Utafiti huu umechunguza kwa experimental measurements na one-dimensional counterflow simulations jinsi methane-hydrogen co-firing flames katika dual-swirl gas-turbine injector zinavyostabilize zikiwa attached kwenye injector au lifted kutoka kwenye injector. Watafiti walitumia high-speed OH planar laser-induced fluorescence imaging, particle image velocimetry na CHEMKIN-based OPPDIF calculations katika operating conditions 36. Kuongeza hydrogen fraction kwa ujumla kuli-support flame attachment kwenye injector, huku kuongeza main-flow velocity kutoka 10 m/s hadi 15 m/s kukipanua lifted-flame region. Flame width na pilot-flame lift height ziliongezeka pamoja na hydrogen fraction na zilionyesha strong relations hasa na momentum ratio kati ya pilot na main passages. Hata hivyo, study ni preprint ambayo haijapitia peer review; one-dimensional model haiwakilishi absolute dimensions za three-dimensional turbulent flame, bali only trends za change.

Experimental images zilionyesha two basic flame structures. Katika attached flame, outer reaction layer iliendelea hadi injector exit, huku katika lifted flame root ya layer hii ikizimika locally na reaction zone ikastabilize tena farther downstream. Wider appearance ya time-averaged OH region katika lifted flame ilielezwa si kwa physical thickening ya individual flame layers, bali kwa fluctuation, wrinkling, intermittent behavior ya flame surface na partial merging ya inner na outer reaction layers.

Main question ya research ni nini?

Main question ya research ni jinsi premixed CH₄/air flow inayotolewa kutoka outer main passage na pure H₂ flow inayotolewa bila oxidizer kutoka inner pilot passage zinavyoingiliana katika dual-swirl injector, na jinsi interaction hii inavyobadilisha flame kuwa structure attached kwenye injector au lifted kutoka kwenye injector. Study pia ilichunguza kama main reaction layers za complex three-dimensional turbulent flame zinaweza kushughulikiwa kama local flamelets na kuelezeka kwa one-dimensional counterflow model.

Ingawa literature ina studies kuhusu stability ya dual-swirl flames, extraction ya reproducible geometric indicators kama flame width na pilot-flame lift height kutoka mean OH-PLIF images, correlation ya indicators hizi na pilot-main-flow momentum, na comparison ya same trends na one-dimensional OPPDIF model imebaki limited. Research ililenga gap hii kwa kuunganisha experiment, image processing na reduced numerical modeling katika framework moja.

Dual-swirl injector inafanyaje kazi?

Combustion chamber ni square structure yenye four quartz windows zinazoruhusu optical measurements, internal cross-section ya 70 mm × 70 mm na height ya 260 mm. Premixed CH₄/air flow iliyoandaliwa kwa methane yenye purity ya %99,999 ilitolewa kutoka outer annular main passage, huku hydrogen yenye purity ya %99,999 ikitolewa kutoka inner annular pilot passage. Air au oxidizer nyingine haikuongezwa kwenye pilot hydrogen flow kwenye inlet.

Main swirler ni tangential, huku pilot swirler ikiwa six-vane axial type. Kwa sababu flows zote mbili ziliswirl counterclockwise, setup ilitengeneza co-rotating dual-swirl structure. Main na pilot swirl numbers zilitolewa kama 0,51 na 0,83 respectively. Katika geometric schematic, main exit diameter imeonyeshwa kuwa 20,0 mm, huku diameters zinazohusiana na pilot section zikiwa 10,7 mm na 7,0 mm.

Swirling flow inatengeneza inner recirculation zone ambapo burned hot gases zinarudishwa kutoka central region kuelekea injector. Returning hot gas hii inafanya kazi kama continuous source ya heat na active species inayosaidia reignition ya fresh fuel-air mixture. Hata hivyo, existence ya inner recirculation zone pekee haikumaanisha flame lazima iwe attached kwenye injector. Jinsi recirculation zone inavyokaribia injector, axial velocity ya main flow, velocity gradient katika shear layer na momentum ya pilot hydrogen jet kwa pamoja ziliamua location ya flame root.

Difference kati ya attached na lifted flame ni nini?

