Ejection characteristics of micropumps for motorcycle fuel atomizer in high-temperature environment

This study applied thermal bubble micropump on motorcycle fuel atomizer which is installed on the upper end of intake manifold and 20 cm away from the engine, and used ink and Stoddard solvent as work liquid. Based on computational fluid dynamics (CFD) simulation, it discussed the ejection characteristics of a single micropump and two adjacent micropumps with time-lagged ejections in a high-temperature environment, the temperature is higher than room temperature and lower than water boiling temperature. The results showed that due to contact with high-temperature external air, the surface tension of the ejected droplet string decreases. Therefore, the volume of the main ejected droplet decreases, and the neck and tail of the droplet string are scattered. The flying velocity of ejected droplet decreases as well. As the surface tension of the work liquid inside the micropump decreases, the air trapped inside the micropump is less obvious. As a result, the work liquid replenishes more smoothly, and the starting time of replenishment is advanced. Consequently, the work liquid replenishment rate is improved. The shape and velocity of droplet strings ejected from two adjacent micropumps are approximate. Because the density of Stoddard solvent is low, as it is driven by flowing external air, the offset value of the movement track of ejected droplet is large. As a result, the particle shape of ejected droplet is irregular. If the external air is still, the starting time of the same work liquid replenishment for both single and two adjacent micropumps is approximate. The starting time for Stoddard solvent is faster than that for ink, but the replenishment rates for both are very close, with the rate for two adjacent micropumps is higher than that for a single micropump. The flowing external air has insignificant effect on the work liquid replenishment rate for two adjacent micropumps in a high-temperature environment.