Rijke热声不稳定性的有源控制

Active control of Rijke thermoacoustic instability

从理论上推导出一个确定带有控制系统的Rijke管的稳定性的条件，并研究了管中声模式的复本征频率与放大倍数和相移的关系。然后通过分析管末端声波反射条件的变化，阐述了有源控制热声不稳定性的机理。最后对有源控制进行了实验研究．该研究说明了起源于线性扰动（声学量级）的非线性的不稳定增长过程，可以用一个线性的小扰动去控制，使系统达到稳定．我们的理论与实验结果再一次证明了有源控制流体动力不稳定性的可能性。

Abstract: A method is theoretically developed to determine the stability behaviour of Rijke tube with control system. The dependence of complex eigenfrequencies of acoustic modes in the tube on the amplifying coefficient and phase angle is studied. Then, the mechanism of active control of thermoacoustic instability is explained by analyzing the change of reflection of sound waves at the end of the tube. Finally,experimental investigation is made on active control. Theoretical and experimental results show that a nonlinear unstable increasing procedure originated from a linear perturbation (of acoustic quantity) can be controlled by another linear perturbation, and the system can then be stabilized. The theoretical and experimental results of this work prove the availability of actively controlling the dynamic instabilities in fluids.