Moja ya important interpretations za study ni kwamba lifted flame haipaswi kuchukuliwa kama entire flame structure kuhamishwa juu kama single piece. Katika first stage, local reaction-transport balance katika root ya outer reaction layer karibu na injector inavunjika, local extinction inatokea na flame inareattach katika downstream position yenye more suitable velocity na mixing conditions.

Thicker appearance ya mean OH region katika lifted flame pia haithibitishi kwamba internal structure ya single instantaneous flame front imekuwa thicker. Instantaneous images zilizochukuliwa kwa frames 10.000 kwa second zilionyesha flame surface ikihamia positions tofauti over time, ikiwinkle more strongly na inner-outer layers zikioverlap mara kwa mara. Averaging ya images elfu nne inaonyesha movements hizi zote kama broad reaction region.

Hydrogen fraction ilibadilishaje flame stability?

Kuongezeka kwa hydrogen fraction kwa ujumla kuli-support flame attachment kwenye injector. Hydrogen fraction ilipoongezeka, si chemical reactivity ya mixture pekee iliyobadilika; velocity na momentum ya hydrogen kutoka pilot nozzle pia ziliongezeka. Hivyo, pilot jet ya center ilitengeneza stronger aerodynamic na chemical effect inayosupport outer CH₄/air flame root karibu na injector.

Kwa mfano, wakati main-flow velocity ilikuwa 10 m/s na global equivalence ratio 0,6, attached flame ilionyeshwa kwa %60 hydrogen content, huku lifted flame ikionyeshwa kwa %50 hydrogen content. Hydrogen fraction ilipopunguzwa kutoka %60 hadi %50, local equivalence ratio ya main CH₄/air mixture iliongezeka na change hii, ikitathminiwa peke yake, ingeweza kuelekea positive effect kwa burning velocity. Hata hivyo, flame lifting ilionyesha kwamba transition haikutegemea main-flame chemistry pekee; weaker velocity, momentum na ignition support ya pilot hydrogen jet vilikuwa more determining.

Katika stability map, kwa methane-only case, lean-blowoff ilionekana around Φ_g ≤ 0,5 region. Wakati small amount ya hydrogen iliongezwa, flame iliweza kudumishwa katika lower global equivalence ratios. Finding hii inaonyesha kwamba pilot hydrogen flow inaweza kupanua lean-burning limit kwa kutoa heat na active-radical support katika central region. Hata hivyo, kwa sababu study haikupima emissions, fuel consumption au system efficiency, increase hii ya stability haipaswi kutafsiriwa directly kama environmental au economic gain.

Effect ya main-flow velocity ni nini?

Kuongeza bulk velocity katika main passage kutoka 10 m/s hadi 15 m/s kulipanua lifted-flame region significantly. Katika all conditions ambapo OH-PLIF ilipimwa, main velocity ilikuwa 15 m/s, hydrogen ilikuwa %20-%60 na Φ_g = 0,5-0,7, outer flame root ilidetach kutoka injector na lifted-flame morphology ikabaki.

Higher main velocity iliongeza axial convection ya premixed flow na velocity gradient katika main shear layer. Hivyo, local burning na reignition conditions zinazohitajika ili flame surface ibaki karibu na injector zikawa more difficult. Ingawa higher hydrogen fraction iliongeza pilot support, katika 15 m/s condition support hii haikutosha kushinda dominant convective effect ya main flow na kureattach flame kwenye injector.

Kwa nini global equivalence ratio haitoshi peke yake?

Global equivalence ratio Φ_g inaonyesha stoichiometric state ya total fuel katika system relative kwa total air. Hata hivyo, katika experimental setup, Φ_g ilipobadilishwa, equivalence ratio ya main passage, total thermal power, pilot velocity, velocity ratio na pilot-main interaction pia zilibadilika pamoja. Kwa hiyo, simple conclusion kwamba higher Φ_g daima itaattach flame kwa injector more strongly haikuweza kutolewa.

Katika images, kadiri Φ_g ilivyoongezeka, reaction region ilionekana kuspread kwenye wider area, na heat release pamoja na thermal expansion zikifanya flame iunde more developed structure downstream. Katika some conditions, persistence ya lifted morphology licha ya richer main mixture ilionyesha kwamba flame stability haitegemei chemical burning velocity pekee, bali aerodynamic balance kati ya pilot na main flows.

