Turbulent combustion statistics in a diffusion flame for space propulsion applications

Martínez-Sanchis, Daniel; Sternin, Andrej; Haidn, Oskar

doi:10.1063/5.0130537

Cited by 9 publications

(15 citation statements)

References 48 publications

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“…This grid size provides a resolution of the stoichiometric premixed flame front with roughly 5.3 cells. Nevertheless, in turbulent methane-oxygen diffusion flames the thinnest realized flamelets at least double this value, as evaluated in previous works [72,80]. Therefore, the effective flame front resolution is in the order of 10-20 cells.…”

Section: Strategymentioning

confidence: 58%

“…The definition of a suitable function for the reaction progress variable is strongly dependent on the used propellant combination and the operating conditions. For oxygenmethane combustion at high pressures, the following expression has been used in previous research [71,72]:…”

Section: Progress Variablementioning

confidence: 99%

“…This cell size ensures enough resolution for the smallest Kolmogorov eddies [44]. The used resolution was proved to ensure convergence of the turbulent statistics in a mesh sensitivity analysis virtually identical setups [72,79]. This grid size provides a resolution of the stoichiometric premixed flame front with roughly 5.3 cells.…”

Section: Strategymentioning

confidence: 99%

See 2 more Smart Citations

Subgrid Turbulent Flux Models for Large Eddy Simulations of Diffusion Flames in Space Propulsion

Martinez-Sanchis,

Sternin,

Banik

et al. 2024

Preprint

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Subgrid scale models for unresolved turbulent fluxes are investigated with a focus on combustion for space propulsion applications. An extension to the gradient model is proposed, introducing a dependency on the local burning regime. The dynamic behavior of the model's coefficients is investigated, and scaling laws are studied. The discussed models are validated using a DNS database of a high-pressure turbulent fuel-rich methane-oxygen diffusion flame. The operating point and turbulence characteristics are selected to resemble those of modern combustors for space propulsion applications to support the future usage of the devised model in this context.

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Section: Strategymentioning

confidence: 58%

Section: Progress Variablementioning

confidence: 99%

See 1 more Smart Citation

Subgrid Turbulent Flux Models for Large Eddy Simulations of Diffusion Flames in Space Propulsion

Martinez-Sanchis,

Sternin,

Banik

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

“…However, in space propulsion applications, due to the absence of inert gases, high temperatures take place, with a signi cant proliferation of free radicals and hydroxyl molecules. For this reason, the mixture fraction de nition used was the same in recent works [11,30]:…”

Section: Turbulent Diffusion Amesmentioning

confidence: 99%

“…This is generally enough, although a higher resolution would be desirable. The convergence of the turbulent statistics for the used setup has been addressed in a prior work [30]. The effect of increasing the resolution is marginal.…”

Section: Combustion Pressurementioning

confidence: 99%

Combustion regimes in turbulent non-premixed flames for space propulsion

Sanchis

Sternin

Haidn

2022

Preprint

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Direct numerical simulations of non-premixed fuel-rich methane-oxygen flames at 20 bar are conducted to investigate the turbulent mixing burning of gaseous propellants in rocket engines. The reacting flow is simulated using the EBI-DNS solver, within the OpenFOAM frame. The transport of species is resolved with finite rate chemistry, using a complex skeletal mechanism that entails 21 species. Two different flames at low and high Reynolds numbers are considered to study the sensitivity of the flame dynamics to turbulence. Regime markers are used to measure the probability of the flow to burning in premixed and non-premixed conditions at different regions. The local heat release statistics are studied to understand the drivers in the development of the turbulent diffusion flame. Despite the eminent non-premixed configuration, a significant amount of combustion takes place in premixed conditions. Premixed combustion is viable in both lean and fuel-rich regions, relatively far from the stoichiometric line. It is found that a growing turbulent kinetic energy is detrimental to combustion in fuel-rich premixed conditions. This is motivated by the disruption of the local premixed flame front, which promotes fuel transport into the diffusion flame. In addition, at downstream positions, higher turbulence enables the advection of methane into the lean core of the flame, enhancing the burning rates in these regions. Hence, the primary effect of turbulence is to increase the fraction of propellants burnt in oxygen-rich and near stoichiometric conditions. As a consequence, the mixture fraction of the products shifts towards lean conditions, influencing combustion completion at downstream positions.

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Investigation of Sidewall and Reynolds Number Effects in a Ribbed Square Duct

Santese,

Martinez-Sanchis,

Sternin

et al. 2024

Flow Turbulence Combust

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This paper presents a comprehensive three-dimensional Direct Numerical Simulation (DNS) investigation of flow characteristics over a roughened wall in a duct, exploring bulk Reynolds number variations from 4400 to 13,200 and considering the influence of side walls. Notably, a significant increase in friction factor highlights heightened resistance to flow due to surface roughness, emphasizing the importance of considering surface conditions in engineering applications. The study reveals three recirculation zones in the streamwise direction, indicating intricate separation phenomena caused by the interaction between the ribbed wall and the flow. Furthermore, the presence of sidewalls creates two major vortices perpendicular to the flow direction, highlighting the complexity of the vortical structures in this configuration, crucial for predicting flow behavior and optimizing system performance. The study demonstrates that the influence of the Reynolds number on these vortices is not well-scalable with respect to outer units, in contrast with respect to smooth ducts. Investigating side-wall effects, increased turbulent production rate, and non-equilibrium turbulence along the side walls highlight the sensitivity of turbulent stresses to Reynolds number and side-wall proximity. In conclusion, the paper provides novel insights into the interplay between Reynolds numbers, roughened surfaces, and boundary conditions in turbulent flows, laying a foundation for a deeper understanding of the flow in duct with high roughness.

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Turbulent combustion statistics in a diffusion flame for space propulsion applications

Cited by 9 publications

References 48 publications

Subgrid Turbulent Flux Models for Large Eddy Simulations of Diffusion Flames in Space Propulsion

Subgrid Turbulent Flux Models for Large Eddy Simulations of Diffusion Flames in Space Propulsion

Combustion regimes in turbulent non-premixed flames for space propulsion

Investigation of Sidewall and Reynolds Number Effects in a Ribbed Square Duct

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