Dynamic behavior and evaporation characteristics of micro-nano bubble premixed fuel droplets impacting on the heated surface

To understand the differences between micro-nano bubble premixed fuel (MBPF) and ordinary diesel, MBPF is prepared by adding micro-nano air bubbles to diesel through the porous membrane tube. The dynamic behavior and evaporation process of MBPF droplets after impacting aluminum alloy walls are experimentally studied using high-speed photography and schlieren photography methods. The results show that the incorporation of micro-nano bubbles reduces the kinematic viscosity of droplets and weakens the viscous resistance of the spreading process after hitting the wall, leading to an enlarged spreading factor and spreading rate. In addition, heat is transferred from the solid wall to the MBPF droplet, where the bubble expands and floats upward until it eventually breaks through the surface tension in the upper part of the droplet and bursts. This leads to a significant increase in the micro-explosion of the MBPF droplet as it evaporates on the heated surface, which has a larger diffusion width and diffusion area than ordinary diesel. Meanwhile, the diffusion width and diffusion area will be further augmented when the bubble concentration in the MBPF increases, which effectively accelerates the evaporation rate.