Scalar and velocity field measurements in a lifted CH4–air diffusion flame

Watson, K.A.; Lyons, Kent; Donbar, Jeffrey M.; Carter, C.D

doi:10.1016/s0010-2180(98)00086-8

Cited by 117 publications

(41 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Figures 2a and 2b (zero co-flow) show the leading edge of the reaction zone stabilized near the fuel nozzle (7.8 mm downstream). These images portray a single branch structure similar to that witnessed in lifted gaseous jet diffusion flames [34]. Since the leading edge of the flame is located close to the tip of the fuel nozzle both axially and radially, there is insufficient entrainment of ambient air to support an inner reaction zone.…”

Section: Research Results In Spray Flames At Ncsumentioning

confidence: 65%

“…These leading edge flames are often present at the stabilization point of lifted spray investigated by a twodimensional laser-sheet imaging technique, as has been described earlier. The nature of the flamefront in the stabilization region of the spray-jet flame is vibrant topic of research [34][35][36], along with the corresponding work in gaseous flames [39][40][41][42][43][44][45][46][47]. Whether all spray flames exhibit "leading edge' flame structures as shown by our group for the gaseous and for some spray cases case is a major question to be addressed by our group in future work.…”

Section: Research Results In Spray Flames At Ncsumentioning

confidence: 84%

“…The results of these ARO-sponsored investigations, along with those of other research groups, provide evidence of the presence of a single-and double-flame structures [33][34][35][36] that are surmised to function in a capacity that permits stabilization of the flame. These leading edge flames are often present at the stabilization point of lifted spray investigated by a twodimensional laser-sheet imaging technique, as has been described earlier.…”

Section: Research Results In Spray Flames At Ncsumentioning

confidence: 86%

“…This cusp is thought to exist as a result of transient large scale mixing structures, interacting intermittently with the flame base, that can stretch the reaction zone around the leading edge as they rotate (see Fig. 9 in [26], [34]). This observation explains why no cusp is observed in Fig.…”

Section: Research Results In Spray Flames At Ncsumentioning

confidence: 99%

See 3 more Smart Citations

Stabilization and Blowout of Gaseous- and Spray-Jet Flames

Lyons¹

2004

View full text Add to dashboard Cite

Public Reporting burden for this collection of information is estimated to average I hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information. Send conmient regarding this burden estimates or any other aspect of this collection of information, including suggestions for reducing this burden, to Washington Headquarters Services, Directorate for information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget, Paperwork Reduction Project (0704-0188,) Washington, DC 20503.

show abstract

Section: Research Results In Spray Flames At Ncsumentioning

confidence: 65%

Section: Research Results In Spray Flames At Ncsumentioning

confidence: 84%

Section: Research Results In Spray Flames At Ncsumentioning

confidence: 86%

Section: Research Results In Spray Flames At Ncsumentioning

confidence: 99%

See 2 more Smart Citations

Stabilization and Blowout of Gaseous- and Spray-Jet Flames

Lyons¹

2004

View full text Add to dashboard Cite

show abstract

“…The spray path is marked by the bright, blue-colored part of the low-soot ethanol flame, primarily due to the chemiluminescence of CH radicals (CH*). The CH radical is a good indicator of the reaction zone due to its short lifetime and is mainly present at the fuel-rich side of this zone [77,147]. Figure 2.13b has been obtained by using a bandpass filter (430 ± 2 nm) to isolate the emission from this specific reaction intermediate.…”

Section: Droplet Evaporationmentioning

confidence: 99%

On the atomization and combustion of liquid biofuels in gas turbines : towards the application of biomass-derived pyrolysis oil

