Influence of gas turbulence modulation by particles in sudden-expansion flows

The gas turbulence modulation by particles in vertical axi-symmetric sudden-expansion gas-particle flows was studied using a DANTEC 3-D phase Doppler particle anemometer (PDPA) which measured the mean and RMS gas velocities with and without heavy particles. The results show that the turbulence modulation in separated flows with 150 μm particles differs from such flows in channels or pipes reported in the literature. In these more complex flows, not only the particle size but also the local flow field affect the gas turbulence modulation. In the recirculation zone, the particles enhance the gas turbulence in the forward-flow region and reduce the gas turbulence in the reverse-flow region, while in the downstream flow zone particles only reduce the gas turbulence.