2017 Vol. 12, No. 3
 Pure loss of stability calculation of naval ship in regular waves…ZHU Jun,LIU Ruijie,GE Yijun,et al (1) Comprehensive calculation and safety assessment of parametric roll of very large container ship…MA Chengyuan,MA Ning,WANG Tinghao,et al (7) NURBS-based parametric optimization and design of bulbous bow…ZHANG Wenshan,LU Xiaoping,WANG Zhong (16) Ananysis of resistance characteristics of twin-skeg passenger ship based on CFD…ZHAO Bingqian,FANG Zhaozhao,YU Lu,et al (23) Ergonomic evaluation model of operational room based on team performance…YANG Zhiyi,LIU Shuang,LIAO Zhen,et al (29) Combat capability evaluation method of surface warship considering impact of wind and waves…ZHANG Heng,ZHU Jun (36) An algorithm for merging part nodes of JT models exported by FORAN…FANG Xiongbing (43) Mock-up development of new warship protective armor structure and feasibility analysis of ship installation…ZHENG Pan,LI Yongqing,ZHU Xi,et al (51) Calculation of explosion bending moment in hull girders subjected to non-contact underwater explosions…WU Guangming,CHEN Wei,WU Di,et al (58) Development of in-house high-resolution hydrocode for assessment of blast waves and its application…XU Weizheng,WU Weiguo (64) Development of sea ice element and direct analysis method of predicting ice loads based on ABAQUS…GONG Yufeng,ZHANG Zhengyi,LIU Jingxi,et al (75) Influencing factor analysis for direct calculation of trimaran structure's fatigue strength…ZHEN Chunbo,WANG Tianlin,YU Pengyao (86) Twin-truss system design for antarctic krill trawl processing ship…ZHOU Chungkai,WANG Wei (91) Design factors analyses of second-loop PRHRS…ZHANG Hongyan,SHI Erbing,FANG Chengyue (98) Parameter optimization method for longitudinal vibration absorber of ship shaft system…LIU Jinlin,LAI Guojun,ZENG Fanming (105) LQR pitch control strategy of AUVs based on the optimum of sailing resistance…YAO Xuliang,MENG Lingwei,NIU Xiaoli (111) H∞ robust control of load frequency in diesel-battery hybrid electric propulsion ship…LI Hongyue,WANG Xihuai,XIAO Jianmei,et al (120) Disposal testing characteristics of highly emulsified oily wastewater based on dialysis membranes…WANG Liangwu,LI Huizi,XIE Chengli,et al (128) Architecture oriented modeling and simulation method for combat mission profile…CHEN Xia (135) Corrosion risk assessment and comprehensive evaluation of ship sea water pipe systems…YANG Guangfu,QIU Dafu,PAN Jinjie,et al (142)
The pure loss of stability of a ship is one of the failure modes of the second-generation intact stability criteria. Based on the static surface coordinate system, the generalized pitch angle and draught variable are defined, and a wave equation with clear physical meaning is deduced. Based on the Froude-Krylov hypothesis, combined with AutoCAD 2D surface area computing technology and the VBA programming method, a calculation method of the loss of pure stability of ships in regular waves is proposed. For a naval ship, the righting arm is calculated in regular waves, and the large heel ship state is shown to have an identical convergence. The results of the calculations show that a significant reduction in the meta centric height of the maximum righting arm occurs not just in a wave crest but also in a trough. By analyzing the wave profile under the hull, it can clearly be seen that wave amplitude above the deck or below the bottom of the hull causes the pure loss of stability, and in oblique waves or beam seas, the pure loss of stability is caused the asymmetry of the wave profile on the hull. The coinciding convergence of the calculations shows that the process of the definition of generalized pitch can be employed to assess the pure loss of stability of naval ships in regular waves.