OH-PLIF images ziliquantifiwaje?

Watafiti wali-average instantaneous OH-PLIF images 4.000 kwa kila condition, wakafanya laser-sheet intensity correction na kutumia OTSU thresholding method kutenganisha flame na background. OTSU method inagawa image-brightness histogram kuwa classes mbili na automatically kuchagua threshold inayomaximize between-class variance. Hivyo, subjectivity inayoweza kutoka kwa fixed threshold iliyochaguliwa manually na researcher inapunguzwa.

Normalized OTSU thresholds zilizochaguliwa katika conditions tofauti zilisambaa roughly kati ya 0,20-0,30 ya maximum OH intensity, huku average value ikiwa roughly 0,25. Result hii baadaye ilitumika pia katika numerical model na position inayolingana na %25 ya maximum OH mole fraction ikachaguliwa kama comparison boundary. Level hii ya %25 si absolute physical boundary ya real flame surface; ni empirical criterion inayosaidia kulinganisha experimental na numerical shape indicators kwa reference ileile.

Geometric indicators mbili zilifafanuliwa:

• Flame width: Radial distance kati ya injector centerline na OTSU boundary ya outer reaction layer.
• Pilot-flame lift height: Axial distance kati ya nozzle-exit plane na base ya inner reaction layer.

Ikisomwa approximately kutoka graphs, katika conditions ambapo main velocity ilikuwa 10 m/s, flame width katika %20 hydrogen level ilikuwa roughly 7,3-7,8 mm, huku katika %80 hydrogen level ikifikia roughly 14-17,7 mm depending on Φ_g. Pilot-flame lift height iliongezeka katika same hydrogen range kutoka roughly 3,4-4,6 mm hadi roughly 14,8-18,8 mm. Hizi ni values zilizosomwa approximately kutoka graph na hazipaswi kuchukuliwa kama exact raw data.

Katika case ambapo main velocity ilikuwa 15 m/s na all measurement conditions zilitengeneza lifted flame, increase ya width ilibaki more limited. Flame width katika %20 hydrogen level ilikuwa roughly 6,8-7,7 mm, na katika %60 hydrogen level ilikuwa roughly 8,3-10,5 mm. Pilot lift height, hata hivyo, ilionyesha more different absolute levels depending on Φ_g. Hii inaonyesha kwamba lift height haiwakilishi attached-lifted transition pekee, bali pia position ya inner reaction layer within lifted regime.

Kwa nini momentum ratio ilichukuliwa kama key parameter?

Hydrogen fraction, main velocity na equivalence ratio ni operating variables zinazoathiriana. Ili kuunganisha aerodynamic consequence ya variables hizi katika quantity moja, watafiti walitumia momentum-flux ratio ya pilot na main passages:

\[ J = \frac{\rho_P U_P^2}{\rho_M U_M^2} \]

Hapa J ni dimensionless momentum ratio, ρ_P na ρ_M ni mixture densities katika pilot na main passages, huku U_P na U_M zikiwa nozzle-exit velocities. Kwa kuwa momentum flux inategemea product ya density na square ya velocity, change katika velocity inabadilisha balance kati ya pilot na main flows strongly.

Katika horizontal axis za graphs, transformation J^0,16 - 0,23 iliyotumiwa na authors imeonyeshwa. Linear fits zilizopatikana katika experimental results ni hizi:

Lower R² ya flame width katika lifted regime inaonyesha kwamba single parameter haiwezi kueleza entire morphology ya regime hii. Baada ya outer flame root kujitenga na injector, local mixing, reverse flow, shear-layer strain, degree ya partial premixing na temporal fluctuation zinachukua stronger roles. Kwa upande mwingine, pilot lift height ili-response more regularly kwa momentum ratio kwa sababu ina-reflect directly mahali ambapo center jet inakutana na recirculation zone.

One-dimensional OPPDIF model inawakilisha nini?

Numerical model haikusolve entire combustion chamber au three-dimensional swirling turbulence. Watafiti waliidealize two main reaction layers zinazoonekana katika OH-PLIF images kama separate local counterflow flames.

