半无限长引压管动态响应特性

Dynamic response characteristics of semi-infinite pressure tube

在燃烧不稳定试验中,通常通过半无限长引压管对振荡压力进行取样,采样到的振荡压力幅值有所衰减且相位存在延迟。采用管道声波传播理论分析、试验研究与数值模拟相结合的方法,研究了引压管直径及安装座结构等对半无限长引压管动态响应特性的影响规律,分析了引压管测量压力脉动的增益及相位差等参数。结果表明:当半无限长引压管的长度不足时将会引起响应曲线的末端反射振荡;减小引压管直径将会增加压力幅值衰减,此时可以适当缩短半无限长引压管长度;安装座结构将导致引压管的幅频特性及相频特性存在安装座反射振荡,安装座空腔体积越大则振荡越剧烈。此外,通过理论分析和数值模拟分析了安装座引起响应振荡的原因。研究内容可准确预测、修正引压管的测量偏差,对于燃气轮机燃烧室压力脉动的测量具有参考意义。

In the combustion instability experiment,oscillation pressure was usually sampled by the semi-infinite pressure tube,the amplitude of the sampled oscillation pressure was attenuated and the phase was delayed.Therefore,the method of combining theoretical analysis of acoustic propagation in tube,experimental research and numerical simulation was adopted to study the influences of the diameter of the semi-infinite pressure tube and the structure of the mounting seat on the dynamic response characteristics of the semi-infinite pressure tube,and the parameters such as gain and phase difference of the oscillation pressure measured by the semi-infinite pressure tube were analyzed.The results showed that when the length of the semi-infinite pressure tube was insufficient,it caused oscillation in the response curve produced by terminal reflection.Reducing the diameter of the semi-infinite pressure tube could increase the pressure amplitude attenuation,so the length of the semi-infinite pressure tube can be appropriately shortened.Mounting seat structure could lead to the oscillation in the amplitude-frequency characteristics and phase-frequency characteristics of the semi-infinite pressure tube due to the mounting seat reflection,and the larger volume of mounting seat cavity indicated the more stronger oscillation.In addition,the reason of response curve oscillation caused by mounting seat was analyzed by theoretical analysis and numerical simulation.The research content can accurately predict and correct the measurement deviation of the semi-infinite pressure tube,which has reference significance for the measurement of oscillation pressure in the gas turbine combustor.