ターボジャブの空力特性の計測

抄録

In order to improve the record of the javelic throw in the junior Olympic games, it is important to elucidate the flight characteristics of the “turbo-jav” used in this throwing event. Unlike the spear used in the javelin throw, the turbo-jav has four tail fins. Focusing on the effect of the fins, we investigate the flight characteristics of the turbo-jav, by means of wind tunnel tests, throwing experiments and numerical simulations. In the wind tunnel test, we measured the drag force, lift force and pitching moment acting on intact turbo-javs as well as turbo-javs with their fins cut, in a low speed wind tunnel at the flow speed up to 25 m/s. The experimental results showed that the drag and lift coefficients for the intact turbo-javs are larger than the corresponding values for the turbo-javs without fins. As the angle of attack increases from 0, the moment coefficients for the intact turbo-javs decrease from 0, whereas the moment coefficients for the turbo-javs without fins increase. In accord with this property for the pitching moment, the throwing experiments showed that intact turbo-javs fly stably with oscillating angle of attack around 0. The flying distance, the orbit and the variation of angle of attack for the intact turbo-javs launched by a launcher agree closely with the numerical simulation performed based on the wind tunnel test. A comparison of throwing experiments by an athlete and by the launcher suggested that the turbo-javs flying without rolling could reach farther than turbo-javs with rolling.