Counter jet stagnation flows

Rolon, Juan-Carlos; Veynante, Denis; Martín, J. P.; Durst, F.

doi:10.1007/bf00194863

Cited by 101 publications

(64 citation statements)

References 10 publications

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“…As pointed out by Rolon et. al [33], the 2U air /H approximation only converges on the measured -1/2 axial and radial SRs well beyond H/D > 1, or preferably at > 1.5. In our subsequent analysis of published n-heptane/N 2 -air extinction data, derived from a 22 mm matrix burner [36], we applied the above correction factor of 0.42 to allow a SR data comparison (discussed later).…”

Section: Resultsmentioning

confidence: 89%

“…Finally, (9) a comprehensive "Idealized Flameholding Scale" will be shown that includes all the results discussed above, extends a factor of 50 to pure H 2 , and includes the effects of HC reactivity with H-atoms. [33]. Both the measured radial SR, and -1/2 the measured axial SR, are shown as a function of nozzle separation.…”

Section: Resultsmentioning

confidence: 99%

“…This correction has two parts. First, based on Rolon's measurements of axial and radial SRs as a function of nozzle separation distance [33], discussed earlier with Fig. 2, a correction factor of 0.42 was applied to the Ref.…”

Section: Extinction Of Pure and N 2 -Diluted Vaporized N-heptane Jp-mentioning

confidence: 99%

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Opposed Jet Burner Approach for Characterizing Flameholding Potentials of Hydrocarbon Scramjet Fuels

Pellett¹,

Convery²,

Wilson³

2006

42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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Opposed Jet Burner (OJB) tools have been used extensively by the authors to measure Flame Strength (FS) extinction limits of laminar H 2 /N 2 -air and (recently) hydrocarbon (HC)-air Counterflow Diffusion Flames (CFDFs) at one atm. This paper details normalization of FSs of N 2 -diluted H 2 and HC systems to account for effects of fuel composition, temperature, pressure, jet diameter, inflow Reynolds number, and inflow velocity profile (plug, contoured nozzle; and parabolic, straight tube). Normalized results exemplify a sensitive accurate means of validating, globally, reduced chemical kinetic models at ~ 1 atm and the relatively low temperatures approximating the loss of non-premixed "idealized" flameholding, e.g., in scramjet combustors.Laminar FS is defined locally as maximum air input velocity, U air , that sustains combustion of a counter-jet of g-fuel at extinction. It uniquely characterizes a fuel. And global axial strain rate at extinction (U air normalized by nozzle or tube diameter, D n or t ) can be compared directly with computed extinction limits, determined using either a 1-D Navier Stokes stream-function solution, using detailed transport and finite rate chemistry, or (better yet) a detailed 2-D Navier Stokes numerical simulation. The experimental results define an "idealized flameholding reactivity scale" that shows wide ranging (50 x) normalized FS's for various vaporized-liquid and gaseous HCs, including, in ascending order: JP-10, methane, JP-7, n-heptane, n-butane, propane, ethane, and ethylene. Results from H 2 -air produce a unique and exceptionally strong flame that agree within ~1% of a recent 2-D numerically simulated FS for a 3 mm tube-OJB. Thus we suggest that experimental FS's and/or FS ratios, for various neat and blended HCs w/ and w/o additives, offer accurate global tests of chemical kinetic models at the Ts and Ps of extinction.In conclusion, we argue the FS approach is more direct and fundamental, for assessing, e.g., idealized scramjet flameholding potentials, than measurements of laminar burning velocity or blowout in a Perfectly Stirred Reactor, because the latter characterize premixed combustion in the absence of aerodynamic strain. And FS directly measures a chemical kinetic characteristic of non-premixed combustion at typical flameholding temperatures. It mimics conditions where gfuels are typically injected into a subsonic flameholding recirculation zone that captures air, where the effects of aerodynamic strain and associated multi-component diffusion become important.

