Predictions of the Acoustic Nearfield on a Carrier Deck Navy SBIR FY2010.2 Sol No.: Navy SBIR FY2010.2 Topic No.: N102-128 Topic Title: Predictions of the Acoustic Nearfield on a Carrier Deck Proposal No.: N102-128-1139 Firm: ATA Engineering, Inc 11995 El Camino Real Suite 200 San Diego, California 92130-2566 Contact: Michael Yang Phone: (858) 480-2040 Web Site: www.ata-e.com Abstract: The noise levels caused by the jet plumes of modern high-performance military jets are a health hazard to nearby service personnel as well as a significant fatigue load. A methodology is proposed to derive source models for supersonic jet engines which can be used to predict propagation into the near- and far-field. Proprietary experimental databases will be used to express the source models as partial fields and wavepackets. Partial fields are calculated in a way that represents as much of the total energy in as few basis functions as possible. The underlying physics are not considered, but this approach is very robust since the capture of the total energy is the goal. Wavepackets have a higher physical relevance and if a deep understanding of the physics is available, predictions of jet noise sources may be made for configurations that have not been explicitly tested. These models will be integrated into a leading commercial vibroacoustic code and the sound will be propagated using the Boundary Element Method (BEM), which can model the effects of reflecting surfaces such as the aircraft carrier deck or jet blast deflectors without the meshing difficulties or extremely high computational expense of the finite element method. Benefits: The capability to accurately predict project sound from a jet plume has several benefits for military jets. These include the development of quieter aircraft, the identification of safer areas for service personnel, and characterization of the sound environment which may lead to improved safety regulations or hearing protection. Furthermore, the methods developed here can be extended to any other application with a jet plume as the primary sound source. This includes civilian aircraft at commercial airports, auxiliary power units on these aircraft, and rocket plumes from liquid and solid fuel launch vehicles. The methodology will eventually be placed into a software module compatible with a leading commercial vibroacoustic code, making the method widely accessible. Return