Max Schneider, Hendrik Nicolai, Vinzenz Schuh, Matthias Steinhausen, Christian Hasse
{"title":"热扩散不稳定氢/空气火焰的火焰壁相互作用,第二部分:等效比、温度和压力的参数变化","authors":"Max Schneider, Hendrik Nicolai, Vinzenz Schuh, Matthias Steinhausen, Christian Hasse","doi":"10.1016/j.combustflame.2025.114319","DOIUrl":null,"url":null,"abstract":"<div><div>Fuel-lean hydrogen combustion systems hold significant potential for low pollutant emissions, but are also susceptible to intrinsic flame instabilities. While most research on these instabilities has focused on flames without wall confinement, practical combustors are typically enclosed by walls that strongly influence the combustion dynamics. In part I of this work (Schneider et al., Combust. Flame, 2025), the flame-wall interaction of intrinsically unstable hydrogen/air flames has been studied for a single operating condition through detailed numerical simulations in a two-dimensional head-on quenching configuration. This study builds upon the previous investigation by examining a wide range of gas turbine and engine-relevant operating conditions, including variations in equivalence ratio (0.4–1.0), unburnt gas temperature (<span><math><mrow><mtext>298</mtext><mspace></mspace><mtext>K</mtext></mrow></math></span>–<span><math><mrow><mtext>700</mtext><mspace></mspace><mtext>K</mtext></mrow></math></span>), and pressure (<span><math><mrow><mtext>1.013 25</mtext><mspace></mspace><mtext>bar</mtext></mrow></math></span>–<span><math><mrow><mtext>20</mtext><mspace></mspace><mtext>bar</mtext></mrow></math></span>). These parametric variations allow for a detailed analysis and establish a baseline for modeling the effects of varying instability intensities on the quenching process, as the intensity of thermodiffusive and hydrodynamic instabilities depends on the operating conditions. While the quenching characteristics remain largely unaffected by hydrodynamic instabilities, the presence of thermodiffusive instabilities significantly increases the mean wall-heat flux and reduces the mean quenching distance. Furthermore, the impact of thermodiffusive instabilities on the quenching process intensifies as their intensity increases, driven by an increase in pressures and a decrease in equivalence ratio and unburnt gas temperature. The corresponding relative increase in wall heat flux, compared to a one-dimensional inherently stable head-on quenching flame under identical operating conditions, strongly correlates with the enhanced local reactivity associated with the thermodiffusive instability across all operating conditions. Finally, a joint model fit is proposed to estimate the relative increase in wall heat flux due to intrinsic flame instabilities based on characteristic quantities of a corresponding stable one-dimensional freely-propagating flame.</div><div><strong>Novelty and Significance Statement</strong></div><div>This work presents a novel parametric study of flame-wall interactions (head-on quenching) of intrinsically unstable hydrogen/air flames. It builds upon an investigation of an unstable head-on quenching hydrogen/air flame (part I (Schneider et al., Combust. Flame, 2025)) and extends it to a wide range of operation conditions, including variations in equivalence ratio, unburnt gas temperature, and pressure. Additionally, simulations in which either the thermodiffusive or the hydrodynamic instability is selectively suppressed are conducted to enable a separate analysis of each effect. Based on this comprehensive dataset, the study demonstrates the influence of both thermodiffusive and hydrodynamic instabilities on the quenching process by analyzing the local wall heat flux as well as global quenching characteristics. Furthermore, the study reveals that the intensity of thermodiffusive instabilities correlates well with the increase in the peak wall heat flux relative to a one-dimensional simulation for all operating conditions investigated. To enable the assessment of thermal loads in technical applications, a novel model fit is proposed that allows to estimate the peak wall heat flux during quenching based on characteristic quantities of one-dimensional flames.