MILD燃烧条件下掺氢比对甲烷-氢气湍流扩散火焰的影响

采用二维轴对称的仿真方法对JHC实验中的第二级MILD燃烧进行数值模拟,研究了燃料体积流量不变时,掺氢比对甲烷-氢气湍流扩散火焰的影响规律.结果表明:随着掺氢比增加,燃料与氧化剂的混合程度逐渐提高,混合气体的总流速及其径向分量不断减小,火焰锋面逐渐向氧化剂侧倾斜,OH自由基的最大质量分数呈现出先上升后下降的趋势;在燃烧温度方面,虽然MILD燃烧主要放热反应区域内的燃烧温度随掺氢比的增加不断增大,但当掺氢比大于20%时,掺氢比的进一步提高对最高燃烧温度影响很小.

Effect of Hydrogen Content of CH4-H2 Mixture on Structure of Turbulent Diffusion Flame Under MILD Condition

MILD combustion in the second stage of JHC experiment was simulated by using two-dimensional axisymmetric numerical simulation method. The influence of hydrogen content of CH₄-H₂ mixture on the turbulent diffusion flame was studied under the condition of constant volume flux of fuel mixture. The results show that the mixing between fuel and oxidant augments， the velocity magnitude and its radial component falls down with the increase of hydrogen content of fuel mixture. In addition， as the hydrogen content of fuel mixture goes up， the flame front gradually leans to the oxidant side and the max mass fraction of OH free radical goes up firstly and then goes down. As for the combustion temperature， although the combustion temperature in the main exothermic reaction zone increases with increasing the hydrogen content of fuel mixture， the influence of hydrogen content on the temperature is very small when it is over 20%.