Contributions to the investigation of reaction pathways in fuel-rich flames

Development and validation of detailed reaction mechanisms for fuel-rich combustion have a continuing need for quantitative experimental flame data. In this study, an overview is presented of recent experimental investigations of a series of fuel-rich premixed low-pressure flames burning acetylene, propene, linear and cyclic C5-alkenes and C5-alkanes with a combination of laser spectroscopy and molecular beam mass spectrometry (MBMS). Particular attention was devoted to the reaction pathways leading to the first aromatic ring. Fuel-specific aspects with respect to benzene formation are discussed. The potential of resonance-enhanced multi-photon ionisation (REMPI) MBMS as a quantitative technique for the measurement of stable species is examined for benzene as an example. Also, first results of the investigation of a fuel-rich ethanol flame under similar conditions are given. Advantages and potential drawbacks of the applied diagnostic methods are discussed in view of the importance of reliable, quantitative measurements for the understanding of fuel-rich chemistry preceding polycyclic aromatic hydrocarbon (PAH) and soot formation as well as for the related modelling of these chemical processes.