Minimization of Acoustic Potential Energy in Irregularly Shaped Cavities

Abstract

This study presents a software design tool for solving active noise control problems in irregularly shaped cavities with continuous and noncontinuous design variables and appropriate constraints. The optimum amplitude, phase, and location of the secondary source were simultaneously determined by minimizing the total acoustic potential energy of the control volume in the cavity. The boundary element method was utilized for computing the sound field in the cavity. An optimizer based on sequential quadratic programming was selected for its accuracy, efficiency, and reliability. In order to cope with noncontinuous design variables, the optimizer was linked with a modified branch and bound procedure for practical applications. Simulations indicated that the optimal secondary source in an irregularly shaped car cabin could always be positioned in a region close to the primary source if the primary source was located in a corner of the cavity and the excitation frequency was not a resonance. However, different findings were obtained if the primary source was not located in a corner and the excitation frequency was a resonance. Optimal secondary source locations could appear at antinodal points of the dominant mode not necessarily near the primary source.