• Case I: Inawakilisha outer reaction layer. Premixed CH₄/air ilitolewa kutoka side moja na pure H₂ kutoka opposite side. Both inlet temperatures ziliwekwa 298 K, CH₄/air inlet velocity 10 m/s, na hydrogen velocity kama variable depending on experimental condition.
• Case II: Inawakilisha inner pilot reaction layer. H₂ yenye temperature ya 298 K ilitolewa kutoka lower side, na burned-gas composition kutoka Case I calculation ikatolewa kutoka opposite side. Burned-gas temperature iliset equal kwa adiabatic flame temperature ya relevant condition.

Katika both models, nozzle spacing iliwekwa 20 mm, pressure 1 atm na adaptive computational mesh 600-900 points. GRI-Mech 3.0 ilitumika kama chemical reaction mechanism.

Katika Case I, position ya boundary inayolingana na %25 ya maximum OH mole fraction ilifafanuliwa kama counterpart ya experimental flame width. Katika Case II, same %25 criterion ilitumika kuamua pilot lift height kati ya hydrogen inlet boundary na reaction zone.

Katika one-dimensional model, both flame width na pilot lift height ziliongezeka regularly kadiri hydrogen fraction ilivyoongezeka. Katika linear fit na momentum indicator, R² = 0,95 ilipatikana kwa Case I na Case II. Strong fit hii ilionyesha kwamba main trends za local reaction layers zinaweza kuelezeka kwa reduced counterflow model.

Hata hivyo, absolute flame width katika simulation ilikuwa roughly 2,1-3,9 mm, na pilot lift height roughly 2,0-6,6 mm, na hazikumatch directly experimental macroscopic values. Watafiti pia wanaona value ya model si katika absolute-dimension prediction, bali katika kueleza direction ambayo flame shape inabadilika kadiri hydrogen fraction na momentum zinavyobadilika.

Main equations zilizotumika katika study

Main swirl number

\[ S_M = \frac{\pi(r_o^2-r_P^2)(r_i-t/2)}{4\,t\,h}\,r_o \]

S_M ni dimensionless swirl intensity ya main swirler. r_o, r_P na r_i zinaonyesha respectively main-nozzle exit radius, pilot-nozzle radius na inner radius ya main passage; t ni tangential-channel width, na h ni vane height. Katika equation typesetting, kuonekana kwa last r_o term outside the fraction kunatengeneza typographic ambiguity kuhusu kama term hii ni multiplier au continuation ya denominator. Study haijaeleza parenthesization hii separately; expression imehamishwa hapa kwa kufuata symbol order katika text.

Pilot swirl number

\[ S_P = \frac{2}{3}\left[\frac{1-(d_h/d)^3}{1-(d_h/d)^2}\right]\tan\theta \]

S_P ni pilot swirl number. d_h inaonyesha center-hub diameter, d pilot-swirler diameter na θ pilot-vane angle. Kwa kuwa diameter ratios na tangent term ni dimensionless, S_P pia ni dimensionless.

Global equivalence ratio

\[ \Phi_g = s\frac{\dot{m}_{CH_4}+\dot{m}_{H_2}}{\dot{m}_a} \]

Φ_g ni global equivalence ratio. ṁ_CH₄ na ṁ_H₂ ni mass flow rates za fuels, huku ṁ_a ikiwa mass flow rate ya air. Flow rates zikitumika kwa same unit, kwa mfano kg/s, ratio ni dimensionless. s inawakilisha stoichiometric fuel-air ratio ya blended fuel.

Stoichiometric ratio

\[ s = \frac{(2-1.5X_{H_2})(W_{O_2}+3.76W_{N_2})}{X_{CH_4}W_{CH_4}+X_{H_2}W_{H_2}} \]

W_i inaonyesha molecular weight ya relevant species, huku X_CH₄ na X_H₂ zikiwakilisha mole- au volume-based fractions za fuel components. Coefficient 3,76 ni model coefficient inayowakilisha nitrogen-oxygen mole ratio katika air.

Hydrogen content

\[ X_{H_2} = \frac{\dot{V}_{H_2}}{\dot{V}_{CH_4}+\dot{V}_{H_2}} \]

V̇_H₂ na V̇_CH₄ ni volumetric flow rates za hydrogen na methane. Same volumetric-flow unit ikitumika, X_H₂ ni dimensionless na imeelezwa kama percentage katika study.

