Control of Thermoacoustic Chaotic Oscillations

在热声振荡器中，施加在气柱上的温度梯度会引起自持声振荡。为了开发新一代、高效率的热声发动机，人们努力提高压力振荡的幅度，这将导致出现混沌振荡等非线性现象。为了保持这些系统的能源效率，控制方法变得非常必要。另一方面，暴露在极端温度下的燃气轮机或火箭发动机可能会发生热声振荡。在威胁这些系统的稳定运行和增加NOx颗粒排放的同时，高幅度的热声振荡会对发动机造成严重的破坏。在简单的热声系统中引入局部收缩后，我们以前观察到了低温率下的混沌振荡。通过对两个新系统的耗散耦合，我们成功地将振荡稳定为周期运动，并根据耦合强度和失谐参数完全停止了振荡。我们还在一个振子上施加了被动延迟反馈，并通过将延迟设置为振荡周期的一半来观察到混沌路径上的模式被抑制。通过改变延迟反馈强度来稳定不同的模式，并观察到起始温度比的增加。稳定为周期运动和振荡抑制分别在新型热声发动机和内燃机的开发中得到应用。

In thermoacoustic oscillators, a temperature gradient imposed on a gas column induces self-sustained acoustic oscillations. For the development of next generation, highly efficient thermoacoustic engines, lots of efforts are made to increase the pressure oscillations amplitude, which will lead to encounter nonlinear phenomena such as chaotic oscillations. In order to maintain these systems energy efficient, control methods are becoming necessary. On the other side, thermoacoustic oscillations can occur in gas turbine or rocket engines exposed to extreme temperatures. While threatening the stability operation and increasing NOx particles emissions of these systems, high amplitude thermoacoustic oscillations can severely damage the engines.After introducing a local contraction in simple thermoacoustic systems, we previously observed chaotic oscillations at low temperature ratios. By dissipatively coupling two of our new systems, we successfully stabilized the oscillations into a periodic motion as well as completely stopping the oscillations depending on the coupling strength and detuning parameters.We also applied a passive delay feedback on one oscillator and observed a suppression of the modes in the route to chaos by setting the delay to half of the oscillation period. Different modes were stabilized by varying the delay feedback strength and we observed an increase of the onset temperature ratio.Both the stabilization into a periodic motion and oscillation suppression find application in the development of new thermoacoustic engines and combustion engines respectively.