Structure and Liftoff In Combustion Experiment (SLICE) - 07.15.14
ISS Science for Everyone
Science Objectives for Everyone
Structure and Liftoff In Combustion Experiment (SLICE) investigates the nature of flames in microgravity. The results from these experiments could lead to improved fuel efficiency and reduce pollutant emissions in practical combustion on Earth.
Science Results for Everyone
ZIN Technologies Incorporated, Cleveland, OH, United States
Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)
Human Exploration and Operations Mission Directorate (HEOMD)
ISS Expedition Duration
March 2011 - May 2012
Previous ISS Missions
ISS Expedition 29/30 is the first mission for the SLICE experiment which utilizes the existing SPICE hardware on orbit aboard the ISS.
- Predicting the shape and temperature of burning gases is complicated on earth by buoyancy effects. Observations of the temperature and shape of flames from burning gases in microgravity will help scientists and engineers improve fuel efficiency and reduce pollutant emissions inof practical combustion on Earth.
- The goal of the Structure and Liftoff In Combustion Experiment (SLICE) is to improve computer models of flames using the unique data that can be obtained in a microgravity environment.
ISS Science Challenge Student Reflection
ISS Science Challenge Selected Project
We chose to do our ISS Science Challenge Presentation on SLICE because we are concerned with the well-being of the Earth and want to both learn and educate others about the different processes that contribute to global pollution. We are all fascinated by the science behind rocketry and we knew that SLICE would be the perfect experiment to increase our knowledge of combustion and its applications to rockets. We all enjoyed working with students across the nation toward a common goal and we have learned much along the way, including several past, present and future missions on the International Space Station, how combustion works and how to communicate effectively over the computer.
-Joshua, Grade 10, Dublin High School, Dublin, California
-Josh, Grade 10, Norfolk Academy, Norfolk, Virginia
-Abra, Grade 12, Richview Collegiate Institute, Ontario, Canada
ISS Science Challenge Selected Project
Learning about new innovations always helps me think about how I can help my world. By doing both the Avatar Explore and the SLICE topics, I was able to learn how communication and the search for cleaner energy are the forefront in technological innovation. It makes me ask myself what I would like to be a part of when I grow up especially since I am working my way towards engineering. These topics showed me that there is so much more to engineering than I thought; that there is such a wide array of topics to choose from and it constantly makes me rethink my perception on engineering and innovation.
(This was a very informative activity. I never knew NASA did so many different tests and experiments; I mean I know you guys did a lot but the sheer number of experiments posted on the site still amazed me!)
-Abishek, Grade11, Thomas Jefferson High School, Federal Way, Washington
The SLICE experiment investigates the structure of lifting and lifted flames, where flow conditions and the combustion chemistry cause the flame to detach from the burner and stabilize at a downstream position. It is a precursor to the Coflow Laminar Diffusion Flame (CLD Flame) experiment, where the SLICE results will be used to maximize the scientific return of that upcoming space station experiment.
The SLICE objectives are to characterize the structure of the flame, especially its base (i.e., stabilizing region), from attached through lifted conditions as a function of the fuel, burner diameter, and flow conditions. SLICE also identifies the liftoff velocity limits as a function of the fuel and burner diameter, for diffusion flames of methane, nitrogen-diluted methane, and nitrogen-diluted ethylene burning in a coflow of air.
A flame of gaseous fuel is ignited within a low-speed flow duct and photographed. The fuel flow or air velocity is adjusted to assess its effect on the flame structure and liftoff. Other experimental parameters include the gaseous fuel (including nitrogen dilution) and the diameter of the circular burner tube. Flame measurements include the structure (e.g., size and shape), soot temperature, soot volume fraction, and thermal radiation. The results will be used to refine computational models of the flames.
The goal of the SLICE experiment is to improve our understanding of the physical and chemical processes controlling diffusion (i.e., nonpremixed) flame structure and lifting phenomena (i.e., stabilization) and to provide for rigorous testing of numerical models including thermal radiation, soot formation, and detailed chemical kinetics. Good agreement between experimental and computational results has been demonstrated for lifted flames at moderate flame conditions, but that agreement breaks down when the fuel is highly diluted or the soot production is high. SLICE is a precursor for the CLD Flame experiment, which is one of five experiments in the Advanced Combustion via Microgravity Experiments (ACME) project that are currently in development for conduct in the Combustion Integrated Rack (CIR). A common goal of the two experiments is to improve computational techniques such that a broader range of flame conditions can be effectively modeled than is currently possible.
SLICE is not being conducted to serve any space applications, but it is possible that its findings could aid the development of future space-based combustion devices (e.g., for solid waste processing).
SLICE enables improvements in the design of practical combustion devices such as engines and furnaces. The improved design capability leads to reduced time and cost for the development of new products.
