Study on noise control effect based on generalized Lorenz system

Abstract The suppression of ship radiation noise is studied through a generalized Lorenz system. The system integrates a classical Lorentz system with a time-delay feedback control and an external acoustic excitation. The output of the system can be categorized into three different states: the quasi-periodic state, the periodic state and the chaotic state. The output state is characterized by the trajectory, the bifurcation diagram and the Lyapunov exponent of the system. The dependence of the output state on different excitation parameters like amplitude, frequency, time delay and the number of external excitations are simulated. It is found that the chaotic state and noise suppression is largely dependent on the amplitude of the external excitation. The noise suppression in the generalized Lorenz system is characterized by the changes in power spectrum of the acoustic energy, which is investigated through Fourier transformation. The suppression is optimized by specified excitation parameters: an acoustic energy reduction up to 26.67 dB is realized with excitation source of small amplitude, high frequency, and a phase synchronized with the noise phase. The noise suppression through multiple excitations in the system is also investigated.