Fundamental investigations for lowering emissions and improving operability

This paper first highlights recent developments in lean direct injection (LDI) combustion technology. In view of the needs and opportunities to lower emissions and expand the operability range of LDI, fundamental research has been undertaken to elucidate the effects of air swirler vane angle, air swirler rotation direction, and overall equivalence ratio on the LDI flow field and flame structure/response. Moreover, additional investigation has been conducted to understand the fundamental differences between representative LDI and airblast injectors in order to highlight the importance of the flare feature to LDI venturi geometry. The results of these fundamental studies are discussed to help identify possible areas for optimization to generic LDI designs that may improve individual swirler performance.