2019 Vol. 14 No. 4
2019, 14(4)
Abstract：
[1] Comparative study on vibration response test of buoyancy-core and rubber-core grid sandwich panels…Liu Jianliang,Mei Zhiyuan,Zhang Yanbing,et al(1)[2] Test analysis of anti-shock ability of high hardness polyurea-coated FRC composite structure…Zhao Pengduo, Jia Zijian, Wang Zhijun, et al(7)[3] Numerical simulation on anti-explosion performance of cabin composite structure…Wu Guangming, Xu Yadong, Li Zhengguo, et al(14)[4] Method for theoretically predicting time history of afterburning reaction rate of internal explosion and determining energy release constant…Xu Weizheng, Wu Weiguo, Kuang Zheng(22)[5] Study on numerical simulation method for vibration characteristics of shell embedded with acoustic black hole…Wang Bohan, Yang Deqing, Xia Lifu(30)[6] Analysis on external pressure bearing capacity of cylindrical shell based on measured geometric defects…Wang Wei, Zhu Shiyang, He Weiping(40)[7] Simulation study on ultimate strength of CFRP-reinforced cracked stiffened panels…Shi Xinghua, Ren Hengjia, Xu Wenqiang, et al(47)[8] Deformation detection method and numerical analysis of filament-wound flexible pipe…Fan Yuqi, Sun Qian, Lü Zhiqiang, et al(55)[9] Bending calculation of multi-span beam under arbitrary boundary conditions and engineering application thereof…Xiong Jianfeng, Yan Xiaojie, Jiang Puyu, et al(61)[10] Lightweight analysis on double-arm propeller shaft bracket on basis of different rules…Xu Xueqiang, Li Tianyun, Zhang Xu, et al(67)[11] Numerical simulation of vertex induced motion for Spar platform with helical strakes…He Jiawei, Zhao Weiwen, Wan Decheng(74)[12] Analysis on the influence of turbulence model on elbow erosion calculation…Liu Qi,Mao Shaohua, Liu Sheng, et al(85)[13] Large eddy simulation of the flow field in centrifugal fan and numerical prediction of noise in pipe…Li Ya, Liu Zhongzu, Xu Yingbo, et al(91)[14] Numerical simulation and experimental study of infrared suppression of diesel engine exhaust gas under water…Tang Simi, Li Xianbin(98)[15] Dynamic analysis on star type compressor based on cylinder pressure signal…Lou Jingjun, Li Chaobo, Zhang Zhenhai, et al(104)[16] Aerodynamic design and strength check of a two-stage dual-rotor opposed centrifugal compressor…Geng Shaojuan, Ni Ming, Ding Linchao, et al(111)[17] Coupling matching research and torsional vibration characteristics prediction of MTU diesel propulsion shaft system…Hu Yunfei, Zhou Ruiping, Xu Yong, et al(120)[18] Building method and application of improved models for design quality of marine power plant based on QFD and FMEA…Wang Taixiang, Liu Jinlin, Zeng Fanming,et al(128)[19] Numerical simulation of steam submerged jet and condensation…Wang Guanghuai, Sun Lu, Wang Chang, et al(135)[20] Pressure tracking control of large pressure vessel…Zhang Wei, Liao Yide(143)[21] Study of on-line monitoring and fault diagnosis system for a naval transformer…Kang Xing, Li Weibo, Yu Wanxiang, et al(147)[22] Seawater pipeline corrosion monitoring system based on AC impedance technology…Zhang Xiaodong, Xu Zhixiong, Zhang Cong, et al(155)[23] Design and performance test of USV information management system based on time-series database…Huang Yi,Wang Hongdong, Cheng Fengrui, et al(161)
