摘要
对数值模拟的不同频率下非定常激励的扩压通道流场采用POD方法分析,对取得的各级模态系数进行频谱分析,对不同变量的能谱进行对比分析,研究非定常激励对流场的控制机理。分析表明:非定常信号能够强制与流场发生共振作用,低阶模态共振作用较强,随之会出现衰减现象;同时流场的"固有频率"不会被改变,只会暂时抑制或加强,流场中的"保护"机制同样如此;动能谱显示非定常激励使流场中代表大涡的2、3阶动能份额增大,同时也增大了流场的第一阶模态拟涡能份额,从而使流场小尺度脉动能量和平直流动能减少。
Data of flow field affected by unsteady jet of different frequencies in diffuser,are analyzed by the POD method,and the modal coefficients spectrum and the energy spectrum are then analyzed in order to explaining the control mechanism of flow field with unsteady excitation.The results show that：1） The flow field tends to resonate with the unsteady excitation,and the low order modal resonates strongly while higher modal weakly;2） ’Natural frequency’ of flow field will not be changed by excitement,whereas its strength tends to be stronger or weaker and so as the field ’protection’mechanism;3） Energy spectrum demonstrates that the energy percents representing the second and third modal kinetic energy become bigger by unsteady excitement,and so as those representing the first modal quasi vortex energy,indicating that the decrease of small-scale fluctuations energy and the parallel flow energy.
出处
《工程热物理学报》
EI
CAS
CSCD
北大核心
2016年第7期1450-1458,共9页
Journal of Engineering Thermophysics
基金
青年科学基金项目(No.5306089)
关键词
非定常
POD
时间模态系数
频谱
能谱
unsteady
POD
time modal coefficient
frequency spectrum
energy spectrum