As the significant variation of GM in waves for very large container ships, strict demands are raised for this ship type in the evaluation and safety assessment of parametric roll. Targeting a 10 000 TEU container ship sailing in head sea, this study conducts a series of calculations and evaluations on parametric roll motion in which each loading condition is calculated step-by-step. Direct calculation is conducted if neither Level 1 nor Level 2 is satisfied. In this paper, an independently developed time-domain simulation is conducted for loading conditions that fail to match the Level 2 criteria, which is based on a typical 3-DOF weakly nonlinear numerical model. Ship velocity and wave conditions are taken into consideration to explore sensible conditions concerning parametric roll. Finally, according to the results, corresponding safety assessments and several avoidance measures are proposed, such as reducing the height of the center of gravity and raising the speed moderately. In addition, if wave predictions can be detected in advance, the circumstance of the natural rolling period being twice as great as the encountering period should be avoided, which is the most sensible factor for inducing parametric roll. Comprehensive calculation and checking for the 10 000 TEU ship can instruct the general design and improve safety for very large container ships; as a result, remarkable engineering applications and reference value can be recognized.
The well-designed bulbous configuration influences making-waves created by ship, which can be utilized to improve the resistance performance of whole ship, thus the configuration parameters should be optimized. In this research, the data-point mesh generation and control-point calculation of parent-bulb configuration were carried out on the basis of the bulb parametric description and B-spline theory. According to the needs of the optimization, control points were improved to produce a preferable bulb. Next, CFD software was utilized to simulate and calculate models to directly compare the resistance and waveform of the parent-ship to embody the parametric resistance characteristics shown by the orthocenter in the optimization results. The results show that, with the help of B-spline to effectively present the parametric optimization characteristic, the method obtains a vivid and visual pattern, and the efficiency of bow configuration description and optimization is clearly improved. The method simplifies processes of optimization, and the expected goal of resistance reducing has been achieved.
With the implementation and promotion of Rules for Green Ships, more and more attention has been paid by the maritime industry to the ship energy efficiency index. In order to evaluate the function relationship between speed and effective horsepower, and acquire the accurate flow field information of twin-skeg ships, a method for resistance prediction of twin-skeg ships based on the Computational Fluid Dynamics (CFD) theory is outlined. Numerical simulation and resistance prediction by FINE/MARINE for a twin-skeg passenger ship advancing at different speeds are carried out respectively. The effects of the mesh characteristics, calculating speed range, and existence of appendages such as rudders on resistance are discussed. Comparisons between present results and corresponding experimental are made, showing that the prediction error can be controlled below 3%. The results demonstrate that the proposed method is efficient enough to be realized and will meet the engineering requirements.
A theoretical calculation model based on the ergonomic evaluation of team performance was proposed in order to carry out the ergonomic evaluation of the layout design schemes of the action station in a multitasking operational room. This model was constructed in order to calculate and compare the theoretical value of team performance in multiple layout schemes by considering such substantial influential factors as frequency of communication, distance, angle, importance, human cognitive characteristics and so on. An experiment was finally conducted to verify the proposed model under the criteria of completion time and accuracy rating. As illustrated by the experiment results, the proposed approach is conductive to the prediction and ergonomic evaluation of the layout design schemes of the action station during early design stages, and provides a new theoretical method for the ergonomic evaluation, selection and optimization design of layout design schemes.
In order to evaluate the combat capability of surface warships while considering the impact of wind and waves, the impact on seagoing performance and weapon operation is analyzed, an evaluation index system for the combat capability evaluation of surface warships is determined, and an evaluation method is presented on the basis of the Analytic Hierarchy Process(AHP) and multi-attribute utility theory. Next, a typical example is used to validate the proposed method. It is found that the integrated combat capability of an evaluated destroyer in sea state 5 is approximate to 81.5% of that in calm water (sea state 0). The results show that the proposed method can quantitatively evaluate the actual combat capability of surface warships while considering the impact of wind and waves, which provides technical support for new ship demonstration and development.