[1] Comparative study on vibration response test of buoyancy-core and rubber-core grid sandwich panels…Liu Jianliang,Mei Zhiyuan,Zhang Yanbing,et al(1)[2] Test analysis of anti-shock ability of high hardness polyurea-coated FRC composite structure…Zhao Pengduo, Jia Zijian, Wang Zhijun, et al(7)[3] Numerical simulation on anti-explosion performance of cabin composite structure…Wu Guangming, Xu Yadong, Li Zhengguo, et al(14)[4] Method for theoretically predicting time history of afterburning reaction rate of internal explosion and determining energy release constant…Xu Weizheng, Wu Weiguo, Kuang Zheng(22)[5] Study on numerical simulation method for vibration characteristics of shell embedded with acoustic black hole…Wang Bohan, Yang Deqing, Xia Lifu(30)[6] Analysis on external pressure bearing capacity of cylindrical shell based on measured geometric defects…Wang Wei, Zhu Shiyang, He Weiping(40)[7] Simulation study on ultimate strength of CFRP-reinforced cracked stiffened panels…Shi Xinghua, Ren Hengjia, Xu Wenqiang, et al(47)[8] Deformation detection method and numerical analysis of filament-wound flexible pipe…Fan Yuqi, Sun Qian, Lü Zhiqiang, et al(55)[9] Bending calculation of multi-span beam under arbitrary boundary conditions and engineering application thereof…Xiong Jianfeng, Yan Xiaojie, Jiang Puyu, et al(61)[10] Lightweight analysis on double-arm propeller shaft bracket on basis of different rules…Xu Xueqiang, Li Tianyun, Zhang Xu, et al(67)[11] Numerical simulation of vertex induced motion for Spar platform with helical strakes…He Jiawei, Zhao Weiwen, Wan Decheng(74)[12] Analysis on the influence of turbulence model on elbow erosion calculation…Liu Qi,Mao Shaohua, Liu Sheng, et al(85)[13] Large eddy simulation of the flow field in centrifugal fan and numerical prediction of noise in pipe…Li Ya, Liu Zhongzu, Xu Yingbo, et al(91)[14] Numerical simulation and experimental study of infrared suppression of diesel engine exhaust gas under water…Tang Simi, Li Xianbin(98)[15] Dynamic analysis on star type compressor based on cylinder pressure signal…Lou Jingjun, Li Chaobo, Zhang Zhenhai, et al(104)[16] Aerodynamic design and strength check of a two-stage dual-rotor opposed centrifugal compressor…Geng Shaojuan, Ni Ming, Ding Linchao, et al(111)[17] Coupling matching research and torsional vibration characteristics prediction of MTU diesel propulsion shaft system…Hu Yunfei, Zhou Ruiping, Xu Yong, et al(120)[18] Building method and application of improved models for design quality of marine power plant based on QFD and FMEA…Wang Taixiang, Liu Jinlin, Zeng Fanming,et al(128)[19] Numerical simulation of steam submerged jet and condensation…Wang Guanghuai, Sun Lu, Wang Chang, et al(135)[20] Pressure tracking control of large pressure vessel…Zhang Wei, Liao Yide(143)[21] Study of on-line monitoring and fault diagnosis system for a naval transformer…Kang Xing, Li Weibo, Yu Wanxiang, et al(147)[22] Seawater pipeline corrosion monitoring system based on AC impedance technology…Zhang Xiaodong, Xu Zhixiong, Zhang Cong, et al(155)[23] Design and performance test of USV information management system based on time-series database…Huang Yi,Wang Hongdong, Cheng Fengrui, et al(161)
2019, 14(4): 1-6, 13.
DOI: 10.19693/j.issn.1673-3185.01289
Abstract：
Objectives To explore the influence of core materials on the vibration of composite grid sandwich panels,
Methods taking the panels as the research object, the vibration response of rubber-core grid sandwich panels and buoyancy-core grid sandwich panels under different conditions is compared by means of experiment, with emphasis given to the analysis of vibration suppression effect of core material on the two composite panels.
