采用分离变量法和HP E1432A高速动态数据采集系统对Rijke燃烧器热声振动频率进行了数学推导和试验研究。由牛顿第二定律、质量守恒定律及物态方程推导出声波振动频率的计算公式,求得其解析解。试验采用不锈钢管作为研究对象,下端封闭,上端开口;致密堇青石材质的多孔介质作为火焰稳燃体;甲烷与空气预混气体在稳燃体上方形成平面火焰作为加热热源。试验通过压力传感器和HP E1432A测得管内各处的压强信号,并通过快速傅立叶变换得到其相应的热声振动频谱。结果表明,Rijke燃烧器热声振动频率的数学解析解和试验结果基本一致。
The mathematical derivation and experimental study on thermoacoustic vibration frequency of a Rijke combustor were carried out by adopting the method of Separation of Variables and HP E1432A High-Speed Data Acquisition System. The acoustic vibration frequency formula was derived by Newton's Second Law, Mass Conservation Law and State Equation, and the analytical solution is obtained accordingly. Stainless steel tubes which were closed in one end and open in the other were used in the experimental setup, the porous flame holder made of dense cordierite was installed inside the square place from the bottom of the combustor, over which the premixed methane/air mixture were ignited to form a flat flame, acting as a heat source. Pressure signals along the tube were measured with pressure sensors and HP E1432A, and their corresponding spectrums were obtained by Fast Fourier Transform. The results showed that the analytical solutions of thermoacoustic vibration frequency agree well with the experimental data.