Study on the active jet spark induced combustion technology for aviation kerosene piston engine

Aviation kerosene is increasingly being used in aviation piston engines because it is safe for use. However, if the traditional compression ignition (CI) mode is adopted for such engines, the high compression ratio will lead to an increase in the weight of moving parts and a decrease in the engine speed, thereby restricting the improvement of the power–weight ratio. If the traditional spark ignition (SI) mode is adopted, a high-performance output cannot be achieved owing to the restriction of knock. To overcome the abovementioned problems and realize kerosene high efficiency and knock free combustion, in this study, we designed a new combustion mode for active-jet spark-induced (AJSI) compound combustion in aviation kerosene piston engines. In order to verify the feasibility of AJSI combustion, a detailed three-dimensional in cylinder combustion simulation model was established, and the combustion process of AJSI combustion was studied. The results showed that the ignition delay period of kerosene could be reduced by 30% in the AJSI combustion mode. Compared to the ordinary SI combustion, the maximum pressure rise rate reduced by 26%, and knock index reduced by 34%. From the research results, AJSI combustion can effectively suppressing knock. In this paper, the combustion mechanism of AJSI combustion is analyzed in detail. The AJSI combustion process in an engine is divided into five stages, and the combustion characteristics are similar to those of SI in the early stage and similar to those of CI in the later stage. The period of similar–SI lasted for a long time, and the temperature and pressure increased gradually, which was mainly used for preparing for the similar–CI. Combustion during the period of similar–CI was intense. Spontaneous combustion of a large amount of premixed fuel occurred during this period, which lasted for a short time, with a rapid release of large amounts of heat. In this process, owing to the rapid combustion, the knock intensity can be decreased.