Results The results show that the mid-frequency and low-frequency(0-1 000 Hz) vibration response of the buoyancy-core grid sandwich panels in air is low, while the high-frequency(1 000-3 000 Hz) vibration response of the rubber-core grid sandwich panels is low. The influence of the factors such as the mass of the sandwich panel and the damping of the core on the vibration response of the panel is weakened due to the added mass effect and the added damping effect and the integral of the sandwich structure and the local bending stiffness of the panel are the main factors. The vibration response of the buoyancy-core grid sandwich panel within full-frequency band (0-3 000 Hz) is lower than that of the rubber-core grid sandwich panel.
Conclusions To reduce the vibration response of the panel, the core stiffness of the grid sandwich panel shall be close to the grid stiffness. In addition, the smaller the density and damping of the core, the greater the difference between the vibration response in air and water.
2019, 14(4): 7-13.
DOI: 10.19693/j.issn.1673-3185.01414
Abstract：
Objectives To analyze anti-shock ability of the composite structure whose base metal is coated with polyurea,
Methods we obtained ballistic limit velocity by using a 12.7 mm ballistic gun and obtained the limit specific absorption ability of the composite structure under different conditions. In addition, by examining the macroscopic damage form of target plate structure, we discussed the advantage and disadvantage of two different polyurea structures in terms of anti-shock ability. We also make comparison to soft polyurea composite structure to verify the optimum anti-shock performance of hard polyurea-coated composite structure.
Results The results show that the anti-shock ability of soft polyurea composite structure is the best when the polyurea coating is coated on the back of target; the anti-shock ability of hard polyurea composite structure is the best when the polyurea coating is coated on the front of target; furthermore, the anti-shock ability of the composite structure with the two types of polyuria coating as the front coating is better than when the coating is on the back surface and double-face structure.
Conclusions The high hardness polyurea can be used as the front protective coating for general engineering application which has the better protective effect.
2019, 14(4): 14-21.
DOI: 10.19693/j.issn.1673-3185.01222
Abstract：
Objectives With the development of modern ship technology and the higher requirement for the ship hull's own resistance capability to the anti-ship weapons, the composite materials have been more widely used in warship protective structure. In order to analyze anti-explosion performance of protective structures with Kevlar materials under the action of explosion in cabin,
Methods based on the finite element model from full-scale ship compartment with multi decks, a structural model of the cabin between two decks is established, and armored protective structure with Kevlar materials is laid inside the surrounding wall of the cabin. The dynamic response and damage of the armored protective structure with Kevlar materials under the action of explosion are calculated in this way. In order to correctly simulate the material properties of the anisotropy of Kevlar materials, the armored protective layer is established by solid elements. The upper unit nodes of the surrounding wall and unit nodes of the Kevlar materials are constrained by 'tie' to make these two types of nodes move together.
Results The bulkhead without protective material is completely torn and destroyed by explosion load, while the bulkhead with protective material is only partially torn and destroyed in the position where shock wave is directly impacting.
Conclusions By comparing and analyzing the cabin damage characteristics of different explosion initiation positions as well as armored protective structure with or without Kevlar materials, the anti-explosion protective design of the cabin can be supported to some extent.
2019, 14(4): 22-29.
DOI: 10.19693/j.issn.1673-3185.01338
Abstract：
Objectives Since the afterburning effect on explosion in confined space involves complex multi-component chemical combustion process, describing the afterburning effect approximately with a simplified reaction rate model has certain rationality and engineering application value. However, it is still required to determine the means of predicting the time history of reaction rate in the model and determine an energy release constant. Therefore
Methods , a theoretical prediction method for the time history of afterburning reaction rate is proposed, and a chemical reaction kinetics method is used to determine the time of chemical reaction in internal explosion so as to determine the energy release constant.
Results The results show that although there are certain differences between the theoretical prediction and the numerical calculation results in the early and later stages of explosion, the overall trend is in good agreement, and it is reasonable and reliable to approximately determine the final time of chemical reaction according to the chemical reaction kinetics analysis method.
Conclusions The research results in this paper can provide certain reference and basis for the design of anti-explosion structure and assessment of damage.
