Numerical simulation on gas–solid flow characteristics of a fluidic oscillator with geometry variations

When the fluidic oscillator is used as the nozzle of the aerosol generation device, it can produce a larger diffusion range, but the particles will agglomerate during the process of passing through the fluidic oscillator. A numerical study was conducted to investigate the effects of the mixing chamber inlet width W1, mixing chamber width W2, and mixing chamber outlet width W3 on the gas–solid two-phase flow field of a fluidic oscillator. The structural parameters were normalized by the fluidic oscillator inlet width W0. It is found that W1 influences the development of the recirculation bubble and the jet sweeping motion by controlling the magnitude and direction of the flow within the feedback channel. Specifically, when W1/W0 = 1.2, the oscillation frequency, the spreading angle, and the Sauter mean diameter at 25W0 downstream from the outlet reach their maximum values. W2 primarily affects the spreading angle by regulating the scale of the recirculation bubble, with a relatively minor impact on the oscillation frequency. As W2 increases, the spreading angle expands, leading to higher particle volume fractions in both the feedback channel and the main jet region, thereby increasing the likelihood of particle agglomeration. An increase in W3 reduces the constraining effect of the outlet on the jet sweeping motion, resulting in increased oscillation frequency and spreading angle. A wider W3 also enhances the influence of the shear effect of dissipative vortices on the particles, promoting more significant particle agglomeration.