Many cognominal parts exist in JT models exported by FORAN V70 R2.0 software, and this leads to an increase in time consumption and the space analysis results becoming hard to process when using clearance analysis software to perform distance computing for such JT models. Aiming at this problem, an algorithm for merging component nodes is put forward based on investigating the assembly configuration and inherent information (i.e. geometric and material information) of JT models created by FORAN. The method is composed of four steps:coordinate transformation, model node renaming, node geometric data transferring and material attribute processing. Finally, the proposed method is implemented by C++ and JT Open Toolkit. The results show that the new JT models generated by the proposed method are comprised of only one assembly node, and they preserve the intrinsic information of the original JT models. Its validity is illustrated by a great deal of examples, and the content of the worked JT models are reduced by about 7% to 20%.
To ensure the installation of the new design of protective armor structure on larger warships, a study into the installation process of the structure of this armor is carried out to improve installation efficiency and ensure the protective effect. This paper proposes a typical composite armor structure design which is composed of 'silicate aerogel/ballistic ceramic/high-strength polyethylene/silicate aerogel'. The study analyzes the modeling design, down-selection of materials and equipment, and real ship mock-up technical development. The reliability and application of high strength polyethylene in response to high temperatures in the real ship installation process is discussed. The results show that high-temperatures during welding have no negative impact on the high strength polyethylene of the armored structure. The design demonstrates that this installation process is feasible and can be provided as an alternative solution by virtues of its good maneuverability, controllable precision, checkable quality and high reliability.
Non-contact underwater explosion can generate violent movement on hull girders, which may cause longitudinal strength problems. The explosion bending moment can be calculated using a detailed finite element ship model, but this costs considerable working time. This paper advances a new method for calculating explosion bending moment by a hull girder model. The explosion bending moment of typical ship sections is calculated according to a detailed ship model and simplified hull girder model using ABAQUS software. Comparisons between the results indicate that the simplified hull girder model is easily created and has good precision, enabling it to provide a reference for the estimation of explosion bending moment in hull girders subjected to non-contact underwater explosion.
The propagation and evolution characteristics of blast waves in confined spaces are complicated due to the constraint of the surrounding walls, by which the enhanced reflected shock waves will cause more serious damage to the internal structures, facilities and personnel. In order to investigate the characteristics of explosions in confined spaces, an in-house high-resolution hydrocode was developed in this present work. The third-order WENO finite difference scheme (weighted essentially non-oscillation scheme) was implemented in the code to capture the shock waves generated by cylindrical explosives. The Sod shock tube problem, interacting blast wave problem and blast in air problem were simulated to validate the code. The validated code was then used to simulate the blast waves generated by condensed explosives in closed, vented and connected spaces. The propagation of blast waves and the characteristics of blast load were subsequently investigated. The developed code appears to accurately predict the process of explosions in confined spaces. This high-resolution hydrocode can be used to study the propagation paths of blast waves in complicated spaces and evaluate the internal blast load, which can provide reliable input for the design of explosion-resistant structures.
With the global temperature continuing to rise, the Arctic ice is melting. The development of the Arctic route and exploitation of Arctic resources are drawing the wide attention of international society. Many countries are starting a new round of the construction of polar ships. In recent years, domestic and foreign researchers have begun to focus on the numerical study of ice loads on structure. However, the current commercial finite element software lacks a specialized element used for simulating the mechanical properties of sea ice. This lack increases the difficulty of the numerical study of ice loads on structure. In this paper, based on Reinicke and Remer's elliptic failure criteria and Winkler's elastic foundation, an element has been developed to simulate the bending failure of isotropic granular ice. The ice loads of typical marine structures, such as slope structure and conical structure, are calculated through the direct analysis method with the developed element. A comparison between the results of the direct analysis method and analytical method show good agreement. In brief, the proposed direct analysis method may provide tools and certain references for structural design in an ice environment.
