Comparison of fibre-based phase Doppler analysers

Abstract

Laser diagnostics techniques are widely used in experimental fluid mechanics. By far the most widely used systems for getting spatial velocity fields and turbulence data are laser Doppler anemometers (LDA). Further, in the cases of two-phase flows phase Doppler analysers (PDA) are typically chosen to measure the size and velocity of the droplets or bubbles. The PDA system is non-intrusive laser technique with high spatial and temporal resolution. Moreover, the PDA system does not require additional calibration as, for example, hot-wire anemometers. However, with a growing number of PDA users, there is a need for verification of the results among the workplaces and systems themselves. The current paper deals with the comparison of two fibre-based PDA systems. The main scope of the investigation is an evaluation of the system's age and the influence of lasers type. One of the systems is older, operated with Argon-Ion laser and the second one is brand new equipped with Diode-pumped solid-state lasers. Both have the same optics and were manufactured by the same company. Various properties of the PDA system are tested to show particular influence on the quality of results when measuring in a spray generated by a small air-blast atomizer.