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Abstract

Turbulence modifications in an axisymmetric opposed jets flow are experimentally investigated by means of a simultaneous two-phase PIV measurement technique. The measurements are conducted at a Reynolds number of 14,500. Glass beads with an averaged diameter of 100 μm (corresponding to a Stokes number of 59.5) are used as dispersed phase. Relatively low mass loading ratios (0.04) and large nozzle separation (12 times nozzle diameter) are tested. It is found that the presence of the particles can distinctly modify the gas-phase characteristics, including both macroscopic turbulence statistics and mesoscopic turbulence structures. In the present dilute gas-particle opposed jets flow, inter-particle collision can be neglected, and particles can penetrate into the opposite stream until to the vicinity of the opposite nozzle. The penetrating and counter-moving particles bring about a lower particle velocity and a larger relative velocity between gas- and particle-phase, which result in a more noticeable modulation of opposed jets. The presence of particles decreases the time-averaged velocity of the opposed jets, increases the turbulence in the axial jet and suppresses the transfer between gas reactants in the impingement region. Moreover, the presence of particles also significantly modifies the axial jet structures, representing the coherent vortex elongating in streamwise direction and shortening in transverse direction, meanwhile noticeably suppresses the turbulence kinetic energy transport from the axial jet to the radial jet.