A series of direct numerical simulations (DNS) of iso-octane/air turbulent premixed flames in the thin reaction zones regime have been performed in order to investigate the effect of pressure on heat release rate under conditions relevant to spark-ignition (SI) engines (up to 20 bar and 800 K in the unburnt gas). Chemistry is represented by a reduced kinetics mechanism containing 74 species and 976 reactions (reduced from CaltechMech). The effect of pressure has been isolated by fixing the Karlovitz numbers, the Lewis numbers, and the ratio of integral length scale to laminar flame thickness. On one hand, the results suggest that pressure has very limited effect on the mean heat release rate, such that turbulent burning velocity is proportional to the turbulent surface area. In addition, while the chemical pathways are strongly affected by pressure in laminar flames, the global effect of turbulence on these pathways is negligible, independent of pressure. On the other hand, the local distribution of heat release rate was found to be significantly affected by pressure through differential diffusion-chemistry effects.

iso的一系列直接数值模拟（DNS）为了研究与火花点火（SI）发动机相关的条件（未燃烧时最高20 bar和800 K）下压力对放热率的影响，已在稀薄的反应区中进行了辛烷/空气湍流预混火焰的研究气体）。化学反应是由减少的动力学机理代表的，该机理包含74种和976个反应（从CaltechMech还原）。通过固定Karlovitz数，Lewis数以及积分长度标度与层流火焰厚度的比值，可以隔离压力的影响。一方面，结果表明压力对平均放热率的影响非常有限，因此湍流燃烧速度与湍流表面积成正比。此外，虽然化学途径受到层流火焰中压力的强烈影响，湍流对这些路径的整体影响可以忽略不计，而与压力无关。另一方面，通过微分扩散化学作用，发现放热率的局部分布受到压力的显着影响。