Liquid jets exposed to the gas stream is a common method in fuel injection systems to break liquid fuel into droplets. In some applications such as, the after burner of a fighter jet engine, the fuel injector is a simple tubular manifold with orifice holes spread around the manifold, allowing multiple liquid jets interacting with the gas stream in cross-flow, counter-flow and co-flow configurations. The efficiency of the combustion process is highly dependent on the size of droplets formed by the breakup of liquid fuel jets as they interact with the gas stream.The liquid jet interactions with the gas stream in different configurations, in particular, the jet in cross-flow has been extensively studied in the past. However, in such investigations, while the liquid jet and droplet behaviour was characterized locally, the gas stream flow conditions were primarily characterized at bulk or global level. As such, the impact of local structure of gaseous flow on the droplet dynamics has not been investigated. As a result, the underlying physical mechanism influencing the droplet formation due to the local interaction of gas and liquid flows is not well-understood. &nbsp;&nbsp;The present study is focused on investigating the behaviour of liquid droplets in relation to the local turbulent airflow. The driving parameter for investigation is the momentum flux ratio, which is a dimensionless parameter relating the gas flow and liquid jet kinetic energy. Experiments were conducted in a high-speed and low-disturbance wind tunnel for cross-flow and counter-flow configurations. Particle image velocimetry (PIV) was used to simultaneously capture the gas flow and liquid droplets. An algorithm was used to isolate droplets from PIV images to separately compute the gas flow mean and turbulent velocity fields and the droplet properties. Detailed results describing the influence of local gas flow behavior on the droplets formation will be presented and discussed.

Influence of the Local Airflow Behavior on Liquid Jet Droplet Dynamics

Paper Proceedings: https://asmedigitalcollection.asme.org/FEDSM/FEDSM2021/volume/85284

ASME 2021 Fluids Engineering Division Summer Meeting (FEDSM2021)

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