旋流预混燃烧室火焰动力学奇异谱分析研究

Singular Spectrum Analysis of Flame Dynamics in a Premixed Swirl Combustor

为了从预混燃烧室大涡模拟产生的非稳态、短时及含噪声的热释放率时序数据中有效提取火焰动力学特性以指导设计。首先采用激励响应法获得该序列,使用奇异谱分析重构并降解,并用传递路径函数识别火焰动态响应,同时与动力学模态降解模态对比。结果表明,采用传统火焰传递函数方法,火焰响应特性易被噪声掩盖。采用奇异谱分析重构的热释放率序列可吻合原始序列。获得的奇异谱模态可解析出更多的内在火焰响应频率。该频率与动力学模态降解法获得的频率一致。从动力学模态降解法获得的模态形状可以看出火焰内外层有剪切运动,回流区有混合作用。

Due to the high cost of large eddy simulations,the heat release rate(HRR)series were always non-stationary,short,and noisy during the combustor design and it was difficult to extract useful flame dynamics.Singular spectrum analysis(SSA)was used to reconstruct HRR series and decomposed modes were acquired.The parameter named transfer path response was defined to identify the flame frequency response.The results were also compared with those extracted from the dynamic mode decomposition.Results indicated that critical frequencies could be masked by using traditional flame transfer function.Via SSA,reconstructed series were able to efficiently track the original HRR time series.More frequency response information could be found inside SSA modes.Those response frequencies were consistent with those of the dynamic mode decomposition.Shear layer instabilities at the flame front and the mixing in recirculation zones could be observed in mode shapes from dynamic mode decompositions.