To enhance the stability and safety of the underwater structure of the submersible pressure hull, this study focuses on its multi-objective optimization design, aiming to achieve a synergetic improvement of quality, strength and stability. The parametric analysis process is used to analyze the initial ring-stiffened pressure shell scheme, using the optimal Latin hypercube sampling method to explore the influence of design variables on target responses. A high-precision response surface model and a multi-objective optimization model are also established, thereby enabling the multi-objective optimization of the pressure hull using the NSGA-II genetic algorithm. The results show that among the four optimized schemes, the weight of scheme A and scheme C is reduced by 7.3 kg and 6.6 kg, respectively, while the ultimate strength of scheme B and scheme D is increased by 0.177 MPa and 0.031 MPa, respectively. It is confirmed that the multi-objective optimization method integrating response surface models and genetic algorithm can effectively improve the performance of submersible pressure hull. It can provide a valuable reference for the design of deep-sea exploration equipment.

In the era of digital transformation, to address uncertainty, improve quality and efficiency, and enhance enterprise profitability, integrating digital technology into ship design technology to reconstruct a full three-dimensional (3D) ship design model has become a design development trend. A model-based integrated 3D digital design definition and technical connotation are proposed by using Hexagon Smart 3D as the 3D design platform. The solutions for 2D-driven 3D rapid modeling, integration of CAD/CAE, integration of detailed design and production design, 3D submission for approval and design tool development are also discussed. A number of design tools are developed based on parametric modeling and knowledge-driven approaches, forming a modeling strategy and design master schedule (DMS). This addresses the integration of CAE/CAD and the integration of detailed design and production design, enabling the share and reuse of the unified data sources and model data, as well as the 3D design collaboration among various design departments. The research results have been applied in merchant ships and cruise ships, laying a solid foundation for reconstructing the fully 3D design model of ships.

Azimuth waterjet propulsion system can broaden the navigation range of the ship, enhance the adaptability of ships in the shallow water area and other complex environments, and improve the mobility of the ship, which has a wide range of application prospects. In this paper, the numerical simulation was applied to investigate internal flow of azimuth waterjet propulsion system, the accuracy of numerical simulation was validated by experiment. The thrust and efficiency at different speeds were compared, the entropy generation rate is introduced to evaluate the loss ratio of different hydraulic component, the internal flow fields of azimuth waterjet propulsion system were analyzed in detail to reveal the flow mechanism caused by the variation of speed, which will provide guidance for the optimization design of azimuth waterjet propulsion system.

The cavitation of a push-type ducted azimuth propulsor with the design target of balancing the large thrust under bollard condition and the required speed is numerically simulated under the maximum speed condition and the bollard conditions by using the Reynolds-Averaged Navier-Stokes (RANS) method with the SST k-ω model and Schnerr-Sauer cavitation model. The calculated cavitation pattern is generally in accordance with the experimental results. It captures the sheet cavitation on the back blade, the blade face cavitation, the tip-vortex cavitation and the tip-leakage cavitation. The propeller-hull vortex (PHV) cavitation is observed due to the close distance between the strut and the duct and ducted propeller. The correlation between the distance of the strut and the ducted propeller and the strength of the PHV is then analyzed to propose the distance that can suppress the generation of the PHV. The distance which is greater than 0.35D can basically eliminate the PHV. It provides an important support for the optimization design of the ducted azimuth propulsor based on the cavitation performance.

