PSI-68 · FLEX-2
“The primary goal of the FLEX-2 flight experiments is to extend the results of FLEX-1 to fuels and environmental conditions that mimic real combustor conditions, as well as, provide benchmark experimental data on bi-component droplet combustion over a wide range of initial conditions in order to validate numerical simulations and to develop new theoretical models.” [PSI JSON: objective]
“4 mole fraction with the diluent gas making up the balance.” [PSI JSON: approach]
Overview
Objective [text]
The primary goal of the FLEX-2 flight experiments is to extend the results of FLEX-1 to fuels and environmental conditions that mimic real combustor conditions, as well as, provide benchmark experimental data on bi-component droplet combustion over a wide range of initial conditions in order to validate numerical simulations and to develop new theoretical models. Detailed experimental objectives can be further itemized as: 1. Investigate the role of liquid-phase mixing on the burning characteristics of bi-component fuel droplets. 2. Examine the steady and unsteady liquid and gas-phase phenomena in pure fuel combustion. 3. Study flame extinction mechanisms and their boundaries. 4. Analyze the soot formation process, including soot volume fraction soot-shell dynamics. 5. Determine the influence of droplet interactions on the flammability limits and extinction behavior of droplet arrays. 6. Validate theoretical models of droplet combustion through comprehensive experimental data collection in microgravity environments.
Source
data/raw/psi-data/PSI-68/_investigation/PSI-68.json: objective · PSI investigationApproach [text]
The chamber was filled with the appropriate atmosphere, which was varied in pressure between 0.5 atm to 3.0 atm and O2 concentration between 0.1 to 0.4 mole fraction with the diluent gas making up the balance. A settling time of approximately 2 minutes elapsed prior to initiating the test in order to ensure that the temperature and pressure of the chamber gases have stabilized. This settling time was followed by the dispensing of a predetermined amount of fuel (based on the target droplet size) onto the support fiber for those tests in which the droplet is not freely deployed. When sufficient fuel has been dispensed the dispensing needles were retracted and a dwell period of at least 10 seconds was allowed for the droplet internal fluid motion induced by deployment to subside. This was then followed by initiating power to the ignitor for a selectable amount of time ranging from 1 second to 5 seconds after which the ignitor was retracted from the field of view. If the flow field is to be generated by translating the droplet then droplet motion would commence at the same time that the ignitor is retracted. A near real-time download of the color camera video was employed in order to verify successful droplet deployment, ignition, and overall progress of the experiment. Pressure and temperature data of the chamber environment was also recorded in near real time. The overall investigation approach can be summarized as: 1. Test parameters are determined, including pressure, temperature, fuel mixture, and humidity. 2. Fill the combustion chamber with the selected gas mixtures. 3. Deploy the droplet(s) carefully controlling the droplet diameter. 4. Allow the droplet to stabilize in the microgravity environment. 5. Ignite the droplet in a uniform and controlled fashion. 6. Monitor combustions and track flame evolution using high speed photography. 7. Monitor and adjust experimental conditions as needed. 8. Analyze data. The independently varied experimental parameters during FLEX-2 experiments were 1) Fuel type 2) Ambient gas composition 3) Ambient Pressure 4) Droplet initial diameter 5) Droplet translation velocity (and acceleration) 6) Droplet spacing and initial size in a binary linear array.
Source
data/raw/psi-data/PSI-68/_investigation/PSI-68.json: approach · PSI investigationHypothesis [text]
Fairly sophisticated numerical simulations of convective droplet combustion have been developed in the last decade where the key contribution is the inclusion of full Navier-Stokes equations for the gas-phase flow field. However, due to the inherent complexity of the problem, varying degrees of approximations have been made in treating the chemistry, radiation, and the coupling between the gas and liquid phases. The validity of the assumptions or the hypothesis used in these simulation have not been confirmed by using benchmark data. By conducting these experiments in a microgravity environment, the effects of buoyancy are minimized, and the droplet can be characterized only as a function of thermocapillary or solutalcapillary stresses allowing for a clear observation of the fundamental combustion processes, The present FLEX-2 experiments using bi-component mixtures. In addition, the microgravity environment allows study of such phenomena as the transitions between radiative and diffusive extension of the flame. The primary goal of the flight experiments is to provide benchmark experimental data on bi-component droplet combustion over a wide range of initial conditions that could be used to validate numerical simulations and to develop new theoretical models.
