温度和压力对低热值燃料层流燃烧特性的影响

为阐明低热值燃料在燃气轮机工况下的燃烧特性，在定容燃烧弹中测试了初始压力分别为0.10、0.15、0.20 MPa，初始温度分别为303、353、403、453 K，当量比范围为0.8~1.6，体积分数为7% H₂、21.72% CO、21.45% CO₂、49.83% N₂的高炉煤气层流燃烧速度，并采用Gri-Mech 3.0化学反应机理对其进行了数值模拟。实验和模拟均发现，低热值燃料的层流燃烧速度随着初始压力的降低而增高，随着初始温度的增加而升高，且层流燃烧速度随温度和压力并非呈现单调性的变化规律，并在实验工况范围内对层流燃烧速度进行了温度和压力拟合。通过敏感性分析发现:主要的正向促进反应为R99、R46，主要的逆向抑制反应为R45、R36，层流燃烧速度受高活性自由基的影响，与链终止反应与链分支反应关于高活性自由基的竞争有关；随着初始压力的降低和初始温度的升高，高活性自由基摩尔分数增大，从而导致层流燃烧速度升高。 

Effects of temperature and pressure on laminar flame characteristics of low heat value fuel

In order to illustrate the combustion characteristics of low heat value fuel under operation conditions of gas turbines, the laminar flame velocity of blast furnace gas, with volume fraction of 7%H₂, 21. 72%CO, 21. 45%CO₂, 49. 83%N₂, was measured in a constant volume vessel, under initial pressures of 0. 10, 0. 15, 0. 20 MPa, initial temperatures of 303, 353, 403, 453 K, and equivalent ratios within the range of 0. 8~1. 6,in comparison with calculation results using the Gri-Mech 3. 0 kinetic mechanism. It was concluded that the laminar flame velocity of low heat value fuel increased with the decrease of the initial pressure and the increase of the initial temperature. The change of the laminar flame velocity was not monotonous and thus was fitted by high-order polynomials based on the experimental data. Further sensitivity analysis showed that the main reactions with positive sensitivities were R99 and R46,and the main reactions with negative sensitivities were R45 and R36,respectively. The laminar flame velocity was highly dependent on reactive free radicals,and affected by the competition between chain termination reactions and chain branching reactions. The mole fraction of active free radicals increased with the decrease of initial pressure and the increase of initial temperature, resulting in an increase in the laminar flame speed.