贫燃预混旋流火焰热声特性研究

Study on thermoacoustic characteristic of lean premixed swirling flames

以贫燃预混旋流模型燃烧室为研究对象,以当量比为变化参数,从不稳定振荡频率、脉动压力幅值和分布、热释放响应特性等方面分析,研究了燃烧不稳定性从开始到极限环的非线性演化过程.利用低阶热声网络模型加以数值模拟验证.结果表明:脉动压力方均根、热释放响应会随着当量比的增大而呈现典型的非线性激发过程,火焰结构在发展过程中发生明显的变化.计算分析结果表明当量比低于0.7时计算结果与实验结果频率误差小于1%,而在当量比大于0.7时,计算结果与实验结果频率误差为13%.

A lean premixed swirling combustor was constructed.The data of frequency of instable fluctuation,amplitude and distribution of pressure oscillation and the response of heat release from varying equivalent ratio were applied to obtain the nonlinear development of combustion instability from stability to limit cycle.A thermoacoustic network model with low orders was utilized to analyze the oscillating solutions for the experiments.The results from the experiments show that a typical nonlinear process can describe the root mean square of pressure oscillation and heat release response with the increasing equivalent ratio,and the flame has significantly different structures in different states.The results indicate that the frequency error between the calculation and experiment is less than 1% when the equivalent ratio is less than 0.7,while the frequency error is 13% when the equivalent ratio is greater than 0.7.