Abstract：
Objectives To study a numerical simulation method for a plate embedded with a two-dimensional acoustic black hole,
Methods a method for discrete modeling of the structure with acoustic black hole by a shell element is proposed. Firstly, an example of a plate embedded with a two-dimensional acoustic black hole is designed in this paper, a finite element model of the plate is established with a solid element, and the acoustic black hole effect of the plate is verified; secondly, the plate embedded with two-dimensional acoustic black hole is simulated with a shell element with the same size, and the modes and vibration responses obtained by the two modeling methods are numerically compared and verified; and finally, the influence of step change scale and power law of acoustic black hole region on the vibration characteristics of the whole structure are discussed.
Results The results show that it is reliable to calculate the accuracy of the vibration characteristics of the shell with acoustic black hole by means of shell element dispersion, and the shell element discrete method can reduce the computation scale and improve the computation efficiency compared with the solid element discrete method. At the same time, the reasonable adjustment of the step change scale and power law of the acoustic black hole region will influence the natural frequency of local modes.
Conclusions The research results can provide guidance for the design and application of the structure with acoustic black hole.
Abstract：
Objectives The purpose of this paper is to study the way to establish finite element models with real geometric defects, and to predict and analyze the bearing capacity of a scale down pressureresisting cylindrical shell structure based on different types of defects.
Methods Therefore, a geometric defect extraction method based on quadratic transformation is proposed, then the method of introducing the measured initial geometric defect, which is expressed by double Fourier series, is established. Finally, the buckling capacity of scale down pressure-resisting cylindrical shell under external pressure is analyzed and obtained based on eigenvalue modal defect and measured defect.
Results The results indicate that Fourier series method only involves traversing of grid nodes and calculation of a few function values and can significantly improve the calculation efficiency of defect introduction without reducing the accuracy of calculation.
Conclusions Fourier series method can provide guidance for accurate analysis of ultimate bearing capacity of cylindrical shell structure and structural optimization design.
2019, 14(4): 47-54.
DOI: 10.19693/j.issn.1673-3185.01436
Abstract：
Objectives In order to investigate the ultimate strength of CFRP-reinforced cracked stiffened panel in ship structure repair process,
Methods in this paper, nonlinear finite element method is used to analyze the ultimate strength of CFRP-reinforced cracked stiffened panels subjected to axial compressive loads. Based on CFRP-reinforced cracked stiffened panel model, we compare the simulation results with the recorded test results, to verify the accuracy of the proposed method. By using double-side CFRP -reinforced cracked stiffened panel as the example, we study the ultimate strength of stiffened panel, and the peeling mechanism and the stress of the adhesive layer were analyzed.
Results The results show that the ultimate strength of CFRP-reinforced cracked stiffened panels is significantly increased, and is close to the ultimate strength of stiffened panel with geometric initial defects; CFRP repairs the debonding of cracked stiffened panel after the ultimate strength is achieved.
Conclusions The repair of the cracked stiffened panel by using CFRP can enhance the ultimate strength. It may provide guidance for the ships and offshore structure repair.
2019, 14(4): 55-60.
DOI: 10.19693/j.issn.1673-3185.01215
Abstract：
Objectives This paper aims at solving the problem of pipe body failure by the local abnormal deformation of Filament-Wound Flexible Pipe (FW-FP).
Methods A method of monitoring the deformation of the pipe body on the basis of the principle of resistance detection is proposed. By optimizing the design of the sensor winding model, the three kinds of deformation state of the pipe body are analyzed, a reference threshold model established and a typical DN100 flexible pipe used for numerical calculation and analysis.
Results The current variation of circuits caused by local abnormal deformation can reach 0.25 A, but the current variation of circuits caused by normal deformation is negligible.
Conclusions It is proven that this method can effectively identify the local abnormal deformation of FW-FP and eliminate the signal interference caused by normal deformation. The results of this study can provide references for the follow-up service life evaluation of FW-FP.
Abstract：
Objectives To find the worst-case of a deck structure under patch loading quickly.
