Semisubmersible naval ships are versatile military crafts that combine the advantageous features of high-speed planing crafts and submarines.At-surface,these ships are designed to provide sufficient speed and maneuver...Semisubmersible naval ships are versatile military crafts that combine the advantageous features of high-speed planing crafts and submarines.At-surface,these ships are designed to provide sufficient speed and maneuverability.Additionally,they can perform shallow dives,offering low visual and acoustic detectability.Therefore,the hydrodynamic design of a semisubmersible naval ship should address at-surface and submerged conditions.In this study,Numerical analyses were performed using a semisubmersible hull form to analyze its hydrodynamic features,including resistance,powering,and maneuvering.The simulations were conducted with Star CCM+version 2302,a commercial package program that solves URANS equations using the SST k-ωturbulence model.The flow analysis was divided into two parts:at-surface simulations and shallowly submerged simulations.At-surface simulations cover the resistance,powering,trim,and sinkage at transition and planing regimes,with corresponding Froude numbers ranging from 0.42 to 1.69.Shallowly submerged simulations were performed at seven different submergence depths,ranging from D/LOA=0.0635 to D/LOA=0.635,and at two different speeds with Froude numbers of 0.21 and 0.33.The behaviors of the hydrodynamic forces and pitching moment for different operation depths were comprehensively analyzed.The results of the numerical analyses provide valuable insights into the hydrodynamic performance of semisubmersible naval ships,highlighting the critical factors influencing their resistance,powering,and maneuvering capabilities in both at-surface and submerged conditions.展开更多
Radar cross section（RCS） is the measurement of the reflective strength of a target.Reducing the RCS of a naval ship enables its late detection,which is useful for capitalizing on elements of surprise and initiative....Radar cross section（RCS） is the measurement of the reflective strength of a target.Reducing the RCS of a naval ship enables its late detection,which is useful for capitalizing on elements of surprise and initiative.Thus,the RCS of a naval ship has become a very important design factor for achieving surprise,initiative,and survivability.Consequently,accurate RCS determination and RCS reduction are of extreme importance for a naval ship.The purpose of this paper is to provide an understanding of the theoretical background and engineering approach to deal with RCS prediction and reduction for naval ships.The importance of RCS,radar fundamentals,RCS basics,RCS prediction methods,and RCS reduction methods for naval ships is also discussed.展开更多
The paper identifies twelve elements of ship recycling recycling system. The source and items of knowledgebase for ship and highlights their respective roles and duties in a proposed ship recycling have been brought o...The paper identifies twelve elements of ship recycling recycling system. The source and items of knowledgebase for ship and highlights their respective roles and duties in a proposed ship recycling have been brought out. A new philosophy focusing clean and safe ship recycling namely design for ship recycling has been introduced based on principles such as ecofriendliness, engineering efficiency, energy conservation and ergonomics. The role of naval architects in ship recycling industry has been described based on the above factors. The paper brings out the role of naval architects in ship recycling the way it has been practiced worldwide and proposed by regulatory bodies. The authors have brought out the new concept of design for ship recycling and various aspects of it. The role of naval architects in the practice of this new design philosophy which is ready to be embraced by the maritime industry has been reiterated.展开更多
The study of emergency evacuation in public spaces,buildings and large ships may present parallel characteristic in terms of complexity of the layout but there are also significant differences that can hinder passenge...The study of emergency evacuation in public spaces,buildings and large ships may present parallel characteristic in terms of complexity of the layout but there are also significant differences that can hinder passengers to reach muster stations or the lifeboats.There are many hazards on a ship that can cause an emergency evacuation,the most severe result in loss of lives.Providing safe and effective evacuation of passengers from ships in an emergency situation becomes critical.Recently,computer simulation has become an indispensable technology in various fields,among them,the evacuation models that recently evolved incorporating human behavioral factors.In this work,an analysis of evacuation in a Landing Helicopter Dock(LHD)ship was conducted.Escape routes specified by the ship’s procedures were introduced in the model and the six emergency scenarios of the Naval Ship Code were simulated.The crew and embarked troops were introduced with their different evacuation behavior,in addition,walking speeds were extracted from data set collected in experiments conducted at other warships.From the results of the simulations,the longest time was chosen and confidence intervals constructed to determine the total evacuation time.Finally,results show that evacuation time meets regulatory requirements and the usefulness and low cost of the evacuation simulation for testing and refining possible ships’layouts and emergency scenarios.展开更多
Verification of ship stability is based on rules which account for the effects of wind. Restrictive hypotheses are employed to define those rules and especially the influence of ship heeling. This study reviews some s...Verification of ship stability is based on rules which account for the effects of wind. Restrictive hypotheses are employed to define those rules and especially the influence of ship heeling. This study reviews some stability rules and applies them to the case of the F70 frigate. Then, two alternate approaches are considered： （1） accounting for the actual lateral areas and respective centroids of the heeled ship; and （2） CFD （computational fluid dynamics） calculations to determine aero and hydro dynamic coefficients at each heel angle. Finally, comparison is made between the results of these alternate approaches and the stability rules.展开更多
With the development of large liquid cargo ships,liquid tank sloshing has gradually become a hot research topic in the area of shipping and ocean Engineering.Liquid tank sloshing,characterized by strong nonlinearity a...With the development of large liquid cargo ships,liquid tank sloshing has gradually become a hot research topic in the area of shipping and ocean Engineering.Liquid tank sloshing,characterized by strong nonlinearity and randomness,not only affects the stability of the ship but also generates a huge impact force on the wall of the tank.To further investigate liquid tank sloshing,a comprehensive review is given on the research process of the most focused subjects of liquid sloshing.Summarizing the existing research will help to identify issues in the current field and provide useful references.The methods for investigating sloshing,the research progress and the situations worldwide are discussed.The advantages and defects of experiments and numerical simulations are also explored.The problems which need to be explored in the future are subsequently proposed.展开更多
文摘Semisubmersible naval ships are versatile military crafts that combine the advantageous features of high-speed planing crafts and submarines.At-surface,these ships are designed to provide sufficient speed and maneuverability.Additionally,they can perform shallow dives,offering low visual and acoustic detectability.Therefore,the hydrodynamic design of a semisubmersible naval ship should address at-surface and submerged conditions.In this study,Numerical analyses were performed using a semisubmersible hull form to analyze its hydrodynamic features,including resistance,powering,and maneuvering.The simulations were conducted with Star CCM+version 2302,a commercial package program that solves URANS equations using the SST k-ωturbulence model.The flow analysis was divided into two parts:at-surface simulations and shallowly submerged simulations.At-surface simulations cover the resistance,powering,trim,and sinkage at transition and planing regimes,with corresponding Froude numbers ranging from 0.42 to 1.69.Shallowly submerged simulations were performed at seven different submergence depths,ranging from D/LOA=0.0635 to D/LOA=0.635,and at two different speeds with Froude numbers of 0.21 and 0.33.The behaviors of the hydrodynamic forces and pitching moment for different operation depths were comprehensively analyzed.The results of the numerical analyses provide valuable insights into the hydrodynamic performance of semisubmersible naval ships,highlighting the critical factors influencing their resistance,powering,and maneuvering capabilities in both at-surface and submerged conditions.
