Partial field decomposition of jet noise using optimally located virtual reference microphones

Abstract

The application of partial field decomposition (PFD) techniques based on a singular value decomposition to jet noise fields is useful for estimating the number of incoherent (equivalent) noise sources within a jet and for implementing near-field acoustical holography, but it does not generally provide physically meaningful partial fields (i.e. partial fields related to individual sources). Among several PFD methods that were designed to generate physically meaningful partial fields, the method developed by Kim et al. [JASA 115(4), 2004] finds the optimal locations of references in a sound field and places virtual references at those locations. In past investigations this method has been successfully applied to locate discrete numerical and physical sources and to generate partial fields related to each source. In this study, Kim’s method is applied to a full-scale jet installed on a military aircraft in an attempt to obtain physically meaningful partial fields. The partial fields obtained using these optimally located virtual references are compared to the partial fields obtained from other PFD methods.