Simulation Of The Interaction Of Lightning Leaders And Structures

In order to study the interaction of lightning leaders and structures, the connection process of downward leader and upward leader was simulated in this paper. Physical model selected the direction of next step is the direction of maximum potential gradient. Random model selected the direction of next step randomly according to probability.Simulation results of a 2D physical model show that the length of stepped leader ranges from 14.2m to 82.9m. The induced charge of downward leader is about 10 ?5 C/m. The length of stepped leader and the induced charge of downward leader increase with the propagation of downward leader. Simulation results are consistent to the observed results. The model simulated several different conditions, such as different potential of downward leader, different dimension of the structure and different height and location of lightning rod. Simulation results show that attractive radius of lightning rod is different in different condition. The corner of structure has some attractive radius and can compete with lightning rod on structure. In the design of lightning protection, attractive effect of corner to lightning leader should be considered.Simulation results of a 2D random model show that the length of the final jump ranges from 41m to 81m. The induced charge of downward leader is about 10 ?4 C /m. Downward leader has the branch phenomenon. The branch of downward leader increases with the propagation of downward leader. There are diversiform forms in connection process. The downward leader above lightning rod does not have 100 percent probability to connect with the lightning rod. The downward leader far away from lightning rod is much possible to connect with the lightning rod. In most condition, lightning rod can provide the structure from lightning. In the condition of the same dimension of the structure, the larger the distance between downward leader and lightning rod is, the smaller the probability of effective lightning rod protection is. In the condition of the same distance between downward leader and lightning rod, the wider the structure is, the lower the structure is, the smaller the probability of effective lightning rod protection is.On the base of a 2D random model, simulation results of a 3D random model show that the length of the final jump is consistent with the result of 2D projection. Downward leader has the branch phenomenon obviously. The branch of downward leader increases with the propagation of downward leader. The induced charge of downward leader from 2D projection increases with the propagation of downward leader and the induced charge of downward leader is about 10 ?4 C /m.