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The characteristic of flow field and emissions was investigated by numerical simulation for a concentric staged lean direct injection combustor, the non-reaction and reaction flow fields were studied under idle and takeoff conditions, and the effect of combustion heat release on flow field was analyzed, then the influence of injection angle on emissions were obtained. The investigation results indicated that the steady central recirculation zone could be formed under non-reaction and reaction conditions by medium swirl strength which the swirl angle is 32°, however, the size and reverse mass flow at reaction conditions is significantly increased than non-reaction conditions; the combustion reaction zone moves toward the outlet as the decrease of fuel injection angle, which reduce the resistant time of hot gas in combustor, and then the production of nitrogen oxides would be decreased.

Plain orifice and direct injector nozzle are increasingly used in advanced combustion chamber. In order to reduce the sensitivity of the single-phase liquid jet to the changes of air flow, another air jet can be added to form a air-liquid two-phase flow. In this paper, the atomization characteristics of the air-liquid two-phase jet during cross-airflow jetting are experimentally studied with optical instruments. The structure of the two-phase flow is to wrap a layer of annular air jet outside the liquid jet.Experiments show that when the mass flow rates of the annular air and liquid jets are relatively large, the jets will bifurcate and the droplet size will also be significantly different. When the air-liquid ratio continues to increase, the atomization-assisting effect of the annular air will also increase, and the droplet size difference will also decrease.