Effect of mixing gas-fine particle suspension flow with small amount of coarse ones in a horizontal pipe

A phase doppler anemometer (PDA) was used to measure axial components of me an and fluctuation velocities of air and particles in a pipe of 80 mm. insi de diameter. Glass beads having mean diameter of 55 and 468 mum, respective ly, were used, the density being 2590 kg/m(3). The fine particles suppress the air flow turbulence while the coarse ones increase it. Mixing fine part icles with coarse ones in 5-9% in mass increases the turbulence above that by coarse ones alone. The acceleration pressure drop due to the particles i s increased as well above that by the fine particles alone, which is larger than that by the coarse ones alone. (C) 2001 Elsevier Science Ltd. All rig hts reserved.