Cool Flames Investigation (Cool Flames Investigation) - 01.18.17
Some types of fuels initially burn very hot, then appear to go out — but they continue burning at a much lower temperature, with no visible flames (cool flames). Understanding cool flame combustion helps scientists develop new engines and fuels that are more efficient and less harmful to the environment. The Cool Flames Investigation provides new insight into this phenomenon, as well as new data on fire safety in space. Science Results for Everyone
Information Pending Experiment Details
Daniel L. Dietrich, Ph.D., Glenn Research Center, Cleveland, OH, United States
Forman A. Williams, Ph.D., University of California, San Diego, La Jolla, CA, United States
Frederick L. Dryer, Princeton University, Princeton, NJ, United States
NASA Glenn Research Center, Cleveland, OH, United States
ZIN Technologies Incorporated, Cleveland, OH, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
NASA Research Office - Space Life and Physical Sciences (NASA Research-SLPS)
Earth Benefits, Scientific Discovery
ISS Expedition Duration
March 2016 - February 2017; March 2017 - September 2017
- Understand the low temperature combustion characteristics of normal alkanes by conducting droplet combustion experiments in low gravity in order to help combustion chemists develop new computational models to compute performance and efficiency for many practical applications on earth including high-efficiency Homogeneous Charge Compression Ignition (HCCI) engines
- Investigate the low temperature burning behavior of droplets consisting of pure fuels, bio-fuels, and surrogate reference fuels to determine the relationship between the cool flame burning characteristics and the octane/cetane behavior of the fuel.
- Explore the low temperature chemistry of alkanes further by mixing additives to the fuel that disrupt the low temperature chemical pathways.
This investigation studies the low-temperature burning behavior of several fuels (burned as droplets), including pure hydrocarbons, biofuels and mixtures of pure hydrocarbons. Results provide new understanding of low temperature chemistry, which benefits development of new engines and fuels and improves crew safety.
Cool flame chemistry is important for developing fuels for advanced engines, such as high-efficiency Homogeneous Charge Compression Ignition engines. Results help combustion chemists design new computer models used to determine a fuel’s combustion performance. Next-generation fuels and engines produce less soot, improving air quality and benefiting people on Earth.
Operational Requirements and Protocols
Following setup and initialization of the CIR rack and MDCA, the chamber is filled with the appropriate atmosphere for the day’s test points. Conditions vary in pressure (0.5 atm to 5.0 atm) and oxygen concentration (10 to 30%). A settling time of approximately 2 minutes elapses prior to initiating the test in order to ensure that the temperature and pressure of the chamber gases have stabilized. This settling time is followed by the dispensing of a predetermined amount of fuel (based on the target droplet size) onto a support fiber. When sufficient fuel has been dispensed the dispensing needles are retracted and a dwell period of at least 10 seconds is allowed for the droplet internal fluid motion induced by deployment to subside. This is then be followed by initiating power to an igniter pair for a selectable amount of time ranging from 1 second to 5 seconds after which the igniter will be retracted from the field of view. A near real-time download of the color camera video is required in order to verify successful droplet deployment, ignition, and overall progress of the experiment. Pressure and temperature data of the chamber environment is also required in near real time. ^ back to top
Decadal Survey Recommendations
Applied Physical Science in Space AP7
Applied Physical Science in Space AP8
Information Pending^ back to top
Ground Based Results Publications
Nayagam V, Dietrich DL, Williams FA. Partial-burning regime for quasi-steady droplet combustion supported by cool flames. AIAA Journal. 2016 January 11; epub: 5 pp. DOI: 10.2514/1.J054437.