LASER GRATING TECHNIQUE FOR MEASUREMENT OF LOCAL VELOCITY OF LARGE DROPS AND JETS IN LIQUID-LIQUID SYSTEMS

Measurements of the local rise velocity of large liquid drops of 3-7 m m in diameter and the local axial wave propagation velocity on a liqui d jet surface in liquid-liquid systems were successfully performed usi ng a Laser Grating Velocimeter (LGV). The primary frequency of the pho todetector signal that is required for evaluation of the local velocit y, was determined unambiguously by a frequency-domain Fast Fourier Tra nsform analysis of the velocity signal. The validity of this technique , which eliminates potential measurement errors, was confirmed by a co ntrolled experiment. The LGV was applied to the determination of the d rop terminal rise velocity distribution of a population of 300 drops, and axial distribution of the jet surface wave velocity in order to de monstrate the capability and effectiveness of the technique. Copyright (C) 1996 Elsevier Science Ltd