PhD Studentship: Advanced Laser Diagnostics Investigating the Fluid Mechanics of Primary Breakup

Efficient spray atomization plays a notable role in society, ranging from effective medical delivery, to product manufacturing, to cleaner propulsion systems. Primary breakup – the process of disintegrating an intact liquid core into large droplets, called primary drops – is the first consequential first step of atomization, but is also the least well understood.

This PhD position focuses on sophisticated experimental measurements that resolve the fundamental fluid dynamics that govern the primary breakup processes at liquid/gas interfaces at the core of an atomizing spray. Experiments will utilize short-pulse laser diagnostics applied within an atomizing spray. The diagnostics will include (1) Ballistic Imaging, which allows one to visualize intact liquid elements inside a dense droplet cloud and (2) Two-Photon Laser Induced Fluorescence imaging, which mitigates multiple scatter at lower optical depths. These diagnostics will be combined with wavelet-based optical flow to spatially resolve the velocity and acceleration along liquid/gas interfaces from successive image frames. These sophisticated techniques will be used in combination with passive imaging techniques to visualize events such as cavitation and turbulence with transparent spray nozzles.

Experiments will be conducted in a simplified spray nozzle geometry intended to isolate primary breakup mechanisms of shear, turbulence and cavitation. Experiments will investigate the flow physics (velocity and acceleration) at liquid/gas interfaces to understand the efficacy of each breakup mechanism to break apart the liquid core into drops. 

Candidates who enjoy fluid mechanics and are interested in laser diagnostics are encouraged to apply. Project partners include RWTH Aachen University (Germany) and Sandia National Laboratories (California, USA). There is opportunity to work closely and visit these institutions during the PhD.

The intended PhD start date is in late Summer, early Autumn 2023.