12. The Effect of Air-Blast Injector Design on Swirl Number and Spray

This study investigates the impact of the air-blast injector design on airflow vortex intensity and spray characteristics. Flow field simulation is used to calculate the number of airflow vortices, and planar laser-induced fluorescence (PLIF) technology and a particle size measuring instrument are employed for spray observation. Analysis is conducted on spray atomization angle, liquid mass distribution, spray non-uniformity, and sauter mean diameter (SMD) among other atomization characteristics.

The results demonstrated an inverse relationship between the airflow vortex intensity and the average particle size of the spray, as well as the spray hollow intensity. On the other hand, a positive correlation was observed between the airflow vortex intensity and the spray atomization angle, spray hollow range, and spray uniformity. Therefore, the design of air-blast injectors with larger airflow vortex numbers, such as increasing blade angles or adopting airfoil-shaped blade designs, resulted in sprays with smaller average particle sizes, larger spray atomization angles, weaker hollow intensity, wider spray hollow range, and more uniform spray distribution. Under conditions where the gas mass flow rate continued to increase or the gas channel width was narrower, the airflow exhibited higher axial velocities, lower airflow vortex numbers, and stronger recirculation ranges and velocities. Consequently, the spray atomization angle, spray hollow intensity, and spray hollow range increased. The study also revealed an inverse relationship between the axial velocity of the airflow and the SMD of the spray. Thus, increasing axial velocity of the airflow led to sprays with smaller average particle sizes.