Armament systems built on new physical principles can be called, in particular, promising complexes that use an electromagnetic pulse to temporarily or even permanently disable radar, radio and digital systems, computers of enemy ships. In addition, it is possible to use the electric power of the ship to launch and accelerate the projectile (railgun). Do not just forget that all such systems require very large reserves of electrical energy on board the ship, as well as the possibility of restoring it or maintaining it at the required level without a ship entering the base.
Nowadays, electric motors are used on warships and as part of the main power plant, and as an auxiliary propulsion unit. Since modern engines are high-speed, it is necessary to place a reduction gear between them and the propeller, power losses in it can reach 2%. In the case of an electrical system, it is necessary to use frequency converters and generators with a total efficiency of less than 90%. This is lower than that of the “purely mechanical” system (for example, a gas turbine and the main turbo-gear unit). Therefore, in economic terms, the electromotive is unprofitable.
At the time, the invention of the propeller electric motor gave a rather sharp leap to the entire development of underwater shipbuilding, while in relation to surface combat ships it solves only auxiliary tasks. Despite this, enthusiasts of wider application on navy "Electromagnetic forces" do not disappear anywhere. In an effort to warm up interest in this topic, they introduce new terms, for example, "the expanded use of electric motion." It is possible to realize full electric movement only when the propeller (or other mover) in all modes of movement of the ship is driven only by an electric motor. In the event that there are mechanical sources of energy on board the vessel (turbine, diesel engine, etc.) that have the ability to rotate the propeller shaft (most often at high speeds), then we can talk about “direct drive with an auxiliary electric motor”, or "Partial electric movement."
“Full electromotive motion”, which is based on the conversion of mechanical energy into electrical energy, and then again into mechanical energy, reduces the overall efficiency. This must be taken into account and shipbuilders, and naval sailors. It seems that the expected appearance of electromagnetic guns (on frigates, corvettes and destroyers) and catapults (on aircraft carriers) will make some of the energy losses that occur when it is converted from one type to another, justified and possible.
Lithium-ion submarine batteries
In connection with the general trend of increasing energy consumption by a variety of ship systems (including radar, BIUS, GAK and others), designers need to be more careful in their approach to the generation and conservation of electricity. In this regard, the advanced scientific and technical countries of the world are quite actively working on the creation of high-capacity lithium-ion batteries. There are successes in this area and in Russia.
It is worth noting that the lithium-ion battery itself (Li-ion) was first released by Sony back in the 1991 year, but for a long time these batteries were used only in the civilian sphere. This type of battery today is very widespread in all household appliances and electronics, finding also application as an energy storage device in various energy systems, and as an energy source in electric vehicles. Today it is the most popular type of battery for devices such as laptops, mobile phones, digital video cameras and cameras, as well as electric cars. Lithium-ion batteries have proven themselves very well in the work, but until recently they have not been used in the fleet. Despite the fact that these batteries have a number of important advantages over classic acid batteries, including the ability to withstand increased discharge and charging currents, increased capacity, longer life cycle, lower costs during operation, etc.
Naturally, all this could not stay away from the designers of naval technology. For example, at the end of 2014, the Russian Rubin Design Bureau, specializing in submarine design and leading in our country, the submarine shipbuilding bureau, announced the success of the test cycle for new lithium-ion batteries intended for non-nuclear submarines. The general director of the TsBB Rubin Igor Vilnit told journalists about this then. Such batteries significantly increase the autonomy of the submarines, having a long service life, and also do not require for the maintenance and operation of complex equipment. At the same time, in the Russian fleet, batteries are used, the validity of which is limited, and the price, according to experts, can reach 300 million rubles. According to Andrei Dyachkov, who previously headed the Rubin Central Design Bureau, modern lithium-ion batteries will allow the submarines to stay under water at least 1,4 times, while the potential of this technical idea is currently used only by 35-40%, RIA reported News.
The direction is promising for the fleet, it has long been noticed all over the world. According to shephardmedia.com, in March 2020, the Japanese Navy self-defense forces are about to launch the world's first non-nuclear submarine (11-I in a series of submarines such as Soryu), which will receive lithium-ion batteries. This will allow the Japanese to stop using not only traditional lead-acid batteries, but also air-independent Stirling engines on submarines.
