Size and velocity measurements in combustion systems

Abstract

Two-phase flow measurements for size and velocity determination in combustion systems are discussed; the pedestal technique and phase Doppler anemometry (PDA) are described in detail. The experimental apparatus tor the pedestal method includes the optical laser-Doppler anemometry (LDA) package and the electronic data acquisition system. The latter comprises three channels for recording the Doppler frequency, ana the pedestal amplitude as well as the validation pulse. Results of measurements performed in a dump combustor, into which kerosene droplets were injected, are presented. The principle of the PDA technique is explained and validation experiments, using latex particles, are reported. Finally the two methods are compared; it is concluded that the PDA technique is preferable for spherical particles exceeding a minimum diameter of a few μm, since it allows to achieve higher accuracy than the pedestal method. When, however, the particle shape is irregular or the particle size is smaller than a few μm (down to about 0.1 μm) and in presence of impurities, the pedestal technique should be used, after appropriate calibration.Two-phase flow measurements for size and velocity determination in combustion systems are discussed; the pedestal technique and phase Doppler anemometry (PDA) are described in detail. The experimental apparatus tor the pedestal method includes the optical laser-Doppler anemometry (LDA) package and the electronic data acquisition system. The latter comprises three channels for recording the Doppler frequency, ana the pedestal amplitude as well as the validation pulse. Results of measurements performed in a dump combustor, into which kerosene droplets were injected, are presented. The principle of the PDA technique is explained and validation experiments, using latex particles, are reported. Finally the two methods are compared; it is concluded that the PDA technique is preferable for spherical particles exceeding a minimum diameter of a few μm, since it allows to achieve higher accuracy than the pedestal method. When, however, the particle shape is irregular or the particle size is smaller than a few μm (d...