According to the problem of a trimaran cross-deck structure's fatigue strength, taking one trimaran as an example, the responses of ship motion and hydrodynamic pressure on the ship's surface in regular waves are calculated on the basis of the 3D linear potential flow theory. Next, the stress responses of hot-spots in regular waves with different wave angles are evaluated by the finite element analysis of the global trimaran structure. On the basis of linear cumulative damage theories, the fatigue damage is calculated according to the direct calculate method using spectral analysis. Finally, the effect of different sea areas and heading angles' time factors are discussed. The results show that the fatigue damage is greater when using an inshore sea area and considering the time factors of heading angles. The result can offer a reference for the design and development of trimarans.
Aiming to improve the fishing efficiency of antarctic krill processing ships by averting the potential crushing of krill in the trawl to meet quality requirements, a twin-truss system design is proposed which has higher efficiency compared with the traditional system installed in ships. To simulate this design, an analysis of forces acting on the twin-truss structure is conducted under tethered and operating conditions using the structure model method, and an appropriate distance between trawl winch and truss structure, as well as the range for limiting the distance of the horizontal locating cable and truss structure, are obtained. It can also prevent the truss structure from breaking down, enabling the efficiency of trawling and horizontal locating cables during fishing operations. The simulation shows that the new twin-truss system design can improve the efficiency of trawl processing ships, whilst maintain the safety of the truss structure. This design can provide an optimal solution for the truss systems of national antarctic krill processing ships.
In order to study the operating characteristics of a second-loop Passive Residual Heat Removal System (PRHRS), the transient thermal analysis code RELAP5 is used to build simulation models of the main coolant system and second-loop PRHRS. Transient calculations and comparative analyses under station blackout accident and one-side feed water line break accident conditions are conducted for three critical design factors of the second-loop PRHRS:design capacity, emergency makeup tank and isolation valve opening speed. The impacts of the discussed design factors on the operating characteristics of the second-loop PRHRS are summarized based on calculations and analyses. The analysis results indicate that the system safety and cooling rate should be taken into consideration in designing PRHRS's capacity, and water injection from emergency makeup tank to steam generator can provide advantage to system cooling in the event of accident, and system startup performance can be improved by reducing the opening speed of isolation valve. The results can provide references for the design of the second-loop PRHRS in nuclear power plants.
The longitudinal vibration of the ship shaft system is the one of the most important factors of hull stern vibration, and it can be effectively minimized by installing a longitudinal vibration absorber. In this way, the vibration and noise of ships can be brought under control. However, the parameters of longitudinal vibration absorbers have a great influence on the vibration characteristics of the shaft system. As such, a certain shafting testing platform was studied as the object on which a finite model was built, and the relationship between longitudinal stiffness and longitudinal vibration in the shaft system was analyzed in a straight alignment state. Furthermore, a longitudinal damping model of the shaft system was built in which the parameters of the vibration absorber were non-dimensionalized, the weight of the vibration absorber was set as a constant, and an optimizing algorithm was used to calculate the optimized stiffness and damping coefficient of the vibration absorber. Finally, the longitudinal vibration frequency response of the shafting testing platform before and after optimizing the parameters of the longitudinal vibration absorber were compared, and the results indicated that the longitudinal vibration of the shafting testing platform was decreased effectively, which suggests that it could provide a theoretical foundation for the parameter optimization of longitudinal vibration absorbers.
When an Autonomous Underwater Vehicle(AUV) sails near the surface of the sea, it will inevitably be subjected to wave disturbance. The heave and pitch motion caused by wave disturbance not only affects the navigation attitude of the AUV, but also leads to an increase in sailing resistance. As such, its energy consumption is increased. In this paper, the six degrees of freedom model of AUVs is established and linearized in order to achieve the weighted optimization of the sailing attitude and the resistance of the AUVs. The drag force model of the AUV is derived using the theory of potential flow. The Q matrix and R matrix are determined in the controller based on research into the drag force model. The Linear Quadratic Regulator(LQR)controller of the AUV is designed using the drag force model as the performance index. The simulation results show that after adding the LQR controller, the effects of reducing heave motion and pitch motion are 46.64% and 77.62% respectively, and the increased resistance caused by the pitch motion is reduced to 1/6 of its original value. The results show that the multiple optimum of attitude and sailing resistance is realized, the energy consumption is decreased and the endurance of the AUV is increased.
