CH*/OH* Chemiluminescence Response of an Atmospheric Premixed Flame Under Varying Operating Conditions

Guyot, Daniel; Guethe, Felix; Schuermans, Bruno; Lacarelle, Arnaud; Paschereit, Christian Oliver

doi:10.1115/gt2010-23135

Cited by 30 publications

(37 citation statements)

References 3 publications

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“…Muruganandam et al [26] have shown that the CH ⁄ /OH ⁄ signal ratio for turbulent jet flame, swirl dump combustor, and gas turbine simulator exhibit the same trend and similar value for equivalence ratios between 0.65 and 0.95. Other researches have reached similar conclusions on the trend of CH ⁄ /OH ⁄ ratio (or OH ⁄ /CH ⁄ ) in swirl burners [27][28][29]. Muruganandam et al [28] have shown that the CH ⁄ /OH ⁄ ratio remains almost the same for Reynolds numbers in the range of 11,700 and 23,300.…”

Section: Equivalence Ratiomentioning

confidence: 63%

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Internal entrainment effects on high intensity distributed combustion using non-intrusive diagnostics

Khalil

Gupta

2015

Applied Energy

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h i g h l i g h t sExamined the role of entrainment on distributed combustion under different conditions. N 2 and CO 2 are used to simulate entrained combustion gases from within the combustor. Local equivalence ratio distribution obtained through OH ⁄ and CH ⁄ chemiluminescence. NO chemiluminescence significantly reduced under distributed combustion conditions. Reaction distribution demonstrated at 15% O 2 and lower, with almost invisible flame. a b s t r a c tHigh intensity colorless distributed combustion (CDC) provides high efficiency combustion with stable operation and ultra-low emissions. The role of internal entrainment of hot reactive gases requires further investigation in order to obtain minimum requirements for distributed combustion. In this paper, the impact of internal entrainment of reactive gases on the flame behavior and structure is investigated with focus on fostering distributed combustion. A mixture of nitrogen and carbon dioxide was introduced to the air stream prior to mixing with the fuel to simulate the recirculated product gases from within the combustor. Increase dilution with nitrogen or carbon dioxide increased the reaction zone volume to result in uniform distribution of CH ⁄ and OH ⁄ chemiluminescence signal and uniform equivalence ratio (measured optically). These conditions replaced the normally present blue flame with a uniform almost invisible faint bluish flame. The increased entrainment also decreased NO chemiluminescence significantly for the same amounts of fuel burned. The chemiluminescence data suggested that lowering oxygen concentration from 21% to 15% resulted in improved distributed combustion conditions with the reaction volume occupying most of the combustor. These conditions provide the minimum entrainment requirement and reduction of oxygen concentration for achieving distributed combustion. Results obtained at different equivalence ratios and entrained gas temperatures showed similar behavior at oxygen concentration of 15%. The reaction distribution was further enhanced at lower oxygen concentration ($11%) with further reduction in pollutants emissions.

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Section: Equivalence Ratiomentioning

confidence: 63%

“…They also showed that their swirl combustor data agrees favorably well with high pressure premixed laminar flame results [18]. Guyot and Lacarelle [29] measured the CH ⁄ /OH ⁄ ratio for Alstom EV-10 burner. They concluded that this ratio depends exponentially on the equivalence ratio and is independent of the air mass flow.…”

Section: Equivalence Ratiomentioning

confidence: 73%

Internal entrainment effects on high intensity distributed combustion using non-intrusive diagnostics

Khalil

Gupta

2015

Applied Energy

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“…Specifically, the chemiluminescence of OH ⁄ is a technique widely used in combustion investigation [14,16,15], in which OH ⁄ radicals are emitted when they decay at their ground state and the generated luminescence can be captured to several diagnostics as the detection of high-temperature regions or estimations of the equivalence ratio [19]. In this connection, before going further in the technique explanation, it is pertinent to define the ignition parameter that was characterized in this work using OH ⁄ chemiluminescence method: the lift-off length.…”

Section: Oh ⁄ Chemiluminescencementioning

confidence: 99%

“…This technique has been also employed for ignition delay measurements under the knowledge of the light intensity characteristics of each combustion phase [14,15]. Furthermore, several authors have underlined the effect of air-fuel mixture on soot formation, which can be associated with lift-off length [16][17][18][19]. It has been determined that ambient oxygen concentration rises products effective temperature, which continues increasing reactant temperatures and consequently reducing the ignition delay time [20].…”

