摘要
铝颗粒由于具有能量密度高、易储存、燃烧过程不产生温室气体等优势,有望成为未来化石燃料替代的解决方案.本文建立了铝颗粒粉尘火焰的燃烧模型,其中考虑了相间传热、相变、表面化学反应、气相详细化学反应及辐射传热等过程,并针对铝颗粒粉尘对冲火焰开展了数值模拟研究.首先,通过仿真McGill大学的铝颗粒粉尘对冲火焰实验进行模型验证,并分析了实验中使用铝颗粒本身作为示踪粒子引起的气相速度测量误差,结果表明,数值模拟得到的离散相速度分布与实验结果基本一致,火焰传播速度的预测值也同实验数据吻合较好.当颗粒粒径小于10μm时,连续介质假设不再成立,相间传热模型必须考虑过度区机制,随着颗粒粒径的增加,火焰传播速度不断降低.随着对冲火焰拉伸率的增加,颗粒在火焰区的停留时间减少,并出现燃烧不完全的现象,粉尘火焰由双峰变为单峰结构.火焰传播速度随着拉伸率的增加而增大,通过线性外推可得到未拉伸的火焰传播速率约为29 cm/s.辐射引起的热损失会导致气相温度大幅降低,但辐射传热对颗粒的加热作用相对较小.
Aluminum is widely used as an additive in solid rocket propellants and pyrotechnics due to its outstanding characteristics such as high energy density and combustion temperature,environmentally benign products,and good stability.Recently,aluminum powders are found to present great potential serving as alternative fuel in a low-carbon economy.In this paper,a detailed model including the effects of interphase heat transfer,phase change,heterogeneous surface reactions,homogeneous combustion and radiation is employed to investigate aluminum dust counterflow flames.The numerical model is first validated by simulating the aluminum dust counterflow flames of McGill University.The results indicate that the particle velocity profile is in very good agreement with the experimental measurements.A detailed analysis of estimating the gas phase velocity based on the particle velocity is performed by using Stoke timeτ;.The results show that a correct value ofτ;is the key to this method,and using a single value ofτ;can bring a notable bias to the results,which may also affect the evaluation of flame speed from the counterflow flame.It is suggested that model validation should be carried out by directly comparing the particle velocity profiles from the simulations with those from the experiments.The flame structure of the aluminum dust counterflow flame is discussed,and the interphase heat transfer model is found to have a great influence on the flame for particle sizes smaller than 10μm.Therefore,when simulating the aluminum dust flames with small particle sizes,the interphase heat transfer model should be selected carefully so that it can cover the transition heat transfer regime.The effect of particle diameter is examined.With the increase of the particle size,the flame speed continues to decrease,and most particles with a diameter of 15μm cannot be fully burnt in the present configuration.The strain rate is found to be an important factor affecting the dust flame.As the strain rate increases,the residence time of the par
作者
张家瑞
夏智勋
方传波
马立坤
冯运超
Oliver Stein
Andreas Kronenburg
Zhang Jia-Rui;Xia Zhi-Xun;Fang Chuan-Bo;Ma Li-Kun;Feng Yun-Chao;Oliver Stein;Andreas Kronenburg(College of Aerospace Science and Engineering,National University of Defense Technology,Changsha 410073,China;Qinghe Building Ding-3,Beijing 100085,China;Institute for Combustion Technology,University of Stuttgart,Stuttgart 70569,Germany)
出处
《物理学报》
SCIE
EI
CAS
CSCD
北大核心
2022年第7期229-240,共12页
Acta Physica Sinica
基金
国家自然科学基金(批准号:52006240)
湖南省自然科学基金(批准号:2020 JJ4665,2021 JJ30775)
国家留学基金(批准号:201903170201)资助的课题。
关键词
铝燃烧
对冲火焰
颗粒粉尘
火焰传播速度
aluminum combustion
counterflow flame
particle clouds
flame speed
