基于辐射光谱的对冲扩散火焰碳烟温度和体积分数的测量实验研究

对冲扩散火焰是研究碳烟生成特性的理想平台, 温度是碳烟生成的重要影响因素, 碳烟体积分数是衡量碳烟生成率的重要指标, 因此对冲火焰中碳烟温度和体积分数的准确测量对于开发减少碳烟排放策略至关重要。文章基于碳烟多光谱辐射(soot spectral emission, SSE)方法同步测量对冲火焰中的碳烟温度和体积分数。考虑到对冲火焰空间尺度小, 需要较高测量空间分辨率和位置精度的特点, 开发一种用于对冲火焰精准测量定位的方法, 有效地提高实验测量的位置精度; 同时建立一套基于热电偶的光谱响应函数原位标定系统; 最后使用SSE方法对常压环境不同工况下乙烯对冲扩散火焰的碳烟温度和体积分数进行测量。测量结果验证了对冲火焰碳烟温度场和浓度场的准一维性质; 通过与消光法实验数据和采用详细化学反应机理的数值计算结果的对比, 验证了SSE方法测量对冲火焰中碳烟温度及体积分数分布的可行性。

Counterflow diffusion flame is an ideal platform to investigate formation characteristics of soot. Temperature is an important factor to affect the formation of soot, and soot volume fraction is a key index to evaluate the soot formation rate. Hence, the accurate measurements of soot temperature and volume fraction in the counterflow flames are very important for developing strategies to reduce the soot emission. In this paper, soot temperature and volume fraction in ethylene counterflow diffusion flames were measured based on the soot spectral emission (SSE). Considering the requirement for the high spatial resolution and position accuracy due to the small spatial scale of the counterflow flames, a precise positioning method for the counterflow flames was developed, which can effectively improve the position accuracy of experimental measurement. At the same time, a spectral response function calibration system based on thermocouple was established. Finally, SSE method was used to measure the soot temperature and volume fraction of ethylene counterflow diffusion flames at atmospheric pressure under different working conditions. The experimental results verify the quasi one-dimensional properties of the soot temperature field and soot concentration field in the counterflow flames. Compared with the experimental data of light extinction method and the numerical results u