Sound propagation in saturated gas-vapor-droplet suspensions considering the effect of transpiration on droplet evaporation

The Sound attenuation and dispersion in saturated gas-vapor-droplet mixtures with evaporation has been investigated theoretically. The theory is based on an extension of the work of Davidson (1975) to accommodate the effects of transpiration on the linear particle relaxation processes of mass, momentum and energy transfer. It is shown that the inclusion of transpiration in the presence of mass transfer improves the agreement between the theory and the experimental data of Cole and Dobbins (1971) for sound attenuation in air-water fogs at low droplet mass concentrations. The results suggest that transpiration has an appreciable effect on both sound absorption and dispersion for both low and high droplet mass concentrations. Nomenclature Co = sound speed in undisturbed (particle-free) gaseous mixture (air and water vapor), ~rRoTo c sound velocity in mixture cp mixture specific heat at constant pressure c p mixture specific heat at constant volume c pp = specific heat of droplet at constant pr~ssure CD droplet drag coefficient, Fp ;[~P: d~ (u p U)2 ] C rn droplet mass loading (ratio of mass of droplets to mass of gaseous mixture per unit volume of undisturbed mixture-droplet system, PrnO / Po = nom p / Po https://ntrs.nasa.gov/search.jsp?R=20120006668 2017-09-14T02:56:50+00:00Z