Soot evolution and flame response to acoustic forcing of laminar non-premixed jet flames at varying amplitudes
| Autor: | Bassam B. Dally, Kae Ken Foo, Graham J. Nathan, Paul R. Medwell, Zeyad T. Alwahabi, Zhiwei Sun |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
Jet (fluid)
Materials science 020209 energy General Chemical Engineering General Physics and Astronomy Energy Engineering and Power Technology Laminar flow 02 engineering and technology General Chemistry Mechanics Forcing (mathematics) medicine.disease_cause 01 natural sciences Soot 010309 optics Fuel Technology Amplitude 13. Climate action 0103 physical sciences Volume fraction 0202 electrical engineering electronic engineering information engineering Combustor medicine Intensity (heat transfer) |
| Zdroj: | Combustion and Flame. 198:249-259 |
| ISSN: | 0010-2180 |
| DOI: | 10.1016/j.combustflame.2018.09.022 |
| Popis: | New details regarding the soot evolution and its controlling parameters in steady and forced flames have been studied using high spatial resolution laser diagnostic techniques. Steady laminar non-premixed ethylene/nitrogen flames with three different diameters burners were acoustically forced using a loudspeaker. 10-Hz-sinusoidal signals of different amplitudes were transmitted to the loudspeaker to drive the flames. The results reveal that the spatial correlation between the soot field and the temperature profile is influenced by the burner diameter and forcing conditions. The soot field in steady laminar flames is confined to a relatively narrow temperature range, 1500–2000 K. In contradiction, the soot field in forced flames spread across a wider range of temperature, 1400–2100 K. Furthermore, the spatial correlation between the normalised soot concentration and primary particle size can be described with an exponential function. While it is observed that the exponential coefficients vary with burner diameter and forcing conditions, further study is necessary for a better understanding. In general, laminar flames forced at a lower amplitude ( α = 25 % ) tend to produce less soot than moderately forced ( α = 50 % ) flames. Further increasing the forcing amplitude to α = 75 % does not increase the soot production in laminar flames; conversely, lower peak and volume-integrated soot volume fraction are observed in the strongly forced flame ( α = 75 % ) as relative to the moderately forced counterpart. These findings shed new light on the seemingly contradictory results published in the literature regarding the effect of the forcing intensity on the soot production. |
| Databáze: | OpenAIRE |
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