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data/raw/psi-data/PSI-68/_investigation/PSI-68.json: hypothesis · PSI investigationResearch impacts [text]
The combustion of liquid fuels is the overwhelming energy source in the transportation sector. Insights gained from these studies can lead to more efficient and cleaner combustion technologies which are crucial for reducing pollution and greenhouse gas emissions. By improving fuel efficiency and developing better fuels, these experiments can contribute to: 1) More sustainable energy production. 2) Future combustor designs with minimal carbon footprint, maximum fuel efficiency and less pollutant emissions. 3) Allow quantitative evaluation of the performance of future fuels in combustors through the development of surrogates (mixtures of pure fuels that simulate the behavior of real fuels). 4) Validation of jet engine models by engine manufacturers with support from prior droplet results.
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data/raw/psi-data/PSI-68/_investigation/PSI-68.json: researchImpacts · PSI investigationHardware [text]
Combustion Integrated Rack (CIR), Multi-user Droplet Combustion Appartatus (MDCA)
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data/raw/psi-data/PSI-68/_investigation/PSI-68.json: experimentHardware · PSI investigationFlight program [text]
International Space Station (ISS)
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data/raw/psi-data/PSI-68/_investigation/PSI-68.json: flightProgram · PSI investigationStart date [text]
08-12-2016
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data/raw/psi-data/PSI-68/_investigation/PSI-68.json: investigationStartDate · PSI investigationEnd date [text]
09-30-2019
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data/raw/psi-data/PSI-68/_investigation/PSI-68.json: investigationEndDate · PSI investigationTests
8 tests with extracted table records (SAME-R aging sub-runs grouped by parent ID) · 126 extracted values (source: data/conditions/PSI-68.csv).
Variation is observed in extracted values; it does not establish the experimental design.
| Variable | Observed | Distinct values / tests | Range |
|---|---|---|---|
| ambient_temperature [data/conditions/PSI-68.csv] | observed constant | 1 / 8 | 298.15 K |
| diluent [data/conditions/PSI-68.csv] | distinct values as recorded | 2 / 8 | He, N2 |
| droplet_diameter_initial [data/conditions/PSI-68.csv] | observed constant | 1 / 8 | 1.5..5 |
| flow_velocity [data/conditions/PSI-68.csv] | observed constant | 1 / 8 | 0.1..5 |
| fuel [data/conditions/PSI-68.csv] | distinct values as recorded | 8 / 8 | Decane (pure), Ethanol (pure), Heptane (50%) IsoOctane (50%) (mixture), Heptane (pure), IsoOctane (pure), Propanol (80%) Glycerol (20%) (mixture), Propanol (95%) Glycerol (5%) (mixture), n-Octane (pure) |
| o2_mole_fraction [data/conditions/PSI-68.csv] | varied | 4 / 8 | 17.0% – 30.0% |
| pressure [data/conditions/PSI-68.csv] | varied | 5 / 8 | 50.7 kPa (7.35 psia) – 304 kPa (44.1 psia) |
Loading test data…
Additional outcome cells, where available, are displayed as written. Source: data/derived/outcomes_extra.csv.
