Facilities

N00174-96-C-0034

We have supported the product areas of Ships and Ships Systems, Littoral Warfare Systems, Ordnance, Undersea Warfare Weapons & Vehicles, with the following accomplishments:

• Continued development of analytical and numerical tools for the characterizing of  damage potential of underwater explosions to submerged and floating structures including in shallow water.

• Continued development and use of experimental techniques to validate the numerical/analytical methods.

• Furthered development of Dynaflow's 3D Boundary Element Method code, 3DynaFS^©, for UNDEX bubble modeling to include post-touchdown analysis of re-entrant jet.

• Coupling of 3DynaFS^© with finite element structural dynamics codes for fluid-structure interaction modeling.

• Developed analysis techniques for multi-cycle dynamics of UNDEX bubbles resulting in development of the codes MultiCycle^© and DFMigrate^©.

• Conducted parametric numerical and analytical studies in support of these tasks and in support of various other NSWC, ONR, and NAVSEA efforts.

• Conducted controlled scaled tests and parametric studies in Dynaflow's vacuum spark test cells utilizing high speed photography and pressure measurements for code validation and support of other NSWC activities.

• Conducted experiments and design of a device, the CVRG (Cavitating Vortex Ring Generator), employing hydrodynamic means of deactivation of mines in the surf zone.

• Conducted predictive simulations for underwater explosion work conducted by Indian Head, Carderock, and NAVSEA.

This work has continued and been expanded under additional contracts from ONR including the following:

• Contract N00014-98-C-0104: Study of Single and Multiple UNDEX Bubble Behavior Near Structures.

• Contract N00014-99-M-0285: Investigation of Advanced Mechanisms to Enhance UNDEX Bubble Lethality.

• N00014-00-C-0344: Investigation of Advanced Mechanisms to Enhance UNDEX Bubble Lethality.

N00167-02-M-0391

     We are developing predictive models and software for the behavior of multiple bubble nuclei in the vortical fields of Navy propulsors.  The interaction and growth of the bubbles, their propensity to produce cavitation inception, and the resulting cavitation acoustic noise generated is simulated in the propulsor flow field. We also seek to determine scaling laws for this behavior. The work includes a fundamental physical investigation of the bubble/vortical flow interaction, the incorporation of models into CFD (Computational fluid dynamics) codes and their predictive use, and validation with available experimental data. This supports the product area Ships and ships systems.
 

N00167-03-C-0063

     We, together with Anteon and BAE Systems, are developing a system for performing ship shock qualification tests in response to underwater explosions. It utilizes an array of non-explosive devices to elicit a ship loading response that is the same as that due to an actual explosive test but without the danger, expense, and time consumption of the use of explosives. The non-explosive nature together with bubble screening will enable conduct of the tests in confined quarters such as near a dock rather than in open water. The work includes small scale experimentation, numerical modeling, evaluation of different concepts and a conceptual design and tradeoff study of a full scale system. This work falls under the Ships and ships systems product area).
 

N00167-04-M-0060

     We are developing an underwater cleaning system utilizing cavitating jets to strip rust and paint from ship hulls to enable repair and rapid repainting underwater by divers to selected hull areas requiring maintenance between dry dock times. This involves the design and fabrication of specialized high pressure cavitating water jets, testing on actual Navy paint systems and rusted panels over a parameter space, and development of concepts for integration of the jets into a practical Navy system and evaluation of performance. This supports the product areas of Ships and ships systems, and Surface warfare logistics and maintenance.
 

N00174-96-C-0034

    We have supported the product areas of Engineering, System Engineering and Process Engineering, with the following accomplishments:

• Developed and used a Boundary Element Method code, 3DynaFS^©, for UNDEX bubble modeling and prediction of loads on nearby targets.
• Developed analysis techniques for multi-cycle dynamics of UNDEX bubbles resulting in development of the codes MultiCycle^© and DFMigrate^©.
• Conducted parametric numerical and analytical studies in support of these tasks and in support of various other NSWC, ONR, and NAVSEA efforts.
• Conducted controlled scaled tests and parametric studies in Dynaflow's vacuum spark test cells utilizing high speed photography and pressure measurements for code validation and support of other NSWC activities including design of larger scale test evaluation experiments.
• Designed, built, tested and evaluated a device CVRG (Cavitating Vortex Ring Generator) employing hydrodynamic means of deactivation of mines in the surf zone.
• Conducted predictive simulations for underwater explosion work conducted by Indian Head, Carderock, and NAVSEA.

N00174-96-C-0034

We have

• Developed analytical and numerical tools for the characterization of the damage potential of underwater explosions to submerged or floating structures including in shallow water.
• Developed and used experimental techniques to validate the numerical/analytical methods.
• Furthered development of Dynaflow's 3D Boundary Element Method code, 3DynaFS^©, for UNDEX bubble modeling to include re-entrant jet post-touchdown analysis.
• Coupled 3DynaFS^© with finite element structural dynamics codes for fluid-structure interaction modeling.
• Developed analysis techniques for multi-cycle dynamics of UNDEX bubbles resulting in development of the codes MultiCycle and DFMigrate.
• Conducted parametric numerical and analytical studies in support of these tasks and in support of various other NSWC efforts.
• Conducted controlled scaled tests and parametric studies in Dynaflow's vacuum spark test cells utilizing high speed photography and pressure measurements for code validation and support of other NSWC activities.
• Conducted predictive simulations for underwater explosion work conducted by Indian Head, Carderock, and NAVSEA.

These efforts supported the product areas of Ships and Ships Systems, Littoral Warfare Systems, Ordnance, and Undersea Warfare Weapons & Vehicles.