EXPERIMENTAL STUDY OF TWO-PHASE TURBULENT WAKE USING PIV TECHNIQUE

Abstract

Near-wake regions of the turbulent wake flows behind a long cylinder at two Reynolds numbers (Re<sub>d</sub> = 3860 and 9650) and laden with the particles with mean size of 55 μm are studied using a two-phase particle image velocimetry (PIV) technique. Four mass-loading ratios (α) of 0 (equivalent to the single-phase case), 1, 3, and 5% corresponding to the dispersed-phase volume fractions of 1.248 × 10<sup>-6</sup>, 3.743 × 10<sup>-6</sup>, and 6.241 × 10<sup>-5</sup> for the last three cases, respectively, are investigated. In the particle-laden cases, complex variations of turbulence intensity are discovered; in the near-wake regions, turbulent intensity is either suppressed or enhanced locally compared with the single-phase case. No correlation between the turbulence-intensity modulation and the parameter of either α or Re<sub>d</sub> is found to exist. However, the turbulent mixing capability is attenuated for the cases with particles laden in the wakes. This attenuation is increased with α in both Re<sub>d</sub> cases. In contrast to the turbulence modulation, the turbulent dispersion of the laden particles increases as either α or Re<sub>d</sub> is increased.