Pilot-main momentum ratio

\[ J = \frac{\rho_PU_P^2}{\rho_MU_M^2} \]

Equation hii inalinganisha momentum flux ya pilot flow dhidi ya momentum flux ya main flow. Kadiri J inavyoongezeka, aerodynamic influence ya center pilot flow relative kwa main flow inaongezeka. Main conclusion ya study ni kwamba flame shape inaweza kuelezwa more regularly kwa relative momentum balance hii kuliko kwa fuel composition pekee.

Graphs na figures zinaonyesha nini?

• Experimental-setup schematic: Inaonyesha geometric relation kati ya outer CH₄/air passage, inner H₂ pilot passage, two different swirlers na combustion chamber yenye quartz windows.
• OH-PLIF na PIV schematics: Zinaonyesha OH-radical imaging system yenye 283 nm excitation light na PIV system inayotoa velocity field kutoka particle motion kwa 532 nm laser.
• Attached-lifted comparison: Inaonyesha difference kati ya structure ambayo outer reaction layer inaendelea karibu na injector na structure ambapo inazimika kwenye root na ku-form tena downstream.
• PIV velocity fields: Zinaonyesha inner recirculation zone katika regimes zote mbili, lakini reverse flow inakaribia injector zaidi na velocity gradient katika main shear layer inaongezeka katika lifted flame.
• Instantaneous na mean OH images: Zinaonyesha kwamba broader mean OH region ya lifted flame inatokana na instantaneous flame wrinkling na positional variability.
• Stability map: Inaonyesha kwamba hydrogen increase inapanua attached region, huku main-velocity increase ikipanua lifted region.
• OTSU graph: Inaonyesha automatic thresholds katika different conditions zikikusanyika roughly kati ya %20-%30 ya maximum OH signal.
• Shape-parameter graphs: Zinaonyesha kwamba flame width na pilot lift height kwa ujumla zinaongezeka pamoja na hydrogen.
• Momentum correlations: Zinaonyesha inner reaction-layer position iki-response more regularly kwa momentum ratio kuliko lifted-flame width.
• OPPDIF results: Zinaonyesha kwamba one-dimensional model inaweza kureproduce directions za change na relations na momentum, si experimental absolute dimensions.

Kila OH-PLIF image iliyotolewa kulingana na hydrogen na equivalence ratio imenormalize separately kwa own maximum OH intensity. Kwa hiyo, images haziwezi kutumika kulinganisha absolute OH amount au total reaction intensity kati ya different conditions. Images zinatoa comparison only kuhusu position, width na shape ya reaction region.

Conclusions zinazoungwa mkono na study

• Kuongeza hydrogen fraction kuliimarisha pilot support katika dual-swirl injector iliyochunguzwa na kupanua attached-flame regime.
• Kuongeza main-flow velocity hadi 15 m/s kuliongeza lifted-flame conditions significantly.
• Lifted flame ilielezwa kwa local extinction ya outer flame root na restabilization downstream.
• Flame width na pilot-flame lift height kwa ujumla ziliongezeka pamoja na hydrogen content.
• Pilot lift height ilionyesha strong relation na momentum ratio katika attached na lifted regimes.
• One-dimensional counterflow model ilireproduce qualitatively main flame-shape-change trends za three-dimensional turbulent flame.

Conclusions ambazo study haithibitishi

• Study haionyeshi field performance au long-term operating success katika commercial gas turbine.
• NOx, CO, unburned hydrocarbons au total CO₂ emissions hazikupimwa.
• Haijabainishwa hydrogen fraction inabadilisha system efficiency, electricity-generation cost au turbine life kwa kiwango gani.
• Flashback safety haijamapiwa experimentally na material durability haijatathminiwa.
• OH-PLIF images si absolute heat-release measurements.
• Kuonekana kwa stronger wrinkling katika lifted flame hakuthibitishi definitively increase ya turbulence intensity au turbulent burning velocity.
• One-dimensional simulation haisolve entire swirling flow field, three-dimensional turbulence au time-dependent acoustic interactions.
• Correlations hazithibitishi causality peke yake, na momentum ratio haielezi all variability hasa katika lifted-flame width.

