Experimental Study on Droplets Entrainment and Film Breakup Characteristics Under in Rotating Churn Flow

Abstract The separation performance of swirl-vane separators, including pressure drop and separation efficiency, is closely related to the two-phase flow pattern and the liquid film breakup behavior. In the swirling-swirl-vane separators, the droplets collision and film breakup happen. Influenced by the spiral blade structure and the central hub, the swirl-vane outlet region is prone to the formation of churn flow. Due to the complex and variant thickness of the liquid film in churn flow, it is extremely difficult to visually observe the generation and development process of the droplet entrainment from the side or the top under normal working conditions. Data on the phenomenon of droplet entrainment under the rotating flow field are rare, resulting in the entrainment mechanism of droplets under the rotating flow field is unclear. In this paper, investigations on the entrainment of droplets downstream of the swirl-vane has been carried out for a small liquid flow rate. A rotary flow field visualization experimental device has been developed. The churn flow is formed under the condition of near-zero liquid flow. The motion characteristics of the droplets in the churn flow are extracted by observing the movement of a small number of droplets in a rotating flow field. The rotational churn flow and droplet entrainment process are obtained through visual photography. The liquid film ligament and bag breakup characteristics under the rotating flow field are obtained, as well as the particle size characteristics of the entrainment droplets.