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114319"},"PeriodicalIF":5.8000,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Flame-wall interaction of thermodiffusively unstable hydrogen/air flames, Part II: Parametric variations of equivalence ratio, temperature, and pressure\",\"authors\":\"Max Schneider, Hendrik Nicolai, Vinzenz Schuh, Matthias Steinhausen, Christian Hasse\",\"doi\":\"10.1016/j.combustflame.2025.114319\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Fuel-lean hydrogen combustion systems hold significant potential for low pollutant emissions, but are also susceptible to intrinsic flame instabilities. While most research on these instabilities has focused on flames without wall confinement, practical combustors are typically enclosed by walls that strongly influence the combustion dynamics. In part I of this work (Schneider et al., Combust. Flame, 2025), the flame-wall interaction of intrinsically unstable hydrogen/air flames has been studied for a single operating condition through detailed numerical simulations in a two-dimensional head-on quenching configuration. This study builds upon the previous investigation by examining a wide range of gas turbine and engine-relevant operating conditions, including variations in equivalence ratio (0.4–1.0), unburnt gas temperature (<span><math><mrow><mtext>298</mtext><mspace></mspace><mtext>K</mtext></mrow></math></span>–<span><math><mrow><mtext>700</mtext><mspace></mspace><mtext>K</mtext></mrow></math></span>), and pressure (<span><math><mrow><mtext>1.013 25</mtext><mspace></mspace><mtext>bar</mtext></mrow></math></span>–<span><math><mrow><mtext>20</mtext><mspace></mspace><mtext>bar</mtext></mrow></math></span>). These parametric variations allow for a detailed analysis and establish a baseline for modeling the effects of varying instability intensities on the quenching process, as the intensity of thermodiffusive and hydrodynamic instabilities depends on the operating conditions. While the quenching characteristics remain largely unaffected by hydrodynamic instabilities, the presence of thermodiffusive instabilities significantly increases the mean wall-heat flux and reduces the mean quenching distance. Furthermore, the impact of thermodiffusive instabilities on the quenching process intensifies as their intensity increases, driven by an increase in pressures and a decrease in equivalence ratio and unburnt gas temperature. The corresponding relative increase in wall heat flux, compared to a one-dimensional inherently stable head-on quenching flame under identical operating conditions, strongly correlates with the enhanced local reactivity associated with the thermodiffusive instability across all operating conditions. Finally, a joint model fit is proposed to estimate the relative increase in wall heat flux due to intrinsic flame instabilities based on characteristic quantities of a corresponding stable one-dimensional freely-propagating flame.</div><div><strong>Novelty and Significance Statement</strong></div><div>This work presents a novel parametric study of flame-wall interactions (head-on quenching) of intrinsically unstable hydrogen/air flames. It builds upon an investigation of an unstable head-on quenching hydrogen/air flame (part I (Schneider et al., Combust. Flame, 2025)) and extends it to a wide range of operation conditions, including variations in equivalence ratio, unburnt gas temperature, and pressure. Additionally, simulations in which either the thermodiffusive or the hydrodynamic instability is selectively suppressed are conducted to enable a separate analysis of each effect. Based on this comprehensive dataset, the study demonstrates the influence of both thermodiffusive and hydrodynamic instabilities on the quenching process by analyzing the local wall heat flux as well as global quenching characteristics. Furthermore, the study reveals that the intensity of thermodiffusive instabilities correlates well with the increase in the peak wall heat flux relative to a one-dimensional simulation for all operating conditions investigated. To enable the assessment of thermal loads in technical applications, a novel model fit is proposed that allows to estimate the peak wall heat flux during quenching based on characteristic quantities of one-dimensional flames.</div></div>\",\"PeriodicalId\":280,\"journal\":{\"name\":\"Combustion and Flame\",\"volume\":\"279 \",\"pages\":\"Article 114319\"},\"PeriodicalIF\":5.8000,\"publicationDate\":\"2025-07-10\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Combustion and Flame\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0010218025003578\",\"RegionNum\":2,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"ENERGY & FUELS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Combustion and Flame","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0010218025003578","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENERGY & FUELS","Score":null,"Total":0}
Flame-wall interaction of thermodiffusively unstable hydrogen/air flames, Part II: Parametric variations of equivalence ratio, temperature, and pressure
