In view of the lack of evaluation methods for acceleration ability of domestic trade container ships in wind and waves,starting from the characteristics of low-speed and fat-hull-typed container ships,combining with the hydrodynamic charac-teristics of propellers and the analysis of ship's acceleration in wind and waves,the ship's propulsion conditions in extreme wind and waves was simplified to analyze several key factors related to the ship's acceleration capacity.Considering the conditions for the main engine to quickly cross the barred speed range,the evaluation of the ship's acceleration ability was set forth.Taking the torque margin at the upper limit of the barred speed range under the ship's bollard state as the first level criterion,and taking the torque margin at the service speed of the propeller under the high sea state as the second level criterion,the ship's acceleration ability in the wind and waves can be valued during the design stage.The calculation process was given,which had been verified by a real ship calculation example.
Poor heave performance is the bottleneck that restricts the wide application of cylindrical FPSO in offshore oil and gas development.The extended cylinder and damping structure were added at the bottom of the platform to improve the hydrody-namic performance of the cylindrical FPSO,so as to reduce its heave amplitude to meet the requirements of dry production equip-ment.Based on the 3D potential flow theory,the hydrodynamic analysis model of cylindrical FPSO with motion suppression de-vice was established to analyze the influence of different heights,widths,cross-sectional shapes and sea valve of the motion sup-pression system on the hydrodynamic performance.Comparing the response transfer functions of motion amplitude with different motion suppression equipment,it was found that the hydrodynamic performance of the cylindrical FPSO can be improved by open-ing damping holes to connect the water inside the motion suppression device to the sea;properly increasing the height and width of the damping structure is conducive to increasing the natural period of heave motion,so as to avoid the wave period of 100-yr scenario in the South China sea,which will contribute to reducing the motion of cylindrical FPSO.
In view of the lack of uniform standards during the FE modeling,leading to inconvenience of generating,manage-ment,merging and data exchange with FEM,a complete set of standards of ship hull FEM was proposed,based on the industry rules and practical experience.The method of model expression was specified,and the standard definitions of material and prop-erty were introduced in detail especially.In order to generate and manage the standard FE model quickly,a standardization tool was developed based on FEMAP.The customized data interface was developed for several common software.The practical appli-cation results showed that the standard is scientific and reasonable,and it has good practicability.Related tools would be a great help to modeling efficiency.
In view of the requirements of designing and installing the waste gas SCR treatment equipment and system on ships,taking the loading style of SCR system of 85 000 DWT bulk carrier as an example,the types and characteristics of marine waste gas treatment technology,as well as the requirements and actual components of SCR technology were analyzed.The practi-cal application and workflow analysis of marine waste gas SCR treatment system showed that in the practical application of SCR waste gas treatment technology in marine systems,equipment installation,system pipeline length and direction,exhaust tempera-ture and urea solution injection volume control will affect the actual treatment effect of NOxin waste gas,and the system design should follow certain design principles,layout methods and pipeline design requirements.
The foremast with crane supporting for container ship is subjected to the load of crane on the crane support be-cause of the ship tilting,motion and wind and its structural strength is the focus of attention.The D-type foremast of a container ship was taken as an example,and the structural strength of the foremast with crane supporting of this ship was assessed by finite element method.The numerical results showed that structural stress concentration in the bracket toe has been reduced by adjus-ting the design of the bracket,so as to meet the rule requirement.
Based on the construction status of the pump tower dome in the tank of LNG carriers and the actual needs of the production department,the lifting platform for hydraulic dome construction was designed,including determination of the main size of the lifting platform,the design of every truss beam and connector,the lifting device,stabilizing device and locking device and so on.The finite element method was used to analyze the force and strength assessment for the main components of the platform and the parts where the eye plate of the pump tower was set.The operating method and practical application of the platform were also introduced.
The air gap of two semi-submersible drilling platforms was simulated based on a linear radiation/diffraction anal-ysis in frequency domain.An asymmetry factor was adopted to account for the asymmetry of the waves and the effect of non-linear diffraction.Sensitivity analysis was made to know the influence of asymmetry factor on the air gap of semi-submersible drilling platforms.When predicting air gap,a series of irregular sea states were considered to study the relation between the platform mo-tion and irregular wave energy.The results showed that the asymmetry factor has a significant influence upon the air gap predic-tion,when the asymmetry of the waves and the effect of non-linear diffraction was considered,air gap of platforms will become worse.Even though the significant wave heights were not too high,the platforms may experience dangerous negative air gap when irregular wave energy was closed to the natural frequency of platform vertical relative motion.
