Experiment and simulation research on super-knock suppression for highly turbocharged gasoline engines using the fuel of methane

Super-knock has been the main obstacle to improve power density and engine efficiency of modern highly turbocharged gasoline engines. Previous researches show that pre-ignition is the inducement of super-knock, while detonation is the root reason of how super-knock could damage engines dramatically. Lots of studies have been conducted to eliminate pre-ignition for suppressing super-knock indirectly. This work applies the fuel of methane to suppress detonation and then to suppress super-knock directly using a rapid compression machine (RCM). Furthermore, 1-D simulation model was set up to investigate the mechanism why methane could suppress detonation and super-knock. Finally, through single cylinder engine tests, this suppression strategy in engine practical usage was validated. The experiment and simulation results show that replacing the fuel from iso-octane or gasoline to methane while keeping other conditions identically could transfer detonation combustion mode to flame propagation. The peak pressure could be reduced dramatically and there is no pressure oscillation. Therefore, methane mixture could suppress detonation and then to suppress super-knock effectively, even if preignition already exists. It could be an effective and practical control strategy to protect modern highly turbocharged engines. (C) 2019 Elsevier Ltd. All rights reserved.