Laminar burning velocities are of great importance in many combustion models as well as for validation and improvement of chemical kinetic schemes. Determining laminar burning velocities with high accuracy is quite challenging and different approaches exist. Hence, a comparison of existing methods measuring and evaluating laminar burning velocities is of interest. Here, two optical diagnostics, high speed tomography and Schlieren cinematography, are simultaneously set up to investigate methods for evaluating laminar flame speed in a spherical flame configuration. The hypothesis to obtain the same flame propagation radii over time with the two different techniques is addressed. Another important aspect is the estimation of flame properties, such as the unstretched flame propagation speed and Markstein length in the burnt gas phase and if these are estimated satisfactorily by common experimental approaches. Thorough evaluation of the data with several extrapolation techniques is undertaken. A systematic extrapolation approach is presented to give more confidence into results generated experimentally. The significance of the linear extrapolation routine is highlighted in this context. Measurements of spherically expanding flames are carried out in two high-pressure, high-temperature, constant-volume vessels at RWTH in Aachen, Germany and at ICARE in Orleans, France. For the discussion of the systematic extrapolation approach, flame speed measurements of methane / air mixtures with mixture Lewis numbers moderately away from unity are used. Conditions were varied from lean to rich mixtures, at temperatures of 298–373 K, and pressures of 1 atm and 5 bar.

层流燃烧速度在许多燃烧模型以及化学动力学方案的验证和改进中都非常重要。高精度确定层流燃烧速度是非常具有挑战性的，并且存在不同的方法。因此，比较现有的测量和评估层流燃烧速度的方法是很有意义的。在这里，同时建立了两个光学诊断技术：高速断层摄影和Schlieren摄影，以研究在球形火焰配置中评估层流火焰速度的方法。提出了使用两种不同技术获得随时间变化的相同火焰传播半径的假设。另一个重要方面是火焰特性的估算，例如未拉伸的火焰传播速度和燃烧气相中的马克斯坦长度，以及是否可以通过常规实验方法令人满意地估算出这些长度。使用几种外推技术对数据进行了全面评估。提出了一种系统的外推方法，以使人们对实验产生的结果有更多的信心。在这种情况下，线性外推程序的重要性得到了强调。球形膨胀火焰的测量是在德国亚琛的RWTH和法国奥尔良的ICARE的两个高压，高温，恒定体积的容器中进行的。对于系统外推方法的讨论，使用甲烷/空气混合物的火焰速度测量值，该值的混合路易斯数适度远离单位。