The intensity potential approach for predicting sound power flow through partial enclosures

Paper in proceeding, 2011

The intensity potential approach is developed for prediction of sound power flow through partial enclosures. A typical application is the prediction of radiated noise from an engine bay with respect to geometry, position and acoustical properties of screens and absorbers. The approach is based on the Helmholtz decomposition of the vector field of the time-averaged sound intensity into its irrotational and rotational components. The local power balance in a lossless medium and the Helmholtz decomposition gives a Poisson equation for the scalar intensity potential of the irrotational component only. The paper presents the approach and evaluates it by canonical examples and by comparison to measured data. It is demonstrated that the prediction of sound power through any closed surface is exact provided that the geometry and boundary conditions are correct. The comparison to experimental data shows that the method is useful in practical applications. The approach has its strength for cases with complex geometry and multiple broadband sources, but it has the potential to become more general by further development of boundary conditions. It is concluded that the intensity potential approach provides a robust prediction tool for the mid- and high-frequency range.