| Research Abstract |
Measurement of unsteady aerodynamic force using control technique can avoid the serious problem caused by inertial force. In this study, the method to control the displacement of the supporting points of spring mounted model is proposed. Since this system can be used for the free vibration test under the arbitrary damping condition changing the control program, it is possible to built highly flexible aero elastic testing system.
The validity of the new idea was verified theoretically and formula for the calculation of aerodynamic force was introduced. Then, the accuracy of this method is investigated by the numerical calculation. It is revealed that the aerodynamic force may be measured precisely, provided that the feedback gain is greater than 10.The stability of the system was also examined numerically. The system Was found to be strongly stable.
To realize the idea, two tests were conducted. One is the test to control the damping of simple one degree of freedom system, and another is the test to cancel the effect of the aerodynamic force acting on the flat plate mounted in the wind tunnel. The test results show that the validity of the proposed method qualitatively. However, the time lag in the control system affects the test result considerably and further study is necessary to make the system practicable.
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