This work covers investigations of the static and dynamic behaviour of a confined, co-swirled and liquid-fuelled airblast injection system. The focus lies on the application of ion current sensors for the qualitative measurement of the heat release rate or for flame monitoring purposes in complex technical combustion processes. The ion current sensor is to operate in a feedback control loop in order to react on combustion dynamics in real time. The first part of the work analyses experimental data, which were obtained with different techniques, e.g. dynamic pressure, chemiluminescence, fine-wire thermocouples and ion current. The results show that the thermo-acoustic instability and the precessing vortex core generate an interaction mode. The frequency of this interaction mode is the difference of the other two modes. This has not yet been observed for partially premixed and liquid-fuelled injection systems before and also was not detected by the chemiluminescence of the flame. The ion current measurement technique is able to detect the helical mode of the precessing vortex core as well as the interaction frequency, leading to the conclusion that the chemical reactions are influenced by this helical structure. Contour maps of the frequencies reveal this influence in the outer shear layer. The second part of the study focused on the ion current probe as a method to predict static combustion instabilities, such as lean blowout. According to the results, the ion current is a fast responding method to detect lean blowout, provided that the detector is mounted at a suitable position. Measurements at different positions in the flame were compared with phase-locked chemiluminescence measurements. Precursors in the ion current signal for lean-blowout prediction were found using a statistical approach, which is based on ion peak distance. The precursor events allow for the use of this approach with a feedback control loop in future applications.

中文翻译：

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液体燃料燃气轮机燃烧室离子流的实验研究

这项工作包括对密闭，共涡旋和液体燃料的喷丸喷射系统的静态和动态行为的研究。重点在于将离子电流传感器用于排热速率的定性测量或在复杂的技术燃烧过程中进行火焰监测。离子电流传感器将在反馈控制回路中运行，以便实时响应燃烧动力学。工作的第一部分分析了实验数据，这些数据是通过不同的技术获得的，例如动态压力，化学发光，细线热电偶和离子电流。结果表明，热声不稳定性和旋进的旋涡芯产生了相互作用模式。此交互模式的频率是其他两个模式的差。之前尚未对部分预混和液体燃料的喷射系统观察到这一点，也没有通过火焰的化学发光检测到这一点。离子电流测量技术能够检测旋进旋涡核的螺旋模式以及相互作用频率，从而得出结论，化学反应受此螺旋结构影响。频率的等高线图显示了外部剪切层中的这种影响。研究的第二部分集中于离子电流探针，作为预测静态燃烧不稳定性（如稀薄喷出）的方法。根据结果​​，如果将检测器安装在合适的位置，则离子电流是检测稀薄吹出的快速响应方法。将火焰中不同位置的测量结果与锁相化学发光测量结果进行了比较。使用基于离子峰距离的统计方法，找到了用于稀薄吹出预测的离子电流信号中的前体。前兆事件允许在将来的应用中将此方法与反馈控制回路一起使用。