An Ultra-High-Speed Imaging System for Droplet Breakup in High-Speed Combustion
Abstract
The next generation of high-performance propulsion and power generation devices require more efficient, high-speed combustion usingliquid fuels. High-speed multiphase combustion is complicated by multiphase effects, such as droplet breakup and vaporization, occurring at small length (<10 #m) and time (<1 #s) scales. Our current ONR project (N00014-20-1-2796, PI: McFarland, PM: Steve Martens)aims to understand how droplet breakup and evaporation occur under detonation conditions, and how these physics affect the propagation of detonation waves through perturbed (spatial and size) distributions of fuel droplets. The project will develop newtheory for high-speed multiphase mixing and reaction using an integrated multiscale experimental and simulation approach, combining multiphase hydrodynamics simulations, and high temperature/pressure shock and detonation tube experiments. Our experiments will provide bulk measurements of the large-scale combined effects of droplet breakup, evaporation, and reaction that can be used to validate the performance of our new droplet model at similar conditions. To develop a complete understanding of high-speed droplet breakup, evaporation, and reaction though, requires experimental observations of the droplet physics at sub-micron scales occurring at sub-microsecond times. A more extensive understanding of these droplet-scale events will allow for the development of models that are predictive overa wide range of conditions (new fuels, and oxidizer conditions), leading to new pathways for enhanced and resilient high-speed combustion.This DURIP proposal will fund the acquisition of a new ultra-high-speed (up to 1 billion FPS), high resolution (>1MP) imagingsystem to visualize the morphology of droplet breakup during evaporation and reaction in detonation waves. While such systems now exist, they have yet to be applied to high-speed multiphase combustion problems. The proposed system consists of a SIMX 16 camera from specialized imaging, capable of acquiring 16 images with an interframe time of less than 5ns. The camera will capture images of the droplet morphology during breakup with a resolution of 100+ pixels per droplet diameter. Two light sources will be acquired for the camera; one high-power pulsed red laser for Schlieren (density gradient) imaging, and one continuous green laser for planar fluorescence imaging of the droplet morphology. We have a unique opportunity to capture first-of-their-kind images of droplet breakup at unprecedented length and time scales under high-speed combustion (detonation) conditions using this system. These novel measurements will provide a new fundamental understanding of droplet breakup with evaporation at conditions never before explored and enable a robust process by which new models may be developed for additional fuels and oxidizers at varying thermodynamic conditions. The new imaging system will greatly enhance our current project, allowing us to collect time-resolved dataand to enrich the training of graduate student researchers. This will enhance the impact of our experimental data, allowing it to be used for detailed validation of high-resolution simulations (DNS) of droplet breakup. This time-resolved data will allow us to determine the driving parameters for droplet breakup and reaction, reducing the parameter space and enabling a more efficient process for developing models for new fuels, and conditions. Further, this equipment will the first of its kind at Texas A&M and will provide new training opportunities for our diverse student body both in the lab and classroom.Approved for Public Release
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 06, 2023
- Source ID
- N000142312265
Entities
People
- Jacob McFarland
Organizations
- Office of Naval Research
- Texas Engineering Experiment Station
- United States Navy