Estimation of acoustic forces on submicron aerosol particles in a standing wave field

• The net acoustic force acting on submicron particles suspended in a gas and exposed to a standing wave field is investigated as a function of particle size, by measuring both the aerosol number density and size distribution in a flow-through resonator. By taking into account all contributions relevant to the net force, this experimental study provides a first estimate for the acoustic radiation force in a size range where molecular effects are expected to be significant. The experiment consists of an electrostatic transducer generating a standing wave in the 50–80 kHz frequency range, with the submicron aerosol particles concentrated at pressure antinodes located across the height of a rectangular channel. A section of the flow is sampled isokinetically and analyzed using a Scanning Mobility Particle Sizer (SMPS), while the nodal patterns are visualized simultaneously using light scattering. The net acoustic force is calculated from their measured displacement along the axis of the 1D standing wave field. The component of this force resulting from radiation pressure is estimated by subtracting contributions from other forces. The results provide the first experimental estimation of the size dependence of the acoustic contrast factor for submicron aerosol particles, demonstrating the possibility of performing acoustic separation for diameters as small as 150 nm. 

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Maskinteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Mechanical Engineering (hsv//eng)

Keyword

Aerosols

Atmospheric movements

Elastic waves

Light scattering

Particle size

Radiation effects

Shape memory effect

Acoustic radiation force

Acoustic separation

Electrostatic transducers

Experimental estimations

Rectangular channel

Scanning mobility particle sizer

Standing-wave field

Sub-micron particles

Acoustics

aerosol

Article

conceptual framework

force

priority journal

radiation

Publication and Content Type

ref (subject category)

art (subject category)