Direct Numerical Simulation data obtained earlier from two statistically 1D, planar, fully-developed, weakly turbulent, single-step-chemistry, premixed flames characterized by different (7.53 and 2.50) density ratios σ are analyzed to explore the influence of combustion-induced thermal expansion on the turbulence and the backward influence of such flow perturbations on the reaction zone. For this purpose, the actual velocity fields are decomposed into solenoidal and potential velocity subfields, followed by independently processing each subfield. Results show that the potential and solenoidal velocities are negatively (positively) correlated in unburned reactants (burned products, respectively) provided that $\sigma =7.53$. Moreover, not only potential, but also solenoidal velocity subfields contribute to countergradient turbulent scalar transport. Furthermore, correlation between strain rates generated by the solenoidal and potential velocity fields and conditioned to the reaction zone is positive (negative) in the leading (trailing, respectively) halves of the mean flame brushes. The potential strain rate correlates negatively with the flame curvature within the reaction zone, whereas the solenoidal strain rate and the curvature are negatively (positively) correlated in the leading (trailing, respectively) halves of the mean flame brushes. If $\sigma =7.53$, the stretch rate conditioned to the reaction zone is negative (positive) in regions characterized by large positive (negative, respectively) potential strain rates, whereas the opposite trend is observed for the solenoidal strain rate. Thus, the potential and solenoidal velocity fields differently affect the reaction zone. In the case of $\sigma =2.5$, such differences are significantly less pronounced. Finally, an approximate decomposition of the mean rate of viscous dissipation of flow kinetic energy into solenoidal and potential contributions is suggested and supported by DNS data. The results also show that the dilatation-induced dissipation plays an important role. Therefore, the influence of thermal expansion on the dissipation rate is not reduced to an increase in mixture viscosity in the rotational dissipation rate.

较早地从两个统计的一维，平面的，完全发展的，弱湍流的，单步化学的，具有不同（7.53和2.50）密度比σ的预混火焰中获得的直接数值模拟数据进行了分析，以探索燃烧引起的热的影响湍流的膨胀以及这种流动扰动对反应区的向后影响。为此，将实际速度场分解为螺线管和潜在速度子场，然后分别处理每个子场。结果表明，在未燃烧的反应物（分别为燃烧产物）中，势能和螺线管速度呈负（正）相关。$\sigma =7.53$。此外，不仅势能，而且螺线管速度子场都有助于反梯度湍流标量传输。此外，在平均火焰刷的前半部分（分别是后半部分）中，由螺线管速度场和势速场产生并适应于反应区域的应变率之间的相关为正（负）。潜在的应变率与反应区内的火焰曲率呈负相关，而螺线管的应变率和曲率在平均火焰刷的前半部（分别为拖尾）中呈负（正）相关。如果$\sigma =7.53$，在以大的正（负）电位应变率为特征的区域中，调节到反应区的拉伸速率为负（正），而对于螺线管应变率则观察到相反的趋势。因此，势场和螺线管速度场不同地影响反应区。如果是$\sigma =2.5$，这种差异明显不那么明显。最后，DNS数据建议并支持将流动动能的粘性耗散平均速率分解为螺线管和潜在贡献。结果还表明，膨胀引起的耗散起重要作用。因此，热膨胀对耗散率的影响不会减小到旋转耗散率中的混合物粘度的增加。