ENERGY, PROPULSION, AND HYDRODYNAMICS

Don Walsh

INTRODUCTION

The countries of the former Soviet Union collectively have the world's largest nuclear submarine force, both in absolute numbers and diversity of designs. With the end of the Cold War and the dissolution of the USSR, this capability represents an enormous technology base for underwater applications.

Understandably, until less than two years ago, these were considered sensitive technical areas that were discussed with few Soviet citizens and were not discussed at all with foreign visitors. Now, with a solid and urgent commitment to defense conversion prevalent in Russia and Ukraine, the WTEC team was shown a great many applications for nuclear power sources reactors but few technical details. The same was true for other power systems, hydrodynamics and propulsion systems.

Time was extremely limited at each stop on the trip, a matter mentioned as often by the hosts as by the WTEC team members. Therefore it is not clear whether the lack of technical details was due to insufficient time or a residual reluctance to reveal details of former military research work. What is clear is that the team members have all received invitations to visit most of the sites again, and for longer time periods.

It was not appreciated until recently that there had been a wide variety and number of manned deep submersible vehicles (DSV) designed and built in the former Soviet Union. Prior to the dissolution of the Soviet Union it was believed that no more than a handful of relatively simple submersibles had been built. It appeared that the most advanced DSVs, such as the two 2,000 m Pisces and the two 6,000 m Mirs, were procured from the West. Now it appears that between 30 and 40 Soviet-designed DSVs have either been built or are in the process of construction. From the information supplied to WTEC teams, the energy systems used in these sources are fairly conventional storage batteries. Again, time limitations prevented a more in-depth review of DSV energy sources.

In short, much more was discovered than had been anticipated during the planning of this trip. A major technology base in submarines and submersibles has supported a wide range of technical development in all of the areas of interest to the WTEC team.

Concurrent with nuclear submarine development, the Soviet Union also maintained a program of development for diesel-electric submarines. Within this program there was some experimentation on air-independent propulsion (AIP) energy sources.

In the following section on energy and power systems, several Russian nuclear reactor concepts are discussed. Clearly, most of this work has come from submarine programs. There are also descriptions and specifications for various types of fuel cells, as well as primary and secondary battery systems. The specifications are shown in tables for clarity. However, these are not complete brochure-type specifications, but rather a sample of each power unit's parameters and capabilities.

Perhaps the most useful baseline specification for undersea vehicles power and energy sources is its energy density in terms of watt hours per kilogram of weight (Wh/kg). This value has been given for almost every unit cited. But giving Wh/kg without a calibration reference may not be very useful. Therefore, Table 3.1 compares various types of energy sources. Note that these are sample relative values; designs within each category may have slightly different energy densities.

The second major section of this chapter is hydrodynamics. As a result of military development programs it was evident that a lot of USSR research work was done on high speed vehicles (i.e., submarines and weapons with speeds up to 75 kt). However, this does not have much carryover value for manned submersibles, remotely operated vehicles or most AUV designs. For long-duration mission AUVs (up to 30 days is forecast), the skin drag reduction and hull shape developments shown to the WTEC teams can be important where energy efficiency and conservation are prime concerns for the designer.

Table 3.1
Some Sample Energy Densities for Power Sources

Propulsion, an area of particular relevance to submersibles, is the subject for the third section of this chapter. To use the aviation analogy, most underwater vehicles do not fly underwater by use of propeller(s) and lifting and control surfaces. In general, submersibles are dynamically positioned by use of thrust vectors. Horizontal movements are in the order of a few thousands of meters. Thus, the energy efficiency of thrusters is a key design consideration in development of a vehicle's overall energy budget. The ideal thruster develops high thrust with minimal energy consumption. This conservation permits mission tradeoffs where onboard energy can be allocated to a longer mission time or the carriage of more electrically powered equipment.

The emphasis in the following sections will be on developments in Russia and the Ukraine. European developments that are discussed generally represent technologies that are readily available in the open literature. In the case of Russia and Ukraine, almost everything the WTEC teams saw was new.

In many -- if not most -- visits to Russian and Ukrainian organizations, the degree of technical information provided to the WTEC team tended to be superficial. This was mostly due to time limitations and a general lack of printed materials. This lack of technical detail should not be an excuse for not at least citing developments of interest at places visited, even though the information is more anecdotal than technical. Further, the mention of a development at a specific location can help provide a roadmap for others who wish to follow up on this information.


Published: June 1994; WTEC Hyper-Librarian