Preferential diffusion is very important in simulations of hydrogen flames. Flame stretch and curvature induce strong preferential diffusion effects in laminar premixed hydrogen flames, causing strong local deviations from the unburnt mixture fraction in the reaction zone. In tabulated chemistry methods, this necessitates the use of a partially premixed model even if the inlet mixture is purely premixed. Furthermore, in realistic combustion problems heat losses often play a dominant role. In this paper we derive a preferential diffusion model for constant but non-unity species Lewis numbers using three controlling variables, namely mixture fraction, progress variable and enthalpy. The model has been implemented in the Flamelet Generated Manifold (FGM) approach and validated by comparing with detailed chemistry simulations. As a test case we investigate a 2D laminar premixed hydrogen flame stabilised on an isothermal slit burner. Additionally, the model was compared with the standard treatment of preferential diffusion in FGM to show the increase in accuracy of the new model presented in this paper. The new model shows a significant improvement compared to the previous model, which can be attributed to the inclusion of cross-diffusion. The importance of the additional diffusion terms and its variation in mixture fraction for initially purely premixed hydrogen flames is highlighted.

优先扩散在模拟氢火焰中非常重要。火焰拉伸和曲率在层流预混氢火焰中引起强烈的优先扩散效应，导致与反应区未燃烧混合物部分的强烈局部偏差。在列表化学方法中，即使入口混合物是纯预混的，也需要使用部分预混模型。此外，在实际燃烧问题中，热损失通常起主导作用。在本文中，我们使用三个控制变量，即混合分数、进程变量和焓，推导出恒定但非统一物种路易斯数的优先扩散模型。该模型已在 Flamelet Generated Manifold (FGM) 方法中实施，并通过与详细的化学模拟进行比较来验证。作为测试案例，我们研究了在等温狭缝燃烧器上稳定的二维层流预混氢火焰。此外，该模型与 FGM 中优先扩散的标准处理进行了比较，以显示本文提出的新模型的准确性提高。与之前的模型相比，新模型显示出显着改进，这可归因于包含交叉扩散。强调了附加扩散项的重要性及其在最初纯预混氢火焰中混合分数的变化。与之前的模型相比，新模型显示出显着改进，这可归因于包含交叉扩散。强调了附加扩散项的重要性及其在最初纯预混氢火焰中混合分数的变化。与之前的模型相比，新模型显示出显着改进，这可归因于包含交叉扩散。强调了附加扩散项的重要性及其在最初纯预混氢火焰中混合分数的变化。