Advanced car engine noise control requires the simulation of the sound field in a receiver position at some distance from the vehicle. For today's cars the engine induced pass-by noise is dominated by the airborne sound path through the apertures in the engine bay, the sound transmission through the body panels may in general be neglected. The sound transfer function addressed in this section is defined by the ratio of the sound pressure in a receiver position at some distance from the vehicle and the volume velocity of a point source on the engine surface. This transfer function is frequently used in both experimental and computational acoustics to describe engine noise propagation into the environment. For an accurate numerical simulation of the interior and exterior noise of lightweight vehicles the coupling between structure and ambient fluid needs to be taken into account. The resulting models tend to grow very complex and large which, apart from the considerable modelling effort, frequently leads to prohibitive computational costs and calculation time. But above all these giant models tend to become unstable and to produce unreliable results. It is therefore of paramount importance to keep the size of these calculation models within reasonable bounds, that is, to omit all non-relevant details and to avoid excessive resolution of the discretisation. Often, however, it is extremely difficult to assess the degree of detail required to obtain a desired result. Analytical models can assist in this task by giving the necessary insight into the physics of the governing noise generation and propagation problem. A further advantage of analytical models is the possibility to considerably extend the frequency range of interest with only little additional computational costs. Moreover analytical models play a relevant role in early stage design when fundamental, frequently irreversible, conceptual choices have to be made before details are completely defined. Three examples of relatively simple analytical models addressing tough mid- and high-frequency range problems are given in this paper: airborne sound transmission from the engine bay to the pass-by position, structural power transmission in a car body floor and damping in engine structures.


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    Titel :

    Simple analytical models for tough mid-frequency range problems


    Weitere Titelangaben:

    Einfache analytische Modelle für schwierige Probleme im Mittelfrequenzbereich


    Beteiligte:
    Nijman, E. (Autor:in)


    Erscheinungsdatum :

    2005


    Format / Umfang :

    18 Seiten, 17 Bilder, 2 Tabellen, 15 Quellen


    Medientyp :

    Aufsatz (Konferenz)


    Format :

    Print


    Sprache :

    Englisch




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