On Bubble Sizing in Water by Ultrasound

Abstract

Abstract-Classifying bubbles in liquids is a crucial problem that is demanded within multiple fields. This paper discusses a new method for classifying bubble sizes in non-contact and inexpensive approach using ultrasound analysis. Exploiting the principle of buoyancy, free rising bubbles with larger volumes elevate faster to the surface compared to the smaller ones, given that they have the same densities. An envelope detector is proposed which tracks the changes in the ultrasound signals reflected by the bubbles when they cross the ultrasound field. These changes in the reflected signals are distinctive for the sizes under consideration. Relevant spectral and linear predictive coding features that represent the distinct characteristics are extracted. These features are fed to a feed-forward artificial neural network to successfully classify air bubbles according to their sizes with an accuracy of 98.8%. This method provides promising applications to be implemented in industrial, biomedical and environmental fields.

Bubble Size Detection by Process Ancillaries

“…According to the current state of the art, the air bubble size introduced into a flow can be measured using different measurement methods. These include ultrasonic imaging 4, X‐ray imaging 3 and optical measurement methods in which air bubble flows are evaluated with high‐speed camera images 2–4, 8, 11–16. To apply much simpler and automatable measuring methods, the process ancillary variables occurring during the dispersion process are to be investigated with regard to their significance for the process stability and the quality of the signal.…”

“…Representation of different influencing variables on the natural frequency of oscillation of the dispersed air bubbles with different resonance bodies; bubble frequency f B , frequency of the bubblehose f H , frequency of the nozzle f N on basis of 3.…”

“…The production of liquid-gas dispersions places high demands on process technology and can be found in industrial sectors such as the chemical industry, the plastics industry, the automotive industry and also the food industry [1][2][3]. Dispersion processes are used there to intersperse liquids with air, producing plastic foam, or metal foam for lightweight structures.…”

“…Unless the fluid is optically transparent, iterative design processes must be used. In addition to high-speed video-based design processes, X-ray images or ultrasonic images are also possible in some cases, but these provide much poorer resolutions and are therefore not applicable for most applications [3,4,6].…”