An experimental investigation of evaporative sprays in axial acoustic fields

This paper presents the effect of axial acoustic fields on evaporative sprays. Investigations were performed using ethanol as the spray liquid, inside a duct fitted with acoustic drivers. The spray field was characterized using phase Doppler particle size analyzer (PDPA) and three component laser Doppler velocimetry (3C-LDV) measurements. The spray velocity fields are altered with respect to the acoustic velocity oscillations in an acoustic cycle. Variation in phase averaged droplet diameter and their distribution in presence of acoustic velocity oscillations in an acoustic cycle is noticed. The variation of droplet velocity, diameter and their distribution in presence of acoustic velocity oscillations increases with increase in amplitude of the acoustic field. Maximum variation of 30% in phase averaged droplet diameter is observed in an acoustic cycle. The harmonics in the phase averaged droplet diameter are observed when there is reversal of droplet velocity. Smaller diameter droplets are entrained by the acoustic velocity oscillations.