Time-domain simulation for active noise control in a two dimensional duct

Abstract

1 Time-Domain Simulation for Active Noise Control In a Two Dimensional Duct Ning HANa,b, Chunqi WANGa,c This paper presents a time-dependent simulation scheme which emulates the real-time acoustic wave propagation controlled by an active noise control (ANC) system. The proposed numerical scheme models the electrical control system (including the secondary loudspeaker, the reference and error sensors, and the adaptive control algorithm) and its interaction with the acoustic field as a whole, which contrasts existing simulation schemes that usually concern only one aspect of them. An accurate time-domain pseudo-spectral method (Chebyshev collocation) is used to solve the acoustic wave equation so that the numerical error in the acoustic field is minimized and will not adversely affect the ANC simulation. Experimental studies are carried out to validate the numerical scheme. Good agreement is observed between the experimental results and the numerical simulations. The numerical model is used to examine the controlled acoustic impedance of a single-channel feedforward ANC system in ducts. It is found that the major function of the control algorithm is to adjust the negative equivalent mass of the ANC system so as to cancel the inertial radiation reactance of the secondary loudspeaker as much as possible. For broadband noise control, the controlled impedance of the ANC system oscillates around the target value, resulting in worse noise reduction performance than in the situation of tonal noise control.