SBIR-STTR Award

In the 14 years since the last revision of SNAME's Design Guide for Shipboard Airborne Noise Control, acoustic prediction techniques and control methods have significantly improved. Current prediction techniques effectively utilize sophisticated computer programs. These could possibly be tied to CAD/CAE programs. NCE believes that the government, naval architects and shipyards can greatly benefit from these improvements. When properly implemented, this latest technology can improve the noise and vibration environment on all vessels. At the same time, associated adverse impacts on space, weight, maintainability of systems, and cost will be reduced. This process would also provide an integrated systems approach while reducing the effort needed to predict and control noise on-board vessels. Many of the approaches used in Statistical Energy Analysis can be easily coded and used by any engineer involved in the design process. Noise control treatment types and their expected effectiveness have also changed. These changes can be factored into various databases. Databases can be setup for machinery and equipment acoustic source levels; airborne, structureborne, and waterborne path transmission effects; and acoustic characteristics of materials used in shipboard constructions. This software would be very effective for predicting and reducing noise on all types of vessels.

As part of Phase 1, Noise Control Engineering Inc (NCE) developed and documented algorithms that create a noise prediction tool tailored to ships. This approach facilitates the prediction process and increases the accuracy over that achieved by existing 'cook books' or software not specifically geared toward the unique features of ship constructions. The shipbuilding industry presently does not have an established approach to acoustical design. Phase 1 identified algorithms and methods that can remedy this situation. Creating a modern program addressing the unique features presented in the marine environment solves these problems. The Phase 1 report identified the vessel's structural features that are considered as input data for the prediction process. NCE's approach is to account for the universal and unique acoustic features of marine vessels. The prototype program is combination of Statistical Energy Analysis (SEA) modeling approach, an acoustic architectural engineering model and empirical formulas and databases that have been verified and utilized over many years. The algorithms consider the acoustic impact of many factors that are specific to marine vessels, including water loading of surfaces, finite size and orientation of mechanical sources in small compartments, hydrodynamic sources like propellers, thrusters, and splash noise. The Phase 1 effort and the existing prototype software showed applicability to all types and sizes of vessels - monohulls, SWATHs, hydrofoils, catamarans - constructed of various materials. These methods, documented in the Phase 1 effort and contained in the prototype program have proven to be very accurate in the prediction of machinery induced noise [3,4]. The Phase 1 effort identified modifications to improve and extend the program to cover HVAC induced noise. Additional algorithms are needed to extend the capacity and accuracy of the existing prototype. Phase 1 identified the need for a GUI for both the input and data output. The proposed Phase II effort facilitates the input/output process and includes additional source and material databases.

Keywords:
Shipboard Noise Prediction, Ship Design , Shipboard Noise Control, Software