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Burns W.,M Ship Co. | Perrotti T.J.,M Ship Co. | Todter C.,Keppel Professional Services | Casal D.,M Ship Co. | And 2 more authors.
3rd Chesapeake Power Boat Symposium, CPBS 2012 | Year: 2012

M-Ship Co. has developed an innovative Rapid Empirical Innovation (REI) approach to open-water ship model testing with the goal of providing a system targeted towards rapid, low cost ship design. The system is designed to provide test data quality close to that of a towing tank, at a substantially lower cost. It is capable of both smooth water drag and trim measurement as well as rough water drag and motions assessment, comparable to towing tank measurements. After developing, testing, and refining the testing platform, and its systems, a series of arbitrary models (including the classic Series 62 model) of widely varying concepts were designed, produced, and tested using the REI system. This process consisted of an extensive set of smooth water, and rough water tests to characterize the models as well as the testing platform. The final phase of the program was validation, by taking three of the models (including the historically tested Series 62 model) to the NSWCCD David Taylor Model Basin (DTMB) for both smooth and rough water testing so comparisons could be made between the towing tank data (DTMB) and the REI system. All phases of platform development and data quality investigation were successfully completed in 2011. Our report will summarize M Ship's testing methodology and comparative results.

Nikoukhah R.,French Institute for Research in Computer Science and Automation | Campbell S.L.,North Carolina State University | Drake K.,NSWCCD
International Journal of Systems Science | Year: 2010

The methodology of auxiliary signal design for robust fault detection based on a multi-model (MM) formulation of normal and faulty systems is used to study the problem of incipient fault detection. The fault is modelled as a drift in a system parameter, and an auxiliary signal is to be designed to enhance the detection of variations in this parameter. It is shown that it is possible to consider the model of the system with a drifted parameter as a second model and use the MM framework for designing the auxiliary signal by considering the limiting case as the parameter variation goes to zero. The result can be applied very effectively to many early detection problems where small parameter variations should be detected. Two different approaches for computing the test signal are given and compared on several computational examples. © 2010 Taylor & Francis.

Roemer M.J.,Impact Technologies, LLC | Palmer C.A.,Impact Technologies, LLC | Bharadwaj S.P.,Impact Technologies, LLC | Savage C.,NSWCCD
Proceedings of the ASME Turbo Expo | Year: 2010

Energy conservation measures currently employed by U.S. Navy surface combatants require labor-intensive, time-consuming data entry from which fuel curves are generated to drive each ship's propulsion plant machinery alignment. From these rudimentary curves optimal transit speeds, configurations, and refueling requirements are determined for specific operational demands and mission profiles. This paper describes an automated process for optimizing shipboard fuel consumption rates by integrating advanced diagnostic and maintenance optimization techniques with the onboard data information system. The automated energy conservation decision support system described herein addresses fossil fuel propulsion (gas turbines, steam turbines, and diesel engines), power generation and auxiliary systems. The software tool consists of diagnostic, fuel management, and maintenance modules. The diagnostic module tracks and trends the health state of components that use fuel (and their supporting systems) to provide real-time information on the impact of their current condition on fuel consumption. The fuel management module automates data collection and the generation of fuel curves through open-systems architecture communication with ICAS. It also enables planning by recommending an optimal machinery configuration to minimize fuel consumption based on either speed or time to destination constraints. Additionally, a fuel management module provides real-time information on fuel consumption and optimizes the load of each component based on its health condition, operating requirements and the number and condition of similar components. Finally, overall decision support comes from the maintenance management module that tracks the maintenance actions being performed on fuel consuming systems and recommends future maintenance to be performed (from a fuel conservation standpoint) based on current health information. Copyright © 2010 by ASME.

Shih T.-M.,University of Maryland University College | Thamire C.,University of Maryland University College | Sung C.-H.,NSWCCD | Ren A.-L.,Zhejiang University
Numerical Heat Transfer; Part A: Applications | Year: 2010

A comprehensive survey of the literature in the area of numerical heat transfer (NHT) published between 2000 and 2009 has been conducted. The journals surveyed in this review include Numerical Heat Transfer (both parts A and B), ASME Journal of Heat Transfer, International Journal of Heat and Mass Transfer, and, selectively, and International Journal for Numerical Methods in Fluids. During the survey, the authors noticed that some terminology and jargon have been used extensively, but sometimes appear somewhat non-unified. Galerkin method is a numerical technique in which the weighting functions are chosen to be the same as the basis functions. If the basis functions are piecewise functions, such as x and 1-x within [0, 1] and zero elsewhere in 1-D examples, then the method should belong to Galerkin finite element method. In the system of a channel flow, generally there are inlets and outlets and the flow is confined by surrounding walls. The fluid flows predominantly in one direction. The pressure drop is significant in comparison with the momentum changes.

Chang III P.A.,Naval Surface Warfare Center Carderock Division | Vargas A.,NSWCCD | Jiang M.,NSWCCD | Lummer D.,NSWCCD | Mahesh K.,University of Minnesota
20th AIAA Computational Fluid Dynamics Conference 2011 | Year: 2011

A high-accuracy large eddy simulation (LES) is applied to flows over a sphere and an underwater vehicle. Both objects have relatively weak separated stern flows that may depend upon the accurate resolution of turbulence structures in the attached flow regions upstream of the separation point. For the sphere we compute flows over a range of Reynolds numbers from sub- to super-critical (Re = 1×104 to Re = 1:14×106, respectively) for which we obtain decent agreement for the separation location, pressure distributions and integrated forces. Long time series data shows evidence of low-frequency shedding phenomena. We perform LES on the Advanced SEAL Delivery System (ASDS), an underwater vehicle with a rounded-rectangular cross section and stern slope that promotes weak flow separations. We compute the fully resolved flow over the ASDS for length-based Reynolds numbers 128 × 103, 256 × 103 and 512 × 103. We show that the mean flow fields over the attached flow region are reasonable in that the boundary layer profiles, shape factors and skin friction agree with other examples of developing turbulent boundary layer flows. The instantaneous flow fields exhibit near-wall turbulence structures with the correct length scales and dynamics as compared with the wall-bounded turbulent flow literature. The separation point moves aft and the extent of the separation region decreases markedly as the Reynolds number increases.

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