Experimental Study on Characteristics of Entrained Droplets and Liquid Film at Swirler Outlet in Swirl-Vane Separator

Abstract The swirl-vane separator, recognized for its compact design and high separation efficiency, experiences a gas-liquid flow transition from non-swirling to swirling after passing through the swirler. Driven by centrifugal force due to gas-liquid density disparities, efficient separation is achieved as liquid is propelled towards the wall. However, complexities arise in the flow filed within the separator due to significant variations in cross-sectional area from upstream to downstream of the swirler. In conditions of insufficient gas flow or low liquid phase flow, a swirling churn flow emerges at the swirler outlet, causing fluctuations in the liquid film and entrained droplet generation. The limited separator riser height impedes timely droplet-wall contact, leading to compromised separation efficiency. To delve into this complexity, an air-water experimental facility was established, investigating the two-phase flow at the swirler outlet. Wire mesh sensors gauged liquid film and droplet characteristics under varying conditions (air superficial velocity: 12.4–20.4 m/s, liquid superficial velocity: 0.1–1.3 m/s). Results revealed that liquid film thickness increases with decreasing gas velocity and rising liquid velocity. Entrained droplet diameter correlates positively with liquid velocity and swirl vane inclination but inversely with gas velocity. Notably, a 45° swirl vane inclination induced dispersed liquid droplets within the swirling annular gas core. Understanding these distribution characteristics is pivotal for setting separator working conditions to enhance separation efficiency and optimize swirler structure.