为确定同轴离心式喷嘴燃烧不稳定的线性增长率，基于随机动力学Fokker-Planck体系系统识别方法，利用脉动压力时间序列识别喷嘴四种工况下的增长率，并分析了结果的不确定性和参数敏感性。结果表明：变换脉动压力的单位进行识别，增长率不变，饱和系数和噪声强度存在确定的变换关系，且三者的识别精度不变。负增长率的声模态在噪声作用下也可能发生较大幅值的压力振荡。增加脉动压力采样时间可以提高增长率的识别精度，不同工况下存在各自较优的采样率。从脉动压力时间序列线性增长阶段识别增长率同样需要考虑噪声导致的不确定性。
Abstract
In order to determine linear growth rates of combustion instability of swirl coaxial injectors, the output-only system identification method, based on the Fokker–Planck formalism in stochastic dynamics, was used to identify growth rates from dynamic pressure time series under four operating conditions. Uncertainty and sensitivity analysis were also conducted. It is shown that the growth rates are unchanged after conversion of pressure units, while conversion relationships were obtained for saturation coefficient and noise intensity. And accuracy of identification for the three parameters was invariable. Large amplitude oscillations may occur for acoustic modes with negative growth rates due to the influence of noise. The improved accuracy of identifi-cation can be realized with increasing the sampling time, and for optimal sampling rates, it depends on operat-ing conditions. It is also found that uncertainties introduced by combustion noise need to be considered when growth rates were extracted from the linear growth region of dynamic pressure time series.
关键词
同轴离心式喷嘴 /
燃烧不稳定 /
燃烧噪声 /
增长率 /
输出识别
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Key words
Swirl coaxial injector /
Combustion instability /
Combustion noise /
Growth rate /
Output-only system identification
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