Understanding the temperature fields/profiles in aluminum dust flames is critical to the design of aluminum-based sustainable fuels and the development of aluminum combustion simulation tools. Although emission spectroscopy has been applied in aluminum flames, the signals in most works were integrated along the recording path and over the whole flame and, therefore, the measurements could not provide information of the flame spatial structure. In addition, the details of the diagnostic method were scarcely introduced. This work develops a dual-range emission spectroscopy diagnostic system for 1D measurements of the liquid temperature and the flame temperature of aluminum flames. The important aspects for diagnostics, such as the instrument specifications, signal acquisition strategy, data processing, accuracy and precision, are introduced and quantified in detail. The continuous spectrum from the liquid phase of Al and/or AlO, rovibrational AlO spectrum from the micro-diffusion flame, and 2D flame luminosity are recorded simultaneously. Based on Planck's law, a linear fitting method is implemented to derive a continuous spectrum temperature. A nonlinear minimization framework based on the stick spectrum is introduced to fit the AlO spectra and derive a AlO temperature. The accuracy and precision are quantified by a comparison of the average temperatures against the equilibrium temperatures and the standard deviations. The effectiveness of this technique for temperature measurements of aluminum dust flames is verified by the agreement of the continuous spectrum temperature and the AlO temperature in the post-flame region. The 1D distribution of the continuous spectrum temperature indicates the boiling of Al and the dissociation/condensation of AlO from upstream to downstream through the flame. The 1D temperature distributions also present a lag of the continuous spectrum temperature compared to the AlO temperature, indicating that the continuous spectrum temperature is dominated by the Al fuel droplets and the AlO caps, instead of the AlO nanometric droplets.

中文翻译：

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用于铝粉尘层流火焰温度测量的双范围发射光谱

了解铝粉尘火焰中的温度场/分布对于铝基可持续燃料的设计和铝燃烧模拟工具的开发至关重要。尽管发射光谱已应用于铝火焰，但大多数工作中的信号是沿着记录路径和整个火焰积分的，因此测量不能提供火焰空间结构的信息。此外，诊断方法的细节也很少介绍。这项工作开发了一种双范围发射光谱诊断系统，用于一维测量铝火焰的液体温度和火焰温度。详细介绍和量化了诊断的重要方面，如仪器规格、信号采集策略、数据处理、准确性和精度。同时记录 Al 和/或 Al2O3 液相的连续光谱、微扩散火焰的旋转 Al2O3 光谱和二维火焰光度。基于普朗克定律，采用线性拟合方法得出连续光谱温度。引入基于棒谱的非线性最小化框架来拟合 Al2O3 光谱并导出 Al2O3 温度。通过将平均温度与平衡温度和标准偏差进行比较来量化准确度和精密度。通过连续光谱温度与火焰后区域 Al2O 温度的一致性，验证了该技术用于铝尘火焰温度测量的有效性。连续光谱温度的一维分布表明 Al 的沸腾和 Al2O3 通过火焰从上游到下游的离解/缩合。与 Al2O3 温度相比，一维温度分布还呈现出连续光谱温度的滞后，表明连续光谱温度主要由 Al 燃料液滴和 Al2O3 帽主导，而不是 Al2O3 纳米液滴。