TVS）.该模拟器主要由顶部悬吊的控制风机、环状管道以及导流板组成；并设置水平轨道，使其可以0.4 m·s-1的最大速度在水平方向移动.基于该龙卷风模拟器，试验中采用眼镜蛇探头测试了涡流比从0.11到0.54（导流板角度20°~60°）情况下的龙卷风风场，并与1998年5月30日发生在南达科他州Spencer的龙卷风，1999年5月3日发生在俄克拉荷马州Mulhall的龙卷风以及2003年6月24日发生在南达科他州Manchester的龙卷风多普勒雷达观测数据进行了比较.结果表明切向速度和静压均符合真实龙卷风分布.由此说明该模拟器可产生稳定的龙卷风涡旋，可用于龙卷风风场的模拟.

Abstract:

Tornado vortex simulator (TVS) in Tongji University was constructed to generate translating tornado like vortices for the physical simulation of tornado like vortex and quantifying tornado induced aerodynamic loads on structures. A controlled fan, an annular duct and turning vanes suspended from the overhead crane composed the main parts generating tornado like vortex, which could also be translated as a whole along a ground plane at the maximum speed of 0.4 m·s-1. The tornado like flows with swirl ratios ranging from 0.11 to 0.54 achieved by changing vane angle (θV=20°~60°) were simulated by the simulator and measured with TFI Cobra Probes. The flow structures of the vortices were validated by comparing with the mobile Doppler radar observations of three major tornados happened in Spencer, South Dakota May 30, 1998 and Mulhall, Oklahoma May 3, 1999 and Manchester, South Dakota June 24, 2003 respectively. The structures of the tangential velocity and the surface pressure of the simulated tornado like flow were found to agree well with the measured data of the tornados, indicating that this simulator could generate stable tornado like vortex and be used to simulate tornado like flow physically.