To establish the equivalent design waves that dominate the strength assessment of ultra large container ship,a 20 000 TEU container ship was selected as the research object.According to the structural characteristics of the ship,43 initial e-quivalent design waves were customized,and the stress results of the whole ship under each design wave were calculated.The stress spectrum analysis method was used to predict the long-term stress of the typical positions and nodes of the whole ship.Through the comparison of the two results,10 of the 43 design waves that really play a leading role in the strength of the whole ship structure were obtained.
In order to improve measurement accuracy and reliability of the oil mist detector and prevent oil mist particles from adhering to the photoelectric generating source or receiving source in the measuring chamber,two modified design schemes were proposed by using CFD-DPM method based on the prototype measuring chamber.Using polyhedral grids discrete the compu-tational domain.The bidirectional coupling calculation model of air-oil mist particles in measuring chamber was established.The calculation results indicated that a large number of oil mist particles were attached to walls of the generating source and receiving source in prototype measuring chamber;the conditions of oil mist particles attached to the measuring chamber of the two schemes are different.Anti-pollution experiment was carried out on the prototype and scheme 2 measuring chambers.The testing results showed that when oil mist is drained,the oil mist concentration readings of the prototype measuring chamber cannot return to ze-ro,while those in scheme 2 return to zero,which prove that scheme 2 measuring chambers can effectively avoid oil mist particles attaching to the generating source and receiving source walls,and improve the measuring accuracy of the oil mist detector.
According to the characteristics of key structural details form,structure optimization and anti-fatigue details of the medium-scaled membrane LNG carrier,the design details of a new-developed LNG carrier were analyzed,as well as the corre-sponding key points of quality control and treatment methods in ship construction.The working principle and design concept of the air pocket tube device were discussed,and the reason why this device can make the ship meet the IGC requirement and in-crease the loading rate was analyzed.
Based on the relevant requirements of IMO regulations,in view of the characteristics of large luxury cruise ship with a large number of passengers,a large number of lifeboats,and limited deck space,combined with the development status and supporting conditions of domestic equipment,the shape,structure and performance characteristics of various kinds of equip-ment were compared.The factors of limiting configuration and arrangement of equipment on cruise ships was analyzed,so as to select the types of equipment suitable for cruise ships.
Aiming at the low efficiency and inconvenient modification of manual nesting for ship plates,an automatic sheet nesting solution was proposed.Based on the principle of minimum potential energy,the heuristic algorithm was used to realize the automatic plate layout of two-dimensional irregular parts.Several modules were developed by using the SPD system with inde-pendent intellectual property rights,thus the function of nesting graphics platform management,nesting data model management and automatic nesting was achieved.By comparison with CADWIN software showed that the nesting efficiency and plate utilization rate of the two software are very close,while solution based on single data source adopted by this function effectively avoids the data loss caused by model transfer between heterogeneous software.Moreover,the nesting software can be controlled autonomous-ly.
Aiming at the problem of conventional high pressure common rail system in the injection process,such as the low fuel injection pressure and unable to flexibly change the fuel injection rate,an ultra-high pressure common rail system of marine diesel engine was designed based on domestic processing capacity and technology.The simulation model of system was estab-lished to analyze the pressure and fuel injection control characteristics of the system,as well as the influence of the key structural parameters of the pressure-amplifier device upon the system performance.The results showed that,compared with the pressuriza-tion chamber volume,the fuel outlet diameter and spool displacement have greater influence on the performance of this system;with the increase of fuel outlet diameter and spool displacement,the pressurization pressure and fuel injection rate peak value both increase,but the fuel leakage rate increases first and then decreases.
In the traditional design of ship cabin noise reduction,the selection of noise reduction measures depends more on experience,and the cost-effectiveness ratio of noise reduction measures is limited.Taking three ships of the same type as exam-ples,the different noise reduction schemes of the medical room of these ships were analyzed using the source-path-receiver meth-od,to obtain the contribution of each sub item to the total sound pressure level,and find out the main causes of the noise excee-ding the standard.The validity of the calculation model was verified by comparing the calculated results with the test data of the real ship.By analyzing the contribution of each item to the total sound pressure level in the calculation process,the original noise reduction measures were simplified,and a more economical noise reduction design scheme was given.
