Laminar flame speed (LFS) is one of the most important physicochemical properties of a combustible mixture. At normal and elevated temperatures and pressures, LFS can be measured using propagating spherical flames in a closed chamber. LFS is also used in certain turbulent premixed flame modelling for combustion in spark ignition engines. Inside the closed chamber or engine, transient pressure rise occurs during the premixed flame propagation. The effects of pressure rise rate (PRR) on LFS are examined numerically in this study. One-dimensional simulations are conducted for spherical flame propagation in a closed chamber. Detailed chemistry and transport are considered. Different values of PRR at the same temperature and pressure are achieved through changing the spherical chamber size. It is found that the effect of PRR on LFS is negligible under the normal and engine-relevant conditions considered in this study. This observation is then explained through the comparison between the unsteady and convection terms in the energy equation for a premixed flame.

中文翻译：

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正常和发动机相关条件下压力上升速率对层流火焰速度的影响

层流火焰速度 (LFS) 是可燃混合物最重要的物理化学特性之一。在正常和升高的温度和压力下，LFS 可以使用在封闭室中传播的球形火焰进行测量。LFS 还用于某些用于火花点火发动机燃烧的湍流预混火焰建模。在封闭的燃烧室或发动机内部，在预混火焰传播过程中会发生瞬时压力升高。本研究以数值方式检验了压力上升率 (PRR) 对 LFS 的影响。对封闭室内的球形火焰传播进行一维模拟。考虑了详细的化学和运输。通过改变球室尺寸，在相同温度和压力下获得不同的 PRR 值。发现在本研究中考虑的正常和发动机相关条件下，PRR 对 LFS 的影响可以忽略不计。然后通过比较预混火焰能量方程中的不稳定项和对流项来解释这一观察结果。