A flow visualization system using smoke was developed in a close-return type low speed wind tunnel. The purpose of developing this system was to investigate the unsteady flow patterns around the NASA GA(W)-1 2D airfoils which are oscillated in a pitching quasi-harmonic motion around axes near the leading and the trailing edge. The feature of this system is that both the smoke creating and smoke exhausting devices are installed in the settling chamber and at the down stream part of the test section. Consequently, it is possible to conduct long experiments without any other efforts to exhaust the smoke of any significant pollution of the tunnel walls by the smoke oil. The model driving system enables quasi-harmonic oscillation up to a frequency of 8 Hz, with three electric motors controlled by a personal computer. It is also possible to automatically change the parameters; the mean-angle of attack, the amplitudes and the frequencies in a short time by monitoring the information on the CRT (Cathode Ray Tube). The efficiency of experiments is highly improved as a result. The following is an outline of the visualization system ad it's performance.
回流式低速風洞に於ける煙を用いた振動翼まわりの流れの可視化実験装置の開発
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