| Summary: | 碩士 === 國立成功大學 === 工程科學系碩博士班 === 100 === Using experimental methods to analyze the acoustic effects of jet-excited Helmholtz resonators with different shapes.Making different resonators by paper tubes and pvc plastic tubes.
The experimental content is to observe the acoustic characteristics of several basic parameters of Helmholtz resonators,which includes length of neck,height of cylinder,diameter of cylinder,area of aperture,shape of aperture,position of aperture. Observing the acoustic characteristics of some Helmholtz resonators of special shapes,which includes the curved cylinder,the combination of inner and outer cylinder, the narrow-mouth bottle.
The results show that all basic parameters of Helmholtz resonators are roughly conformed with theorical equations except the shape of aperture and the area of aperture,which can cause some deviations because of the change of vibration mode. For the combinations of inner and outer cylinder, when the inner cylindr occupies volume smaller than 50% of outer cylinder, the frequency will decrease. For the curved cylinders, the frequency of the curved cylinders with sharper angle(90°) will decrease compared with the straight cylinders,and the curved cylinders with easer angle(135°) will increase compared with the straight cylinders. But the change of the frequency of the curved cylinders are within 10%. For the narrow-mouth bottle, when the ratio of narrower diameter to wider diameter is smaller than 0.5, the frequency will decrease compared with the cylinders with the same height and bigger volume.
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