Methods For the bending of a multi-span beam under arbitrary boundary conditions, an Improved Fourier Series Method(IFSM)is used to describe the displacement functions of the multi-span beam, list the boundary equations that the displacement functions need to meet and solve such equations to obtain the relational expressions of coefficients; and then an energy control equation is obtained on the basis of the Hamilton principle, the displacement functions of beam structure satisfying the boundary conditions is acquired with the Galerkin method, and the functions are compared with the finite element results by means of example analysis. Finally, this method is applied to the calculation of the worst-case analysis of multi-span beam under patch loading.
Results The results show that the error between the result of this paper and the finite element analysis is less than 0.05%, indicating good accuracy.
Conclusions Compared with finite element method, the speed of solving the worst-case of the multi-span beam is greatly reduced by using this method, and a more accurate location to which the worst-case of patching loading is applied is obtained by combining the genetic algorithms.
2019, 14(4): 67-73.
DOI: 10.19693/j.issn.1673-3185.01369
Abstract：
Objectives To achieve lightweight design of double-arm propeller shaft brackets.
Methods By comparing and analyzing the requirements of the current domestic rules and the main classification societies in the world for the dimension of propeller shaft brackets, this paper interprets the differences between the rules, and searches for ways to reduce the weight of the double-arm shaft brackets from such differences. According to the differences between the rules, DNV-GL rules with significant differences from the CCS rules in the relevant aspects are selected. Based on the same propeller parameters, double-arm propeller shaft brackets are designed according to the minimum sizes requirements specified in the two rules. Subsequently, the strength and vibration performance of the double-arm propeller shaft brackets are verified by the relevant regulations of the national military standard.
Results The results show that the strength and vibration performance of the propeller shaft brackets designed according to the two rules meet the requirements. The total weight of the propeller shaft brackets designed according to the minimum sizes requirements of DNV-GL rules is reduced by about 16.8%.
Conclusions If the double-arm propeller shaft brackets are designed with the DNV-GL rules, the weight thereof can be reduced to some extent. This paper provides an idea for the lightweight design of the double-arm propeller shaft brackets in practical engineering.
2019, 14(4): 74-84.
DOI: 10.19693/j.issn.1673-3185.01280
Abstract：
Objectives Long-lasting Vortex Induced Motion(VIM)may cause the Spar platform mooring system fatigue and even the structure damage. Therefore, the adverse effects of VIM must be fully taken into account.
Methods In this paper, the CFD solver naoe-FOAM-SJTU and dynamic grid method developed by ourselves are used to make numerical simulation of the characteristics of the vortex induced flow field around the Spar platform. The time Delayed Detached-Eddy Simulation(DDES) turbulence model based on shear-transport-stress equation is used to simulate the three-dimensional fine wake vortex structure of the Spar platform with helical strakes. The longitudinal motion, transverse motion and yawing of the Spar platform with helical strakes at different reduced velocities are studied. The platform mooring system is stimulated by using the linear spring system. The research also takes into account the effects that the platform coupling effect at different degrees has on VIM. Then the numerical simulation results are compared with the model test results, to analyze the time history, spectral characteristics and locking of longitudinal and transverse VIM of Spar platform with helical strakes and to reveal the intrinsic mechanism of VIM.
Results The results show that the helical strakes can effectively reduce the response amplitude of Spar platform's VIM; the CFD solver naoe-FOAM-SJTU has good accuracy and reliability for the calculation and simulation of the offshore platforms' VIM.
Conclusions The numerical simulation and analysis of the VIM of Spar platform with helical strakes is of great significance to the practical design of Spar platform.
2019, 14(4): 85-90.
DOI: 10.19693/j.issn.1673-3185.01390
Abstract：
Objectives The elbow is a common component of ship piping system. Efforts have been made in order to predict the elbow erosion accurately.
