This paper presents a numerical method of predicting dynamic motion of a net in the wind flow. The flexible and incompressive net method was used for the numerical simulation for dynamic motion of a net. The large eddy simulation was used for the numerical calculation for unsteady turbulent flow around the net. The net was modeled as a mesh consisting of nonlinear line components. The wind force to the modeled net was evaluated as a drug force, which was described as a function with the angle between the wind vector and the normal vector to the modeled net component based on the wind tunnel experiment. The force term equivalent to the reacting force of the wind force to the net was added to the momentum equation of the flow. The dynamic motion of the net and turbulent flow were calculated simultaneously. The calculated results were compared with the wind tunnel data and evaluated quantitatively. The predicted motion of the net shows good correlation to the experimental results.
We manufactured an air-cannon, that is a missile-propulsion device, for the impact resistant test of cladding against windborne debris. The air-cannon consists of a compressed-air supply, pressure control and release valves, a barrel, a support frame and a speed-measuring system. Sets of photoelectric sensors mounted on the barrel are used for measuring the speed of the missile. The cannon is capable of propelling a missile at a specified speed and orientation towards a specified impact location. We calibrated the speed measuring system by a high-speed video camera. The fastest speed was 75m/s for a 3kg lumber. Tolerances for the measured impact speed were satisfied the specification of ISO16932.