Experimental investigation on the turbulence modification of the gas-particle flow within a 90° bend

Simultaneous measurements of both the carrier gas phase and the dispersed particulate phase were carried out inside a curved 90° duct bend using Phase Doppler Anemometry (PDA). These measurements were undertaken in order to investigate the effects of dilute turbulent particulate flows on the gas phase and vice versa. The main objective of the current study is to decipher the effect of the particles on to the gas phase at both the mean as well as at the turbulence level. Glass spheres with mean diameter of 77µm were used to represent the solid phase, while the carrier phase has a working Reynolds number of Re=1.0 × 105 (bulk velocity Uo=10m/s). The gas phase results were analyzed as both clean gas (without any particles) and unclean gas (with particles). The unclean gas results were separated from the particles based on their size in the post-processing step of the laser data. At the mean level, the velocities of the unclean gas phase 'lagged' behind the clean gas from the mid section of the duct towards the inner bend. Almost, the same feature is observed along the vertical duct past the 90° bend. This phenomenon is mainly attributed to the effect of the particles drag on the continuous gas phase. While at the turbulence level, the unclean gas phase was seen 'leading' the clean gas causing an enhancement of gas phase turbulence. This is characteristic of the energy transferred onto the gas phase from the high energy particulate phase. The particles attain these high energies due to the collisions when it experiences all along the bend section.