Methods In this paper, the numerical simulation is conducted to calculate and analyze the flow field inside the pipe. From the two aspects, i.e. the influence of the turbulence model on the prediction of the flow field in the elbow and the influence of turbulence model on elbow erosion calculation, intensive research into the method to predict the erosion of elbow by solid and liquid flows.
Results The results show that the SST k-ω turbulence model, together with the Oka erosion model, can accurately predict the flow field distribution in the elbow. Turbulence model brings a significant impact on the abrasion calculation, where it affects the calculated value of final erosion and also makes a great difference in the distribution of predicted relative erosion.
Conclusions The obtained results can provide guidance for future pipe erosion prediction.
Abstract：
Objectives In order to predict the vibration noise of centrifugal fan,
Methods the whole flow field is meshed by the structured grid and the fluctuating force on the impeller surface that varies with time is obtained by using the Large Eddy Simulation(LES)method. Using the rotating dipole radiation model, the noise from the pipe is predicted by the acoustic finite element method. Taking the surface dipole in the volute wall as the sound source, the noise from the wall pressure fluctuation is calculated and compared with the test results.
Results The results show that the flow noise from the wall is higher than that of the impeller in the low frequency band, but lower in the high frequency band and have a good agreement with the test results.
Conclusions The prediction methods for impeller noise and volute wall pressure fluctuation noise can meet the engineering application requirements.
2019, 14(4): 98-103.
DOI: 10.19693/j.issn.1673-3185.01375
Abstract：
Objectives To reduce the thermal wake of submarine during snorkeling,
Methods a two-stage cooling method is proposed, which can suppress the infrared radiation of high-temperature exhaust gas under water; and then the water surface temperature fields before and after infrared suppression are analyzed on the basis of the finite element fluid analysis method; and finally, an underwater exhaust gas experiment platform is built on the basis of the preliminary data obtained by simulation, so as to test the infrared radiation brightness of water surface and the temperature of underwater section before and after infrared suppression.
Results The results show that the two-stage cooling measure has an excellent infrared suppression effect on the high-temperature exhaust gas of diesel engine, and the maximum infrared brightness of the water surface can be reduced by 90%.
Conclusions This method has a good engineering application value and military significance for the improvement of submarine's concealment.
2019, 14(4): 104-110.
DOI: 10.19693/j.issn.1673-3185.01308
Abstract：
Objectives For star type multistage high-pressure reciprocating compressor, the change of cylinder pressure under different working conditions has not been mastered accurately, and the related dynamic analysis can only be calculated on the basis of theoretical value. Measurement of the actual cylinder pressure of the compressor is helpful to improve the accuracy of the dynamic analysis of the star type compressor.
Methods In this paper, on the premise of not damaging the cylinder structure, each cylinder pressure under different working conditions is successfully measured by the valve stem drilling method, and the vibration acceleration of the cylinder head and base is tested. and the self-balance performance of compressor has good for second-order inertia force is obtained by theoretical analysis. The crank connecting rod mechanism is simplified to establish ADAMS dynamic model, and the parameterized design method is used to obtain the optimum balance weight. Under the working condition of 25 MPa exhaust pressure, the measured gas force is converted into a force applied to the piston and then loaded on the piston centroid, and then the force of the main bearing is obtained.
Results The results show that the stress of the main bearing is the first-order and three-order inertia forces, the change of the compressor working condition mainly affects the three-stage and four-stage cylinder pressures, and the vibration of the first cylinder is relatively severe.
Conclusions The crank connecting rod mechanism of the compressor has good self-balance. The test results provide reference for mastering the characteristics of the cylinder pressure of the star type compressor and analyzing the vibration characteristics of the compressor.
2019, 14(4): 111-119.
DOI: 10.19693/j.issn.1673-3185.01453
Abstract：
Objectives To accomplish the design of a two-stage dual-rotor opposed centrifugal compressor for a small gas turbine,
Methods the compressor is subject to aerodynamic design and three-dimensional flow field check by using the software Concepts NREC and the Numeca. The impeller is made of 0Cr17Ni4Cu4Nb. The strength and vibration characteristics of the centrifugal impeller are analyzed and checked with the ANSYS within the linear elasticity range.
