annularflöde

Annularflöde refers to a specific flow regime in fluid dynamics, particularly relevant in two-phase flow. This regime occurs when a liquid flows along the wall of a pipe, forming a continuous annulus, while a gas flows through the central core of the pipe. This is distinct from other two-phase flow patterns like bubbly flow, slug flow, or stratified flow, where the phases are dispersed or separated differently.

The characteristics of annular flow are influenced by factors such as the flow rates of both the liquid and gas phases, the pipe diameter, and the fluid properties like viscosity and surface tension. At lower liquid flow rates, the liquid might form a more continuous film. As the liquid flow rate increases, the film can become thinner and potentially develop waves. The gas core can entrain liquid droplets from the film, which then travel through the gas phase. These entrained droplets can reattach to the liquid film or travel along the pipe.

Understanding annular flow is crucial in various industrial applications, including petroleum production (oil and gas multiphase flow in pipelines), chemical engineering processes (e.g., heat exchangers, reactors), and nuclear reactor safety systems (coolant flow). Predicting and characterizing annular flow is important for designing efficient and safe systems, as it affects pressure drop, heat transfer, and mass transfer rates. Experimental studies and computational fluid dynamics (CFD) simulations are commonly used to analyze and model this complex flow pattern.