Fuel-lean hydrogen combustion systems hold significant potential for low pollutant emissions, but are also susceptible to intrinsic flame instabilities. While most research on these instabilities has focused on flames without wall confinement, practical combustors are typically enclosed by walls that strongly influence the combustion dynamics. In part I of this work (Schneider et al., Combust. Flame, 2025), the flame-wall interaction of intrinsically unstable hydrogen/air flames has been studied for a single operating condition through detailed numerical simulations in a two-dimensional head-on quenching configuration. This study builds upon the previous investigation by examining a wide range of gas turbine and engine-relevant operating conditions, including variations in equivalence ratio (0.4–1.0), unburnt gas temperature (–), and pressure (–). These parametric variations allow for a detailed analysis and establish a baseline for modeling the effects of varying instability intensities on the quenching process, as the intensity of thermodiffusive and hydrodynamic instabilities depends on the operating conditions. While the quenching characteristics remain largely unaffected by hydrodynamic instabilities, the presence of thermodiffusive instabilities significantly increases the mean wall-heat flux and reduces the mean quenching distance. Furthermore, the impact of thermodiffusive instabilities on the quenching process intensifies as their intensity increases, driven by an increase in pressures and a decrease in equivalence ratio and unburnt gas temperature. The corresponding relative increase in wall heat flux, compared to a one-dimensional inherently stable head-on quenching flame under identical operating conditions, strongly correlates with the enhanced local reactivity associated with the thermodiffusive instability across all operating conditions. Finally, a joint model fit is proposed to estimate the relative increase in wall heat flux due to intrinsic flame instabilities based on characteristic quantities of a corresponding stable one-dimensional freely-propagating flame.
Novelty and Significance Statement
This work presents a novel parametric study of flame-wall interactions (head-on quenching) of intrinsically unstable hydrogen/air flames. It builds upon an investigation of an unstable head-on quenching hydrogen/air flame (part I (Schneider et al., Combust. Flame, 2025)) and extends it to a wide range of operation conditions, including variations in equivalence ratio, unburnt gas temperature, and pressure. Additionally, simulations in which either the thermodiffusive or the hydrodynamic instability is selectively suppressed are conducted to enable a separate analysis of each effect. Based on this comprehensive dataset, the study demonstrates the influence of both thermodiffusive and hydrodynamic instabilities on the quenching process by analyzing the local wall heat flux as well as global quenching characteristics. Furthermore, the study reveals that the intensity of thermodiffusive instabilities correlates well with the increase in the peak wall heat flux relative to a one-dimensional simulation for all operating conditions investigated. To enable the assessment of thermal loads in technical applications, a novel model fit is proposed that allows to estimate the peak wall heat flux during quenching based on characteristic quantities of one-dimensional flames.
期刊介绍:
The mission of the journal is to publish high quality work from experimental, theoretical, and computational investigations on the fundamentals of combustion phenomena and closely allied matters. While submissions in all pertinent areas are welcomed, past and recent focus of the journal has been on:
Development and validation of reaction kinetics, reduction of reaction mechanisms and modeling of combustion systems, including:
Conventional, alternative and surrogate fuels;
Pollutants;
Particulate and aerosol formation and abatement;
Heterogeneous processes.
Experimental, theoretical, and computational studies of laminar and turbulent combustion phenomena, including:
Premixed and non-premixed flames;
Ignition and extinction phenomena;
Flame propagation;
Flame structure;
Instabilities and swirl;
Flame spread;
Multi-phase reactants.
Advances in diagnostic and computational methods in combustion, including:
Measurement and simulation of scalar and vector properties;
Novel techniques;
State-of-the art applications.
Fundamental investigations of combustion technologies and systems, including:
Internal combustion engines;
Gas turbines;
Small- and large-scale stationary combustion and power generation;
Catalytic combustion;
Combustion synthesis;
Combustion under extreme conditions;
New concepts.