2020 年 86 巻 888 号 p. 20-00184
Aerodynamic drag on several types of road cones was measured by wind tunnel experiments purposing improvement of anti-fall-down functions against lateral wind blowing. By opening holes on the side surface of cones, drag coefficient decreased so that maximum endurable wind speed increased over 30 m/s in the best case. This finding contributes to three benefits in road safety; reducing the weight of the cone for workers at roads, cost cutting by manufacturers for the synthetic resin material, and also for security aspects by internal visibility preventing from hidden matters. We also found different aerodynamic characteristics due to bottom plate condition of the cones. That is, when the bottom plate opened to the inner space of the cone, small angle of inclination intensified a recovery moment that pulls back the cone to the standing attitude. This effect significantly improved the maximum endurable wind speed and was explained by the flow allowed inside the cone when the side holes were provided. Such a fluid-structure interaction was analyzed theoretically to clarify the endurance mechanism.