MO Chenglong, CHAN Wenqiang, CHEN Rou, YAN Weiwei
Self-circulating microchannel gas generators have garnered significant attention owing to their zero parasitic power consumption. Elucidating the bubble dynamics mechanism is critical for optimizing microchannel design in high-efficiency gas generators. In this study, a numerical simulation of bubble motion in self-circulating micro gas generators was conducted using Ansys Workbench, based on fluid dynamics principles. The effects of key parameters, i.e., microchannel height ratio h ̅, wall contact angle θ_t, and hydrophobic layer contact angle θ_f were systematically investigated. The results demonstrate that: (1) In hydrophobic layer-free channels, when h ̅≥3 and 0<cosθ_t≤0.5, the bubble transit time can be accurately predicted by 1/Δp. In other cases, shifts in vortex positions and quantities enhance energy dissipation, causing the bubble transit time reduction rate to decelerate and deviate from theoretical predictions. (2) For channels without hydrophobic layers, the bubble transit time decreases monotonically with increasing h ̅. This trend stabilizes when h ̅≥5. Additionally, the transit time decreases with higher cosθ_t, though the rate of decrease diminishes significantly when θ_t≤45°. Notably, θ_t exhibits greater sensitivity to transit time compared to h ̅. (3) Introducing a hydrophobic layer in the main channel triggers damping oscillations at the bubble interface due to abrupt contact angle transitions. Larger |cosθ_f | values amplify oscillation amplitudes, thereby increasing energy dissipation and invalidating theoretical time predictions. Furthermore, the transit time decreases linearly with increasing |cosθ_f |.