High accuracy optical particle sizing in phase-Doppler anemometry

Abstract

A novel structure for phase-Doppler anemometry (PDA) is proposed in order to eliminate the measurement-volume effect (MVE). This new PDA system consists of four receiving detectors in an optimized optical orientation. The method for the determination of the optimized optical orientation angle is introduced. In this method the vector sum of refractive and reflective rays is taken into consideration in describing a dual-mechanism-scattering model caused by a nonuniformly illuminated PDA measurement volume. The constraint of the single-mechanism-scattering model in the conventional PDA is removed. As a result the error caused by MVE, which consists of a Gaussian beam defect and a slit effect, can be eliminated. Analytical and experimental studies were conducted to investigate the accuracy of particle sizing using this new system. Both the experimental results and the simulation based on the generalized Lorenz-Mie theory show that the new method can provide a high-accuracy PDA system free of the MVE.