A review of the development and characteristics of planar phase-Doppler anemometry

Abstract

Phase-Doppler anemometry is now a well-established measuring technique for simultaneous measurements of particle velocity, size, flux and concentration and its usefulness has been demonstrated in a wide range of applications to multiphase flows. Since its introduction in 1975, it took until 1980 to re-discover the measuring technique for particle sizing. Moreover, the increased understanding of the influence of the Gaussian intensity distribution in the probe volume of a phase-Doppler anemometer (PDA) revealed an important feature of PDA in a planar configuration, namely the temporal separation of the contributions of two scattering mechanisms, reflection and refraction, to the light received by the photodetectors. This implies the possibility of suppressing measurement errors caused by the mixing of the two modes of scattered light and even makes it possible to perform refractive-index measurements by comparison of the reflective and the refractive phases. In the most recent development of the so-called dual-mode PDA, the planar set-up is one essential part of the system which ensures that an accurate measurement of the particle size and, therefore, of the particulate volume flux is obtained. The present paper reviews the historical development of planar PDA and its capabilities and present applications.