瞬态发射光谱法研究正十二烷燃烧反应特性

Properties of Combustion Reaction of n-Dodecane by Transient Emission Spectroscopy

采用加热激波管和增强型CCD瞬态光谱测量系统，在波长范围200～900nm，点火压力4．0atm，点火温度（1200～1300）K，当量比0．5、1．0和2．0的条件下，实时测得了正十二烷／空气和正十二烷／氧气／氩气燃烧过程的瞬态发射光谱．结果表明：燃烧过程在此波段内的主要发射光谱带归属于反应中间产物OH、CH和C2自由基；在不同当量比条件下，燃烧过程中OH（306．4nm）／cH（431．4nm）／c2（516．4nm）的光谱强度显著不同，贫油情形有利于OH自由基生成，富油情形有利于C2自由基生成；浴气的不同会导致燃料燃烧温度的不同，从而引起燃料燃烧发射光谱的不同．所测燃烧反应自由基的时间分辩光谱直观反映出正十二烷燃烧过程中重要中间产物OH、CH和C2的变化情况．研究结果有助于认识正十二烷燃烧反应特性和验证其燃烧反应机理．

Using a heated shock tube and an intensified spectroscopic detector CCD, transient emission spectra of n-dodecane in the combustion reaction were measured in the range of 200-900 nm. Experiments were conducted at pressure of 4.0 atm, temperatures of （1 200- 1 300） K, equivalence ratios of 0.5, 1.0, and 2.0. Results show that the main emission bands are attributed to OH, CH and C2 radicals produced during the combustion process. In the different equivalence ratios, the emission intensities of OH （306. 4 nm）/CH （431. 4 nm）/C2 （516. 4 nm） are significantly different in the combustion process, which indicates that fuel-lean situation is good for generation of OH radicals, and fuel-rich situation is good for C2. Different diluent gases lead to different combustion temperatures when the fuel burns, which causes the different patterns of the emission spectra of the fuel. The variation of OH, CH and C2 radicals produced in the combustion of n-dodecane are shown clearly by the time-resolved spectrum obtained. This research is helpful for understanding the properties and validating the mechanism of n-dodecane combustion reaction.