A method and a device for acoustic estimation of bubble properties

A device to estimate one or more properties of bubbles in a liquid or liquid like medium, the device comprising:

• a chamber or vessel to contain or enable passage of a liquid or liquid like medium, the liquid or liquid like medium supporting one or more bubbles;
• at least one acoustic source configured to acoustically excite the one or more bubbles to oscillate at a resonant frequency;
• at least one broadband acoustic detector to detect a first signal emitted from the acoustic source and to detect a second signal produced from the bubble oscillations;
• and
• control means to (i) derive at least a first and a second characteristic by performing frequency domain analysis on the detected first and second signals, the first characteristic comprising a frequency interference minimum f1min and the second characteristic comprising a bubble resonance fundamental frequency maximum f1max;
• and (ii) estimate one or more bubble properties from at least the first and second characteristics.

An acoustical method to estimate the equilibrium size, and location of at least one unloaded bubble in a liquid-like medium, the acoustical method comprising:

• acoustically exciting one or more bubbles in a liquid like medium to oscillate at a resonant frequency;
• detecting a first signal emitted from an acoustic source and arranged to acoustically excite the one or more bubbles and detecting a second signal produced from the one or more bubble oscillations;
• deriving at least a first, a second and a third characteristic by performing frequency domain analysis on the detected first and second signals, the first characteristic comprising a frequency interference minimum f1min, the second characteristic comprising a bubble resonance fundamental frequency maximum f1max and the third characteristic comprising a second harmonic resonance response frequency f2max;
• estimating Ro from each of the three characteristics based on a priori knowledge of the bubble surface dilatational viscosity, liquid viscosity (p) and the density of the liquid-like medium (ρSl);
• and
• estimating the location of the at least one bubble using Ro.

An acoustical method to estimate the equilibrium size, attached solids mass loading and location of at least one loaded bubble in a liquid-like medium, the acoustical method comprising:

• acoustically exciting one or more bubbles in a liquid like medium to oscillate at a resonant frequency;
• detecting a first signal emitted from an acoustic source and arranged to acoustically excite the one or more bubbles and detecting a second signal produced from the one or more bubble oscillations;
• deriving at least a first, a second and a third characteristic by performing frequency domain analysis on the detected first and second signals, the first characteristic comprising a frequency interference minimum f1min, the second characteristic comprising a bubble resonance fundamental frequency maximum f1max and the third characteristic comprising a second harmonic resonance response frequency f2max;
• estimating Ro from each of the three characteristics based on a priori knowledge of the bubble surface dilatational viscosity, liquid viscosity (μ), bubble surface tension (σ)), bubble gas polytropic index (κ) and the ambient pressure of the liquid-like medium (p0);
• estimating the attached solids mass loading Ms using Ro and using Msto estimate the location of said one or more bubbles.