2022, Volume 17, Issue 5
With the continuous innovation of new maritime concepts of operations, the modern form of naval warfare presents the characteristics of multi-domain attack and defense, distributed coordination and efficient killing, accelerating the innovation and development of new surface ship technology. Focusing on combat space, combat system structure, combat units and combat armaments, this paper summarizes the main characteristics of new modern maritime concepts of operations, categorizes the system positioning and combat capability evolution of surface ships, and systematically analyzes the development of new surface ship equipment. It then puts forward several thoughts on the development of surface ship overall integration technology, network information technology, digital intelligence enabling technology, new energy security technology, advanced material technology and environmental protection and energy saving technology.
Intelligent unmanned system combat is moving from concepts to actual combat applications. The military applications of intelligent unmanned systems are emphasized by focusing on the needs of the combat missions that they will undertake on future battlefields and summarizing the development statuses of land, air and maritime unmanned systems. Aiming at the key problems faced by intelligent unmanned systems and the practical difficulties that will be faced on the battlefield in the future, we analyze the key technologies required for intelligent unmanned systems, including autonomous perception and understanding in complex environments, behavioral decision-making and trajectory planning, autonomous navigation and positioning, multi-scenario autonomous skill learning and intelligent control, unmanned cluster cooperative control, natural human-computer interaction, etc. At the same time, aiming at the problems that will be encountered in the further development of intelligent unmanned systems on the battlefield in the future, we start with individual enhancement and cluster enhancement, and conduct a detailed analysis of the development trends of intelligent unmanned systems.
In order to promote and guide the development of autonomous underwater vehicles (AUVs) in China, this paper summarizes the research status of AUVs at home and abroad, and puts forward the development trends of serialization, grouping, systematization and large-scale development. Key AUV technologies such as overall multidisciplinary optimal design, structure and material design, power and propulsion, navigation and control, detection and communication are discussed. Finally, development opinions are put forward on how to make better use of AUVs to navigate the oceans and achieve the strategic goals of "ocean entry, ocean exploration and ocean utilization".
The development of antenna technology has always been restricted by its essential physical limits, but the advancement of artificial structures with unique electric properties, namely metamaterials, offers great opportunities for improving the performance of existing antenna designs and introducing new functions. This article introduces the concepts of "metamaterials" and "metasurfaces". The design of metasurfaces and metasurface antennas is introduced in detail with the example of the microwave meta-lens. The latest progress in the research and development (R&D) of microwave metantenna technology, namely metamaterial and metasurface based antennas, is then briefly summarized. More importantly, the article offers thoughts on future key topics of microwave meta-antenna R&D.
It is a challenge to solve complex fluid-structure interaction (FSI) problems through theoretical derivations, whereas numerical simulation provides an effective solution and is widely applied in naval architecture and marine engineering. Based on grid treatment, FSI methods are classified into the body-fitted grid method, non-body-fitted grid method, overset grid method and particle-based method. The research development of these four types of methods is then reviewed. Both the body-fitted grid method and overset grid method can accurately capture the interface and are suitable for high Reynolds number flow problems, and the former is generally employed when structural deformation is considered, while the latter often works well when considering rigid body motion with complex geometric shapes. The non-body-fitted grid method can avoid the mesh update operation to make calculations simpler, and is widely used in the simulation of flow control, development of underwater flexible bionic vehicles and interference of multi-body motion. The particle-based method plays an increasingly important role in simulating strong nonlinear fluid-structure interaction problems involving severe free surface deformation, slamming, explosion, etc. The properties of different FSI problems determine the applicability of different methods. How to select a suitable numerical method and combine the advantages of various methods to develop novel numerical methods that can handle more challenging problems are important development directions for FSI algorithms.
The steering system noise is one of the main noise sources in submarine stealth condition. Combined with the composition of the steering system, the noise source of each component is sorted out systematically, and corresponding vibration and noise reduction design measures are proposed. As the main noise source of the steering system, emphasis is placed on analyzing the noise mechanism of the rudder hydraulic system, which is divided into two categories and six types according to steady state and transient operating conditions. Finally, it is pointed out that the new type electro-hydraulic steering gear, based on direct drive servo control principle, is the future development trend.
Hydrodynamic noise from an air-water interface is often encountered in marine engineering structures. It involves a complex mechanism, various forms of sound sources and many factors affecting the propagation. It interacts with the free surface and is affected by cavitation and water-air-bubble mixed flow, which has a negative impact on the concealment of the ship, giving this line of inquiry strong research significance. This paper introduces a noise calculation method and its applications in terms of free surface noise, cavitation noise and water-air-bubble mixed flow noise respectively, and describes their computational methods and key issues. The solutions currently in use are also introduced. Finally, future research directions are proposed.
