Numerical simulation of flame propagation and HC-emissions in gas engines

Modern gas engines produce low CO2 emissions, they can be operated with bio gas and natural gas. Due to the longer availability of natural gas an increase of the number of application is expected. Gas engines, however, can emit rather large amounts of unburnt hydrocarbons (of-ten summarized as THC - total hydrocarbon - although consisting mainly as methane). This reduces the efficiency of the engine and gives a greenhouse gas contribution. Especially for stationary gas engines an exhaust gas treatment is disadvantageous due to high maintenance costs. Therefore the aim of this research project is to learn more on the primary sources of the unburnt hydrocarbons in the combustion chamber of the engine in order to reduce the primary emissions with better geometry and better operation conditions. For that, systematic investigations of particular influences are conducted on a 4.77 liter single cylinder research engine at LVK Munich. In parallel a simulation procedure is under development at ITV Hannover, to allow 3D-CFD simulations of the coupled flow and reaction processes inside the real engine. With that the dependencies of the THC sources from the local processes shall be clarified. Additionally a simulation approach shall be developed to be applicable for the optimization of new gas engines.