Ina maana gani kwa mtazamo wa Uturuki?

Research inaonyesha kwamba katika adaptation ya natural-gas-fired gas turbines kwenda hydrogen-enriched fuels, focusing only kwenye fuel percentage haitoshi. Kama geometry, velocities, densities na relative momentum za pilot na main passages hazijadesigniwa pamoja, kutumia more reactive fuel pekee hakuhakikishi flame itabaki katika desired location.

Kwa universities na industrial organizations nchini Uturuki zinazofanya kazi kwenye gas turbines, combustion chambers, energy conversion na hydrogen technologies, most transferable aspect ya research ni kwamba kabla ya kwenda kwenye expensive three-dimensional calculations, OH-PLIF/PIV measurements zinaweza kuquantifiwa kwa OTSU-based shape indicators na local reaction layers kuchunguzwa kwa reduced counterflow models. Hata hivyo, current results zinahusu single laboratory injector na limited operating range. Kwa transfer kwenda real turbines nchini Uturuki, pressurized-combustion experiments, emission measurements, flashback limits, thermoacoustic stability, material durability na long-duration system tests zinahitajika.

Mbinu na Matokeo ya Utafiti

Technical summary ya experimental conditions

OH-PLIF measurement

• 30 W pulsed Nd:YAG laser yenye 10 kHz na 532 nm output ilitumika.
• Dye-laser output iliconvertiwa hadi 283 nm na OH A-X (1,0) transition, Q₁ line, ika-exciteiwa.
• Pulse energy ilikuwa roughly 75 µJ/pulse, pulse duration 10 ns.
• OH signal ilirekodiwa kwa 315 ± 10 nm band-pass filter.
• Kwa kila condition, kwa duration ya 0,4 seconds na sampling rate ya 10 kHz, total images 4.000 zilichukuliwa.
• Laser-sheet intensity profile ilidetermined kwa stable Bunsen flame na calibration ikarudiwa kwa one-hour intervals.
• OH-PLIF spatial resolution iliripotiwa kuwa roughly 0,11 mm/piksel.
• Images ziliprocessiwa kwa MATLAB-based code na frames 4.000 zika-averageiwa.

PIV velocity measurement

• Continuous laser yenye power ya 20 W, 532 nm MGL-W-532, ilitumika.
• Solid alumina particles zilitumika kama flow tracers.
• Images zilichukuliwa kwa NAC MEMRECAM HX-7s camera kwa rate ya 5 kHz.
• Time kati ya consecutive images ilikuwa Δt = 200 µs.
• Velocity vectors zilicalculatiwa kupitia PIVlab kwa cross-correlation method.
• Interrogation window ilikuwa 16 × 16 pixels, overlap ratio %50 na vector spacing roughly 1,17 mm.
• Subpixel displacement error ikichukuliwa roughly 0,1 pixel, relative uncertainty ya velocity measurement iliestimateiwa kuwa roughly %1-%3 ya mean velocity.
• Instantaneous na mean velocity fields zilipatikana kutoka total images 4.000.

Numerical-model conditions

Main findings

1. Two main flame regimes, attached na lifted, zilitambuliwa katika dual-swirl injector.
2. Kadiri hydrogen content ilivyoongezeka, attached-flame region ilipanuka; kadiri main velocity ilivyoongezeka, lifted-flame region ilipanuka.
3. Katika methane-only approach, lean blowoff ilionekana around Φ_g ≤ 0,5, huku hydrogen addition ikiruhusu flame kudumu katika leaner conditions.
4. Katika lifted flame, root ya outer reaction layer ilizimika locally karibu na injector na restabilize downstream.
5. Katika lifted flame, velocity gradient katika main shear layer na penetration ya inner recirculation zone kuelekea injector ziliongezeka.
6. Flame width na pilot-flame lift height kwa ujumla ziliongezeka pamoja na hydrogen content.
7. Fit ya experimental pilot lift height na momentum indicator ilikuwa R² = 0,90 katika attached flame na R² = 0,92 katika lifted flame.
8. Kwa attached-flame width R² = 0,92 ilipatikana, huku lifted-flame width ikiwa na lower R² = 0,67.
9. Katika one-dimensional model, momentum relation ya R² = 0,95 ilipatikana kwa flame width na pilot lift height.
10. One-dimensional model haikutoa experimental absolute dimensions, lakini ilireproduce trends zinazotokana na hydrogen na momentum changes katika correct direction.

