An Assessment of Naval Hydromechanics Science and Technology (2000)

U.S. naval superiority depends critically on the maintenance of leadership in the science and technology that supports the fleet. Hydromechanical performance is fundamental to the basic fighting capability of surface ships and submarines in terms of speed, stealth, seakeeping, endurance, maneuverability, and human performance. These cissues have become more important in recent years as the Navy's focus has shifted from the deep ocean to the littoral environment, where new land-based and sea-based threats now must be addressed. Various factors point to the need for increased speed.

While hydromechanics has application in many fields unrelated to naval needs, there are important ways in which naval hydromechanics is unique, especially ways that affect speed and stealth. These include free-surface effects, including breaking bow and stern waves, surface wakes, submarine wakes, cavitation, drag reduction, wave resistance, and added resistance in waves.

In the absence of a strong commercial shipbuilding industry in the United States, there is no other patron but the Navy to lead research in these areas. Therefore, if the United States is to maintain its naval superiority, ONR must assume responsibility for the fundamental R&D leading to hydromechanics S&T that is unique to the Navy's needs, while drawing on the knowledge and technology base from related fields.

To enable the Department of the Navy to maintain superiority in naval hydromechanics and to allow the necessary resources to be devoted to this aim, ONR should designate naval hydromechanics as a National Naval Need.¹

1. Over the past 20 years there has been a shift away from fundamental research toward applications-driven research with a relatively short-term focus. This shift, apparently driven by budgetary pressures and the desire for immediate transition, threatens to weaken the knowledge base and the pool of scientific talent and hence to decrease the generation of new ideas.

2. There are already disturbing signs of this trend: for example, the reduction in programs at leading research universities, such as the Massachusetts Institute of Technology and the University of California at Berkeley, and in the fundamental hydromechanics research programs at the Navy's laboratories.

3. In the long run, this erosion in the fundamental research program will weaken the future technological leadership of the U.S. Navy.

On the basis of these findings, the committee recommends the following changes in ONR research policy as it relates to hydromechanics:

1. Funding for 6.1 should be less focused on immediate needs and more focused on broad, long-term research on fundamental problems in naval hydromechanics such as linear and nonlinear wave dynamics, including wave breaking, air entrainment effects, and air/sea interactions; all aspects of cavitating and supercavitating flows, including inception, noise, and damage; drag reduction and other aspects of flow control; surface and submerged wakes; hydrodynamic sources of noise; internal wave generation and propagation; and vortex dynamics and turbulence unique to naval surface and subsurface vehicle/sea interaction.

2. The 6.1 resource base should be stable and should be protected from the larger funding fluctuations associated with major acquisition programs.

3. In the 6.1 area, ONR should promote a culture of bottom-up research, which can bring novel developments and lead to solutions for unanticipated problems that may arise in the future.

1. Current ONR hydromechanics efforts are not well coordinated with higher-category technology development and demonstration efforts, for two main reasons. First, there does not appear to be a long-term vision for advanced concepts for ship and submarine platforms, so there is no well-defined 6.2/6.3 program plan with which to coordinate. Nor is there an equivalent to the Conform program of the 1970s, which contributed to the successful development of the Sea Shadow. Second, there is not enough S&T funding to pursue a robust technology development and demonstration program aimed at new platform concepts. This lack of funding is not new. For at least two decades, science and technology (6.1, 6.2, 6.3) funding in ship and submarine technology in general and hydromechanics in particular has been inadequate to support such a program. In the past, S&T funds were supplemented by the periodic infusion of major acquisition funding, which filled the voids and sustained research expertise at the same time as it responded to the needs of the acquisition managers. This reliance on major acquisition funding for S&T activities served as a deterrent to longer-term, more aggressive activities.

2. The lack of a long-term vision for what advanced ship and submarine platforms would offer in improved signature, speed, cost, and payload capability or the lack of an integrated 6.2/6.3 plan to achieve the necessary overall hydromechanical concepts will have significant consequences: funding will remain inadequate, there will be a lack of focus for 6.1 efforts, it will be difficult to sustain expertise and attract new graduates, and the future naval capability by the United States will suffer.

1. ONR, in conjunction with the relevant Office of the Chief of Naval Operations and the Naval Sea Systems Command/Program Executive Office organizations, should formulate and maintain an integrated 6.2/6.3 plan for technology development and demonstration aimed at new platform concepts for ships and submarines and using the results of long-term basic research under ONR sponsorship. Key features of this plan should include (1) significant advances in a 15-year time frame, (2) clearly articulated goals in the related hydromechanics areas of signature reduction, drag reduction, propulsive efficiency, and seakeeping/maneuverability, and (3) the examination of concepts that could achievethese goals. Demonstrations necessary to ensure the validity of predicted performance should be described. The investment required and the resulting payoffs in terms of improvements in stealth, speed,cost, and payload capability should be assessed. The plan should guide 6.2/6.3 research and development efforts. The planning process should involve experts from the industry that engineers and builds naval systems; these experts must have long-term vision. The plan should also (1) require and accommodate innovative and competing approaches, (2) foster collaboration between the Department of the Navy, academia, industry, and, where appropriate, foreign organizations, (3) identify opportunities for areas of fundamental research, and (4) stimulate concepts for spin-off to commercial applications.

2. Continuous channels of communication should be established between the research, design, and operations communities to ensure the effective use of research results and to inform researchers of specific problems as they arise. It is anticipated that improved communications at the Department of the Navy and between the department and the industrial and academic communities will lead to a stronger research program with significant future payoffs for the Department of the Navy.

