Atomization characteristics of centrifugal nozzle for steam desuperheating valve

Abstract

The atomization characteristics of the centrifugal nozzle were studied numerically and experimentally. A multi-scale coupling model was established based on ANSYS Fluent. The effects of structural parameters and operating conditions on spray cone angle and droplet size distribution were analyzed. The experimental photography of nozzle atomization with a high-speed camera verified the reliability of the numerical model. Results indicate that the spray cone angle is positively correlated with inlet pressure and swirl chamber angle, but negatively correlated with swirl hole angle, nozzle stem angle, and air velocity. The nozzle stem angle exhibits the most significant influence on the spray cone angle, while the swirl chamber angle has the least effect. Higher inlet pressure enhances liquid film instability and reduces droplet size. A swirl hole angle of 90° disrupts the swirling flow and causes a sharp increase in SMD. A smaller nozzle stem angle (30°) improves droplet size uniformity. High-speed airflow (> 60 m/s) increases droplet coverage and suppresses accumulation at the axial rear. In the spray near-field, a smaller spray cone angle increases gas–liquid shear stress and reduces SMD. In the far-field, a smaller spray cone angle increases SMD due to higher droplet number density, which elevates the probability of droplet collision and coalescence.