Regime transition from premixed to flameless oxidation in turbulent JP-10 flames

Goh, Kok Hin Henry; Geipel, Philipp; Hampp, Fabian; Lindstedt, R.P.

doi:10.1016/j.proci.2012.06.173

Cited by 35 publications

(39 citation statements)

References 32 publications

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“…The opposed jet configuration (Geipel et al 2010, Goh et al 2013b) was slightly modified (see Fig. 3) to accommodate seeding of the lower nozzle (LN) by a combination of a flame stabilising mesh (FSM) and a flash back arrestor (FBA).…”

Section: Opposed Jet Geometrymentioning

confidence: 99%

“…In summary, the current contribution builds on earlier studies of isothermal and combusting flows in the opposed jet geometry (Geipel et al 2010, Goh et al 2013a, Goh et al 2014, Goh et al 2015 to cover lean premixed flames burning against hot combustion products (Goh et al 2013b). Past studies are extended through the use of fractal grid generated turbulence to quantify the transition from a conventional turbulent flame in the flamelet regime of combustion to a distributed mode using a multi-fluid description.…”

Section: Introductionmentioning

confidence: 98%

“…(Dally et al 2002, Parente et al 2011. The opposed jet geometry has been extensively utilised to investigate -laminar as well as turbulent -non-premixed, partial premixed, and premixed combustion and, more recently, combustion regime transitions for aviation fuels (Goh et al 2013b). The configuration has notable advantages for combustion studies (Mastorakos et al 1995, Geyer et al 2005, Geipel et al 2010): (i) excellent optical access for laser-based diagnostic measurements, (ii) accurate experimental control of boundary conditions, (iii) aerodynamic flame stabilisation, rather than via pilot flames, leading to flame dynamics and extinction being related to the inherent aerothermochemistry of the combustion process; and (iv) individual control of variables affecting the chemical and turbulent time-scale.…”

Section: Introductionmentioning

confidence: 99%

“…The statistical description of combustion approaching distributed reaction zones necessitates a more complex methodology as significant reaction zone broadening and intermediate fluid states are expected. Such effects have recently attracted attention in terms of the impact on scalar gradients (Goh et al 2013b, Minamoto & Swaminathan 2014. The current work utilises a back-to-burnt opposed jet configuration, with fractal grids for enhanced turbulence generation, to investigate the impact of the chemical timescale on the combustion regime transition for lean premixed flames.…”

Section: Introductionmentioning

confidence: 99%

“…The approach permits the identification of five fluid states (reactant, combustion product, mixing, mildly reacting and flamelet fluids) and a range of Da numbers, from the conventional propagating flamelet regime well into the distributed reaction zone regime, are investigated. Böhm et al (2009) and Goh et al (2013aGoh et al ( , 2013bGoh et al ( , 2014 have shown that the combination of PIV and OH-PLIF can be used to obtain velocity-scalar statistics describing the dynamics of opposed jet flames approaching extinction and the techniques form the basis for the investigations reported here.…”

Section: Introductionmentioning

confidence: 99%

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Fractal Grid Generated Turbulence—A Bridge to Practical Combustion Applications

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Abstract.Practical applications typically feature high turbulent Reynolds numbers and, increasingly, low Damköhler numbers leading to distributed combustion. Such conditions are difficult to achieve on a laboratory scale that permits detailed experimental investigations. The aerodynamically stabilised turbulent opposed jet flame configuration is a case point -an exceptionally flexible canonical geometry traditionally featuring low turbulence levels. Fractal grids can be used to increase the turbulent Reynolds number, without any negative impact on other parameters, and to remove the classical problem of a relatively low ratio of turbulent to bulk strain. The use of fractal grids to ameliorate such problems is exemplified for fuel lean combustion with combustion regime transitions achieved through the stabilisation of turbulent premixed flames against hot combustion products. An analysis is presented in the context of a multi-fluid formalism that extends the customary bimodal pdf approach to include multiple fluid states. The approach is quantified via simultaneous OH-PLIF and PIV, permitting the identification of five separate states (reactant, combustion product, mixing, mildly reacting and flamelet fluids). The sensitivity of the distribution between the fluid states to threshold values is also evaluated. The work suggests that a consistent treatment of the delineating thresholds is necessary when comparing different types of simulations (e.g. DNS) and experiments for reacting fluids with multiple states. The use of fractal grids in a flame driven shock tube provides a further example and is shown to generate turbulent Re numbers of the order 10 5 for flows with Mach numbers approaching unity. The conditions are of relevance to flame stabilisation in hypersonics and are analysed through OH-PLIF and high speed PIV with optimal fractal grids selected on the basis of maximum flame acceleration.

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Section: Opposed Jet Geometrymentioning

confidence: 99%