Acoustic levitation in a free‐jet wind tunnel

In this article we describe a laboratory device which provides stable acoustic levitation in the free‐jet working section of a horizontal wind tunnel. This apparatus combination provides a covenient means for conducting experiments while maintaining a wall‐less environment and relative motion between particle(s) and gas. This facility has been calibrated against the known evaporation of pure water. Applications of this facility to studies of the evaporation of volatile nonideal liquid mixtures, the condensation of water vapor onto an evaporating drop of 1‐butanol and the remote thermometry of water drops using laser‐induced fluorescence are described. We have successfully levitated drops of liquid ranging in diameter from ∼150 μm to ∼3 mm in laminar air streams whose velocities span the range from 25 to 350 cm/s. The lower limit in size is air speed dependent. Measurements of the evaporation of water agree exactly with literature predictions illustrating the lack of perturbations due to the acoustic field.

[1]  J. Blitz.  Physical and applied acoustics , 1973 .

[2]  Paul C. Nordine,et al.  Aerodynamic levitation of laser-heated solids in gas jets , 1982 .

[3]  William H. Press,et al.  Numerical recipes , 1990 .

[4]  S. Ellis,et al.  A New Equilibrium Still for the Study of Partially Miscible Systems , 1960 .

[5]  A. R. Hanson,et al.  Acoustical Liquid Drop Holder , 1964 .

[6]  P. J. Westervelt.  The Theory of Steady Forces Caused by Sound Waves , 1951 .

[7]  G. Rubel.  Evaporation of single aerosol binary oil droplets , 1982 .

[8]  E. H. Trinh,et al.  Compact acoustic levitation device for studies in fluid dynamics and material science in the laboratory and microgravity , 1985 .

[9]  Mark C. Lee,et al.  Acoustic levitating apparatus for submillimeter samples , 1982 .

[10]  R. Reid,et al.  The Properties of Gases and Liquids , 1977 .

[11]  N. Jacobi,et al.  Acoustic radiation force on a rigid sphere in a resonance chamber , 1981 .

[12]  G. Brandt,et al.  Flow Visualization Iii , 1985 .

[13]  James W. Davis,et al.  Multicomponent evaporation of single aerosol droplets , 1982 .

[14]  K. Beard,et al.  A Determination of the Terminal Velocity and Drag of Small Water Drops by Means of a Wind Tunnel. , 1969 .

[15]  Louis Vessot King,et al.  On the Acoustic Radiation Pressure on Spheres , 1934 .

[16]  P. J. Westervelt,et al.  The Mean Pressure and Velocity in a Plane Acoustic Wave in a Gas , 1950 .

[17]  C. H. Wang,et al.  On low-gravity droplet combustion , 1988, Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences.

[18]  R. R. Whymark,et al.  Acoustic field positioning for containerless processing , 1975 .

[19]  C. Jørgensen,et al.  High-resolution visible spectroscopy of two europium (III) ethylenediaminetetra-acetates differing in one molecule of ligated water , 1971 .

[20]  P. K. Gallagher.  Absorption and Fluorescence of Europium(III) in Aqueous Solutions , 1964 .

[21]  F. Borgnis,et al.  Acoustic Radiation Pressure of Plane Compressional Waves , 1953 .

[22]  J. Awatani.  Studies on Acoustic Radiation Pressure. I. (General Considerations) , 1955 .

[23]  E. Davis,et al.  Measurement of the Aerodynamic Drag Force on Single Aerosol Particles , 1987 .

[24]  Mass transfer from water droplets under simulated free-fall conditions , 1986 .