Cyclic fluctuations of controlled hot surface ignition in homogeneous charge compression ignition gas engines

• Applicant: Professor Dr. Maurice Kettner
• Subject Area: Hydraulic and Turbo Engines and Piston Engines
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 536805048

The research project aims to identify and investigate the sources of cyclic fluctuations of the ignition event in a hot surface assisted homogeneous charge compression ignition gas engine. In addition to identifying the main factors influencing the occurrence of cyclic fluctuations, their physical mechanisms will be investigated. In this context, the current state of research indicates that the phase of initial flame kernel formation is of central importance. Therefore, the research questions focus on the physical processes during hot surface ignition and are addressed using experimental studies and numerical simulations. It is investigated whether ignition occurs in the regions close to the hot surface where the temperature gradient is lowest. For this initial ignition location its dependency on local flow conditions in the vicinity of the hot surface is investigated. With regard to the magnitude of cyclic ignition fluctuations, it is assumed that these result from changes in the time and location of the initial flame kernel. This assumption is to be verified. In addition to flow and temperature conditions, fuel reactivity influences the ignition process. Since natural gas, hydrogen and ammonia have very different ignition properties, these three gases are used to investigate the influence of fuel reactivity. The main question is whether higher fuel reactivity favors or inhibits the formation of cyclic ignition variations. Finally, the aim is to use the data collected to formulate a physical relationship in the form of a mathematical model that can be used to describe the influence of the factors investigated on the hot surface ignition event. With regard to practical applications, this model is intended to allow for the optimization of design and control parameters in order to reduce the cyclic fluctuations of the hot surface ignition event.

• DFG Programme: Research Grants