This study further develops a method of representing a complex sound source with an equivalent power volume velocity (EPVV) source by introducing localization through a sub-surface mechanism. The developed equivalent power volume velocity (EPVV) technique is then applied to an industrial problem in the form of an open diesel powered electric generator set under normal operating conditions. The characterisation of a sound source usually relies on indirect measurements made in the acoustic domain rather than direct measurements on the surface of the source. In this study near-field sound intensity measurements were made at discrete points which allowed measured power to be allocated to different sub-surfaces of the source. The phase relationships of the various parts of the sound source are not measured and this can limit the reliability of this method. A method of representing monopole phasing is presented which addresses the EPVV random phase assumption for application to numerical methods. Volume velocities were calculated for each sub-surface at each frequency to provide boundary conditions for a BEM model of the source. The results for the sub-surface model maintained an accuracy similar that of the previous model using equally distributed volume velocity sources. This EPVV model using sub-surfaces allows a greater degree of localisation of the distribution of sound power from a complex sound source. The results demonstrate that the EPVV method and the mathematical mechanisms for allocating sound power are valid for monopoles of different volume velocity.
展开▼
