Identification of an aeroacoustic source using the inverse boundary element method

The use of the inverse boundary element method (BEM) to identify aeroacoustic noise sources is explored. In the suggested approach, sound pressure at locations out of the flow field are measured, followed by the reconstruction of acoustic particle velocity on the surface where the noise is generated. Using this reconstructed acoustic particle velocity, the acoustic response elsewhere in the field can be predicted. This paper demonstrates that good results can be obtained using a manageable number of sound pressure measurements that need not be in the flow field or conformal to the source. The first example is an open-ended duct without flow where measurements made around the periphery of the duct are used to reconstruct the particle velocity on the opening. The second example applies the approach to predicting vortex shedding noise resulting from airflow over a cylindrical rod. The reconstructed particle velocity is used to predict sound pressure in the field. The predicted sound pressure agreed with measured results.