1. There are numerous Navy test facilities. Some are new (e.g., the large cavitation channel at NSWCCD) and some are fairly old (the Garfield Thomas water tunnel at ARL/PSU and the facilities at NSWCCD). Some facilities are not fully utilized. Some towing basins would be busier were it not for the fact that the maritime industry in the United States is progressively declining, and many potential users from the United States and abroad turn to overseas facilities.

2. Each center is operated independently of the others. Each has unique features, but there is also some substantial overlap. There seems to be inadequate funding even for upkeep, let alone improvement and modernization. Instrumentation is very basic and in general targets design data rather than flow physics. There seems to be no significant program to upgrade the existing instrumentation.

3. The successful utilization of test facilities depends heavily on their quality and condition. This is controlled by the repair and maintenance (R&M) program. Currently, R&M is funded by organizational overhead funds or a direct surcharge to the project using the facility. This translates to increased project

costs to the customer in either case. The transfer of work to European facilities is motivated by their lower costs and better service. The S&T program could benefit significantly if the cost of hydromechanics testing in the United States could be cut, encouraging the use of U.S. facilities.

4. The primary function of the existing Navy laboratories (other than the Naval Research Laboratory (NRL)) is to support the development of new naval platforms and weapons. A relatively small fraction of each center's efforts is directed at fundamental research. In some cases the size of the scientific staff working on fundamental problems seems below critical mass, and groups in the different centers appear to be working in isolation. The overall management philosophy is geared toward developmental activities and does not nurture fundamental research.

5. Responsibility for the technical management of development work on advanced platforms and weapons has shifted from the centers to the ONR program managers. This dilutes the support for fundamental research in fluid mechanics at ONR and has led to a reduction of the basic research effort.

The Department of the Navy should take the following steps to ensure that high-quality S&T is conducted at the hydromechanics research centers:

1. The Department of the Navy should consider retiring some of the less advanced facilities at the centers so that the rest can be improved and supported by better technical know-how and more man power. Facilities that have shown no significant work or major instrumentation upgrades for a long time (say, 10 years) should be considered for decommissioning.

2. The Department of the Navy should aggressively pursue advanced measurement techniques (e.g., noninvasive, holographic, ultrasonic, and velocimetry techniques).

3. The maintenance and upgrade of hydromechanics facilities at the Department of the Navy centers should be funded from a separate source not linked to the S&T program.

4. The fundamental basis for experimental work at the Department of the Navy's centers should be strengthened. Experts from the different centers should be involved in intercenter scientific committees promoting the scrutiny and discussion of issues such as design and upgrade of facilities, qualification and documentation of the characteristics of an adequate facility, development and acquisition of new instrumentation and measurement techniques, physical interpretation of data, and evaluation of the scientific merit of the proposed experiments and the results obtained. Funding allocations should be based not only on the merit of proposed work but also on a track record of significant contributions from past work. The high quality of the Department of the Navy centers can be maintained by regular internal and external peer review and emphasis on the refereed publication of research results.

5. A more active collaborative relationship between university and center researchers should be facilitated to take advantage of the strengths of both and create a stronger overall research effort. Top-notch researchers from universities and other research institutions should be involved in research at the centers. The centers should use university researchers as active members of working teams in technical and scientific matters, design, facility upgrades and modifications, instrumentation design, and data presentation and interpretation of results. In addition, facilities and their use should be subjected to periodic evaluation by teams of external experts.

6. The quality of the research and technical management staffs should be improved over time by providing a more attractive research environment for the best and brightest university graduates.

1. Recent changes in the missions of the Navy and Navy-funded laboratories have emphasized fleet and design support at the expense of research in naval hydromechanics.

2. Budgetary considerations have further restricted the number of researchers and the scope of the research that can be performed at a single location. However, there is still a large body of enthusiasm and intellectual talent, although it is widely dispersed.

3. Modern means of communication provide new, unexploited opportunities to enhance scientific interactions between geographically separate groups of scientists and engineers. Databases, experimental facilities, libraries, and intellectual talent can be accessed instantaneously and without time-consuming interruptions.

4. Currently there are no centers of excellence for fundamental research in naval hydromechanics.

1. ONR should establish an institute for naval hydrodynamics (INH).

2. The INH should capture the best talents and the largest body of knowledge in hydromechanics from the United States and foreign countries. It should leverage existing funding and ensure a well-coordinated approach to research in hydromechanics.

3. The INH should be directed by a highly qualified scientific leader. The management style and philosophy should be in tune with the intellectual creativity expected of participants in the INH.

4. A small central facility should support the INH. This facility should be open to all INH participants.

5. The form of the center should be carefully determined. One attractive option would be a virtual center that uses distributed assets and extensive Internet communication. The virtual center would havea management committee and a small central supporting entity. The new NASA Astrobiology Institute organized by the NASA/Ames Research Center, the European Research Community on Flow, Turbulence, and Combustion, and the NASA Institute for Advanced Concepts are models for virtual centers. Virtual centers could draw upon researchers from anywhere at any time. Although the idea is relatively new and relatively untested, it is very promising, and the committee recommends that it be given serious consideration. Alternatively, the center could be modeled after the jointly managed NASA/Stanford Center for Turbulence Research and the independently managed Institute for Computer Application Science and Engineering, at NASA/Langley.