Sallevelt¹

View full text Add to dashboard Cite

This document was typeset using L A T E X.Cover image: Structure of a water spray produced by a pressure-swirl atomizer. SummaryThe combustion of liquid biofuels in gas turbines is an efficient way of generating heat and power from biomass. Gas turbines play a major role in the global energy supply and are suitable for a wide range of applications. However, biofuels generally have different properties compared to the conventional fossil fuels. This can lead to various problems when biofuels are directly used in existing installations.This thesis aims to provide better insights into the combustion of biomass-derived pyrolysis oil in gas turbines. Pyrolysis oil can be produced from non-edible biomass via the fast pyrolysis process. In this process, the organic matter is thermally decomposed under mild conditions (~500 • C, 1 atm) through rapid heating in an oxygenfree environment. The vapors formed in the reactor are subsequently condensed to obtain a combustible liquid as the main product. In comparison to the most common biofuels of the first generation, i.e. bioethanol and biodiesel, pyrolysis oil has advantages regarding cost and environmental benefits. From a technical point of view, however, it is a less favorable fuel due properties such as a low heating value, high water content, high acidity, high viscosity, increased surface tension and poor stability. Gas turbines therefore need to be modified before they can successfully operate on pyrolysis oil in pure form. One of the essential tasks is to develop a suitable burner for liquid fuels of such low quality. In this thesis, two research objectives have been formulated to support the development of pyrolysis oil combustion technology.The first objective is to describe the evaporation and flame characteristics of pyrolysis oil. This objective has been addressed by developing a CFD model based on the Euler-Lagrange method in ANSYS Fluent. The modeling approach was first applied to simulate the combustion of ethanol in a modified, downscaled diesel burner of the OPRA OP16 gas turbine rated at 1.9 MW e . This part of the numerical work can be regarded as a first step to validate the model against experiments and literature. Ethanol is a suitable replacement of pyrolysis oil for this purpose, since it is a singlecomponent, nonviscous, volatile and clean burning biofuel that has been studied more extensively in the past. In the next step, the model was further developed to simulate the full-scale combustion of pyrolysis oil in a burner that was recently designed by OPRA for biofuel applications. The complex composition of pyrolysis oil has been approximated by means of a surrogate fuel containing seven components: methanol, water, acetic acid, acetol, phenol, eugenol and levoglucosan. Each comv ponent is known to be present in pyrolysis oil and is used to represent a group of constituents with similar properties. The initial mass fractions of the seven components are chosen such that the surrogate fuel matches the volatility, water content, elemental composition...

show abstract

Flame Lift‐Off and Blow‐Out Stability Limits and Their Application in Gas Burners

2010

Handbook of Combustion

View full text Add to dashboard Cite

Flame stability is associated with the phenomena observed as a result of a balance or mismatch of the local flame speed and the local flow velocity. These phenomena include flame attachment to the burner rim, the flame base lifting off the rim and the flame being extinguished as a lifted flame or an attached flame.Flame stability is usually characterized by three terms, namely lift-off velocity, liftoff height, and blow-out velocity. The lift-off velocity is defined as the mean jet velocity at which the flame lifts above the burner rim. If the jet velocity is further increased, the flame moves downstream to a new position where it stabilizes. Consequently, the distance between the base of the lifted flame and the burner mouth is described as the lift-off height. A further increase in the jet velocity results in the flame being pushed further downstream, where reaction may not be sustained and the flame is extinguished. The velocity at which the flame is extinguished is called the blow-out velocity. The features of a lifted flame are illustrated in Figure 5.1 and an image of a lifted flame is shown in Figure 5.2.Flame extinction could also occur in an attached flame where the flame goes out directly without the lift-off stage. This is sometimes called blow-off to differentiate it from blow-out. Reducing the fuel flow rate could also cause stability problems. If the local flame velocity exceeds the local flow velocity, the flame enters and propagates upstream through the burner tube or port without quenching. This phenomenon is called flashback and it is generally a transient event, occurring as the fuel flow is decreased or turned off. For the safety of the fuel system, a fire arrest device is recommended to prevent flash back and protect the fuel tank.Theseparametersdescribethestableandsafe operatingrangeforaparticularburner. Conditions for lift-off and blow-out are important in the development of burners for combustion and process applications. In some industrial applications, burners may be subject to strong cross-wind and therefore the stability and performance of those burners might be influenced by cross-wind. This chapter provides a comprehensive review of the main theories on the stabilization mechanisms for a turbulent jet flame

show abstract

Scalar and velocity field measurements in a lifted CH4–air diffusion flame

Cited by 117 publications

References 3 publications

Stabilization and Blowout of Gaseous- and Spray-Jet Flames

Stabilization and Blowout of Gaseous- and Spray-Jet Flames

On the atomization and combustion of liquid biofuels in gas turbines : towards the application of biomass-derived pyrolysis oil

Flame Lift‐Off and Blow‐Out Stability Limits and Their Application in Gas Burners

Contact Info

Product

Resources

About