基金Supported by Program for New Century Excellent Talents in University under Grant No.NCET-07-0230the "111" Project under Grant No.B07019 at Harbin Engineering University
文摘Radar cross section（RCS） is the measurement of the reflective strength of a target.Reducing the RCS of a naval ship enables its late detection,which is useful for capitalizing on elements of surprise and initiative.Thus,the RCS of a naval ship has become a very important design factor for achieving surprise,initiative,and survivability.Consequently,accurate RCS determination and RCS reduction are of extreme importance for a naval ship.The purpose of this paper is to provide an understanding of the theoretical background and engineering approach to deal with RCS prediction and reduction for naval ships.The importance of RCS,radar fundamentals,RCS basics,RCS prediction methods,and RCS reduction methods for naval ships is also discussed.
文摘The paper identifies twelve elements of ship recycling recycling system. The source and items of knowledgebase for ship and highlights their respective roles and duties in a proposed ship recycling have been brought out. A new philosophy focusing clean and safe ship recycling namely design for ship recycling has been introduced based on principles such as ecofriendliness, engineering efficiency, energy conservation and ergonomics. The role of naval architects in ship recycling industry has been described based on the above factors. The paper brings out the role of naval architects in ship recycling the way it has been practiced worldwide and proposed by regulatory bodies. The authors have brought out the new concept of design for ship recycling and various aspects of it. The role of naval architects in the practice of this new design philosophy which is ready to be embraced by the maritime industry has been reiterated.
基金the Spanish Ministry of Economy and Competitiveness through the research project TIN2016-76770-R.
文摘The study of emergency evacuation in public spaces,buildings and large ships may present parallel characteristic in terms of complexity of the layout but there are also significant differences that can hinder passengers to reach muster stations or the lifeboats.There are many hazards on a ship that can cause an emergency evacuation,the most severe result in loss of lives.Providing safe and effective evacuation of passengers from ships in an emergency situation becomes critical.Recently,computer simulation has become an indispensable technology in various fields,among them,the evacuation models that recently evolved incorporating human behavioral factors.In this work,an analysis of evacuation in a Landing Helicopter Dock(LHD)ship was conducted.Escape routes specified by the ship’s procedures were introduced in the model and the six emergency scenarios of the Naval Ship Code were simulated.The crew and embarked troops were introduced with their different evacuation behavior,in addition,walking speeds were extracted from data set collected in experiments conducted at other warships.From the results of the simulations,the longest time was chosen and confidence intervals constructed to determine the total evacuation time.Finally,results show that evacuation time meets regulatory requirements and the usefulness and low cost of the evacuation simulation for testing and refining possible ships’layouts and emergency scenarios.
文摘Verification of ship stability is based on rules which account for the effects of wind. Restrictive hypotheses are employed to define those rules and especially the influence of ship heeling. This study reviews some stability rules and applies them to the case of the F70 frigate. Then, two alternate approaches are considered： （1） accounting for the actual lateral areas and respective centroids of the heeled ship; and （2） CFD （computational fluid dynamics） calculations to determine aero and hydro dynamic coefficients at each heel angle. Finally, comparison is made between the results of these alternate approaches and the stability rules.
基金financially supported by the National Natural Science Foundation of China(Grant No.52271271)the National Key Research and Development Program of China(Grant No.2022YFE0104500)+1 种基金“Pioneer”and“Leading Goose”R&D Program of Zhejiang Province(Grant No.2022C03023)Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ17E090003)。
文摘With the development of large liquid cargo ships,liquid tank sloshing has gradually become a hot research topic in the area of shipping and ocean Engineering.Liquid tank sloshing,characterized by strong nonlinearity and randomness,not only affects the stability of the ship but also generates a huge impact force on the wall of the tank.To further investigate liquid tank sloshing,a comprehensive review is given on the research process of the most focused subjects of liquid sloshing.Summarizing the existing research will help to identify issues in the current field and provide useful references.The methods for investigating sloshing,the research progress and the situations worldwide are discussed.The advantages and defects of experiments and numerical simulations are also explored.The problems which need to be explored in the future are subsequently proposed.