Results The aerodynamic design results show that the total pressure ratio of the two-stage centrifugal compressor at design mass flow rate is 7.97, the adiabatic efficiency is 80.39% and the stability margin is 17.2%. The results of strength and vibration analysis show that the impeller strength meets material strength requirements. According to the "triple point" resonance theory, there are no risks of resonance vibration for the two-stage centrifugal impellers.
Conclusions A design scheme for the two-stage centrifugal compressor with high pressure ratio, high efficiency and wide stability margin is obtained, the compressor meeting the requirements for aerodynamics, strength and vibration, which can provide some fundamental support for the design, technology integration and test of a small gas turbine.
Abstract：
Objectives To clarify the torsional vibration calculation method for matching the medium-high speed diesel engine with the multi-elastic coupling, and to obtain the torsional vibration characteristics,
Methods taking a MTU diesel engine propulsion shaft system as the study object, the matching method of multi-elastic coupling was studied, and the calculation model of MTU diesel propulsion shaft torsional vibration was established. The excitation characteristics of MTU diesel engine and the torsional vibration characteristics of the propulsion shaft were analyzed. The prediction of torsional vibration characteristics of MTU diesel engine and multi-elastic coupling matching series was carried out. Based on the measured amplitude, the damping correction calculation method based on analytical method was proposed to correct the prediction results of torsional vibration characteristics of shaft system.
Results This research shows that measured resonant frequency matches the calculated frequency, after correction, the crankshaft stress at the resonant speed is reduced by 16%, and the vibration torque of the elastic coupling is reduced by 15%. The correctness of the torsional vibration calculation method is verified.
Conclusions The results of this research can provide engineering reference for the torsional vibration analysis of the same type of warship.
2019, 14(4): 128-134.
DOI: 10.19693/j.issn.1673-3185.01288
Abstract：
Objectives In order to improve the safety and reliability indicators performance in the design of the marine power plant, the Failure Mode and Effect Analysis(FMEA)is used to predict and propose the control measures.
Methods The quality control method is introduced with Quality Function Deployment(QFD)to analyze the risk assessment objects, clarify the composition and meaning of the risk priority numbers, and improve the calculation formula, thereby improving the accuracy and comprehensiveness of risk assessment. For the multi-attribute decision-making under expert evaluation, a dependent 2-tuple weighted geometric averaging(DT-WGA)operator is used for evaluation.
Results The effectiveness of the proposed method is verified by the shafting design of the ship.
Conclusions The improved models based on QFD and FMEA can provide theoretical and methodological support for improving the performance of design indicators, such as reliability and safety of the power plant, and provide a certain reference for the improvement of design level of marine power plant.
2019, 14(4): 135-142.
DOI: 10.19693/j.issn.1673-3185.01296
Abstract：
Objectives During the discharging of ship-used steam power, steam jet condensation was a common physical process. In order to fully grasp the fundamental physical phenomena within steam submerged jet and condensation under open space, CFD simulation with Mixture multiphase model was carried out.
Methods With the experimental results, heat transfer model was modified. Vapor volume fraction 0.95 was regarded as the critical value to measure the length of plume. Spatial distribution of plume, velocity, temperature and pressure fields for steam submerged jet and condensation under different inlet pressure and condensed water temperature conditions were studied.
Results Simulation results show that different initial state would affect the plume shapes. Within stable steam submerged jet and condensation, a relatively lower temperature area is appeared in the core of plume. Pressure distribution along the axial direction is present in a fluctuating form, verifies the existence of the expand-compress wave inside the plume, amplitude and spatial wavelength of the pressure fluctuation are increased with increasing inlet pressure.
Conclusions Study in this paper could provide guidance for the optimal design of steam submerged jet and condensation.
2019, 14(4): 143-146.
