Non-linear effects are known to occur in high intensity sound fields and have important consequences in the study of a diverse range of applications from medical imaging to musical instruments. Particle Image Velocimetry (PIV) is used to obtain full-field instantaneous velocity information without physical intrusion into the acoustic field. After a review of the theory of PIV, the technique is applied to the investigation of non-linear effects on acoustic streaming in a closed-end cylindrical tube. A distortion of the streaming motion is observed with increasing sound intensity and a comparison to theoretical work is presented. PIV is then used in conjunction with pressure measurements to examine the non-linear behaviour at the termination of a open-ended cylindrical tube. The results are compared to acoustic measurements of the non-linear radiation impedance using conventional techniques. The work is then extended through the introduction of side holes into the open tube. PIV measurements of the streaming motion as a function of frequency and intensity are made and used to draw comparisons with the streaming behaviour present at the toneholes of a modern Boehm flute under normal playing conditions. The results from this work clearly show that PIV has the potential to provide a better understanding of acoustical fields in situations where non-linear effects can have a significant influence, such as that found on musical instruments.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:661330 |
| Date | January 2002 |
| Creators | Rockliff, Dawn |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/11329 |
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