{"title":"Multiphase ignition and combustion model and its characteristics of boron particles based on dynamic experimental phenomena","authors":"Xianju Wu , Zhijun Wei","doi":"10.1016/j.combustflame.2024.113445","DOIUrl":null,"url":null,"abstract":"<div><p>Boron, renowned for its high-energy potential but challenged by combustion difficulties, emerges as an ideal fuel for solid-fuel scramjet engines. This study improved the ignition and combustion model for boron particles in wet air by refining the Penn State University extension models based on the dynamic experimental phenomena. Under atmospheric pressure, the transition in combustion mode for boron particles occurs within the diameter range of 3.5–4.9 µm, with increased ambient temperature or H<sub>2</sub>O concentration promoting the shift towards diffusion-controlled mode. Larger particles exhibit a sequential combustion mode, transitioning from kinetics-controlled to diffusion-controlled, and back to kinetics-controlled, while smaller particles consistently remain kinetics-controlled. The ignition delay proportion increases with the particle diameter but generally stays below 10 %. Increasing the temperature significantly shortens the ignition time, while increasing the pressure significantly shortens the combustion time. Taking the combustion of 1 µm boron particles at atmospheric pressure as an example, as the temperature increases from 1700 K to 3500 K, the ignition time decreases to 0.08 %, and as the pressure increases from 0.5 atm to 15 atm, the combustion time decreases to 1.6 %. Increasing the O<sub>2</sub> concentration significantly shortens the combustion time, with a lesser effect on the ignition time. The addition of H<sub>2</sub>O can reduce both ignition and combustion times, especially for boron particles with an approximate diameter of 5 µm in low temperature environments. However, once <em>X</em>H<sub>2</sub>O exceeds 15 %, the combustion time stabilizes in both combustion modes. Lower ambient temperatures and smaller particles enhance the impact of solidification on the combustion of boron particles.</p></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":null,"pages":null},"PeriodicalIF":5.8000,"publicationDate":"2024-05-04","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/S0010218024001548","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
Boron, renowned for its high-energy potential but challenged by combustion difficulties, emerges as an ideal fuel for solid-fuel scramjet engines. This study improved the ignition and combustion model for boron particles in wet air by refining the Penn State University extension models based on the dynamic experimental phenomena. Under atmospheric pressure, the transition in combustion mode for boron particles occurs within the diameter range of 3.5–4.9 µm, with increased ambient temperature or H2O concentration promoting the shift towards diffusion-controlled mode. Larger particles exhibit a sequential combustion mode, transitioning from kinetics-controlled to diffusion-controlled, and back to kinetics-controlled, while smaller particles consistently remain kinetics-controlled. The ignition delay proportion increases with the particle diameter but generally stays below 10 %. Increasing the temperature significantly shortens the ignition time, while increasing the pressure significantly shortens the combustion time. Taking the combustion of 1 µm boron particles at atmospheric pressure as an example, as the temperature increases from 1700 K to 3500 K, the ignition time decreases to 0.08 %, and as the pressure increases from 0.5 atm to 15 atm, the combustion time decreases to 1.6 %. Increasing the O2 concentration significantly shortens the combustion time, with a lesser effect on the ignition time. The addition of H2O can reduce both ignition and combustion times, especially for boron particles with an approximate diameter of 5 µm in low temperature environments. However, once XH2O exceeds 15 %, the combustion time stabilizes in both combustion modes. Lower ambient temperatures and smaller particles enhance the impact of solidification on the combustion of boron particles.
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.