Abstract:
The intermediate scale measurement system (ISMS) is a state-of-the-art measurement range for Navy structural acoustics research. The range is located in Lake Pend Oreille at the Acoustic Research Detachment (ARD) of the Naval Surface Warfare Center, Bayview, Idaho. The system is designed to accommodate ``high fidelity'' 1:10 to 1:4 scale models of submarines. The ISMS has several unique measurement modes, including: (1) generation of plane-wave ensonification using a phased planar array of 36 projectors; (2) radiated signature measurement using a full 360-deg azimuth, 158 hydrophone, near-field receive array; and (3) acquisition of data from up to 1000 model-mounted sensors. Through use of high precision acoustic location measurement, the ISMS has an integral capability to project near-field bistatic target strength and radiated noise signatures to the far field. Based on these measurement modes, the ISMS can make very accurate, precise and repeatable target strength, radiated noise, and structural response measurements. The receive array is also used for the spatial imaging of the radiated pressure fields. Selected analysis products from a 1:4 scale model test series will be presented. [Work supported by ONR.]