Shixiang Liu , Michael A. Delichatsios , Longhua Hu
{"title":"非垂直湍流喷射火焰的形态特征:实验研究与分析模型","authors":"Shixiang Liu , Michael A. Delichatsios , Longhua Hu","doi":"10.1016/j.combustflame.2024.113589","DOIUrl":null,"url":null,"abstract":"<div><p>Non-vertical turbulent non-premixed jet flame occur in combustion systems and by accidental release of fuels caused fires. Understanding the combustion dynamics of these asymmetric diffusion jet flames is needed to characterize the flame morphology and entrainment, which is a foundation for further detailed analysis of the physics and implications. This paper investigates experimentally and theoretically the flame morphological characteristics of non-vertical turbulent jets at both positive- and negative inclined angles in a systematic way. A total of 168 experimental cases were considered involving various initial fuel flow rates, inclined angles and nozzle diameters. Dimensional analysis was performed taking into account the controlling parameters of the physical mechanisms, namely the momentum flux, the fuel mass flow rate, the flame buoyancy, the stoichiometric ratio and the jet initial inclined angle, which together determine a characteristic length scale and a characteristic volumetric flow rate. These two characteristic parameters provide successful non-dimensional correlations for the location of the flame tip. A new integral model was also developed physically considering the momentum and continuity equations along the trajectory to predict the flame tip, as well as the lowest point for negative inclined jets. By comparing the experimental correlations with numerical prediction, the effective air entrainment coefficients were derived for different jet initial inclined angles, which showed little change with inclined angle from positive to negative, but the constant relating the average values to the integrals of the (Gaussian) radial profiles decreased as the initial angle decreased from positive to negative. This change is related to the variation of the profile properties normal to the trajectory as well as to mass detrainment laterally escaping from the jet flame especially for negative inclined angles. Finally, the local Richardson number and the flame lowest point for negative inclined angles was numerically predicted and compared well with the experimental results.</p></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":null,"pages":null},"PeriodicalIF":5.8000,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Morphological characteristics of non-vertical turbulent jet flames: Experimental investigation and analytical model\",\"authors\":\"Shixiang Liu , Michael A. Delichatsios , Longhua Hu\",\"doi\":\"10.1016/j.combustflame.2024.113589\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Non-vertical turbulent non-premixed jet flame occur in combustion systems and by accidental release of fuels caused fires. Understanding the combustion dynamics of these asymmetric diffusion jet flames is needed to characterize the flame morphology and entrainment, which is a foundation for further detailed analysis of the physics and implications. This paper investigates experimentally and theoretically the flame morphological characteristics of non-vertical turbulent jets at both positive- and negative inclined angles in a systematic way. A total of 168 experimental cases were considered involving various initial fuel flow rates, inclined angles and nozzle diameters. Dimensional analysis was performed taking into account the controlling parameters of the physical mechanisms, namely the momentum flux, the fuel mass flow rate, the flame buoyancy, the stoichiometric ratio and the jet initial inclined angle, which together determine a characteristic length scale and a characteristic volumetric flow rate. These two characteristic parameters provide successful non-dimensional correlations for the location of the flame tip. A new integral model was also developed physically considering the momentum and continuity equations along the trajectory to predict the flame tip, as well as the lowest point for negative inclined jets. By comparing the experimental correlations with numerical prediction, the effective air entrainment coefficients were derived for different jet initial inclined angles, which showed little change with inclined angle from positive to negative, but the constant relating the average values to the integrals of the (Gaussian) radial profiles decreased as the initial angle decreased from positive to negative. This change is related to the variation of the profile properties normal to the trajectory as well as to mass detrainment laterally escaping from the jet flame especially for negative inclined angles. Finally, the local Richardson number and the flame lowest point for negative inclined angles was numerically predicted and compared well with the experimental results.</p></div>\",\"PeriodicalId\":280,\"journal\":{\"name\":\"Combustion and Flame\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":5.8000,\"publicationDate\":\"2024-07-01\",\"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/S0010218024002980\",\"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/S0010218024002980","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}
Morphological characteristics of non-vertical turbulent jet flames: Experimental investigation and analytical model
Non-vertical turbulent non-premixed jet flame occur in combustion systems and by accidental release of fuels caused fires. Understanding the combustion dynamics of these asymmetric diffusion jet flames is needed to characterize the flame morphology and entrainment, which is a foundation for further detailed analysis of the physics and implications. This paper investigates experimentally and theoretically the flame morphological characteristics of non-vertical turbulent jets at both positive- and negative inclined angles in a systematic way. A total of 168 experimental cases were considered involving various initial fuel flow rates, inclined angles and nozzle diameters. Dimensional analysis was performed taking into account the controlling parameters of the physical mechanisms, namely the momentum flux, the fuel mass flow rate, the flame buoyancy, the stoichiometric ratio and the jet initial inclined angle, which together determine a characteristic length scale and a characteristic volumetric flow rate. These two characteristic parameters provide successful non-dimensional correlations for the location of the flame tip. A new integral model was also developed physically considering the momentum and continuity equations along the trajectory to predict the flame tip, as well as the lowest point for negative inclined jets. By comparing the experimental correlations with numerical prediction, the effective air entrainment coefficients were derived for different jet initial inclined angles, which showed little change with inclined angle from positive to negative, but the constant relating the average values to the integrals of the (Gaussian) radial profiles decreased as the initial angle decreased from positive to negative. This change is related to the variation of the profile properties normal to the trajectory as well as to mass detrainment laterally escaping from the jet flame especially for negative inclined angles. Finally, the local Richardson number and the flame lowest point for negative inclined angles was numerically predicted and compared well with the experimental results.
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.