SLICE testing sessions must be conducted during periods when no reboost or docking procedures are underway on the International Space Station. If possible, the following measurements are to be made of the environment during testing: acceleration, pressure (i.e., in the MSG work volume), and oxygen concentration.
SLICE is a crew-operated experiment, where the crew first installs the SPICE hardware in the MSG work volume. The SPICE hardware consists of a small fan-driven flow duct equipped with an exchangeable burner tube and igniter. Outside of the flow duct are two cameras, the fuel supply bottle, and supporting electronics boxes. Before each test, the crewmember installs the specified burner tube and a supply bottle with the selected fuel. The astronaut then sets the fuel flow and air velocity as indicated in the test matrix and ignites the flame. A small number of flame conditions are studied in each test; the crewmember will adjust either the fuel flow or airflow to achieve different flame conditions. At each flow condition, the crewmember will photograph the flame with a high-resolution digital still camera that has been calibrated with a blackbody source, enabling determination of the soot temperature and soot volume fraction via pyrometry. The fuel flow is shut off upon completion of a test. Throughout the SLICE operations, the science team on the ground will monitor video downlink, which includes overlaid sensor data, to guide the crewmember in lifting the flame and selecting flow conditions that will yield the most useful results. The still images and data will be downlinked to the ground for analysis following each session of operations.
Ground Based Results Publications
Luque J, Jeffries JB, Smith GP, Crosley DR, Walsh KT, Long MB, Smooke MD. CH(A-X) and OH(A-X) optical emission in an axisymmetric laminar diffusion flame. Combustion and Flame. 2000; 122: 172-175.
Walsh KT, Fielding J, Smooke MD, Long MB. Experimental and computational study of temperature, species, and soot in buoyant and non-buoyant coflow laminar diffusion flames. Proceedings of the Combustion Institute. 2000; 28: 1973-1979.
Takahashi F, Katta VR. Reaction Kernel Structure and Stabilizing Mechanisms of Jet Diffusion Flames in Microgravity. Proceedings of the Combustion Institute. 2002; 29: 2509-2518.
Brooker JE, Jia K, Stocker DP, Chen LD. The Influence of Buoyant Convection on the Stability of Enclosed Laminar Flames. Fifth International Microgravity Combustion Workshop, Cleveland, OH; 1999
Takahashi F, Katta VR. Further Studies of the Reaction Kernel Structure and Stabilization of Jet Diffusion Flames. Proceedings of the Combustion Institute. 2005; 30: 383-390.
Walsh KT. Quantitative Characterizations of Coflow Laminar Diffusion Flames in a Normal Gravity and Microgravity Environment. Ph.D. Thesis, Yale University, New Haven, CT; 2000.
Smooke MD, Hall RJ, Colket MB, Fielding J, Long MB, McEnally CS, Pfefferle LD. Investigation of the transition from lightly sooting towards heavily sooting coflow ethylene diffusion flames. Combustion Theory and Modeling. 2004; 8: 593-606.
Takahashi F, Schmoll WJ, Katta VR. Attachment Mechanisms of Diffusion Flames. Proceedings of the Combustion Institute. 1998; 27: 675-684.
Walsh KT, Fielding J, Smooke MD, Long MB, Linan A. A comparison of computational and experimental lift-off heights of co-flow laminar diffusion flames. Proceedings of the Combustion Institute. 2005; 30: 357-365.
Venuturumilli R, Chen LD. Comparison of Four-Step Reduced Mechanism and Starting Mechanism for Methane Diffusion Flames. Fuel. 2009; 88: 1435-1443.
Takahashi F, Linteris GT, Katta VR. Extinguishment of Methane Diffusion Flames by Carbon Dioxide in Coflow Air and Oxygen-Enriched Microgravity Environments. Combustion and Flame. 2008; 155: 37-53.
Takahashi F, Katta VR. A Reaction Kernel Hypothesis for the Stability Limit of Methane Jet Diffusion Flames. Proceedings of the Combustion Institute. 2000; 28: 2071-2078.
Walsh KT, Long MB, Tanoff MA, Smooke MD. Experimental and computational study of CH, CH*, and OH* in an axisymmetric laminar diffusion flame. Proceedings of the Combustion Institute. 1998; 27: 615-623.
Walsh KT, Fielding J, Long MB. Effect of light-collection geometry on reconstruction errors in Abel inversions. Optics Letters. 2000; 25: 457-459.
The lifted nature of the flames can be discerned from the outward flare of the flame base in the example images below (which are not at the same scale) and the distance from the nozzle tip (which is not visible). Picture courtesy of NASA Glenn Research Center.
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At high fuel dilutions, there is a significant discrepancy between computational results and experimental results both in microgravity and on Earth. Note that CH4 is the chemical formula for methane and N2 is the chemical formula for nitrogen (these substances are both gases at room temperature and pressure). Picture courtesy of Yale University.
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