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

Abstract

The phase-Doppler technique (PDA) has become one of the most important instrumental methods in two-phase flow research in recent years because of its capability of simultaneously determining the diameter and velocity of spherical particles. However, the shortcomings of this technique with respect to volume flux measurement have become increasingly apparent. In order to study the performance of different PDA instruments, comparative flux measurements in two characteristic sprays using a patternator and three phase-Doppler systems were performed at the Institut für Thermische Strömungsmaschinen of the University of Karlsruhe (ITS) in cooperation with the Lehrstuhl für Strö-mungsmechanik of the University of Erlangen-Nürnberg (LSTM) and DANTEC/invent Measurement Technology GmbH in Erlangen. The results of this study clearly indicate that especially in dense sprays, mass flux determination by the phase-Doppler technique is still critical. Further efforts to improve the reliability of the system and to identify the possible sources of errors are necessary. However, the dual-mode technique shows a significant improvement compared with the other instruments under investigation.

Measurements of droplets characteristics in a swirl-stabilized spray flame

“…In the first configuration, the detectors were located outside of the plane defined by the incident laser beams; conversely, in the second one the detectors were located in the same plane as the incident beams. This design was developed to improve measurement accuracy of liquid volume flux [14].…”

Phase Doppler Flux Comparisons

“…As can be seen from Figure 4, the PDI was able to detect mass from 1 to 5 m away from the sprayer; however string data have yet to be processed to correlate these procedures. A common limitation for all phase Doppler measures is the sampling frequency whereas >10,000 counts are needed for statistical validity (Dullenkopf et al, 1998;Nuyttens, Baetens, De Schampheleire, & Sonck, 2007;Parkin, 1993;Tratnig & Brenn, 2010). The current experiment only observed 2 to 491 counts.…”

Phase Doppler quantification of agricultural spray compared with traditional sampling materials

“…This does not indicate that 85% of the data were missing, but that the spray plume was in the sampling area of the pD interferometer for ≥15% of the time. Similarly, Dullenkopf et al (1998) found that time-sequence data obtained in a laboratory patternation assessment using a similar pD device contained up to 5% gaps.…”