加氢对乙醇燃料层流燃烧特性的影响

Effect of Hydrogenation on Laminar Combustion Characteristics of Ethanol Fuel

在初始温度为400 K,初始压力为0.1 MPa,当量比为0.7~1.6实验条件下,采用定容燃烧弹法研究了乙醇和含有50%(体积分数)氢气的乙醇混合气燃料的燃烧特性,对拉伸火焰传播速度、层流燃烧速度、火焰厚度和马克斯坦长度等参数进行了分析,并对实验结果进行了数值模拟.结果表明,在相同的初始条件下,添加氢气可以有效降低乙醇的可燃极限,并提高乙醇的层流燃烧速度.含有50%氢气的乙醇最大层流燃烧速度为931 mm·s^(-1),比乙醇的层流燃烧速度632 mm·s^(-1)提高了近47%;含有50%氢气的乙醇燃料随当量比的改变,其层流燃烧速度总体趋势与乙醇相似.在乙醇中加入氢气会使火焰厚度和马克斯坦长度发生改变,对流体动力学稳定性和火焰前锋面结构稳定性造成一定影响.最后在不同的工况条件下,通过数值模拟预测了层流燃烧速度的变化趋势.

The combustion characteristics of ethanol and ethanol blended gas fuel containing hydrogen with the volume fraction of 50%were investigated by the constant volume combustion chamber method under the experimental conditions of an initial temperature of 400 K,an initial pressure of 0.1 MPa and an equivalent ratio of 0.7 to 1.6.Parameters such as tensile flame propagation velocity,laminar burning velocity,flame thickness and Markstein length were analyzed and numerical simulations of the experimental results were carried out.The results show that the addition of hydrogen can effectively reduce the flammable limit of ethanol and increase the laminar combustion rate of ethanol under the same initial conditions.The maximum laminar burning velocity of ethanol containing 50%hydrogen is 931 mm·s^(-1),which is nearly 47%higher than that of ethanol at 632 mm·s^(-1).The overall trend of laminar burning velocity for ethanol fuel containing 50%hydrogen is similar to that of ethanol as the equivalence ratio changes.The addition of hydrogen to ethanol also changes the flame thickness and Markstein length,which has an impact on the hydrodynamic stability and the structural stability of the flame front surface.Finally,the trend of laminar burning velocity was predicted by numerical simulation under different working conditions.