<div class="htmlview paragraph">A synthesis of the research undertaken at the Institut Francais du Pétrole to understand phenomena of combustion, of heat transfers, and of knock and controlling to optimize high-compression-ratio combustion chambers has led to the proposing of two specific research topics: - calm chamber with dual ignition; turbulent chamber with squish effect.</div> <div class="htmlview paragraph">A calm chamber with a small surface-area/volume ratio enables heat losses to be minimized because they penalize operating efficiency all the more as the compression ratio is high. Dual ignition combined with a geometry which maximizes the area of the flame front creates high energy discharge release rates which are favorable for efficiency and knock prevention. The main limitation of dual ignition is the technico-economic constraint.</div> <div class="htmlview paragraph">Optimizing squish chambers requires a geometric design which makes a compromise on sufficiently high turbulence intensity to speed up combustion without overly increasing heat transfers.</div> <div class="htmlview paragraph">The geometry must also enhance the development of a maximum-area flame front, and the squish effect must amplify this area even further. Building such a chamber depends on knowing the internal aerodynamics, the interactions between the geometry and the overall movement of gases, and the turbulence.</div>