Noise Radiation Model of a Powertrain Using an Inverse Boundary Element Method and Projection on Wave-Envelope Vectors

The paper deals with the construction of a powertrain acoustic radiation model to be used as a noise source in acoustic finite or boundary element models. This model results from near-field acoustic measurements of the running powertrain. Transfer functions between the measurement points and a meshed envelope of the powertrain (850 nodes) are calculated using a boundary element model of the powertrain in the test-bench. Wave-Envelope vectors are then used as a projection basis to solve the inverse problem providing flow velocities on the surface of the powertrain model. The quality of the model is assessed by comparing computed and measured sound pressures at specific location, away from the initial measurement points. The original free-field configuration, as well as a confined situation, simulating an under-hood around the powertrain, are examined.