The influences of particle mass loading on mean and instantaneous particle distributions in precessing jet flows

Abstract

The influence of particle mass loading on the mean and instantaneous distributions of 20μm spherical particles in the first 10 nozzle diameters downstream from a precessing jet nozzle has been investigated experimentally in an isothermal environment. Fluid flow rates were held constant, adjusting only the mass flow rate of particles, introduced through a co-annular stream around the PJ nozzle. In this way, all conditions were within the two-way coupling regime. Instantaneous planar particle distributions, measured using planar nephelometry, are reported and used to assess centreline, halfwidth and radial profiles of particle concentrations. The locations, numbers, areas and internal particle concentrations of the Instantaneous Cluster Slice (ICS) are also reported. It is found that the mass flow rate of particles has little influence to the mean distribution of particles immediately downstream from the nozzle exit plane. Further downstream, the influence of particle mass flow rate becomes more pronounced, with a narrowing and elongation of the jet. The size and concentration of ICSs increase with increasing particle mass flow rate, while the number of ICSs per image correspondingly decreases. These effects are shown to predominately correspond to the increase in total momentum flux of the particle-laden jet stream; indicating that these particle-laden jets may be estimated from only single-phase data with appropriate momentum flux ratios accounting for solid-phase effects. However, some mass loading effects are identified.