Marine Design and Research Institute of China (MARIC) established the international standard (ISO 4679): Ships and marine technology — Hydraulic performance tests for waterjet propulsion system based on the research on hydraulic performance tests for waterjet propulsion system. The current study focuses on the main contents of the ISO 4679. The ISO 4679 specified the terms and definitions, the acceptance criteria, the test method and the test report of hydraulic performance tests for waterjet propulsion system, and provided the examples of test report template and test devices. The hydraulic performance tests for waterjet propulsion system include hydraulic performance tests and cavitation tests (optional), divided into Class A and Class B for the two different purposes of scientific research and acceptance test, respectively. The Class A is of precision grade for hydraulic model tests with a nominal diameter of 300mm or below, or high precision prototype tests. And the Class B is of engineering level for batch acceptance tests of small and middle-sized models or intermediate tests of pump models. The standard ISO 4679 specifies corresponding acceptance criteria for the two levels. The formulation of ISO 4679 builds a unified communicating platform for relevant parties in the hydraulic performance tests for the waterjet propulsion system, weakening the barriers to the technical exchange and advancing the development of the test technology for the waterjet propulsion system.

Oil and gas explosion is one of the main risks of offshore platforms. Structural design based on explosion risks is the development trend of the design technology. The technical regulations and specifications related to risk analysis are reviewed to summarize the procedures for the assessment of the blast risk, and the method and procedures for the assessment of the blast-resistant performance of the structure. The screening analysis, strength level analysis, plasticity level analysis and performance assessment are carried out to complete the risk-based assessment of the structural performance design for the accommodation of a FPSO offshore platform by using the structural finite element analysis software. The structural designs under different blast risk levels are performed based on three performance levels of function, operation, and life safety, designing out a scheme that meets the criteria of each performance level.

The ocean has huge reserves of natural gas hydrate, which is a strategic alternative energy source with great potential in the future. However, there is still a capacity gap of 2~3 orders of magnitude between the trial production and commercial production. Meanwhile, the drilling of hydrates is faced with many challenges. In view of this, the research and development of economical natural gas hydrate drilling platform or upgrading of existing platforms, and the application of safe drilling technologies are important measures to improve the economic performance of natural gas hydrate drilling. This paper summarizes the relevant hydrate drilling and production platforms based on the drilling and production status of natural gas hydrate reservoirs in the ocean. It analyzes the application potential of deep-water subsea drilling rigs from technical and economic feasibility. Finally, based on the drilling characteristics of hydrate reservoirs, it points out that the exploration and upgrading of managed pressure drilling, open circuit drilling, casing drilling, coiled tubing drilling and others should be strengthened in the future, which has a certain guiding significance for the economical transformation of offshore gas hydrate drilling and production platform and research on safe drilling technologies.

Heterogeneous multi-core technology has become the developing trend of the supercomputers architecture. The effective utilization of the computing power of multi-core processor is a grand challenge in the current CFD industry. The parallel computation for the CFD in hydrodynamics has been explored for heterogeneous multi-core processor based on self-developed code. Firstly, the challenges of the heterogeneous multi-core technology to the CFD parallel computation are analyzed. Secondly. The multi-core parallel computing scheme is designed for SIMPLE algorithm and pseudo-compressible algorithm for SIMPLE and the pseudo-compressible algorithms aiming at the SW26010 processor. The two-dimensional square cavity driven flow are calculated to verify and validate the calculation results and the many-core acceleration effect. Then, the calculation procedure is optimized by using the cyclic fusion method in view of the scattered hot spots of SIMPLE algorithm. The results show that the SIMPLE algorithm and Pseudo-compressible algorithm can achieve the maximum acceleration of 11 times and 24 times, respectively. It preliminarily presents the application potential of the multi-core processor in the parallel computation for the CFD in hydrodynamics.

Aluminum sandwich panels are primarily used on luxury cruise liners and speedboats. The lightweight alterative design for the local structure of the superstructure of a common civilian ship is carried out to expand the application scope of aluminum sandwich panels. The structural configuration and the corresponding type of the connection structure are then determined according to the structural characteristics of the sandwich panel. And the mechanical properties of the superstructure before and after the alternative design are compared and analyzed by using the finite element software ABAQUS. The results show that the superstructure of aluminum sandwich panel have better mechanical properties with the reduced structure weight. It can provide reference for the promotion and application of aluminum sandwich panels in the future.