The effect and mechanism of the flow deflector on ignition performance of the centrally staged combustor

Lean premixed prevaporized combustors with a centrally staged scheme are capable to reduce NOx emissions. Ignition is one of the key performances of the centrally staged combustor. The present study proposes a novel method to improve ignition performance by using a flow deflector. The effects of various flow deflector lengths and pressure drops on ignition performance and flame kernel propagation are investigated in this work. It is found that ignition performance is significantly improved by the flow deflector. The ignition process is obtained using a high-speed camera under different operating conditions. The timescale of the successful ignition process is analyzed using a statistical method, revealing the effects of the flow deflector length and pressure drop on the timescale of each phase of ignition. The flame kernel propagation trajectory is extracted and analyzed by combining the flow and spray fields. The mechanism of the flow deflector is analyzed by numerical simulation. It is found that with the flow deflector, the local fuel/air ratio and droplet diameter are both improved, which benefits ignition performance. This work proves that the flow deflector is a potential method to improve ignition.