Instruments mentioned in the approach
A near real-time download of the color camera video was employed in order to verify successful droplet deployment, ignition, and overall progress of the experiment. [data/raw/psi-data/PSI-68/_investigation/PSI-68.json: approach] PSI investigation
Experimental table columns
- Sample (Fuel Type) [table] data/raw/psi-data/PSI-68/Experimental table/PSI-68_Experimental table_Flex2.csv · PSI investigation
- Initial Droplet Diameter (mm) [table] data/raw/psi-data/PSI-68/Experimental table/PSI-68_Experimental table_Flex2.csv · PSI investigation
- Ambient Gas Mixture [table] data/raw/psi-data/PSI-68/Experimental table/PSI-68_Experimental table_Flex2.csv · PSI investigation
- Oxygen Mole Fraction [table] data/raw/psi-data/PSI-68/Experimental table/PSI-68_Experimental table_Flex2.csv · PSI investigation
- Ambient Pressure (atm) [table] data/raw/psi-data/PSI-68/Experimental table/PSI-68_Experimental table_Flex2.csv · PSI investigation
- Ambient Temperature (C) [table] data/raw/psi-data/PSI-68/Experimental table/PSI-68_Experimental table_Flex2.csv · PSI investigation
- Flow Velocity (cm/s) [table] data/raw/psi-data/PSI-68/Experimental table/PSI-68_Experimental table_Flex2.csv · PSI investigation
Data
Publications
- Experimental Study of Initial Diameter Effects on Convection-free Droplet Combustion in the Standard Atmosphere for n-Heptane, n-Octane, and n-Decane: International Space Station and Ground-based Experiments 10.2514/6.2014-1019 [data/manifest/publications.csv]
- n-Butanol droplet combustion: Numerical modeling and reduced gravity experiments [data/manifest/publications.csv]
- Droplet Combustion Experiments Aboard the International Space Station 10.1007/s12217-014-9372-2 [data/manifest/publications.csv]
- Multistage oscillatory “Cool Flame” behavior for isolated alkane droplet combustion in elevated pressure microgravity condition [data/manifest/publications.csv]
- Computational modeling of the effects of support fibers on evaporation of fiber-supported droplets in reduced gravity [data/manifest/publications.csv]
- Oxygen Lewis Number Effects on Reduced Gravity Combustion of Methanol and Heptane Droplets 10.1080/00102202.2015.1072176 [data/manifest/publications.csv]
- ISS Droplet Combustion Experiments - Uncertainties in Droplet Sizes and Burning Rates 10.1007/s12217-014-9377-x [data/manifest/publications.csv]
- Combustion of Butanol, Gasoline, and Butanol/Gasoline Mixture Droplets 10.1021/acs.energyfuels.5b00158 [data/manifest/publications.csv]
- Computational Modeling of Unsupported and Fiber-Supported n-Heptane Droplet Combustion in Reduced Gravity: A Study of Fiber Effects 10.1080/00102202.2014.971950 [data/manifest/publications.csv]
- The effect of support fibers on micro-convection in droplet combustion experiments [data/manifest/publications.csv]
- Cool-flame extinction during n-alkane droplet combustion in microgravity [data/manifest/publications.csv]
- A short mechanism for the low-temperature ignition of n-heptane at high pressures [data/manifest/publications.csv]
- The role of cool-flame chemistry in quasi-steady combustion and extinction of n-heptane droplets 10.1080/13647830.2014.934296 [data/manifest/publications.csv]
- Combustion of Submillimeter Heptane/Methanol and Heptane/Ethanol Droplets in Reduced Gravity 10.1155/2013/154202 [data/manifest/publications.csv]
- Isolated n-heptane droplet combustion in microgravity: “Cool Flames” – Two-stage combustion 10.1016/j.combustflame.2013.09.011 [data/manifest/publications.csv]
- Sub-millimeter sized methyl butanoate droplet combustion: Microgravity experiments and detailed numerical modeling 10.1016/j.proci.2012.07.074 [data/manifest/publications.csv]
- On the spherically symmetrical combustion of methyl decanoate droplets and comparisons with detailed numerical modeling [data/manifest/publications.csv]
- The spherically symmetric droplet burning characteristics of Jet-A and biofuels derived from camelina and tallow [data/manifest/publications.csv]
- Spherically symmetric droplet combustion of three and four component miscible mixtures as surrogates for Jet-A [data/manifest/publications.csv]
- AUTOMATED DATA ANALYSIS FOR CONSECUTIVE IMAGES FROM DROPLET COMBUSTION EXPERIMENTS 10.5566/ias.v31.p137-148 [data/manifest/publications.csv]
- On the extinction characteristics of alcohol droplet combustion under microgravity conditions – A numerical study 10.1016/j.combustflame.2012.04.005 [data/manifest/publications.csv]