Japanese non-nuclear SS 503 Hakuryū submarine of the Soryu type.
According to retired vice admiral Masao Kobayashi, the use of lithium-ion batteries "should dramatically change the actions of non-nuclear submarines." Such batteries provide submarines with the duration of underwater travel, which is comparable to the duration of travel when using air-independent power plants (VNEU) at low speeds, however, due to the high capacity, they can provide a rather high duration of underwater travel and at high speeds, which is especially important for submarines when they go on the attack or when evading the enemy. At the same time, unlike the VNEU, the submarine is able to constantly replenish energy in lithium-ion batteries by recharging batteries using an RDP device (a device for operating the engine under water).
According to Vice-Admiral Kobayashi, lithium-ion batteries also have a shorter recharge time compared to lead-acid batteries, this is achieved due to the greater current charge. Also, such batteries are more durable, and electrical circuits with their use are easier to build electrical networks and manage. The flip side of the coin is the high cost of lithium-ion batteries. So the contract price of the 11 submarine of the Soryu type is 64,4 billion yen (about 566 million dollars), against 51,7 billion yen (454 million dollars) in the tenth boat of the same type. Almost all the difference in the price of submarines will be in lithium-ion batteries and the corresponding electrical systems.
Use of rowing motors
For sailors, reducing unmasking signs is very important. Best of all this contributes to the use of the propeller motor (HED), which is considered the lowest noise of all common ship propulsion systems today. However, for a surface vessel, the reduction of the acoustic field is not as relevant as for a submarine fleet. The fact is that the main unmasking factor for surface ships is visibility in the radar (radio waves are well reflected from superstructures and board), as well as infrared fields (power plant built on the basis of an internal combustion engine).
Therefore, for surface ships, the reduction of the hydroacoustic field seems to be the most relevant for specialized vessels - anti-submarine (patrol) ships. Most often, they search for enemy submarines in the mode of small and medium travel - no more than 15 nodes (about 28 km / h) using sonar systems with towed, submersible and sub-antenna antennas. The range of such antennas directly depends on the vibration and noise “portraits” of the carrier ship, the lower the ship’s speed, the more efficient the antennas work.
Model HED, render realred.ru
It is less noise - the main advantage of installations with electric propulsion. No other power plant can be made less noisy than an installation with an electric motor. In this case, a significant contribution to the overall noise "background" of the ship makes a rowing shaft, which is rigidly connected through the gearbox with the main engines. To reduce this noise, special couplings are used. In addition, the vibration of the engines is transmitted to the hull of the ship (ship engines, gearboxes, mechanisms are put on the foundation, which is rigidly connected with the hull set, and that in turn is connected with the hull shell). It is the hull of the ship that radiates vibrations into the external environment (into the water), and this is the source of the noise, which is called structural. To reduce the "structural noise" is widely practiced installation of all mechanisms on the shock absorbers.
In power plants with full electric propulsion, the propeller shaft is in no way connected with the main (for it) noise source - the main engine, since in all modes of travel it rotates only by an electric motor. In addition, in the "electric" main power plant, the generator, together with the prime mover, can even be located in the ship's superstructure (for example, this is how some diesel generators are located on British frigates of the 23 project), removing them from the outer skin of the ship to the maximum.
True, at a speed of more than 15 nodes, all the advantages of electric movement in terms of noiselessness of such a move end. This is due to the fact that the main component of the underwater noise (at some distance from the vessel) is the noise from the cavitation propeller cavitation. Therefore, on warships it makes sense to deal with noise reduction from the power plant only at speeds up to 15 nodes. Therefore, the use of electric propulsion can only be used to provide the ship with a search stroke, which is suitable for anti-submarine ships.
Today, there are examples when individual designers tried to reduce the acoustic visibility of warships by reducing the length of the shafts, arguing that such a solution is achieved by correctly positioning the elements of the power plant inside the hull of the warship and superstructure. Some of these solutions were actually implemented in practice, for example, on British destroyers of the 45 Daring type, whose power plant consists of Rolls-Royce 2 gas turbines, a pair of Wärtsilä diesel generators, and Converteam electric motors. For KVMS with 2003 on 2011 year 6 such destroyers were built.
