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  • 1
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    Dual Stokes cars measurements in supersonic combusting flow (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: Coherent antiStokes Raman spectroscopy (CARS) was used to make simultaneous measurements of temperature, nitrogen and oxygen density in a reacting supersonic flow. A supersonic burner (SSB) was designed to provide supersonic flow in which combustion can be studied in the laboratory. Measurements made with the CARS system will be used for validation of computational fluid dynamic (CFD) codes. Preliminary results of the CFD calculations are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Johns Hopkins Univ., The 24th JANNAF Combustion Meeting, Volume 2; p 171-178
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Mach 2 combustion characteristics of hydrogen/hydrocarbon fuel mixtures (1987)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Description: The combustion of H2/CH4 and H2/C2H4 mixtures containing 10 to 70 vol pct hydrocarbon at combustor inlet Mach number 2 and temperatures 2000 to 4000 R is investigated experimentally, applying direct-connect test hardware and techniques similar to those described by Diskin and Northam (1987) in the facilities of the NASA Langley Hypersonic Propulsion Branch. The experimental setup, procedures, and data-reduction methods are described; and the results are presented in extensive tables and graphs and characterized in detail. Fuel type and mixture are found to have little effect on the wall heating rate measured near the combustor exit, but H2/C2H4 is shown to burn much more efficiently than H2/CH4, with no pilot-off blowout equivalence ratios greater than 0.5. It is suggested that H2/hydrocarbon mixtures are feasible fuels (at least in terms of combustion efficiency) for scramjet SSTO vehicles operating at freestream Mach numbers above 4.
    Keywords: INORGANIC AND PHYSICAL CHEMISTRY
    Type: Johns Hopkins Univ., The 24th JANNAF Combustion Meeting, Volume 2; p 155-169
    Format: text
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  • 3
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    Mach 2 combustion characteristics of hydrogen/hydrocarbon fuel mixtures (1987)
    In:  Other Sources
    Details
    Publication Date: 2018-12-01
    Description: The combustion of H2/CH4 and H2/C2H4 mixtures containing 10-70 vol pct hydrocarbon at cumbustor inlet Mach number 2 and temperatures 2000-4000 R is investigated experimentally, applying direct-connect test hardware and techniques similar to those described by Diskin and Northam (1987) in the facilities of the NASA Langley Hypersonic Propulsion Branch. The experimental setup, procedures, and data-reduction methods are described; and the results are presented in extensive tables and graphs and characterized in detail. Fuel type and mixture are found to have little effect on the wall heating rate measured near the combustor exit, but H2/C2H4 is shown to burn much more efficiently than H2/CH4, with no pilot-off blowout at equivalence ratios greater than 0.5. It is suggested that H2/hydrocarbon mixtures are feasible fuels (at least in terms of combustion efficiency) for scramjet SSTO vehicles operating at freestream Mach numbers above 4.
    Keywords: PROPELLANTS AND FUELS
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    NASA TECHNICAL REPORTS
  • 4
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    A 3-level Model for Schumann-Runge O2 Laser-Induced Fluorescence (1996)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: A three level model has been developed for the analysis of Schumann-Runge band (B(sup 3)Sigma(sup -)(sub u ) 〈- X(sup 3)Sigma(sup -)(sub g)) laser-induced fluorescence of molecular oxygen, O2. Such a model is required due to the severe lower state depletion which can occur when transitions having relatively large absorption cross-sections are excited. Such transitions are often utilized via ArF* or KrF* excimer or dye-laser excitation in high temperature environments. The rapid predissociation of the upper state prevents substantial repopulation of the lower state by collisional processes, and the lower state may be largely depleted, even at laser fluences as low as 10-100 mJ/sq cm. The resulting LIF signal in such cases no longer varies linearly with laser pulse energy, and the extent of the sublinear behavior varies with the particular rovibrational transition of interest. Relating the measured signal to the lower state population, then, necessitates the use of exceedingly low laser fluences. These low fluences in turn lead to the need to compromise spatial resolution in order to generate sufficient signal.
    Keywords: Lasers and Masers
    Format: application/pdf
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  • 5
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    Supersonic combustion performance of hydrogen/hydrocarbon mixtures as determined by a nonintrusive temperature monitor (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A simple and reliable OH absorption technique was developed and applied to measure path integrated temperature and OH number density in scramjet combustor hardware. The first series of measurements was made in premixed combustion products at the exit of a Mach 2 nozzle mounted on a hydrogen fueled vitiated heater. The second series of tests was conducted during supersonic combustion evaluation of hydrogen/hydrocarbon fuel mixtures. These measurements were made near the exit of a 48-inch long diverging supersonic combustor. The OH number density measurements indicated that both the nozzle and the combustor flow were not in equilibrium.
