Combustion Regimes in Turbulent Non-Premixed Flames for Space Propulsion

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 by using an EBI-DNS solver within an OpenFOAM frame. The transport of species is r...

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Main Authors: Daniel Martinez-Sanchis, Andrej Sternin, Oskar Haidn, Martin Tajmar
Format: Article
Language:English
Published: MDPI AG 2023-07-01
Series:Aerospace
Subjects:
Online Access:https://www.mdpi.com/2226-4310/10/8/671
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author Daniel Martinez-Sanchis
Andrej Sternin
Oskar Haidn
Martin Tajmar
author_facet Daniel Martinez-Sanchis
Andrej Sternin
Oskar Haidn
Martin Tajmar
author_sort Daniel Martinez-Sanchis
collection DOAJ
description 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 by using an EBI-DNS solver within an OpenFOAM frame. The transport of species is resolved with finite-rate chemistry by 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 burn in premixed and non-premixed conditions at different regions. The local heat release statistics are studied in order 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 has been 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. Therefore, the primary effect of turbulence is to increase the fraction of propellants burnt in oxygen-rich and near-stoichiometric conditions. Consequently, the mixture fraction of the products shifts towards lean conditions, influencing combustion completion at downstream positions.
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spelling doaj.art-9f46bf0602f1422386fc7b19dc2ccce32023-11-18T23:49:37ZengMDPI AGAerospace2226-43102023-07-0110867110.3390/aerospace10080671Combustion Regimes in Turbulent Non-Premixed Flames for Space PropulsionDaniel Martinez-Sanchis0Andrej Sternin1Oskar Haidn2Martin Tajmar3Department of Space Propulsion, Technical University of Munich, 85748 Garching, GermanyDepartment of Space Propulsion, Technical University of Munich, 85748 Garching, GermanyDepartment of Space Propulsion, Technical University of Munich, 85748 Garching, GermanyChair of Space Systems, Technical University of Dresden, 01062 Dresden, GermanyDirect 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 by using an EBI-DNS solver within an OpenFOAM frame. The transport of species is resolved with finite-rate chemistry by 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 burn in premixed and non-premixed conditions at different regions. The local heat release statistics are studied in order 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 has been 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. Therefore, the primary effect of turbulence is to increase the fraction of propellants burnt in oxygen-rich and near-stoichiometric conditions. Consequently, the mixture fraction of the products shifts towards lean conditions, influencing combustion completion at downstream positions.https://www.mdpi.com/2226-4310/10/8/671turbulencecombustiondiffusion flamesspace propulsionCFDquasi DNS
spellingShingle Daniel Martinez-Sanchis
Andrej Sternin
Oskar Haidn
Martin Tajmar
Combustion Regimes in Turbulent Non-Premixed Flames for Space Propulsion
Aerospace
turbulence
combustion
diffusion flames
space propulsion
CFD
quasi DNS
title Combustion Regimes in Turbulent Non-Premixed Flames for Space Propulsion
title_full Combustion Regimes in Turbulent Non-Premixed Flames for Space Propulsion
title_fullStr Combustion Regimes in Turbulent Non-Premixed Flames for Space Propulsion
title_full_unstemmed Combustion Regimes in Turbulent Non-Premixed Flames for Space Propulsion
title_short Combustion Regimes in Turbulent Non-Premixed Flames for Space Propulsion
title_sort combustion regimes in turbulent non premixed flames for space propulsion
topic turbulence
combustion
diffusion flames
space propulsion
CFD
quasi DNS
url https://www.mdpi.com/2226-4310/10/8/671
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AT andrejsternin combustionregimesinturbulentnonpremixedflamesforspacepropulsion
AT oskarhaidn combustionregimesinturbulentnonpremixedflamesforspacepropulsion
AT martintajmar combustionregimesinturbulentnonpremixedflamesforspacepropulsion