The refined description of the flow field information around a ship can provide feedback on the internal essence of the ship's macroscopic hydrodynamic performance from the perspective of the flow mechanism, and high-quality flow field measurement technology is a necessary means of ensuring such a refined description of the flow field. Based on the engineering requirements of ship flow field measurement, the current development status of flow field measurement technology is summarized according to its technical characteristics, and the applications and characteristics of each method are described in detail. The existing flow field measurement methods still have many problems that need to be solved. The exploration of hardware upgrading, technology integration, algorithm optimization, function expansion, data assimilation and machine learning may promote the rapid development of flow field measurement technology in the direction of comprehensiveness, specialization and efficiency.
Air regeneration, harmful gas purification and atmospheric composition monitoring are the key technologies of submarine atmospheric environment control systems. After years of development, China has made great progress in such systems, which have developed from ensuring the safety requirements of submariner and equipment operation to ensuring the health of submariner and reliability of system for long-term underwater operation. This paper reviews the development history of submarine atmospheric environment control technologies and introduces their future development prospects. The developers of integrated atmospheric environment control technology should learn from foreign submarine and aerosphere equipment technologies, which aim to support long-term submerged operation and comfort demands, and better adapt to future submarine technology development and evolving mission, in order to constantly enhance the level of submarine cabin air quality of the Chinese navy.
The application of variable buoyancy systems (VBS) in autonomous underwater vehicles (AUVs) have greatly improved their maneuverability, endurance, adaptability to environmental change and ability to accomplish a variety of tasks. As there are various types of AUVs, the types of VBS are also different. Thus, it is necessary to further research AUV VBS and control technology. First, the principles and characteristics of different types of AUV VBS are explained in detail, and their applicable scenarios summarized. Typical applications of VBS in AUV maneuvering control are then introduced, including balancing, hovering, landing and bottoming. Next, the existing buoyancy adjustment technology, buoyancy observation technology and cooperative maneuvering control technology of AUV VBS are reviewed and evaluated. Finally, the development prospects of AUV VBS are evaluated.
The safety of Arctic ships will be influenced by the interactions with ice ridges and icebergs. Generally, the structural design loads will be governed by these ice features. In order to design ship structures, the principles of risk-based design should be considered and followed. The following limit state design criteria are usually applied in structural design: 1) Serviceability Limit States (SLS); 2) Ultimate Limit States (ULS); 3) Fatigue Limit States (FLS); 4) Abnormal/Accidental Limit States (ALS). The ULS and ALS correspond to impact events with a very low probability to occur, and its intention is to ensure that a ship hull structure does not suffer from a complete loss of integrity. However, for analysis of the ice loads with low probability levels, the number of relevant load cases is significant and the computation amount is huge. In this work, the so-called environmental contour method is introduced in order to reduce the required number for ice loads analysis as well as to identify the most likely combinations of the relevant design parameters. Utilization of this approach is illustrated in connection with the ULS and ALS in the present paper. Application of the proposed method could be a valuable supplementary for structural design of Arctic ships.
With the constant development of power, information and other technologies, the advantages of unmanned ships are emerging in anti-mine, anti-submarine, electronic warfare, maritime security, maritime interception, and other military fields. This paper describes the development of unmanned ships and power technology and clarifies that the integrated power system has become a major trend of medium and large-sized unmanned ships. It also introduces the application of integrated power system in manned and unmanned platforms, and proposes that issues like size, weight, and control of vibration and noise are of essential for the integrated power system for unmanned platforms. In the end, this paper summarizes the trend of integrated power technology for unmanned platforms and identifies the key scientific problems of integrated power technology on unmanned platform, namely the intelligent operation of integrated power system, high-performance motor materials, information perception of complex motor system, power electronic device and system, high-performance power conversion and efficient energy storage.
Initial alignment technology is directly related to the navigation accuracy and startup time of the strap-down inertial navigation system (SINS), and has always been regarded as a challenging focal point in the research field of inertial navigation. This paper makes a comprehensive survey of SINS initial alignment technology, briefly introduces the basic principles of initial alignment without latitude, coarse alignment with known latitude and precise alignment, and points out their advantages, disadvantages and applicable conditions. The research and effects of existing initial alignment error suppression techniques are then analyzed and discussed. Finally, according to the problems of existing initial alignment methods and the development requirements of the carrier, the future research direction of SINS initial alignment technology is predicted.