2019 Vol. 14, No. 5

Contens of CJSR 2019, Vol.14, No.5
Chinese Journal of Ship Research
2019, 14(5): .
Abstract:
[1] Concepts of waterjet propulsion and pumpjet propulsion:their common characteristics, special characteristics and differences…Wang Yongsheng (1)[2] Progress in studies on key technologies for marine propulsion shafting scheme design…Lai Guojun, Liu Jinlin, Lei Junsong, et al (10)[3] Optimal selection of ship's main engine based on interactive weighting and evidential reasoning…Zhao Ruijia, Xie Xinlian, Zhao Jiabao, et al (22)[4] Two-dimensional transient discharge model of zinc-nickel single flow battery…Yao Shouguang, Zhao Qian, Zhao Yunhui, et al (28)[5] Numerical simulation for flow and heat transfer of side exhaust spray of marine diesel engines…Wang Zhen, Wu Wei, Yang Xianyong, et al (36)[6] Study on multi-spectral inversion of temperature and soot concentration in flames…Zhang Qi, Si Mengting, Wang Dongxu, et al (42)[7] Nonlinear vibration characteristics of marine propulsion shafting under bending-longitudinal coupling effect…Xu Peng, Zou Donglin, Lü Fangrui, et al (49)[8] Study on vibration-reduction performance of water-lubricated stern bearing with fluid-saturated perforated slab…Jin Yong, Kuang Junxin, Tian Xiangyu, et al (58)[9] Analysis on propulsion shafting deformation characteristics of underwater vehicle under various condtions…Yu Tongquan, Li Tianyun, Liu Shengchao, et al (64)[10] Body force-based method for determining flow velocity of sea water artesian circulating system…Chen Kang, Yao Zhichong, Zhou Endong, et al (70)[11] Flow analysis and uniformity evaluation of the exhaust pipeline of a marine diesel engine…Li Benke, Huang Bingyang, Li Yanhua, et al (77)[12] Analysis and optimization of resistance characteristics of submarine snorkel air-intake valve…Hu Haibin, Zhou Rui, Zhou Zhe, et al (85)[13] Influence of multi-legged pose of the deep-sea crawling-swimming vehicle on the stability during cruising…Zhang Kang, Wang Lei, Leng Wenjun, et al (90)[14] Simulation analysis tentative scheme of drag reduction by additives in water cannon system…Lin Peng, Gao Yimin, Cai Weihua, et al (98)[15] Analysis on combustion characteristics of pool fire in the confined space with horizontal ceiling openings…Chen Bing, Zhang Shiqi, Shi Xunxian, et al (106)[16] Influence of height of the air supply inlet on the smoke characteristics of the vertical single opening cabin fire during mechanical smoke exhaust…Qiu Jinshui, Ren Guanglu, Liu Boyun, et al (112)[17] Design and realization of a nearby lightning-electric field environment simulator…Wang Ke, Duan Yantao, Shi Lihua, et al (119)[18] Study on theoretical calculation of quasi-static pressure for explosion in confined space…Xu Weizheng, Wu Weiguo (124)[19] Analysis on the damping characteristics of resonance changers based on the wave theory…Li Liangwei, Zhao Yao (131)[20] Design and study on dynamic vibration absorber of fluid-conveying pipes based on the receptance method…Zhang Lin, Li Huafeng, Chen Yong, et al (138)[21] Optimal scheduling of aviation support resources for carrier based aircrafts based on integer linear programming…Tan Dali, Wang Yunfei, Yu Lianfei, et al (145)[22] Spatial positioning method based on visual measurement for carrier-based aircraft…Liu Jiaming (152)[23] Analysis on convergence time of gyrocompass azimuth alignment…He Dongxu, Ge Lei, Zhang Xin, et al (159)
Symposium of Ship Power Technology
Concepts of waterjet propulsion and pumpjet propulsion:their common characteristics, special characteristics and differences
Yongsheng Wang
2019, 14(5): 1-9, 41. doi: 10.19693/j.issn.1673-3185.01605
Abstract:
  Objectives  In view of the lack of complete definition, confusion about denotation of basic concepts of waterjet and pumpjet and confusion of product appellations both at home and abroad at present,   Methods  the common and special characteristics of the two propulsors were refined out and their differences distinguished based on the analysis of their working principle and concrete structures, the definitions of waterjet propulsion and pumpjet propulsion were proposed and their common characteristics, special characteristics and differences were pointed out.  Results  The waterjet and pumpjet are all pump-type propulsors, all of which rely on the matching design of rotors and stators on the flow field inside a duct to produce an axial jet. The first design index of waterjet is high efficiency and the rapidity shall be ensured primarily, whose design result is a waterjet. The first design index of pumpjet is low noise (the acoustic stealth)shall be ensured primarily, whose design result is a pumpjet.  Conclusions  This definition not only includes and distinguishes all existing waterjets and pumpjets, but also points out the problems of some foreign pump-type propulsor's nomenclature and classification. This definition helps the public understand and distinguish between waterjet propulsion and pumpjet propulsion.
