Numerical study of auto-ignition and detonation development
The development of highly boosted and high compression spark-ignition engines with enhanced thermal efficiencies is primarily limited by knock and super-knock. Super-knock is an excessively high intensity knock which has been related to a developing detonation process. The ξ/ɛ diagram with an enclosed detonation peninsula is used to assess the knocking tendency of different fuels. The diagram plots ξ, the ratio of acoustic to auto-ignitive velocity, against ɛ, the ratio of the transit time of an acoustic wave through a hot spot, to the heat release time (τe). Constant volume simulations of auto-ignition delay times (τi) and excitation times (τe) obtained from chemical kinetic calculations, enable calculations of ξ and ɛ. Their location for different fuels and operating conditions on the ξ/ɛ diagram, relative to the detonation peninsula, defines their mode of reaction propagation and the severity of a detonation. Fuels exhibiting a strong negative temperature chemistry (NTC) region are found to enter detonation development and explosion region, and are more likely to result in super-knock events in boosted spark-ignition engines.
Dr. Inna Gorbatenko is a postdoctoral fellow in prof. Mani S. Sarathy’s group. She joined Combustion and Pyrolysis Chemistry (CPC) Family at KAUST in November 2020. Inna completed her Ph.D. as part of Centre of Doctoral Training in Fluid Dynamics at the University of Leeds, UK, in 2020, studying auto-ignition and heat release behaviour of alternative fuels. She obtained her BS.c. in Aviation Technology and Management, University of Leeds, UK, in 2012. She is originally from Riga, Latvia, which is set on the shores of the Baltic Sea. Inna’s research interests cover a range of topics from the combustion of alternative fuels, advanced modes of engine operation, optimisation of bio-fuels for transport, to gas-phase kinetics and fluid dynamics.