Section: Introductionmentioning

confidence: 98%

Experimental study of the injection conditions influence over n-dodecane and diesel sprays with two ECN single-hole nozzles. Part II: Reactive atmosphere

Payri

Salvador

Gimeno

et al. 2016

Energy Conversion and Management

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a b s t r a c tThe second part of this experimental analysis, presented in this paper, seeks to go deep on the characterization of the Spray C and Spray D nozzles from the Engine Combustion Network, investigating the penetration of fuel spray at reacting conditions alongside characteristic parameters of combustion such as ignition delay and lift-off length. Both ECN mono-orifice injectors have similar nozzle flow capacity but different conicity degrees and corner sharpness, being Spray C more susceptible to cavitate. Schlieren imaging technique was employed to quantitatively measure reactive penetration and ignition delay, while lift-off length was identified through OH ⁄ chemiluminescence. As in the inert part of this research, n-dodecane and commercial diesel were selected for the tests, thereby the effect of the fuel properties in the measured parameters was analyzed. Also, once again the concept of R-parameter, defined as the penetration derivative respect to the square root of time was calculated to delve into the penetration behavior. The experiments were performed in a constant pressure-flow facility able to reproduce engine-like thermodynamic conditions. Results revealed that R-parameter evolution can be divided in four stages: an inert zone, a 'bump', a 'valley' part and a quasi-steady one that overlaps the previous inert part. Those stages are highly governed by ambient temperature and oxygen concentration. Nozzle geometry and fuel properties demonstrated to have a noteworthy influence on all measured parameters.

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“…It appears interesting to take into consideration as the CH*/OH* ratio, which is related to the flame's global heat release [38], decreases of 30% lowering the fuel/air equivalence ratio from 0.35 to 0.22.…”

Section: Flame Characterization and Instability Detection By Chemilummentioning

confidence: 99%

Pollutant Formation during the Occurrence of Flame Instabilities under Very-Lean Combustion Conditions in a Liquid-Fuel Burner

et al. 2017

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Recent advances in gas turbine combustor design are aimed at achieving low exhaust emissions, hence modern aircraft jet engines are designed with lean-burn combustion systems. In the present work, we report an experimental study on lean combustion in a liquid fuel burner, operated under a non-premixed (single point injection) regime that mimics the combustion in a modern aircraft engine. The flame behavior was investigated in proximity of the blow-out limit by an intensified high rate Charge-Coupled Device (CCD) camera equipped with different optical filters to selectively record single species chemiluminescence emissions (e.g., OH*, CH*). Analogous filters were also used in combination with photomultiplier (PMT) tubes. Furthermore this work investigates well-mixed lean low NO x combustion where mixing is good and generation of solid carbon particulate emissions should be very low. An analysis of pollutants such as fine particles and gaseous emissions was also performed. Particle number concentrations and size distributions were measured at the exhaust of the combustion chamber by two different particle size measuring instruments: a scanning mobility particle sizer (SMPS) and an Electrical Low Pressure Impactor (ELPI). NO x concentration measurements were performed by using a cross-flow modulation chemiluminescence detection system; CO concentration emissions were acquired with a Cross-flow modulation Non-dispersive infrared (NDIR) absorption method. All the measurements were completed by diagnostics of the fundamental combustor parameters. The results herein presented show that at very-lean conditions the emissions of both particulate matter and CO was found to increase most likely due to the occurrence of flame instabilities while the NO x were observed to reduce.

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CH/OH Chemiluminescence Response of an Atmospheric Premixed Flame Under Varying Operating Conditions

Cited by 30 publications

References 3 publications

Internal entrainment effects on high intensity distributed combustion using non-intrusive diagnostics

Internal entrainment effects on high intensity distributed combustion using non-intrusive diagnostics

Experimental study of the injection conditions influence over n-dodecane and diesel sprays with two ECN single-hole nozzles. Part II: Reactive atmosphere

Pollutant Formation during the Occurrence of Flame Instabilities under Very-Lean Combustion Conditions in a Liquid-Fuel Burner

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