Study of pressure-swirl atomizer with spiral path at design point and outside of design point

Studies on pressure-swirl atomizers have mainly focused on pressure-swirl atomizers with tangential input while there are limited studies on pressure-swirl atomizers with a spiral path. This study applies experimental and computational methods to provide a better understanding of flow development in this type of atomizer at the design point and outside the design point. Experimental results showed that as the pressure increases, the spray cone angle increases. This increase initially occurs with a higher slope and then the slope is toned down. While the drainage coefficient remains constant, the droplet diameter decreases as the pressure increases. It is observed that similar to the pressure-swirl atomizer with tangential input, the pressure-swirl atomizer with a spiral path has a conical hollow spray. At the constant mass flow rate, as the spiral path cross-section, the length of the swirl chamber and orifice diameter increase, the fluid film thickness and average diameter of droplets increase while the spray cone angle reduces. Further, increasing the number of spiral paths causes a wider spray cone angle, higher discharge coefficient, larger fluid film thickness, and larger droplet diameter. The results also showed that increasing the length of the orifice marginally affected the properties of the spray while significantly reducing the spray cone angle. It is important to note that the numerical results are in good agreement with the experimental data.