Effects of swirler structure on the performance of lean-direct-injection combustor

In consideration of swirler design of single element lean-direct-injection (LDI) injector, the effects of the swirler structures, including swirler stage number, swirl direction of dual-stage swirler and shrinking angle of mixing section, on the combustor performance (total pressure loss, combustion efficiency and pollutant emissions) were studied experimentally. The results show that, the swirler structures have great effect on the performance of combustor. The total pressure loss of dual-stage co-swirl combustor is greater than that of the single-stage swirl combustor with the same swirl number as the dual-stage co-swirl combustor. The total pressure loss of dual-stage counter-swirl combustor is slightly lower than that of the dual-stage co-swirl combustor. Combustor's total pressure loss increases with the inerease of shrinking angle. Under different lean fuel-air ratios, compared to the single-stage swirl combustor and dual-stage co-swirl combustor, the dual-stage counter-swirl combustor has higher combustion efficiency and lower pollutant emissions. In addition, combustion efficiency and pollutant emissions are affected by the shrinking angle. The optimal shrinking angle selection should strike a blance among the total pressure loss, the combustion efficiency, and the level of pollutant emissions.