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Section: Resultsmentioning

confidence: 89%

Section: Resultsmentioning

confidence: 99%

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Opposed Jet Burner Approach for Characterizing Flameholding Potentials of Hydrocarbon Scramjet Fuels

Pellett¹,

Convery²,

Wilson³

2006

42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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“…This configuration is briefly described in the next paragraph. More information of the burner can be found in [2,3].…”

Section: Counterflow Burner Devicementioning

confidence: 99%

Experimental and Numerical Studies of Paraguayan Chaco Natural Gas in a Counterflow Diffusion Flame

Maldonado¹,

Alviso²,

Mendieta³

et al. 2015

JMSS

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Combustion is a chemical phenomenon in which a multitude of elementary chemical reactions take place, resulting in the overall process of fuel oxidation. Natural gas fuel has been explored for a few decades and extracted for a few years in the region of Paraguayan Chaco, near Bolivia border. Currently, natural gas is not very important in Paraguay's energy matrix, however it could be in the near future if higher volumes are extracted and transported to the most populated cities, specially to the capital. In order to improve Paraguayan natural gas combustion performance, an understanding of its fundamental properties and the combustion pathways is required. This study presents new data for Paraguayan Chaco natural gas combustion in a laminar counterflow diffusion flame configuration at atmospheric pressure. Visible chemiluminescence of excited radicals * and 2 * is employed experimentally. 1D numerical simulation was carried out using Paraguayan Chaco natural gas chemical composition and a standard kinetic mechanism, to which we added * and 2 * reactions. Typical flame structures resulting from simulation are presented and a validation of the model is realized comparing experimental and numerical * and 2 * radicals profiles.

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“…25 As a result, derived absolute strain rates can be compared directly with extinction limits determined numerically using either a 1-D, or preferably 2 -D, Navier Stokes simulations with detailed transport rates and finite rate kinetics. Initially, numerical extinction results for me thane, 23 based on relatively well-validated chemical kinetics, agreed quite closely (within < 10%) with the absolute strain rate scale.…”

mentioning

confidence: 99%

Unsteady Extinction of Opposed Jet Ethylene / Methane HiFIRE Surrogate Fuel Mixtures vs. Air

Vaden

Debes

Lash

et al. 2009

45th AIAA/ASME/SAE/ASEE Joint Propulsion Conference &Amp;amp; Exhibit

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A unique idealized study of the subject fuel vs. air systems was conducted using an Oscillatory-input Opposed Jet Burner (OOJB) system and a newly refined analysis. Extensive dynamic-extinction measurements were obtained on unanchored (free-floating) laminar Counter Flow Diffusion Flames (CFDFs) at 1-atm, stabilized by steady input velocities (e.g., U air) and perturbed by superimposed in-phase sinusoidal velocity inputs at fuel and air nozzle exits. __________________________________ ___1 Georgia Tech; Atlanta, GA. svaden3@mail.gatech.edu 2 U. of Kansas; Lawrence, KS. rldebes@gmail.com 3 NASA-VA Governor's School; now Lafayette College; Easton, PA. priderock1991@aim.com 4 The U.S Air Force Academy; Colorado Springs, CO. C12Rachel.Burke@usafa.edu (also) schwestigs08@verizon.net 5 NASA-VA Governor's School; now Virginia Tech; Blacksburg, VA. Chaos08@gmail.com 6 Lockheed Martin Space Operations; Hampton, VA. l.g.wilson@larc.nasa.gov 7 Senior Research Scientist, Hypersonic Air Breathing Propulsion Branch/RTG; Senior Member, AIAA. g.l.pellett@larc.nasa.gov Approved for public release; distribution is unlimited.

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Counter jet stagnation flows

Cited by 101 publications

References 10 publications

Opposed Jet Burner Approach for Characterizing Flameholding Potentials of Hydrocarbon Scramjet Fuels

Opposed Jet Burner Approach for Characterizing Flameholding Potentials of Hydrocarbon Scramjet Fuels

Experimental and Numerical Studies of Paraguayan Chaco Natural Gas in a Counterflow Diffusion Flame

Unsteady Extinction of Opposed Jet Ethylene / Methane HiFIRE Surrogate Fuel Mixtures vs. Air

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