基于微细梁振动位移的微尺度射流测速方法

Vibration of micro cantilever applied in micro scale jet velocity measurement

实验研究微尺度射流流场中微细梁发生的振动过程，并提出基于该原理测量微尺度射流速度。实验使用长度56．2ram、直径约0．07mm铜丝作为微细梁，使用直径约0．36mm喷管产生的微尺度射流。使用高速摄影仪观察射流流速在2．7～27．3m／s间梁振动的变化。试验结果发现当射流喷嘴对准梁3／5处时，振动过程中振幅随射流速度上升。而当射流喷嘴对准梁的9／10和3／4处时，在高流速下，振幅不随流速上升。使用霍尔传感器和磁铁测量梁的振动，当喷嘴对准梁的3／4处，霍尔传感器输出电压有效值随射流流速线性增长。但在其他位置，由于磁铁改变了梁的均匀结构，振动随流速的变化不规律。

In the experiment, the vibration of a micro cantilever varying with the jet velocity is studied. It is suggested to measure the micro scale jet velocity based on this mechanism. A copper thread with length 56.2mm, diameter 0.07ram is used as the micro cantilever. The jet velocity comes from a micro nozzle with diameter 0.36ram. The vibration of cantilever is investigated with a high-speed camera while the jet velocity varying between 2.7-27.3m/s. The result shows that the vibration amplitude increase with the jet velocity while the nozzle is amied at 3/5 of the cantilever length. But while the nozzle is aimed at 9/10 or 3/5 of the cantilever length, the amplitude stops increasing at high jet veloicty. A hall sensor and a magnet are used to measure the vibration. The output voltage increases linearly with the jet velocity, while the nozzle is aimed at the 3/4 of the cantilver lenth. But at the other positions, the viburation is not inneratic because the attached magnet change the mass distribuion of the cantilever.