Abstract
We manufacture miniature atomizers by UV-LIGA, and investigate the influence of geometry scale of atomizer on atomization. With CFD simulation study, the air core generation and flow phenomenon within atomizers were understood. Meanwhile, the SMD of atomized droplet was measured by PDPA (Phase Doppler Particle Anemometer). It was found that SMD size of atomized droplet was inversely proportional to air core diameter.Sub-millimeter scale is a transient zone between traditional and MEMS manufacturing. The reasons lie on the precision of traditional fabrication and formation of thick photo-resist. In the traditional fabrication, the drill with its diameter less than 200 □m gets easily shaking, and is hard to drill a concentric circle. Moreover, it can’t manufacture high aspect ratio geometry. This work successfully manufactures micro atomizer with discharge orifice diameter less than 200 □m.Compared simulation data with experimental data, we organize an important parameter, contraction ratio, the ratio of inlet area to outlet area. It affects the air core generating within the atomizer. When contraction ratio is higher than 4, the air core can’t be formed. The data from PDPA also evident it generates coarse droplets even vertical velocity of center droplets is higher than those in the outer field. The spray model has transferred from swirl motion to jet motion. We recommend to design contraction ratio between 1.2~2.5 for reaching good atomization.Atomizer named NAG1 has Sauter mean diameter (SMD) of 105 □m, and it is the best among the designed atomizer in the presented work. And it is superior to those nozzles used in the motorcycles (380 □m).