Improved Distribution of Temperature inside Semitransparent Heat-Insulating Coatings of Combustion Chamber

The paper considers the radiative heat exchange under intensive short (radiant flux of red-hot soot particles) and long (radiation of“hot" hydrocarbonic atmosphere) IR components of total thermal flux in the combustion chamber (CC) of high-speed diesel engines. The analysis is conducted for only one spectral band in the ceramic coating and is assumed to be without any soot layer on it for this preliminary investigation. Temperature distributions are calculated for two layer coating. It consists of a top layer based on the semitransparent heat-insulating coating (SHIC) with varios thickness and a bottom one (semitransparent or opaque which could be metal substrate) with variation of reflection for transient (one complete cycle of piston movement) and steady state (cyclic heating). The improved distributions of temperature due to volumetric radiant heat losses inside semitransparent and opaque heat-insulating coatings are discussed. Subsurface temperature maximum under cycle radiant-convectional heat fluxes in CC of diesel analyzed. It is shown that semitransparent coatings can accumulate penetrating radiant heat of the total thermal flux during the “hot” phase (the combustion of fuel blend) and then act as a heat source in the rest of the cycle.