New Generation of Phase‐Doppler Instruments for particle velocity, size and concentration measurements

Abstract

Phase-Doppler anemometry (PDA) is applied for particle size, velocity and concentration measurements in two-phase or multi-phase flows of ever increasing complexity. For accurate measurements the experimenter must be provided with software and hardware which permit an optimal layout of the PDA optics for a given application, reliable detection of signals over a wide particle diameter range, accurate determination of particle concentration and precise discrimination between particles of different composition. Recent work at LSTM, Erlangen, has been directed to developing a complete PDA package for the above purposes. Progress in this direction is summarized in this paper. This paper summarizes efforts to improve the phase-Doppler technique in terms of the measurement accuracy, the handling of the system and the field of applications. The work has led to new programs based on Mie scattering for initial system layout and to new optical and electronic developments.Q(X) -+ min =$ Q(X*) XEG has to be fulfilled, where X denotes the optical parameters to be determined, G is the group of allowed parameters and X * is the optimized optical parameters.

Effect of aviation fuel temperature on refractive index in droplet size measurement using phase Doppler anemometry

“…For instance, the most studied problems regarding droplet sizing accuracy are well known, such as the Gaussian beam effect for droplets larger than the probe volume size or position in the trajectory (also referred to as the trajectory effect or measurement volume effect), in addition to 2π droplet diameter ambiguity. The variables related to this error sources had been extensively discussed [9][10][11][12][13][14][15][16] and are treated well with the development of dual PDA system [17]. The influence of the Gaussian beam intensity distribution and accordingly the measurement volume error can be minimized by the extension of geometrical optics [10].…”

Comparative Mass Flux Measurements in Sprays using a Patternator and the Phase-Doppler Technique

“…Although in recent years the phase-Doppler instrument has become a powerful tool for spray characterization with respect to the droplet size and velocity, errors of magnitude 100% and greater regarding the mass flux have been reported. Such errors have been attributed to several different sources, including improperly sized droplets [1,2], non-uniform reference area for the measurement [3,4] or incorrect particle counts due to poor signal validation. More recently, considerable efforts have been made to minimize or compensate for such errors and thus increase the reliability of mass flux measurements made using PDA.…”

High accuracy optical particle sizing in phase-Doppler anemometry

“…Apparently the MVE consists of a Gaussian-beam defect and a slit effect that greatly hinder accuracy in particle sizing. Various solutions for minimizing trajectory ambiguity have been proposed for classical geometry (Qiu and Sommerfeld 1992) as well as more original designs such as planar geometry (Aizu et al 1993) and spatial-frequency geometry (Qiu and Hsu 1998b). A promising solution is dual-mode geometry, which integrates a standard PDA (SPDA) with a planar PDA (PPDA) (Tropea et al 1994).…”