高压下氢气-乙醇球形膨胀火焰的层流燃烧速度和火焰不稳定性研究

在初始温度为400 K、不同的初始压力（0.1 MPa、0.4 MPa）、氢气比例（70%、80%）和当量比（0.7～1.4）条件下进行氢气-乙醇预混燃烧实验，使用高速纹影技术记录火焰传播图像。对氢气-乙醇球形膨胀火焰中的层流燃烧速度（LBV）进行实验研究，发现LBV随着氢气比例的增加而增加，压力升高却有着负影响。对火焰发展不同阶段的火焰形貌进行了研究。当火焰表面的大裂纹分裂出现小裂纹并且导致新细胞再生时，火焰变得不稳定。通过热膨胀比、火焰厚度和刘易斯数等参数考察了流体动力学效应和热扩散效应对火焰固有不稳定性的影响。结果表明，流体动力不稳定性随着压力的增加而增加，热扩散不稳定性对压力变化的敏感性较低。此外，增加氢气比例或初始压力会导致火焰更早遭受不稳定。

Investigation of Laminar Combustion Velocity and Flame Instability in Hydrogen-Ethanol Spherical Expansion Flames under High Pressures

Hydrogen-ethanol premixed combustion experiments were carried out at an initial temperature of 400 K, different initial pressures (0.1 MPa, 0.4 MPa), hydrogen ratios (70%, 80%), and equivalence ratios (0.7-1.4). High-speed schlieren technology was used to record flame propagation images. In this study, the laminar burning velocity (LBV) in a hydrogen-ethanol spherical expansion flame was experimentally investigated and it was found that the LBV increased with increasing hydrogen ratio, while increasing pressure had a negative effect. The flame morphology was investigated at different stages of flame development. The flame became unstable when large cracks on the flame surface split into small cracks and led to the regeneration of new cells. The effect of hydrodynamic and thermal diffusion effects on the intrinsic instability of the flame was studied using parameters such as thermal expansion ratio, flame thickness, and Lewis number. The results indicated that hydrodynamic instability increased with increasing pressure, while thermal diffusion instability was less sensitive to pressure changes. Furthermore, increasing the hydrogen ratio or the initial pressure caused the flame to suffer instability earlier.