Progress in studies on key technologies for marine propulsion shafting scheme design
Guojun Lai, Jinlin Liu, Junsong Lei, Ji Xia, Ruiping Zhou, Fanming Zeng
2019, 14(5): 10-21. doi: 10.19693/j.issn.1673-3185.01539
Abstract:
The design quality of the marine propulsion shafting is one of the important guarantees for its safe and stable operation. In view of the number of components and working environment of the marine propulsion shafting, its design is a complex and systematic problem. In order to improve the design quality of the shafting, experts and scholars at home and abroad have carried out a lot of research work, and relevant design units and classification societies have also formulated a series of design specifications and procedures. At present, the shortcomings of the common design methods of marine propulsion shafting have become increasingly prominent, so it is urgent to conduct a comprehensive analysis and study of the existing design methods. Based on the scheme design process of the marine propulsion shafting, the technical progress in the alignment and optimization of the propulsion shafting, the shafting vibration control and vibration reduction control, and the shafting design quality evaluation were mainly summarized. And the research work which needs to be focused on in the future was also proposed, which aims to provide reference and support for the optimal design of marine propulsion shafting.
Optimal selection of ship's main engine based on interactive weighting and evidential reasoning
Ruijia Zhao, Xinlian Xie, Jiabao Zhao, Zhixiang Wang
2019, 14(5): 22-27. doi: 10.19693/j.issn.1673-3185.01512
Abstract:
  Objectives  The optimal selection of ship's main engine is a problem worthy of further study, and also a complicated problem on multi-attribute decision making.  Methods  The criteria system of optimal selection of a ship's main engine was proposed by deeply analyzing the influence factors of the ship's main engine selection. The objective weight was calculated by entropy weight method. And the subjective weight was calculated by deviation entropy model. Then an interactive weighting method was presented to calculate the comprehensive weight of the ship's main engine selection criteria system, which unified the objective weight and the subjective weight. Finally, the evidential reasoning approach was used to fuse information to sort and select the best one from the options.  Results  The method above was proved to be effective and correct by taking the optimal selection of the main engine in the ship building project of a waterway administration as an example. What's more, the influence rule that the interval selection has on utility value of evaluation results, is further explored.  Conclusions  The results show that the combination of interactive weighting and evidential reasoning can provide theoretical support for ship main engine type selection design。
Two-dimensional transient discharge model of zinc-nickel single flow battery
Shouguang Yao, Qian Zhao, Yunhui Zhao, Xiaofei Sun, Jie Cheng
2019, 14(5): 28-35. doi: 10.19693/j.issn.1673-3185.01457
Abstract:
  Objectives  In order to investigate the internal mechanism of the zinc-nickel single flow battery during its operation,   Methods  a two-dimensional transient model for a second generation zinc-nickel single flow battery was established taking into account of the momentum and mass transfer, charge conservation and reaction dynamics equations. The finite element method was used for coupling calculation and the distribution of the flow and concentration inside the battery were analyzed. The calculation results were verified through experiment. On this basis, the effects of the electrolyte flow rate and ion concentration were studied.  Results  The results show that the electrochemical reaction is more intense at larger flow rate. For every 0.5 times increase(or decrease) of flow rate, the hydroxide ion concentration interval decreases(or increases) by 36%-41%, and the zinc ion concentration interval increases(or decreases)by 6.5%-6.6%. The ion concentration distribution tends to be uniform at a larger flow rate, while changing the initial ion concentration has no effect on the uniformity of concentration distribution. The discharge voltage increases by 27 mV on average when the initial hydroxide ion concentration increases by 22%, while the larger initial zinc ion concentration is not conducive to improving the discharge performance of the battery.  Conclusions  The model can accurately calculate the discharge performance of the battery and is suitable for the mechanism study of zinc-nickel single flow battery.
Numerical simulation for flow and heat transfer of side exhaust spray of marine diesel engines
Zhen Wang, Wei Wu, Xianyong Yang, Yifeng An, Yuanchun Liu
2019, 14(5): 36-41. doi: 10.19693/j.issn.1673-3185.01458
Abstract:
  Objectives  In order to solve the problem of evaluating the cooling performance of the side exhaust spray devices for marine diesel engines,   Methods  the Mixture multiphase flow model and evaporation-condensation model were coupled to simulate the flow and heat transfer process of spray in the exhaust pipe numerically. The distribution of exhaust temperature field, the variation of average sectional temperature along the exhaust pipe and the pressure loss under different cooling water flow ratio were obtained and analyzed.  Results  The simulation results show that, under spraying conditions, the high temperature zone in the exhaust pipe is conical due to the compressing of water as well as the gas-water mass and heat transfer. With the increase of the cooling flow rate ξ, the range of the high temperature zone is gradually narrowed. Along the exhaust pipe, the exhaust mixing temperature drops sharply from the dimensionless downstream distance χ=0.1 to χ=0.4, and afterwards, the temperature change slows down. The relationship between the total pressure loss and the cooling water flow rate is non-monotonic, and the influence on the exhaust resistance is small.  Conclusions  The results can provide quantitative support for the optical design of the side exhaust spray devices.