Destroyer type 45 Daring
In the United States are actively building promising destroyers of the new generation, designated Zumwalt. The works started in 2008 year, the lead ship of the series entered service in October 2016. The power plant of the ship includes gas turbines and asynchronous 36,5 MW electric motors with an operating voltage of 6600 B. Lyndon B. Johnson is planning to deliver a high-temperature superconducting synchronous motor with permanent magnets to the third ship of the DDG-1002 series, its power will be the same 36,5 MW and the rotational speed Shaft - 2 revolutions per second. At the same time, the initial operation of the destroyer of a new generation has demonstrated to the whole world that it is still unreliable and suffers from childhood diseases, its operation is accompanied by numerous failures. So 22 November 2016, the Gum destroyer Zumwalt crashed at the moment when it passed the Panama Canal. The immobilized ship had to be towed to the base with the help of the most ordinary tugboats, which are not burdened with new type of power plants.
Another positive quality of electric movement in addition to reducing noise, can be called an increase in the maneuverability of ships. Both the gas turbine and the diesel engine have a minimum power value, therefore, there is also a minimum steady speed. While using an electric motor, you can quite easily change the frequency and direction of rotation of the propeller shaft, which means the speed and direction of the ship. Due to this, the main power plant with an electric motor has been used for a long time on those ships that, according to their purpose, should have the greatest possible maneuverability: tugs, ferries, icebreakers, floating cranes, etc.
In the future, another undoubted advantage of electric movement for warships may be the refusal to use the propeller shafts. Starting with 1992, propeller-and-steering complexes with submerged propulsion engines (podded drive) began to be widely used as the propulsion motors (HED), in which the HED was moved out of the hull of the ship and installed in the underwater capsule (cocoon), which has high hydrodynamic properties.
Azipod - azimuthing podded propulsion system
Typical VRK create or with one stubborn, or with two coaxial (traction and thrust) screws. In our country, Finnish systems under the designation “Azipod” (Azipod - azimuthing podded propulsion system) with one resistant screw and HED with power from 1,5 to 4,5 MW have received the greatest distribution. The main advantages of WRC are: the ability to rotate the capsule in the horizontal plane immediately to 360 degrees, that is, reverse the direction of rotation of the screw at 100% power; shafting and the ability to operate a fixed pitch screw at low speeds (up to 0,1 from normal). In addition, the WRC allows to significantly reduce the level of vibration and noise of the power plant, as well as to install electric power equipment in places difficult to accommodate cargo, this, in turn, allows designers to more efficiently use the space of the ship.
The most effective source of current for the WRC is the AC network, which allows not only increasing the efficiency and reliability of the main power plant, but also using asynchronous motors to drive a screw, equipped with a short-circuited rotor and not requiring maintenance during operation. In order to improve the starting quality of an asynchronous drive, quite often, deep-phase and two-cell rotors of special performance are used. The screw speed in systems called Azipod can be adjusted using thyristor frequency converters. The use of the WRC in practice significantly increases the maneuverability of ships and allows even quite large of them to do in the port without assistance from the tugs. In addition, the lack of propeller shafts increases the useful volume in the hull.
It is known that the electric propulsion systems were used on the Russian weapons transport Akademik Kovalev, which was built at the Zvezdochka CS in Severodvinsk and accepted into the fleet in December 2015 of the year. A special feature of the 20180TV project ship, created by the Almaz Center for Metallurgic Design Bureau, was its propulsion system: the ship’s diesel generators generate electricity, which powers the electric motors in the orientable spin-and-turn steering complexes. Due to the presence on the ship of the WRC, this transport of armaments is characterized by increased maneuverability, it can hold a predetermined course with significant sea disturbances and successfully accomplish the tasks assigned to it by the command of the Navy. Currently, the Zvezdochka CS is building a second ship under the same project.
Experts believe that underwater and surface ships with electric propulsion, the most common today, in the future will only be improved, especially given the increasing use of propeller-steering systems. At the same time, in the future, electric propulsion on the ships of the Navy in all countries of the world will become more and more widespread.
Tseluyko IG. The development of the electrical movement of military fleets in the world // Young Scientist. - 2012. - №4. - S. 54-57.