【摘要】 提出了雷暴冲击风作用下地面风压分布的简便计算公式.以圆柱体计算流域模拟雷暴冲击风场,采用大涡模拟(LES)方法结合壁面射流模型对雷暴冲击风场进行了数值模拟,获得了雷暴冲击风从初始喷射到流场稳定的发展过程.射流前沿有一水平涡环,随着时间的推移而冲向地面,然后沿径向远离中心而去.分析得到了雷暴冲击风作用下地面的风压系数时程和时均风压系数,以及不同时刻的风速剖面.风速剖面与理论结果吻合良好,验证了方法的可靠性.仿真结果表明,雷暴冲击风场中心处压力系数最大,压力系数随着径向坐标的增大而减小,提出的公式能够很好地表达雷暴冲击风作用下地面处风压的分布特征.更多还原

【Abstract】 A simplified formula for the pressure distribution of downbursts is proposed.Using impinging jet model,large eddy simulations were carried out in a cylindrical domain with uniform jet profiles and proper boundary conditions.The time evolution of wind field of a downburst is obtained: there is a level vortex ring at the front of the jet,rushing towards the ground and then radically leaving from the center.Velocity profiles of a downburst were studied,and the results are compared with the data obtained from empirical models.The simulations show that the pressure coefficient reaches maximum at the center of thunderstorm downburst;it decreases as radial coordinate increases.The wind pressure distribution on ground under impingement of downbursts can be expressed very well by the proposed formula.更多还原