Engine Noise Modelling with Boundary Elements Method
simplified BEA model of the engine is built using 442 Linear quadrangular elements,
sufficient to perform calculation up to 1300Hz (according to a 4 elements per
wavelength mesh criterion). The model is subdivided in 18 surfaces defined as
prescribed acceleration pistons.
The ground is taken into account as an infinite rigid plane. At this stage,
transfer functions (Hik) between measurement point pressure (i) and each panel
acceleration (k) are derived by using BEA solver. Then, the equivalent engine
source model is achieved by finding panel acceleration auto interspectra (Akl),
which minimize the error between experimental pressure spectra (Sijexp) and
those derived from the model (Sijnum).
This task is performed by using a linear least squares minimization technique.
The total energy by summing all the autospectra is predicted with an error of
less than 0,5dB. Local result comparison shows discrepancies less than 2dB at