{"title":"Effects of hydrogen addition on flame structures in counterflow n-dodecane/air spray flames","authors":"Jianyi Jiang, Xiaoxu Zhang, Jian Zhang, Hua Zhou, Zhuyin Ren","doi":"10.1016/j.combustflame.2025.114322","DOIUrl":null,"url":null,"abstract":"<div><div>On the path to a carbon-neutral aviation industry, hydrogen drop-in technology could be a viable transition solution that could take advantage of existing infrastructure. The effect of hydrogen addition on the surrogate n-dodecane spray flame dynamics is investigated in a counterflow flame configuration under engine-related operating conditions, with the H<sub>2</sub>ASp-A configuration representing the concept of premixed H<sub>2</sub>/air mixture with n-dodecane droplets opposing an air flow, and ASp-H<sub>2</sub>A representing the droplets introduced in an air flow opposing premixed H<sub>2</sub>/air mixture. Results indicate that the n-dodecane/air spray flame with varying pressure can lead to significant differences in the behavior of multiple solutions, with some single solution behavior transitioning into multiple solutions due to the competition between endothermic evaporation and exothermic chemical reactions. Hydrogen addition on the spray side in H<sub>2</sub>ASp-A configuration can induce some single solution behavior transitioning into multiple solutions, whereas the addition on the non-spray side in H<sub>2</sub>ASp-A has little impact on multiple solution behavior. In addition, Hydrogen addition under both configurations increases flame speed and temperature, but H<sub>2</sub>ASp-A and ASp-H<sub>2</sub>A exhibit different flame dynamics. In ASp-H<sub>2</sub>A, a lean hydrogen/air premixed reaction zone could be formed at low strain rate that significantly enhance the temperature on the non-spray side, while in H<sub>2</sub>ASp-A, it causes non-monotonic speed variation based on autoignition-assisted flame propagation and the balance between hydrogen’s inhibition on low temperature chemistry and enhancing effects on reactions. At the same time, the increased droplet diameter can mitigate the rise in flame speed due to hydrogen addition in both ASp-H<sub>2</sub>A and H<sub>2</sub>ASp-A, and hydrogen addition in the ASp-H<sub>2</sub>A configuration has a better effect on increasing the flame temperature compared to the H<sub>2</sub>ASp-A. In terms of extinction, hydrogen addition and reduced initial droplet diameter enhance the spray flame resistance to strain rate in both configurations, with H<sub>2</sub>ASp-A performing better at lower hydrogen levels and ASp-H<sub>2</sub>A at higher levels.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"279 ","pages":"Article 114322"},"PeriodicalIF":5.8000,"publicationDate":"2025-07-01","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/S0010218025003608","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}
引用次数: 0
Abstract
On the path to a carbon-neutral aviation industry, hydrogen drop-in technology could be a viable transition solution that could take advantage of existing infrastructure. The effect of hydrogen addition on the surrogate n-dodecane spray flame dynamics is investigated in a counterflow flame configuration under engine-related operating conditions, with the H2ASp-A configuration representing the concept of premixed H2/air mixture with n-dodecane droplets opposing an air flow, and ASp-H2A representing the droplets introduced in an air flow opposing premixed H2/air mixture. Results indicate that the n-dodecane/air spray flame with varying pressure can lead to significant differences in the behavior of multiple solutions, with some single solution behavior transitioning into multiple solutions due to the competition between endothermic evaporation and exothermic chemical reactions. Hydrogen addition on the spray side in H2ASp-A configuration can induce some single solution behavior transitioning into multiple solutions, whereas the addition on the non-spray side in H2ASp-A has little impact on multiple solution behavior. In addition, Hydrogen addition under both configurations increases flame speed and temperature, but H2ASp-A and ASp-H2A exhibit different flame dynamics. In ASp-H2A, a lean hydrogen/air premixed reaction zone could be formed at low strain rate that significantly enhance the temperature on the non-spray side, while in H2ASp-A, it causes non-monotonic speed variation based on autoignition-assisted flame propagation and the balance between hydrogen’s inhibition on low temperature chemistry and enhancing effects on reactions. At the same time, the increased droplet diameter can mitigate the rise in flame speed due to hydrogen addition in both ASp-H2A and H2ASp-A, and hydrogen addition in the ASp-H2A configuration has a better effect on increasing the flame temperature compared to the H2ASp-A. In terms of extinction, hydrogen addition and reduced initial droplet diameter enhance the spray flame resistance to strain rate in both configurations, with H2ASp-A performing better at lower hydrogen levels and ASp-H2A at higher levels.
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.