Considering the load frequency fluctuation in the shipboard integrated power system caused by such stochastic uncertainty as wind, wave and current, the battery is adopted here to compensate for the difference between diesel generator output power and ship demand power, and the secondary frequency control is used for the diesel generator to guarantee the power balance in the shipboard integrated power system and suppress the frequency fluctuation. The load frequency control problem is modeled as a state space equation, the robust controller is designed by selecting the appropriate sensitivity function and complementary sensitivity function based on the H∞ mixed sensitivity principle, and the controller is solved by the linear matrix inequality(LMI)approach. The amplitude frequency characteristics denote the reasonability of the designed controller and the design requirement is satisfied by the impact of the impulse signal. The simulation results show that, compared with the classical PI controller, the controller designed by the H∞ robust method can significantly suppress frequency fluctuation under stochastic uncertainty, and improve the power variation of the diesel generator, battery and state of charge(SOC). The robust stability and robust performance of the power system are also advanced.
Ultrafiltration technology is widely applied in the treatment of ship's oily wastewater. In order to study the disposal testing characteristics of highly emulsified oily wastewater based on hydrophilic dialysis membranes, No.1000 cylinder oil and emulsifier is used to make highly emulsified oily wastewater, and a small oil/waster separating tester is created. The relationships between the temperature, consistency of original highly emulsified oily wastewater and dialysis membrane aperture are tested. Not only is the pollution resistance of the dialysis membrane tested on the basis of resolution MEPC.107(49), but the attenuation characteristic of the dialysis membrane is also tested after self-cleaning each time. All the tests show that for dialysis membranes with in the range 0.1 μm to 0.45 μm, the treatment capability will increase with the aperture; they all show a similar flow vs temperature curve, with the treatment capability first increasing and then decreasing with the increasing temperature; when the aperture of the dialysis membrane reaches 0.45 μm, the separation of highly emulsified oily wastewater is best achieved at 55-60℃. All the data and characteristics of this research will be helpful in the design and operation of highly emulsified oily wastewater disposal equipment.
In order to effectively analyze the system behavior and system performance of combat mission profile, an architecture-oriented modeling and simulation method is proposed. Starting from the architecture modeling, this paper describes the mission profile based on the definition from National Military Standard of China and the US Department of Defense Architecture Framework(DoDAF)model, and constructs the architecture model of the mission profile. Then the transformation relationship between the architecture model and the agent simulation model is proposed to form the mission profile executable model. At last, taking the air-defense mission profile as an example, the agent simulation model is established based on the architecture model, and the input and output relations of the simulation model are analyzed. It provides method guidance for the combat mission profile design.
In order to propose a comprehensive corrosion risk evaluation model based on an analysis of the corrosion risk of sea water pipe systems of ships in service, the modes of potential corrosion and their causes were first analyzed by identifying the origins of the inner and outer corrosion of the sea water pipe systems. In accordance with the matrixes of corrosion occurrence possibility and corrosion risk consequence, a corrosion risk matrix was established for a sea water pipe system. The method for the quantitative evaluation value of each mode of corrosion possibly occurring in a sea water pipe system was then presented. The comprehensive evaluation model of the corrosion was first built using the Analytical Hierarchy Process(AHP), which can be used for the comprehensive corrosion evaluation. The results show that the comprehensive evaluation value will be expressed as the corrosion risk level and corrosion-induced consequence of the sea water pipe system. This will be very useful for accurately protecting the sea water pipe systems of ships in service from corrosion, thereby attaining the goals of economy, rationality and timeliness.