Study on ignition characteristics of kerosene pre-combustion plasma jet igniter

The ignition performance of an aeroengine combustion chamber significantly affects the engine's stable operating range. The ignition limit, a crucial factor in determining this performance, has consistently needed enhancement. To improve this and broaden the ignition limit, a kerosene pre-combustion gliding arc plasma jet igniter (KPPJ-Igniter) was developed. This igniter integrates gliding arc discharge, plasma jet ignition, and pre-chamber ignition techniques. Its characteristics were explored using a dual-head fan-shaped combustion chamber test section, where CH* groups produced during ignition were analyzed using the chemical self-luminescence method. The ignition mechanism, limit, and delay time of the KPPJ-Igniter were examined, revealing that increasing the jet flow rate decreases the jet flame length and increases discharge power, with the longest jet flame reaching 69.5 mm. The ignition process involves three stages: ignition transition stage, flame core expansion stage, and stable combustion stage. Two flame cores identified downstream of the igniter and in the combustor dome's recirculation zone significantly influence the combustion process. The KPPJ-Igniter notably extends the ignition limit, especially under low-velocity and low-turbulence conditions. With an inflow velocity of 80 m/s, it can expand the ignition limits by up to 32.6%, increasing the maximum ignition velocity from 80 to 100 m/s. The high ignition performance is attributed to the high-temperature jet flame and its cumulative effects, with the ignition delay time decreasing as fuel supply pressure and inflow velocity increase.