This paper presents new measurements of species concentrations, temperature and mixture fraction in selected regions of a turbulent ethanol spray flame. The line-Raman–LIF–COOH setup developed at the Sandia's Combustion Research Facility is utilised to probe regions of a spray flame where laser breakdown of liquid droplets is avoided and the remaining interferences can be corrected. The spray flame is stabilised on the piloted Sydney needle spray burner, where axial translation of the liquid injecting needle in the air-blast stream can transition the spray from dilute to dense. The solution to obtaining successful measurements is found to be multifaceted and includes: the appropriate selection of flame conditions; high sensitivity of the Raman detection system permitting reduced laser energies; development of a pre-processing algorithm to reject strong droplet interferences; and application of the hybrid matrix inversion method combined with wavelet denoising to account for interference corrections and noise at the very low signal levels obtained. Unique and necessary for the successful measurements reported in this paper, a pre-processing algorithm is outlined that removes data points corrupted with strong interferences from droplets. These interferences arise from a range of sources, but the most intense are due to the laser interaction with surrounding mist or liquid fragments, such that measurements near the jet centreline are corrupted and hence discarded. Reliable measurements of mixture fraction, temperature obtained from the sum of the species number densities, and species mole fractions are reported for regions in the flames sufficiently far from the centreline. The paper demonstrates the feasibility of the judicious use of Raman scattering in turbulent spray flames, the results of which will be extremely useful for validating numerical simulations.

本文介绍了在湍流乙醇喷雾火焰的选定区域中物种浓度，温度和混合比的新测量结果。拉曼–LIF–CO线桑迪亚燃烧研究设施开发的OH装置用于探测喷雾火焰的区域，在该区域避免了液滴的激光击穿，并且可以纠正剩余的干扰。喷雾火焰在先导式悉尼针式喷灯燃烧器上稳定下来，在此处喷流针在空气流中的轴向平移可以使喷雾从稀到浓转变。于获得成功测量的溶液被发现是多方面的，包括：火焰条件适当选择; 拉曼探测系统的高灵敏度可降低激光能量；开发一种预处理算法以拒绝强液滴干扰；混合矩阵求逆方法与小波去噪相结合的方法和应用，以解决在非常低的信号电平下的干扰校正和噪声问题。对于本文报道的成功测量而言，这是独特且必要的，概述了一种预处理算法，该算法可删除因液滴而受到强烈干扰而损坏的数据点。这些干扰来自多种来源，但是最强烈的干扰是由于激光与周围的雾或液体碎片的相互作用所致，因此靠近喷射中心线的测量值被破坏，因此被丢弃。报告了火焰中距中心线足够远的区域的混合物分数，从物种数密度的总和中获得的温度以及物种摩尔分数的可靠测量结果。