A research was performed done to study the effect on the ignition performance by the too long mixing length of sleeve. Two variations of sleeve mixing length were made to test the ignition performance using a single module test combustor under normal temperature and atmospheric pressure. Melvin was used to test the spray particle size

and the software Fluent was used to analyze the experimental results. The research results show:the hardware geometry of sleeve mixing length has a great influence on the flow fields

and spray distributions of the dome. The spray drops will impact on the wall of sleeve when the mixing length of sleeve is long enough

and the radial movement of swirl jets and spray drops will be confined

leading to the decrease of spray cone angle by 32% and the increase of fuel air ratio(FAR) of lean ignition about 20%.