{"title":"Mechanism of liquid oxygen temperature on combustion stability of gas-liquid swirl coaxial injectors","authors":"Pengjin Cao, Peng Cheng, Xiao Bai, Qinglian Li, Ziguang Li, Jingjing Liao","doi":"10.1016/j.combustflame.2025.114050","DOIUrl":null,"url":null,"abstract":"<div><div>Deep-throttling variable thrust cryogenic propellants rocket engines are facing the challenge of unstable combustion caused by propellants temperature. To explore the effect of liquid oxygen temperature on the combustion stability of liquid oxygen/methane engine, spray images and CH* chemiluminescence images were obtained synchronously using laser background light imaging. The dynamic characteristics of spray and flame at different liquid oxygen temperatures were studied. The mechanisms of low- and medium-frequency unstable combustion were analyzed. The liquid oxygen temperature has a significant influence on the combustion stability of the gas liquid swirl coaxial injectors. As the liquid oxygen temperature decreases, the frequencies of low- and medium-frequency oscillation combustion modes decrease, and the oscillation intensity increases. Eventually, both the low- and medium- frequency unstable combustion disappear. At the same total mass flow rate, the spray projection area of liquid oxygen decreases with increasing liquid oxygen temperature, while both the flame projection area and flame length increase. The low-frequency oscillation combustion mode results from the interaction between the fluctuating mass flow of liquid oxygen injected into the combustor and the vaporization of liquid oxygen inside the injector. When the liquid oxygen boiling position is near the surface of the gas core, partial vaporization of liquid oxygen inside the injector occurs, leading to the appearance of the medium-frequency oscillation combustion mode in the combustor. However, when the liquid oxygen boiling position exceeds the liquid sheet thickness of the swirl chamber, the liquid oxygen inside the injector remains in a purely liquid phase, resulting in stable combustion. Both low- and medium-frequency combustion instabilities can be effectively suppressed by increasing the combustor pressure or decreasing the liquid oxygen temperature.</div></div>","PeriodicalId":280,"journal":{"name":"Combustion and Flame","volume":"275 ","pages":"Article 114050"},"PeriodicalIF":5.8000,"publicationDate":"2025-02-18","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/S0010218025000884","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
Deep-throttling variable thrust cryogenic propellants rocket engines are facing the challenge of unstable combustion caused by propellants temperature. To explore the effect of liquid oxygen temperature on the combustion stability of liquid oxygen/methane engine, spray images and CH* chemiluminescence images were obtained synchronously using laser background light imaging. The dynamic characteristics of spray and flame at different liquid oxygen temperatures were studied. The mechanisms of low- and medium-frequency unstable combustion were analyzed. The liquid oxygen temperature has a significant influence on the combustion stability of the gas liquid swirl coaxial injectors. As the liquid oxygen temperature decreases, the frequencies of low- and medium-frequency oscillation combustion modes decrease, and the oscillation intensity increases. Eventually, both the low- and medium- frequency unstable combustion disappear. At the same total mass flow rate, the spray projection area of liquid oxygen decreases with increasing liquid oxygen temperature, while both the flame projection area and flame length increase. The low-frequency oscillation combustion mode results from the interaction between the fluctuating mass flow of liquid oxygen injected into the combustor and the vaporization of liquid oxygen inside the injector. When the liquid oxygen boiling position is near the surface of the gas core, partial vaporization of liquid oxygen inside the injector occurs, leading to the appearance of the medium-frequency oscillation combustion mode in the combustor. However, when the liquid oxygen boiling position exceeds the liquid sheet thickness of the swirl chamber, the liquid oxygen inside the injector remains in a purely liquid phase, resulting in stable combustion. Both low- and medium-frequency combustion instabilities can be effectively suppressed by increasing the combustor pressure or decreasing the liquid oxygen temperature.
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.
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