Statistical na measurement assessment

Linear relations ziliwasilishwa kwa R² values katika study. Kwa upande mwingine, confidence intervals za regression coefficients, p values, number ya independent experimental repeats, au standard deviation na error bars kwa shape parameters hazikutolewa. Frames elfu nne zinasample temporal flame behavior; si same thing kama independent experimental repeats. PIV velocity uncertainty iliestimateiwa kuwa %1-%3, lakini separate uncertainty propagation kwa flame width na lift height haikutolewa.

Internal inconsistencies zinazoonekana katika method

• PIV image scale imetolewa katika text kama 0,146 nm/piksel. Katika same paragraph, pixels 16 zimetajwa kuwa equivalent kwa 2,34 mm. Kwa sababu 16 × 0,146 mm inatoa roughly 2,34 mm, expression “nm” inaonekana likely kuwa “mm”; lakini kwa kuwa study haijathibitisha hili, unit haipaswi kusahihishwa silently.
• OH-PLIF camera model inaitwa Photron HSS6 katika method text, lakini Photron Fastcam SA-X2 katika Kielelezo 2.
• Katika main swirl-number equation, position ya last r_o term ndani ya fraction structure haiko typographically clear.

Maelezo ya Chanzo na Mbinu

Jina kamili la asili la study: Experimental investigation of CH4/H2 co-firing flame structure with comparison to 1D simulation in dual-swirl injector

Waandishi: Jinseong Kim; Hyunchang Lee; Keeman Lee; Matthew Dunn; Assaad Masri.

Author order: List hapo juu inahifadhi original order katika study.

Equal first author: Study haina equal-first-authorship au equal-contribution statement.

Corresponding authors: Keeman Lee na Assaad Masri.

Institutions:

• School of Mechanical and Aerospace Engineering / Center for Aerospace Engineering Research, Sunchon National University, Suncheon 57922, Republic of Korea.
• School of Aerospace, Mechanical and Mechatronic Engineering, The University of Sydney, NSW 2006, Australia.

DOI:10.2139/ssrn.6944015

Journal: Peer-reviewed journal au final journal publication haijathibitishwa kupitia version hii.

Publication platform: SSRN.

Original publisher/platform provider: SSRN si peer-reviewed journal publisher. Ni preprint na early-stage research platform inayoendeshwa na Elsevier Inc.

Publication year: 2026.

Source type: Preprint research article yenye experimental research na one-dimensional numerical modeling.

Peer-review status: Study hii ni preprint na haijapitia peer review. Findings zinapaswa kusomwa kwa kuzingatia limitation hii.

Official source link:https://ssrn.com/abstract=6944015

Funding: Study inataja gas-turbine hydrogen co-firing conversion project namba RS-2023-00254668 ya 150 MW F-class iliyosupportiwa na Korea Institute of Energy Technology Evaluation and Planning, pamoja na hydrogen-blended gas na flame-diagnostics project namba RS-2025-07982969 iliyosupportiwa na KEIT na Ministry of Trade, Industry and Energy of the Republic of Korea. Australian Research Council support imeripotiwa kwa Matthew Dunn na Assaad Masri.

Maelezo haya ya Kituruki yameandaliwa kwa kuchunguza text, equations, tables, graphs na figures za uploaded study. Scientific findings ambazo haziko katika study hazijaongezwa kwenye main content. External sources zilitumika only kwa bibliographic verification ya title, authors, DOI, SSRN record, platform nature na peer-review status.

Main limitations za study ni kwamba haijapitia peer review, ime-limitwa kwa single laboratory injector geometry, imefanywa at atmospheric pressure, independent experimental repeats na shape-parameter uncertainties hazijaelezwa kwa detail, emission na flashback measurements hazipo, na one-dimensional model haiwakilishi three-dimensional turbulent flow kwa absolute values. OTSU na %25 OH criteria ni empirical boundaries zilizochaguliwa kwa comparison; hazipaswi kutathminiwa kama exact physical position ya flame surface.