Pulse Holography and Phase‐Doppler Technique. A comparison when applied to swirl pressure‐jet atomizers

Abstract

AbstractPulse holography and the phase‐Doppler technique are two of the very few methods with which the size and velocity of individual particles within a two‐phase flow may be simultaneously measured. This enables the two‐dimensional frequency distributions of particle size and velocity to be compiled and allows the existence of mutual correlations to be verified.The application of both methods to investigations into water droplet collections within the hollow spray cone of a swirl pressure‐jet atomizer is described. When comparing the results of measurements obtained by the two methods under identical conditions, one fundamental difference must be taken into account: whereas pulse holography delivers space‐averaged concentration‐dependent frequency distributions, those derived from the phase‐Doppler technique are time‐averaged fluxdependent. The methods hence deliver different, but equivalent, results. Since the possibility of conversion exists, both representations are always available. As far as the particle size distributions are concerned, the results obtained from the two methods confirm the expected differences, whilst verifying the compliance of the interconverted size distribution data. Regarding the velocity distributions, however, some unexplained discrepancies still remain.