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.