Extracting flame describing functions in the presence of self-excited thermoacoustic oscillations
Extracting flame describing functions in the presence of self-excited thermoacoustic oscillations
复制标题
在存在自激热声振荡的情况下提取火焰描述函数
DOI：
10.1016/j.proci.2016.06.050
复制
发表时间：
2017
影响因子：
3.4
通讯作者：
Balusamy S
中科院分区：
文献类型：
--
作者：
Balusamy S
预测热声振荡的关键因素之一是确定火焰作为声学网络中的一个元素的声学响应，以火焰描述函数（FDF）的形式。为了获得响应，火焰通常必须被限制在具有其自身声学响应的系统中。分离纯火焰响应和系统响应可能会因火焰对整个系统响应的非线性影响而变得复杂。在本文中，我们调查是否有可能获得一个火焰响应，通过通常的方法，动态化学发光和压力测量，从一个非强迫系统与初期自激在给定的frequencyfs，在一个稳定的火焰的形式，在大气压下与700 mm的管作为燃烧器。迫使火焰在20至400 Hz的离散频率下远离自激，并使用OH* 化学发光测量火焰的响应。这种响应进行了比较，在一个短的管没有其他excitations.Results测量的火焰响应表明，无论是增益和相位可以完全由自激的行为，所以在一般情况下，它是不可能提取可靠的增益和相位信息，如果强迫和自激模式独立和线性的行为。虽然在这种特定情况下的增益没有受到显着影响，原始火焰的相位信息成为主导的触发自激。边界条件和系统用于火焰声强迫，因此，需要仔细控制时，有可能出现自激。
One of the key elements in the prediction of thermoacoustic oscillations is the determination of the acoustic response of flames as an element in an acoustic network, in the form of a flame describing function (FDF). In order to obtain a response, flames often have to be confined into a system with its own acoustic response. Separating the pure flame response and that of the system can be complicated by the non-linear effects that the flame can have on the overall system response. In this paper, we investigate whether it is possible to obtain a flame response via the usual methods of dynamic chemiluminescence and pressure measurements, starting from an unforced system with incipient self-excitations at a given frequencyfs, in the form of a stabilized flame at atmospheric pressure with a 700 mm tube as a combustor. The flame is forced at discrete frequencies from 20 to 400 Hz, away from the self-excitation, and the response of the flame is measured using OH*chemiluminescence. This response was compared to a flame response measured in a short tube with no other excitations.The results show that both the gain and phase can be entirely dominated by the behavior of the self-excitation, so that in general it is not possible to extract reliable gain and phase information as if the forced and self-excited modes acted independently and linearly. Although the gain in this particular case was not significantly affected, the phase information of the original flame became dominated by the triggered self-excitation. Boundary conditions and systems used for flame acoustic forcing therefore need to be carefully controlled whenever there is a possibility of self-excitation.
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DOI：
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发表时间：
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