龙卷风风场的数值模拟研究

基于同济大学研制的龙卷风物理模拟装置,运用数值模拟方法构建了物理模拟器的数值计算模型,并通过对比龙卷风风场的物理试验模拟结果和现场实测结果,验证了数值计算模型的可行性.在此验证基础上,研究了3种不同涡流比条件下的龙卷风风场结构,对比了不同涡流比条件下龙卷风的三维风场速度(切向速度、径向速度和轴向速度)分布形态、风压分布、龙卷风涡核半径和气流脉动特性.研究结果表明:随着涡流比的增大,龙卷风风场最大切向风速逐渐增大,涡核中心气压降明显降低,涡核半径随之变大,涡核中心附近切向风速的标准差变小;涡流比的增大使龙卷风单涡核逐渐破碎,发展到双涡核.

Numerical Study of Tornado-Like Flow

A numerical computational fluid dynamics (CFD) model to simulate tornado-like vortices was proposed. The tornado-generation mechanism was similar to that of the physical generator developed at Tongji University. The feasibility of this numerical model was verified by comparing the simulation results associated with tornado-like vortices with the experimental and field observation data. Furthermore, the three wind velocity components at tangential, radial and axial directions, wind pressures, vortex radii and turbulence characteristics of tornado-like vortices at three swirl ratios were investigated. The result shows that, with the increase of swirl ratio, the maximum tangential velocity and the radius of vortex core increase when the pressure and the standard deviation of tangential velocity around the tornado-like vortex center decrease. In addition, the single tornado-like vortex gradually breaks down and develops into a double-core structure.