乙醇-氢气-空气混合物层流燃烧特性研究

Combustion Characteristics of Ethanol-Hydrogen-Air Mixture Laminar Flow

氢气是一种高效的添加剂,可以改善生物质燃料的层流燃烧特性。为研究氢气对乙醇−空气预混层流火焰燃烧特性的影响,利用定容燃烧弹结合高速纹影摄像技术,系统研究了初始温度为400 K,初始压力为0.1 MPa和0.4 MPa,氢气含量为0%、10%、30%、50%、70%和90%,当量比为0.7~1.4时的氢气−乙醇−空气混合燃料的层流燃烧速度(LBV)、火焰厚度和马克斯坦长度等参数,并采用辐射校正公式使LBV更加精准。通过数值仿真构建预混火焰模型,与实验结果进行对比。结果表明,氢气比例的增加可以提高混合燃料的层流燃烧速度。当氢气比例小于50%时,LBV随氢气比例的增加线性增长。而当氢气比例大于50%,LBV随氢气的增加呈指数增长。初始压力的上升虽然降低了LBV,但提高了LBV的增长率。此外,随着氢气比例和初始压力的增加,火焰厚度减小,马克斯坦长度降低,火焰的不稳定性增强。

Hydrogen is a highly efficient additive that can improve the laminar combustion characteristics of biomass fuel.To study the effect of hydrogen on the combustion characteristics of ethanol-air premixed laminar flame,the constant volume combustion chamber combined with high-speed schlieren camera technology was used to systematically study the laminar combustion velocity,flame thickness,and Markstein length of the hydrogen-ethanol-air mixture with an equivalent ratio of 0.7-1.4 when the initial temperature of 400 K,the initial pressure of 0.1 MPa and 0.4 MPa,the hydrogen content of 0%,10%,30%,50%,70%,and 90%.A radiation correction formula was adopted to make laminar burning velocity(LBV)more accurate.The premixed flame model was constructed by numerical simulation and compared with the experimental results.The results showed that the increase in hydrogen ratio could improve the laminar combustion velocity of the mixed fuel.When the hydrogen ratio was less than 50%,LBV increased linearly with the increase of hydrogen.When the hydrogen ratio was higher than 50%,LBV increased exponentially with the increase of hydrogen.As the initial pressure increased,the LBV reduced while the growth rate of LBV increased.In addition,with the increase of hydrogen ratio and initial pressure,the flame thickness decreased,the Markstein length decreased,and the flame instability increased.