基于成分的燃烧室出口燃气温度计算方法

Calculation method for gas temperature from combustor outlet based on gas composition

针对燃烧室不同温度下燃气组成的不同,提出建立不同燃气模型以推算燃气温度的两种计算方法。基于物质守恒、化学平衡和能量守恒原理建立温度计算方程,根据能量守恒方程的不同表达形式给出平均比定压热容法和焓值法,同时给出两种求解非线性方程组的数学解法:三变量迭代法和牛顿法,并采用VB(Visual Basic)编制燃气分析测试程序实现温度算法。列举计算实例比较两种算法的区别,结果显示:随着油气比的增加,两种计算方法得到的燃气温度相差越大,考虑热离解的高温算法结果更小,原因在于燃气中离解组分的摩尔分数随着温度升高而增加,燃烧实际放热量减小,导致燃气温度减小,所以当燃气温度较高时建议采用高温算法更符合实际燃烧情况。

According to different gas compositions in combustor at different temperatures,two calculation methods for predicting gas temperature by establishing different gas models were proposed.Based on the theory of substance conservation,chemical equilibrium and energy conservation,the equations of temperature calculation were established.According to different expressions of the energy conservation equation,the average specific heat capacity of constant pressure method and the enthalpy value method were given,two mathematical methods for solving nonlinear equations were presented at the same time,including three variables iterative method and Newton method.VB(Visual Basic)was used to compile test program to realize temperature algorithm.The calculation example was enumerated to compare the difference between the two algorithms.The result shows that the difference of gas temperatures obtained by the two methods is greater with the increase of oil gas ratio,the result acquired by the high temperature algorithm considering thermal dissociation is smaller,and the reason is that the molar fraction of the dissociated components in the gas increases with the temperature rise,and the actual heat release decreases,leading to the decrease in gas temperature.Therefore when the gas temperature is higher,the high temperature algorithm is more in line with the actual combustion situation.