常压下预混甲烷和空气微波等离子体放电燃烧的实验研究  

Experimental study on microwave plasma discharge and combustion of premixed methane and air at atmospheric pressure

作　　者：曹树利 李寿哲[1,2] 牛裕龙 李容毅 朱海龙[3] Cao Shu-Li;Li Shou-Zhe;Niu Yu-Long;Li Rong-Yi;Zhu Hai-Long(Key Laboratory of Materials Modification by Laser,Ion and Electron Beams,Ministry of Education,Dalian University of Technology,Dalian 116024,China;School of Physics,Dalian University of Technology,Dalian 116024,China;College of Physics and Electronic Engineering,Shanxi University,Taiyuan 030006,China)

机构地区：[1]大连理工大学,三束材料改性教育部重点实验室,大连116024 [2]大连理工大学物理学院,大连116024 [3]山西大学物理电子工程学院,太原030006

出　　处：《物理学报》2023年第15期159-171,共13页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11975003);中央高校基本科研业务费资助(批准号:DUT22LAB105)资助的课题.

摘　　要：开展了预混甲烷(CH_(4))和空气的微波等离子体放电燃烧实验,研究火焰余辉形态、光谱分布和温度特性随着微波功率、燃空当量比和轴向观测位置的变化规律.实验发现预混CH_(4)/Air的稀薄燃烧极限当量比Φ=0.4;在微波等离子体放电时,当Φ<0.4,以放电诱导的燃烧过程为主要特征,而当Φ≥0.4时,等离子体放电燃烧的中心区会明显收缩并逐渐出现丝状放电,这里低约化场强区的燃烧和高约化场强区的放电燃烧相互影响.利用发射光谱仪测得预混CH_(4)/Air微波等离子体放电燃烧光谱的特征谱带,OH(A-X),NH(A-X)和CN(B-X),沿着轴向空间位置的强度分布和随着当量比的变化,发现了轴向上近余辉的等离子体放电燃烧区和远余辉的燃烧区,并通过分析CN(B-X)振转谱带的强度分布,计算得到振动与转动温度,发现以Φ=0.4为分界点形成两种不同的随当量比变化规律.最后,根据CH_(4)扩散燃烧火焰、CH_(4)/N2混合气体等离子体放电以及CH_(4)/Air混合气体等离子体放电燃烧的发射光谱对比分析讨论了等离子体增强燃烧过程中的反应路径和机理.In this work,we carry out the experiments on an atmospheric-pressure premixed methane and air microwave plasma discharge combustion with premixed methane and air to study the morphology,the spatial distribution of species,and the temperature characteristics for various microwave power values and methane-toair equivalent ratios(Φ)at a series of measurement positions.The experimental results show that the equivalent ratio of 0.4 corresponds to the limit value for lean-combustion of premixed methane and air.And for Φ<0.4,the discharge flame is mainly characterized by the combustion induced by premixed methane and air microwave plasma discharge,while,for Φ≥0.4,the discharge flame is constricted into filaments radially,and the natural combustion occurs in the region of low reduced electric strength and the combustion induced by plasma discharge in the region of high reduced electric strength,which affect each other.The variations of emission intensity of OH(A-X)band,NH(A-X)band and CN(B-X)band with the measuring position and the equivalent ratio Φ are measured by using optical emission spectrometry(OES).It is found that the discharge combustion occurs in near afterglow and the combustion in far afterglow.And the vibrational temperature and the rotational temperature of the plasma discharge combustion are determined by analyzing the emission bands of CN(B-X)and the variations of both vibrational and rotational temperatures with equivalent ratio,exhibiting very different varying tendencies for cases of Φ<0.4 and Φ≥0.4,respectively.Finally,the reaction pathway and mechanism are discussed on the basis of the comparative analyses of the emission spectra of CH_(4) diffusion combustion flame,premixed methane and nitrogen microwave plasma discharge,and premixed methane and air microwave plasma discharge combustion.

关 键 词：大气压 微波等离子体 放电 甲烷 

分 类 号：O53[理学—等离子体物理] O461[理学—物理]