Numerical analysis of ligament instability and breakup in shear flow

What is it about?

Liquid atomization technology is applied in various fields in the industry. Elucidation of atomization characteristics would thus help improve performance. as the ejected liquid (in the form of a liquid sheet or a liquid column) is destabilized by the shearing of gas and liquid, a fine-scale liquid column, called a ligament, is generated and the liquid eventually splits into small droplets. In the high-speed flow field in an atomizer, because both the gas and liquid flows are turbulent, the airflow around a ligament is not uniform; instead, it is a shear flow with a velocity gradient. In this case, because the ligament is deformed by the shear flow, the breakup time and droplet diameter will be different from those of a ligament in a stationary fluid or a uniform airflow. To clarify the behavior of a ligament in turbulent flow, we perform a numerical analysis of a ligament in shear flow and investigate the effects of gas-liquid shear on the growth rate at the ligament interface, break time, and droplet size.

Featured Image

Photo by Susan Wilkinson on Unsplash

Photo by Susan Wilkinson on Unsplash

Why is it important?

Fine-scale liquid splitting, such as ligaments, occurs in the atomization process. Therefore, the breakup characteristics of ligaments should be investigated to clarify spray characteristics. The instability of a ligament formed in the atomization process is often considered based on the linear theory of the instability of a stationary liquid column. It is not easy to theoretically analyze the instability of a ligament in shear flow. Therefore, in this study, we performed a three-dimensional numerical analysis considering nonlinearity and clarified the effects of gas-liquid shear velocity on the growth rate of the ligament interface, breakup time, and droplet diameter as a result of breakup.

Perspectives