FEM/BEM Numerical Modeling of Diesel Engine Acoustic Emission

The present work deals with the numerical prediction of the combustion noise of a newly developing aeronautical diesel engine. The study has been performed on a three dimensional basis by the integration of FEM and BEM codes integration, in order to correlate the radiated noise with the combustion pressure distribution inside the cylinders. The last purpose of such a procedure is the characterization of the engine in terms of acoustic power to be determine according to normative ISO 3746. The set of actions that have been performed may be summarized as follows: 1. Starting from the CAD model, a 3-D finite element model of the engine has been realized; 2. The model has been characterized in terms of eigen-frequencies and modes 3. The surface vibration velocity has been measured under the in-cylinder combustion pressure load (at the investigated engine speeds); 4. Direct BEM approach has been than that used to evaluate the radiated noise field in terms of sound pressure at 1 meter of distance and in terms of sound power according to the ISO 3746. These results have been used as driving parameters for successive engine structural design and will be later on experimentally verified