LES Modeling of Scramjet Combustion

Ingenito, Antonella; Flora, M.G. De; Bruno, Claudio; Giacomazzi, E.; Steelant, Johan

doi:10.2514/6.2006-1383

Cited by 15 publications

(17 citation statements)

References 6 publications

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“…And in order to reduce the grid requirement in near-wall regions, wall-modeled LES [15,33,37,[65][66][67] or hybrid RANS (Reynolds-Averaged Navier-Stokes) / LES [14, 16-21, 26, 28-31, 36, 68-70] is usually used. In terms of existing LES techniques, one of the main challenges for supersonic combustion modeling lies in accounting for the effect of Mach number on flame regime in the Borghi diagram [13,71], which is essentially due to the general lack of physical understanding on the effects of supersonic conditions on turbulence, reaction rates, and flame regimes [25]. Finite-rate-chemistry Direct numerical simulation (DNS) model in conjunction with detailed kinetic mechanism may exactly reveal the TCI modes, but the computational cost is far beyond the affordance of current computer architectures.…”

Section: Introductionmentioning

confidence: 99%

“…inlet/isolator, supersonic combustor and expander/nozzle, while modeling of the integrated flow path in a full-scale combustion is generally scarce. From the literature, the most preferred modeling cases are the HyperShot I&II [3][4][5][6][7][8][9][10] and SCHOLAR [11][12][13][14][15][16], due a large degree to their relative complete data on experimental setup and measurements 2 American Institute of Aeronautics and Astronautics for model validation. Simulations based on the experimental cases tested on some other scramjet combustor facilities, such as the DLR scramjet combustor [17,18], the University of Virginia's Supersonic Combustion Facility (SCF) [18][19][20][21] and the CUBRC Combustion Duct [22], are also growing vigorously.…”

Section: Introductionmentioning

confidence: 99%

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Full-scale Detached Eddy Simulation of kerosene fueled scramjet combustor based on skeletal mechanism

Yao¹,

Wang²,

Lu³

et al. 2015

20th AIAA International Space Planes and Hypersonic Systems and Technologies Conference

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Large Eddy Simulation (LES) of kerosene fueled scramjet combustor is generally scare in the literature, due mainly to the formidable computational cost arisen by complex kerosene mechanism. In this study, the skeletal reduction of a detailed reaction mechanism (2185 species/8217 steps) of aviation kerosene is conducted using directed relation graph with error propagation and sensitivity analysis (DRGEPSA) method, resulting a skeletal mechanism consisting of 39 species/153 elemental reactions for China Daqing RP-3 aviation kerosene. The comparisons of adiabatic flame temperature, total heat release, ignition delay and laminar flame speed predicted by the skeletal mechanism show an overall good accordance with the original detailed reaction mechanism. Then a three-dimensional Detached Eddy Simulation (DES) modeling based on the skeletal kerosene mechanism is employed for the numerical analysis of a full-scale scramjet combustor, which has been experimentally tested in a long-time direct connect supersonic combustion test platform (abbreviated as DTZ) assembled in Chinese Academy of Sciences (CAS). Pressure and heat flux measurement systems are attached to the combustor assembly to monitor the real-time combustion performance and provide validation data for the numerical modeling. Three cases with fuel equivalence ratios from 0.8, 1.0 to 1.2 and the same crossflow conditions at Mach 2.0 are modeled. The time-averaged static pressure and heat flux are in generally good agreement with the experiment with the peak heat flux slightly underpredicted. The instantaneous and/or time-averaged pressure, momentum, temperature and turbulence fields, which are difficult to be measured, are analyzed to reveal the main flow and combustion physics, especially those related to the flame distribution and holding. The combustion is identified as in ramjet mode for the investigated cases. With the increasing of fuel equivalence ratio, the shock train propagates upstream in the isolator and the interaction between the upstream and downstream combustion assumes different patterns.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Full-scale Detached Eddy Simulation of kerosene fueled scramjet combustor based on skeletal mechanism

Yao¹,

Wang²,

Lu³

et al. 2015

20th AIAA International Space Planes and Hypersonic Systems and Technologies Conference

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“…For a SCRJ combustor, where reactants are not premixed but, for instance, cold hydrogen is injected into hot air, temperature varies signi¦cantly with the equivalence ratio throughout the mixing layer around the jet. At lower temperature, ignition delay times decrease and combustion become eventually controlled by kinetics [12]. As shown in the previous section, the ignition delay time (∼ 0.05 ms) is smaller than the residence time (τ conv ∼ L/U = 0.83 ms), so kinetics is fast enough to let the §ame ignite during a convective time.…”