- A comparison of the spherical flame characteristics of sub-millimeter droplets of binary mixtures of n-heptane/iso-octane and n-heptane/toluene with a commercial unleaded gasoline 10.1016/j.combustflame.2011.08.015 [data/manifest/publications.csv]
- Comparison of the Burning Characteristics of Indolene and Commercial Grade Gasoline Droplets without Convection 10.1021/ef3007849 [data/manifest/publications.csv]
- Can cool flames support quasi-steady alkane droplet burning? 10.1016/j.combustflame.2012.07.012 [data/manifest/publications.csv]
- Experiments on Submillimeter Free Droplet Flame Extinction 10.1080/00102202.2012.759946 [data/manifest/publications.csv]
- Influences of support fibers on vaporizing fuel droplets [data/manifest/publications.csv]
- Combustion of Methanol Droplets in Air-Diluent Environments with Reduced and Normal Gravity 10.1155/2012/587987 [data/manifest/publications.csv]
- Microgravity droplet combustion: effect of tethering fiber on burning rate and flame structure 10.1080/13647830.2010.547601 [data/manifest/publications.csv]
- Influence of Gravity and Ambient Pressure on Combustion and Flammability of n-Heptane and 1-Propanol Droplets in Air-Diluent Environments 10.1080/00102202.2010.498798 [data/manifest/publications.csv]
- Ignition and combustion of n-heptane droplets in carbon dioxide enriched environments 10.1016/j.icheatmasstransfer.2009.10.006 [data/manifest/publications.csv]
- Computational modeling of n-heptane droplet combustion in air–diluent environments under reduced-gravity 10.1016/j.ijheatmasstransfer.2010.08.005 [data/manifest/publications.csv]
- Numerical Simulation of Unsteady Flows and Shape Oscillations in Liquid Droplets Induced by Deployment Needle Retraction 10.1007/s12217-008-9096-2 [data/manifest/publications.csv]
- Nonane droplet combustion with and without buoyant convection: Flame structure, burning rate and extinction in air and helium 10.1016/j.proci.2008.06.221 [data/manifest/publications.csv]
- Temperature and fiber optic spectroscopy composition measurements of heated propanol–acetone droplets 10.1016/j.optlaseng.2009.05.004 [data/manifest/publications.csv]
- Laser-induced fluorescence imaging of acetone inside evaporating and burning fuel droplets [data/manifest/publications.csv]
- Reduced Gravity Combustion of Propanol Droplets in Oxygen-Inert Environments 10.1080/00102200903190851 [data/manifest/publications.csv]
- PROPANOL DROPLET FLAMMABILITY AND COMBUSTION IN AIR-DILUENT ENVIRONMENTS UNDER NORMAL AND REDUCED GRAVITY 10.1080/00102200601057394 [data/manifest/publications.csv]
- Developing Surrogates for Liquid Transportation Fuels: The Role of Spherically Symmetric Droplet Combustion 10.1007/978-81-322-2211-8_16 [data/manifest/publications.csv]
- Experimental Observations of the Low-Temperature Burning of Decane/Hexanol Droplets in Microgravity 10.1080/00102202.2016.1225730 [data/manifest/publications.csv]
- Cool-flame dodecane-droplet extinction diameters 10.1016/j.combustflame.2019.10.036 [data/manifest/publications.csv]
- Quasi-steady combustion of normal-alkane droplets supported by Cool-Flame chemistry near diffusive extinction 10.1080/13647830.2019.1588380 [data/manifest/publications.csv]
- Radiative extinction of burner-supported spherical diffusion flames: A scaling analysis 10.1016/j.combustflame.2019.04.027 [data/manifest/publications.csv]
- Unsteady droplet combustion with fuel thermal expansion 10.1016/j.combustflame.2018.01.035 [data/manifest/publications.csv]
- Radiative extinction of large n-alkane droplets in oxygen-inert mixtures in microgravity 10.1016/j.combustflame.2018.04.023 [data/manifest/publications.csv]
- A Burke-Schumann analysis of dual-flame structure supported by a burning droplet 10.1016/j.icheatmasstransfer.2017.06.016 [data/manifest/publications.csv]
- A Burke–Schumann analysis of diffusion-flame structures supported by a burning droplet 10.1080/13647830.2017.1280182 [data/manifest/publications.csv]
- Dynamic Differential Image Circle Diameter Measurement Precision Assessment: Application to Burning Droplets [data/manifest/publications.csv]
- Interpretation of Backlit Droplet Images from ISS Droplet Combustion Experiments 10.2478/gsr-2014-0007 [data/manifest/publications.csv]
Data reuse
Not stated in PSI [not in PSI] data/raw/psi-data/PSI-68/_investigation/PSI-68.json: related_glds · PSI investigation
PSI page
PSI page data/manifest/web_check_2026-11-14.csv: line 1 URL pattern