やりの空気力に振動が与える影響を評価する試み

抄録

The aerodynamics of the javelin is treated as a rigid body in spite of it flies with vibration in actual flight, and it seems there is no wind tunnel test result considered the effect of vibration. The objective of this study is to evaluate the effect of vibration for the aerodynamic force acting on the javelin using 1-m Magnetic Suspension and Balance System (1-m MSBS) in Institute of Fluid Science, Tohoku University. 1-m MSBS can conduct the dynamic wind tunnel test by controlling the coil current. However, the natural vibration frequency of javelin is too high to control with 1-m MSBS. We attempted to control the generation and suppression of natural vibration by adopting the notch-filter which is commonly used to prevent the resonance phenomenon. As a result, it became possible to control the amplitude of vibration. With this method, we performed wind tunnel test with a wind speed of 25 m/s, and angle of attack of 0° to 18°. Although the amplitude of the vibration was only 4.4% respect to the maximum diameter of javelin, a few percent difference was recognized in the aerodynamic coefficient of drag, lift and pitching moment.