Section: Mixing and Combustion For Supersonic Flowsmentioning

confidence: 88%

“…In fact, numerical simulations with the SmagorinskyLilly SGS model often predict neither mixing nor combustion whilst experiments show both occurring over short lengths. Past evidence [1] shows that the physics of mixing and combustion is very di¨erent in subsonic and supersonic regimes. From a previous theoretical analysis [2] of the e¨ects of high Mach number on turbulence and combustion, it has been observed that high Mach number §ows experience mainly streamwise vorticity and consequently maximum helicity.…”

Section: Introductionmentioning

confidence: 99%

Supersonic mixing and combustion: advance in les modeling

Ingenito¹,

Bruno²

2009

Progress in Propulsion Physics

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Mixing and combustion in supersonic reacting §ows are currently under investigation for new generation launchers and trans-atmospheric vehicles. Experimental results with hydrogen injected at Mach 2.5 in a Mach 2 airstreams showed combustion taking place just in ∼ 0.6 m: this indicates that supersonic combustion is feasible within short combustors. Large eddy numerical simulations including the subgrid scale (SGS) model, ISCM, developed speci¦cally for supersonic combustion have been done. This model takes into account the e¨ect of compressibility on reaction rates and on mixing. Numerical simulations have revealed that the §ame is unsteady: it anchors at about 15 cm from the injector, develops downstream, and lifts o¨. Periodical ignition and quenching have been investigated. Also, the combustion regime in supersonic §ows has been investigated and is reported.

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“…Typically, the detailed mechanisms for small-molecule fuels (C 1 -and C 2 -based) consist of less than one hundred species, while largemolecule Jet fuels (C >10 -based) consist of hundreds of or even thousands of species. For this reason, current supersonic combustion modelings are mostly based on hydrogen fuel [24, [37][38][39][40][41][42][43][44][45][46][47][48] and only a small portion of them are based on small-molecule hydrocarbon fuels (.g. ethylene [49,50], methane [51,52] and acetone [53]).…”

Section: B Kerosene Mechanism Reduction and Turbulent Combustion Modmentioning

confidence: 99%

A comparative study of elliptical and round scramjet combustors by Improved Delayed Detached Eddy Simulation

Yao

Yuan

et al. 2017

21st AIAA International Space Planes and Hypersonics Technologies Conference

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To explore the combustion performance of non-rectangular type supersonic combustors, the flow and combustion characteristics in round and round-to-elliptic shape-transition (RdEST) supersonic combustors under the same configurations of flight Mach number and fuel equivalence ratio were compared based on modeling results. The fuel equivalence ratio is maintained the same as 0.8, while two inlet Mach numbers of 2.5 and 3.0 both corresponding to a real flight Mach number of 6.5 are tested. To alleviate the strict requirements on wall-normal and -parallel grid spacing, Improved Delayed Detached Eddy Simulation (IDDES) is employed in this study to enable an automatic choice of RANS or LES mode depending on the local boundary layer thickness and turbulent viscosity. To reduce the computational cost of stiff kerosene oxidation chemistry, a total of four versions of skeletal mechanisms (respectively 48s/197r, 39s/153r, 28s/92r and current 19s/54r) have been developed based on the detailed 2815s/8217r Dagaut mechanism by using a highly efficient and reliable directed relation graph with error propagation and sensitivity analysis (DRGEPSA) method together with manual path analysis. Although the mechanism size has been significantly reduced, key kinetic properties such as adiabatic flame temperature, heat release rate, ignition delay and laminar flame speed all agree well with the original detailed mechanism. The static pressure along streamwise direction is compared with the measurement to validate the modeling results. Two key aspects are well predicted, i.e. the pressure ratio and the initial pressure rise location, indicating that the flame anchoring location and the distribution of wave structures inside the combustor are close to the actual situation. Then the aerodynamic fields are analyzed for the round and elliptic combustors to compare their flow, mixing and combustion related flow structures. The three-dimensional wave structures inside the elliptic combustor are firstly shown to reveal the influence of nonaxisymmetric cross-section on the shock train and Mach field. Especially the time evolution of the flame region is analyzed, and dominant flame modes are extracted by the aid of proper orthogonal decomposition (POD) method.

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LES Modeling of Scramjet Combustion

Cited by 15 publications

References 6 publications

Full-scale Detached Eddy Simulation of kerosene fueled scramjet combustor based on skeletal mechanism

Full-scale Detached Eddy Simulation of kerosene fueled scramjet combustor based on skeletal mechanism

Supersonic mixing and combustion: advance in les modeling

A comparative study of elliptical and round scramjet combustors by Improved Delayed Detached Eddy Simulation

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