Direct Measurement of Aerodynamic Characteristics of Flying Debris Models by Stand-alone Measuring Device

Abstract

Most damage to houses and buildings in strong wind such as typhoon or tornado are caused by the impact of flying debris such as stones or sticks. In order to reduce the damage, the estimation of impact force by clarifying the aerodynamic characteristics of flying debris is required. In many cases, the flying debris has a non-streamline shape, i.e. “bluff-body”. Therefore, this study aims to measure directly the aerodynamic characteristics of bluff-body. Stand-alone measuring device assembled with pressure sensors, three-axes accelerometer, gyro sensor, microcomputer, SD card and battery was developed, and was built in a bluffbody modeled typical shape of flying debris, such as cube, plate and rod. These models were dropped from a stage in a dome located at 50m height from the ground with windless condition. The pressure, the acceleration and the angular velocity were measured, while capturing the falling motion of bluff-body by video cameras. The measuring method with the proposed device in this study was evaluated by comparing with the image analysis of movie records.