Investigation of flame development applying optical metrology in a highly boosted SIDI performance engine for the sports car market

Optical measurements of the flame propagation inside an engine provide essential information for combustion process development. Many published studies in this field of research focus on low load and low speed engine operating points, as the utilized measurement techniques do not provide full load capability. Future emission legislations will include real driving emissions (RDE). As a consequence, there is a strong need for optimization of the full load range considering power and pollutant output.The present paper examines the combustion behavior of a highly boosted SIDI performance engine under high to full load conditions. The applied methodology is based on a fiber optical spark plug (FOSP) in conjunction with a high speed camera system. This approach provides spatial information about the flame position and its propagation and enables an assessment of the flame front velocity. The investigations focus on a variation of the air ratio lambda at constant engine speed and a variation of the engine speed with wide opened throttle.