Droplet spectra and high-speed wind tunnel evaluation of air induction nozzles

A series of air induction nozzles were tested in a high-speed wind tunnel. Droplet size spectra were measured for four air induction nozzles (IDK-120-01, IDK-120-02, IDK-120-03 and IDK-120-04) each at three spray pressures (0.3, 0.4 and 0.5 MPa) and seven different air velocities (121.7, 153.4, 185.5, 218.4, 253.5, 277.5 and 305.5 km.h(-1)). The measurement distance (0.15, 0.25 and 0.35 m) from the nozzle orifice was found to be important for the atomization of the droplets. The response surface method was used to analyze the experimental data. The results indicated that Dv(0.1) and Dv(0.5) of the droplets decreased quasi-linearly with increased wind speed, while Dv(0.9) was affected by the quadratic of wind speed. Dv(0.1), Dv(0.5) and Dv(0.9) of the droplets were all proportional to the orifice size, and were not markedly influenced by the spray pressure. The percentage of the spray volume consisting of droplets with a diameter below 100 mu m (% < 100 mu m) was found to be quadratically related to wind speed, and was not markedly influenced by the spray pressure and orifice size. However, the effect of the orifice size on the % < 200 mu m could not be ignored.