PHASE DOPPLER INTERFEROMETRY VOLUME FLUX SENSITIVITY TO PARAMETRIC SETTINGS AND DROPLET TRAJECTORY

Abstract

Characterization of the volume, or mass, flux distribution for a spray is a first-order determinant for evaluating spray performance. Phase Doppler interferometry has been well established as a means for accurately and reliably measuring drop size and velocity distributions in sprays. The effect of slit aperture width, high voltage gain, and receiver lens focal length on drop size, velocity, and number density is investigated and found to have an optimal settings range; a discussion of the necessary considerations for optimization of these settings is provided. Of particular interest in the current findings is the existence of a large parametric range over which measurement of drop size, velocity, and number density is insensitive to these settings. Additionally, experimental results of volume flux across a spray pattern were acquired using both mechanical patternation and phase Doppler interferometry (PDI) techniques. Through controlled testing methods, an Artium Technologies PDI system, which incorporates the AIMS auto-setup signal processing software, was shown to very accurately determine the local volume flux for a spray nozzle across the spray pattern major axis. Of particular focus in the present investigation is accurate volume flux measurement at large droplet trajectory angles. A common issue with probe volume measurement has been explained and corrected. Finally, local volume flux measurement comparison agreements of 97% were realized between mechanical patternation and the PDI.