Experimental study of the propagation of acoustic waves by means of a Laser Doppler Vibrometer
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Propellant storage in space mi ssions could be more efficient with the ability to control the bubbles within the storage tanks. One of the effective options is to control bubbles using acoustic fields. The following work entails the study of the behaviour of a wall of a cubic test ce ll containing fluid medi a when subjected to acoustic fields of different parameters . These studies are characterized by the change in the wall displacement, us ing a Laser Doppler Vibrometer, a piezoelectric, a shaker and the acquisition instruments. Follow ing these experiments, c alculations are carried out to observe its displacements . These results are checked for reliability and repea tability using a shaker at low frequencies to confirm the correct performance of the Laser Doppler Vibrometer. A large part of this experiment, using the test cell, is carried out using different fluid media ; Air, distilled water and a mix of both. The results observed from the experimental study can be reviewed in three different parts. The first one, regarding the displace ment, which is bigger in the face wall than in the back wall of the test cell and the maximum displacement is done above the focus of the vibration source. The second one, regarding the attenuation of the acoustic wave, it is observed that the attenuation coefficient is not constant along the test cell. The third one is with regards to the frequency applied in the acoustic field, where the resonant frequency of the test cell generates more displacement of the walls than the resonant frequency of the piezoel ectric used. The results obtained in this document are important for the future of long term storage of propellant i n aerospace vehicles , especially in rigid tanks with a mixture liquid - gas submitted to vibrations . Also, they serve as an additional refe rence to the future work and development of space storage systems.