NCE has developed two software programs for monitoring, predicting, and controlling noise in the shipbuilding and marine industries: Designer-NOISE® and Sound-Guard.
Designer-NOISE: Predicting & Controlling Shipboard Noise
Designer-NOISE® is a software program designed to allow for quick and accurate predictions of noise levels on surface ships and other stiffened plate structures. Airborne noise levels are calculated to investigate excitations from various machinery, propeller, and wave slap sources. Noise can be created through multiple airborne and structure-borne paths, and Designer NOISE® allows designers to identify and target the most significant factors for each project. The Designer NOISE HVAC module allows for the prediction of noise from ducted systems, and the combination of the resulting noise levels with machinery noise results to calculate the total noise levels in areas of interest. The causes of noise in any compartment can be evaluated, and various treatment options can be explored including resiliently mounting equipment, adding absorptive insulation and/or damping materials, etc. By using Designer-NOISE®, treatments can be quickly optimized to meet acoustic goals while minimizing impacts to space, weight, and cost.
Who can benefit?
Designer-NOISE® can allow shipbuilders and designers to produce quieter vessels more effectively and efficiently. Noise can be analyzed early in the design process to help with the overall design of the vessel, equipment selection, and treatment requirements. Furthermore, modifications to the vessel that occur as the design progresses can be assessed from a noise perspective, allowing for a more complete cost benefit analysis. Quiet ships ensure operators and crews have a more comfortable working environment, leading to increased productivity, lower fatigue, and a reduced risk of long-term hearing damage–factors which can lower the total cost of ownership. With the proper attention paid to noise by the marine community in general, the noise levels onboard ships can be significantly decreased and noise control treatments can be optimally designed with respect to acoustic and non-acoustic parameters.
How does it work?
Designer-NOISE® uses a 3-D Graphical User Interface (GUI) to facilitate rapid model creation and entry of model parameters. The 3-D GUI provides the user with an intuitive and realistic representation of the vessel and allows for improved “bookkeeping” as compared with spreadsheet methods. The core solver uses a hybrid Statistical Energy Analysis approach to predict spreading of vibration throughout the vessel. Architectural acoustic methods are used to predict the spreading of airborne noise. Solution time for most models is on the order of seconds, allowing the user to perform rapid tradeoff studies of potential noise control treatments, sources, etc. The prediction accuracy is very high, usually within 3 dB for A-weighted noise levels.
Sound-Guard is a PC-based data acquisition system used to measure, monitor, and log the underwater sound levels from any vessel. It is especially useful for research vessels that need to maintain low radiated noise during sensitive scientific operations. Sound-Guard is designed to be used with existing hull mounted hydrophones. However, existing ships without self-noise hydrophones can use Sound-Guard by installing hull-mounted accelerometers.
Sound-Guard will continuously check compliance of a vessel to an underwater sound criterion. The software will display and compare the measured underwater sound to any specified noise limit. An alarm will be provided when noise levels exceed the goal.
The Sound-Guard system consists of an industrial-grade rack-mountable PC and touch screen. All Sound-Guard software features can be operated from the touch screen without the need for a mouse or keyboard. Administrative functions (setting up limits, recalling data) require a keyboard and other software applications such as Notepad and/or Excel. Data acquisition is through a 6-channel PCI-card. The hydrophones and accelerometers are not supplied with the Sound-Guard System. For best results and to compare data to known standards like ICES, a one-time calibration of underwater noise-to-self noise must be performed.
Sound-Guard software features include:
- Measurements for up to 6 channels
- Software selectable underwater noise limits including ICES CRR209 and three user defined limits
- Selectable factors of safety of 0, 5, and 10 dB
- ASCII data logging to a separate file per channel
- User selectable file name prefix
- User selectable time interval between data logging from 5 to 100 seconds
- User selectable number of samples to log
- Computes and displays current minimum, maximum & average signatures
- Computes and displays historical minimum, maximum & average signatures
- Graphic Cursor for both amplitude and frequency
- Quick read noise limit over/under status window
- System configuration in ASCII files