Models based on the linearized G-equation for the response of a premixed flame to acoustic perturbations often rely on a convective velocity model, where a convective wave generates local perturbations of flame shape and surface. The present study scrutinizes the origin and nature of such convective perturbations in flow-flame-acoustic interactions. Given that vortical structures are convected flow features, the study starts from the hypothesis that vorticity shed at the flame anchoring point accounts for the convective nature of flow perturbations. The velocity field induced by an acoustic perturbation is decomposed into irrotational-potential and vortical parts, which are both solved using a Schwarz–Christoffel mapping. The respective effect of each part on the flame response is computed for the case of a slit Bunsen flame by evaluation of the transient response of a linearized G-equation model for the flame dynamics. Any influences of flame front disturbances onto the flow resulting from exothermicity are explicitly excluded from our analysis. It is found that the potential velocity field dominates the flame response, while vortex shedding has only a negligible impact. Based on the observation that the potential part displaces predominantly the flame base, a flame-base-displacement (FBD) model is proposed. Its impulse response is found to compare well with CFD data right after an acoustic velocity perturbation is imposed, but growth of advected flame front perturbations leads to increasing discrepancies for later times and/ or larger confinements. This is attributed to exothermic effects generating vorticity via the Darrieus–Landau mechanism, which was already found to be responsible for convective velocity perturbations in the fresh mixture by previous studies. Since these perturbations are rather an output of flame-flow interactions than a flow-flame model input, it is concluded that modeling approaches that rely on convective velocity perturbations while ignoring exothermic effects misrepresent the causality of flow-flame interactions.

基于线性G方程的预混火焰对声扰动响应的模型通常依赖于对流速度模型，其中对流波会产生火焰形状和表面的局部扰动。本研究详细研究了这种对流扰动在流-火焰-声相互作用中的起源和性质。考虑到旋涡结构是对流流动的特征，该研究从以下假设开始：在火焰锚定点处发生旋涡，这说明了流动扰动的对流性质。由声扰动引起的速度场被分解为无旋势和旋涡部分，这两个部分均使用Schwarz-Christoffel映射求解。对于狭缝的本生火焰，通过评估火焰动力学线性化G方程模型的瞬态响应，可以计算出每个零件对火焰响应的影响。我们的分析明确排除了放热引起的火焰前扰动对流动的任何影响。已经发现，势速场主导了火焰响应，而涡旋脱落的影响却微不足道。基于观察到潜在部分主要发生在火焰基础上的位移，提出了火焰基础位移（FBD）模型。在施加声速扰动后，其冲激响应可以很好地与CFD数据进行比较，但平移火焰前扰动的增长会导致以后时间和/或更大范围内的差异越来越大。这归因于通过Darrieus-Landau机理产生涡度的放热效应，先前的研究已经发现这种机理是导致新鲜混合物中对流速度扰动的原因。由于这些扰动不是流-火焰模型输入，而是流-火焰交互作用的输出，因此可以得出结论，依赖对流速度扰动而忽略放热效应的建模方法错误地表示了流-火焰相互作用的因果关系。