Index of content:
Volume 126, Issue 5, November 2009
- NONLINEAR ACOUSTICS 
Measurement of acoustic streaming in a closed-loop traveling wave resonator using laser Doppler velocimetry126(2009); http://dx.doi.org/10.1121/1.3238162View Description Hide Description
This paper deals with the measurement of acoustic particle velocity and acoustic streamingvelocity in a closed-loop waveguide in which a resonant traveling acoustic wave is sustained by two loudspeakers appropriately controlled in phase and amplitude. An analytical model of the acoustic field and a theoretical estimate of the acoustic streaming are presented. The measurement of acoustic and acoustic streamingvelocities is performed using laser Doppler velocimetry. The experimental results obtained show that the curvature of the resonator impacts the acoustic velocity and the profile of acoustic streaming. The quadratic dependence of the acoustic streamingvelocity on the acoustic pressure amplitude is verified and the measured cross-sectional average streaming velocity is in good agreement with the value predicted by the theoretical estimate.
126(2009); http://dx.doi.org/10.1121/1.3224760View Description Hide Description
The volume of a bubble in a piezoinkjet printhead is measuredacoustically. The method is based on a numerical model of the investigated system. The piezo not only drives the system but it is also used as a sensor by measuring the current it generates. The numerical model is used to predict this current for a given bubble volume. The inverse problem is to infer the bubble volume from an experimentally obtained piezocurrent. By solving this inverse problem, the size and position of the bubble can thus be measured acoustically. The method is experimentally validated with an inkjet printhead that is augmented with a glass connection channel, through which the bubble was observed optically, while at the same time the piezocurrent was measured. The results from the acoustical measurement method correspond closely to the results from the optical measurement.