Taking the shell plating of a 75 ft FRP Yacht as the research object,20 different layer schemes were designed.The test plates were prepared by hand lay-up wet process to carry out he drop weight impact test according to ASTM D7136 stand-ard.Based on the ACP and LS-DYNA module of ANSYS Workbench,a multi-scale FE model for low-velocity impact simulation of shell plating was established by using multi-point constraint method.The effects of lamination parameters on the low-velocity impact properties of shell plating were studied by means of experiment and numerical simulation.The results showed that the stacking sequence has a great influence on the dissipation of impact energy during low-energy impact;the main damage forms are matrix cracking and delamination damage;the farther away from the punch along the impact direction,the larger the delamination area,which is elliptical distribution and expands along the fiber direction.Reasonable design of stacking sequence and layer an-gle can effectively improve the impact resistance of shell plating.
There are different effects on hydrodynamic performance of triple pods vessels with different stern appendages,and absorbed power of the vessels is imbalance.The effects and characteristics of different appendages of a vessel with triple pods were analyzed from views of powering,maneuvering and dynamic positioning performance.The appendages for the vessel were determined.The appendages installation angle was optimized based on ship resistance performance by CFD method.The power imbalance of triple pods under bollard and navigation conditions was calculated and analyzed,showing that the power of the cen-terline pod is larger at the same propeller rotation rate,and the power imbalance of navigation condition is significantly higher than that of the bollard condition.
Considering the unique configuration of large power,small tonnage,and shallow draft ship types of cargo ships in the Lancang river,combined with the still-water navigation velocity prototype tests of 500 t and 300 t class ships in the Lancang river,the deviation between test results and existing velocity estimation methods such as the Navy coefficient method,Pavmir method,Aier method and Эиванков method were analyzed.Based on relative velocity,dimensionless power-load ratio,resist-ance coefficient and comprehensive factors,the ideas and methods for estimating the ships'velocity in the Lancang river were de-veloped.It was proved that the resistance coefficient method and the dimensionless power-load ratio method have higher accura-cy;while the resistance method considers not only thrust characteristics of the propeller but also the resistance property.
The medium container ship needs to select the appropriate voltage level of the power distribution system to match with the power station capacity after the determination of the power station capacity.In terms of classification society rules and combined with the actual situation of the performance limitations of low voltage distribution equipment,the appropriate critical range value of the power station capacity for the AC 440 V low-voltage power distribution system was proposed.It was verified by the calculation data of a container ship.When the power station was at or exceeds the critical capacity range value corresponding to the AC 440 V voltage level,the AC 690 V low-voltage and AC 6 600 V high-voltage power distribution schemes were compared from the aspects of the overall distribution network architecture,equipment installation layout,system economic cost,etc.The results showed that the high-voltage voltage level is a more reasonable technical scheme.
In order to study the system characteristics of floating wind turbine and verify the accuracy of numerical simula-tion,a tank model test procedure was described based on the parameters of CSSC Haizhuang semi-submersible floating wind tur-bine.The key elements of the design of each part of the model and the checking method of environmental conditions were intro-duced.The numerical results of the floating wind turbine system characteristics were compared with that of model test.The re-sults showed that the redesign blade can satisfy the requirements,but the blade mass distribution and inertia control are difficult.The quality of the wind field directly influences whether the thrust calibration meets the requirements.The power production state will increase the damping level of the system,and reduce the RAO peak value near the natural period.
Based on the parent ship,a 62 000 DWT multi-purpose ship was optimized to obtain better performance in design draft and scantling draft.The hull pressure and wave-making resistance of the parent ship were analyzed,and the local geometry was varied in the areas with large pressure gradient variations;the entrance angle at the bow and the length of the run body at the stern were optimized to reduce the wave resistance and the flow separation at the stern.The optimized ship was calculated by u-sing Star ccm + and compared with the results of the parent ship.The results showed that the optimized ship significantly reduced the resistance at design draft and scantling draft compared with the parent ship,and the pressure gradient distribution on the hull surface and the wake distribution at the propeller disc were more uniform,achieving the optimization purpose.Model tests were also conducted at the scantling draft to verify the accuracy of the numerical calculation of the resistance.Hull form optimization makes the ship have better performance,meet the requirement of energy efficiency,and meet the goal of energy saving and emis-sion reduction.