    Keywords: PROPELLANTS AND FUELS
    Type: AIAA PAPER 88-3293
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  • 6
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    Effects of scale on supersonic combustor performance (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: A series of tests has been carried out to investigate the effects of various scale parameters on the direct connect scramjet combustor performance. The calculated combustion efficiency appears to be independent of scale for the same geometry, but tests with more precise scaling of the entire combustor are required to verify this. Combustion, however, can be strongly dependent on geometry for the same scale. It is suggested that the beneficial aspects of certain geometric or scale variations can be combined to improve the overall performance.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: AIAA PAPER 87-2164
    Format: text
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  • 7
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    Observation of Vibrational Relaxation Dynamics in X(sup 3)Sigma(sup -)(sub g) Oxygen Following Stimulated Raman Excitation to the v=1 Level: Implications for the RELIEF Flow Tagging Technique (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The vibrational relaxation of ground-state molecular oxygen (O2, X(sup 3)Sigma(sup -)(sub g)) has been observed, following stimulated Raman excitation to the first excited vibrational level (v=1). Time delayed laser-induced fluorescence probing of the ro-vibrational population distribution was used to examine the temporal relaxation behavior. In the presence of water vapor, the relaxation process is rapid, and is dominated by near-resonant vibrational energy exchange between the v=1 level of O2 and the n2 bending mode of H2O. In the absence of H2O, reequilibration proceeds via homogeneous vibrational energy transfer, in which a collision between two v=1 O2 molecules leaves one molecule in the v=2 state and the other in the v=0 state. Subsequent collisions between molecules in v=1 and v〉1 result in continued transfer of population up the vibrational ladder. The implications of these results for the RELIEF flow tagging technique are discussed.
    Keywords: Inorganic, Organic and Physical Chemistry
    Type: AIAA Paper 96-0301 , 34th Aerospace Sciences Meeting and Exhibit; Jan 15, 1996 - Jan 18, 1996; Reno, NV; United States
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  • 8
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    Sensitivity of supersonic combustion to combustor/flameholder design (1988)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The present test series was conducted to ascertain the effects of various scale and geometric parameters on the combustion and pressure rise limits of a direct-connect supersonic combustor employing hydrogen fuel in a Mach 2 flow and 1-atm static pressure. The injector configuration was similar to that developed by Wagner et al. (1987). Attention is given to the effects of upstream length, fuel-injection gap, and constant-area combustor length, as well as to those of equivalence ratios and stagnation temperature. It is found that, for a given scale, combustion can be strongly dependent on such geometric factors as the use of either constant-area combustion or immediate expansion.
    Keywords: AIRCRAFT PROPULSION AND POWER
    Type: ICAS Congress; Aug 28, 1988; Jerusalem; Israel
    Format: text
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  • 9
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    The NASA Langley Scramjet Test Complex (1996)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The NASA Langley Scramjet Test Complex consists of five propulsion facilities which cover a wide spectrum of supersonic combustion ramjet (scramjet) test capabilities. These facilities permit observation of the effects on scramjet performance of speed and dynamic pressure from Mach 3.5 to near-orbital speeds, engine size from Mach 4 to 7, and test gas composition from Mach 4 to 7. In the Mach 3.5 to 8 speed range, the complex includes a direct-connect combustor test facility, two small-scale complete engine test facilities, and a large-scale complete engine test facility. In the hypervelocity speed range, a shock-expansion tube is used for combustor tests from Mach 12 to Mach 17+. This facility has recently been operated in a tunnel mode, to explore the possibility of semi-free-jet testing of complete engine modules at hypervelocity conditions. This paper presents a description of the current configurations and capabilities of the facilities of the NASA Langley Scramjet Test Complex, reviews the most recent scramjet tests in the facilities, and discusses comparative engine tests designed to gain information about ground facility effects on scramjet performance.
    Keywords: Research and Support Facilities (Air)
    Type: NASA-TM-111658 , NAS 1.15:111658 , AIAA Paper 96-3243 , AIAA/ASME/SAE/ASEE Joint Propulsion Conference; Jul 01, 1996; Lake Buena Vista, FL; United States|AIAA/ASME/SAE/ASEE Joint Propulsion Conference; Jul 01, 1996 - Jul 03, 1996; Lake Buena Vista, FL; United States
    Format: text
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