Analyzing the effects of cooled EGR on the knock of hydrogen-fueled Wankel rotary engine

Abstract

Hydrogen-fuel Wankel rotary engine (HWRE) has higher power density than current marketed gasoline-fueled engines, however, it suffers from the knock. Hence, the purpose of this work is to investigate the impacts of cooled exhaust gas recirculation (EGR) on the knock in a HWRE by analyzing the relationship between some knock-relevant parameters and EGR level, which is conducted at 1500 r/min, wide-open throttle, stoichiometric ratio, and respectively constant ignition timing and CA50. The results show that cooled EGR can be used as an effective means of eliminating the knock in HWRE. As the EGR level is increased, the size and distribution of knock-relevant parameters, such as knock intensity, knock duration, crank angle of peak knock pressure and so on, show their own change characteristics. Besides, the role of the EGR level on the knock-relevant parameters is also influenced by the ignition timing and CA50. Overall, cooled EGR has a positive effect on the suppression of knock.