甲烷-空气预混火焰中化学发光定量化测量放热率的实验研究

Experimental Investigation of Heat Release Rate Quantitative Measurement Using Chemiluminescence in PremixedMethane-Air Flames

关键词:  化学发光  放热率  定量化  层流预混火焰  火焰结构

Key words:  Chemiluminescence  Heat release rate  Quantification  Laminar premixed flame  Flame structure

摘要:

为了研究化学发光定量化测量火焰放热率的方法，对当量比0.8～1.2，流速5cm/s～25cm/s的甲烷-空气预混火焰进行了实验研究。使用直径0.025mm高精度铂铑热电偶测量了平面火焰的温度分布，进一步得到了放热率分布，并对火焰结构及燃烧特性进行了分析；利用ICCD相机测量了甲烷-空气预混火焰中OH和CH的化学发光分布，并研究了两种激发态粒子的化学发光分布与放热率分布的关系。结果表明，常压下层流预混火焰的火焰厚度仅有0.5mm左右；气流速度的变化不改变火焰结构，而当量比对火焰结构有显著影响；OH能够比CH更准确地标识放热率的空间分布；两种激发态粒子的化学发光强度峰值与放热率峰值均呈线性关系，且线性相关性OH强于CH；得到了利用化学发光强度定量化测量放热率的方法。

Abstract:

An experimental study on laminar methane-air premixed flames was performed to evolve the technique of heat release rate (HRR) quantitative measurement using chemiluminescence， varying the equivalence ratios from 0.8 to 1.2， flow velocities from 5cm/s to 25cm/s. The distribution of temperature and heat release rate of the flat flame were measured by high-accuracy coated Pt/13%-Rh-Pt thermocouple with 0.025mm diameters， and analyzed the flame structure and combustion characteristic as well. The OH and CH chemiluminescent images were obtained via the ICCD camera in this study， and the correlation between chemiluminescence and heat release rate has been investigated. It is shown that the thickness of flat flame in normal pressure is only 0.5mm， and the flow velocity could not affect the flame structure but the equivalence ratio has obvious influence on flame structure. Compared with CH， OH is more effective in marking the space distribution of heat release rate. The peak heat release rate as a linear function of the peak chemiluminescent intensity of the two excited state radicals， and the linear correlation between OH chemiluminescent intensity and heat release rate is stronger. The heat release rate quantitative measurement method using chemiluminescence has been acquired.