Investigation on reactive jet and ignition performance of a compact pre-combustion igniter

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To provide ground-based fundamental data supporting reliable reignition under extreme high-altitude conditions, this study presents the design and experimental investigation of a compact pre-combustion igniter. A ground-based experimental platform was established to systematically study the spectral characteristics, jet dynamics, and ignition performance of the igniter. Optical emission spectroscopy revealed the generation of abundant active species, including the N₂ second positive band and NO-γ band. The vibrational temperature initially increased, then decreased, and finally stabilized with increasing gas flow rate, reaching a maximum of 12853 K. Jet visualization experiments showed that both jet flame length and stiffness increased notably with gas flow rate, with a maximum increase in jet stiffness of 169%, indicating effective resistance to crossflow interference. Comparative ignition tests showed that at combustor airflow rates of 250 m³/h and 300 m³/h, the pre-combustion igniter reduced ignition delay time by 37.5% and 28.3%, respectively, compared to a conventional spark igniter. Furthermore, the lean ignition limit was extended by an average of 25.97%, with a maximum improvement of 57.06%. The pre-combustion igniter enhances ignition reliability and adaptability through sustained jet flame, injection of active species, and turbulence intensification, demonstrating performance advantages under ground conditions that are qualitatively indicative of its potential for high-altitude applications