DOI: 10.19693/j.issn.1673-3185.01396
Abstract：
Objectives In light of the requirement for internal pressure tracking control of a large vessel, in order to meet the demand of rapidly high flow of pressurization section, and improve the tracking performance of pressurization section and depressurization section of pressure vessel,
Methods the internal pressure control system for a new type of 75 m3 pressure vessel is developed, in which a high pressure air water tank was used as an energy accumulator. The change of the internal pressure was realized by controlling the liquid volume that comes from the energy accumulator into the large vessel, to achieve accurate tracking of pressurization section. In order to improve the tracking accuracy of the depressurization section, the flow control valve and the high-speed solenoid switch valve were installed on the outlet pipe of the pressure vessel. PID control algorithm with dead zone was used to compensate for phase lag.
Results The test results show that the dynamic tracking accuracy of the system can be kept within 0.4 MPa, and the static pressure maintaining accuracy can be kept within 0.1 MPa, which validated the good pressure tracking performance and static pressure accuracy.
Conclusions This control method can effectively solve the problem that the instantaneous large flow and pressure control precision of the false sea back pressure can not be ensured simultaneously when the land test simulates the application scenario of underwater vehicle with large inertia and variable depth.
2019, 14(4): 147-154.
DOI: 10.19693/j.issn.1673-3185.01434
Abstract：
Objectives The ship transformer is the key to the safe, stable and reliable operation of a large ship integrated power system, so serious faults must be avoided.
Methods Based on the Advanced RISC Machine(ARM), a transformer status online monitoring and fault diagnosis system was constructed. Anti-interference and data processing are used to ensure real-time, reliable and accurate acquisition of operational status data. Diagnostic system data analysis is used to accurately predict and identify fault types and trigger alarm, thereby ensuring timely action of the system to prevent faults from spread. Screen display is used to improve the dispatcher's ability to accurately grasp the operating status of the transformer.
Results Multisim simulation modeling analysis and field operation test results show that the system can accurately collect the operating status data of the transformer, determine the type of transformer fault, and feedback it to the centralized control center in real time to formulate a reasonable control strategy and planning and scheduling scheme, thereby ensuring the normal operation of the ship integrated power system.
Conclusions The research results can provide reference for on-line monitoring and fault diagnosis of ship transformers.
2019, 14(4): 155-160.
DOI: 10.19693/j.issn.1673-3185.01320
Abstract：
Objectives The installation of an insulating spacer is an important measure to prevent electrochemical corrosion between seawater dissimilar metal pipelines. The electrical insulation performance of the insulating spacer reflects the degree of electrochemical corrosion between seawater pipelines.
Methods On the basis of the AC impedance technology, this paper designs and develops a system for monitoring electrical insulation performance between seawater dissimilar metal pipelines. The system mainly includes power module, microcontroller module, Direct Digital Synthesizer(DDS)signal generator and communication module, and upper computer software, and the measurement accuracy is verified with high-precision instruments.
Results The results show that the electrical insulation performance monitoring system has a high measurement accuracy, and the measurement error of the insulation resistance below 10 MΩ is within 5%.
Conclusions The electrical insulation performance monitoring system suitable for both dry and wet states is realized, which meets the actual application requirements.
2019, 14(4): 161-166.
DOI: 10.19693/j.issn.1673-3185.01361
Abstract：
Objectives In recent years, unmanned surface vehicles(USVs) have developed rapidly and will have wide application prospect. Hence it becomes quite urgent to deal with the massive information management problem on long-endurance USVs.
Methods According to the characteristics of six types of data in USVs' electronic information system, the topology of USV information management system based on time-series database and the data flow model are proposed, and a set of performance test methods for USV information management system are designed.
Results The test shows that the USV information management system is able to meet the information management needs of USVs' operation. Compared with the traditional relational database, the compression performance of the system is improved by about 10%. The retrieval performance and aggregation analysis capability are excellent, and the system is high universal applicability.
Conclusions This system is an excellent solution to the problems in information storage and communication transmission on long-endurance USV.