Study on multi-spectral inversion of temperature and soot concentration in flames
Qi Zhang, Mengting Si, Dongxu Wang, Anzhen Wang, Can Li, Zhen Wang, Zixue Luo, Chun Lou, Qiang Cheng
2019, 14(5): 42-48. doi: 10.19693/j.issn.1673-3185.01413
Abstract:
  Objectives  In order to accurately understand the temperature inside the flame and the distribution of soot concentration,  Methods  the distribution of the two-dimensional temperature and the soot volume fraction inverted from the spectral intensity image of the flame was studied using a hyper-spectrometer. Firstly, a hyper-spectrometer was used to capture the laboratory's vinyl laminar diffusion flame to obtain a high-resolution image containing multi-spectral information. Then, the wavelength in the image was analyzed and screened, the multi-wavelength radiation intensity information was obtained by calibrating the blackbody furnace, and the two-dimensional distribution of the flame temperature and the soot volume fraction was obtained by inversion.  Results  Comparing the obtained flame temperature with the results from other literature, the maximum temperature deviation is 2.77%, and the results are in good agreement,  Conclusions  indicating the accuracy of the distribution of temperature and soot volume fraction.
Nonlinear vibration characteristics of marine propulsion shafting under bending-longitudinal coupling effect
Peng Xu, Donglin Zou, Fangrui Lü, Na Ta, Zhushi Rao
2019, 14(5): 49-57. doi: 10.19693/j.issn.1673-3185.01389
Abstract:
  Objectives  The propulsion shafting system of large ships usually has the characteristics of long shafting, large span, and small slenderness ratio. Therefore, there is often elastic coupling effect between the bending deformation and longitudinal deformation, which is easy to cause abnormal vibration of the shafting, and affect the safe and stable operation of the shafting system. In order to study the nonlinear vibration characteristics of the shaft under bending-longitudinal coupling effect,  Methods  the nonlinear vibration equations of the propulsion shafting under bending-longitudinal coupling effect were derived by using the principle of variation, and then solved by numerical methods such as Finite Element Method(FEM)and shooting method and by approximate analysis method such as multi-scale method. Then the influence of bending-longitudinal coupling effect on the nonlinear vibration characteristics of shafting was analyzed and compared.  Results  The results show that the bending-longitudinal coupling effect causes complex vibration phenomena such as multi-frequency response, jumping phenomenon and energy transfer in the shafting response, and increases the natural frequencies in the bending and longitudinal direction of the shafting.  Conclusions  The study in this paper can provide reference for engineering design of large ship propulsion shafting.
Study on vibration-reduction performance of water-lubricated stern bearing with fluid-saturated perforated slab
Yong Jin, Junxin Kuang, Xiangyu Tian, Kunsheng Lao, Wu Ouyang, Zhenglin Liu
2019, 14(5): 58-63. doi: 10.19693/j.issn.1673-3185.01402
Abstract:
  Objectives  As the first element to support the shaft and transfer the vibration, water-lubricated stern bearing becomes an important part of ship shafting. To enhance its dynamic performance on vibration and noise reduction,  Methods  a fluid-saturated perforated slab was designed. Based on the theory of fluid-structure interaction, the modal analysis and harmonic response analysis on conventional water-lubricated stern bearings and the water-lubricated stern bearings with fluid-saturated perforated slab were carried out by using the finite element analysis software ANSYS to analyze the influence of the fluid-saturated perforated slab.  Results  The simulation and test results show that the design of the fluid-saturated perforated slab can effectively reduce the vibration amplitude of stern bearing.  Conclusions  The research results has certain guiding significance for the improvement of the performance of stern bearing.
Analysis on propulsion shafting deformation characteristics of underwater vehicle under various condtions
Tongquan Yu, Tianyun Li, Shengchao Liu, Xiang Zhu
2019, 14(5): 64-69. doi: 10.19693/j.issn.1673-3185.01456
Abstract:
  Objectives  In order to study the laws of the propulsion shafting deformation and variation of the bearing load of a underwater vehicle under various conditions,  Methods  a mixed finite element model of the shaft system and the underwater vehicle was established, with a underwater vehicle as the research object, to which the realistic load and boundary conditions were applied under three conditions including on the slipway, at the pier and underwater to calculate the hull deformation respectively and the deformation of the bearing and the bearing load were extracted. Taking the connecting line of the bearing 1 and bearing 3 as the reference line, the relative deformation of the bearing under three conditions was obtained.  Results  The analysis results show that, for this underwater vehicle, the relative deformation of the centerline of the shaft system, its size and the changing trend of the bearing load are different under the conditions from the slipway to the pier and then to the underwater; the initial deformation of bearing 2 of the shaft system on the slipway is preset to be 0.090 9 mm upward, so that the shaft system is in ideal state on the underwater.  Conclusions  The study in this paper can provide reference for the subsequent shafting alignment.
Body force-based method for determining flow velocity of sea water artesian circulating system
Kang Chen, Zhichong Yao, Endong Zhou, Bin Xia
2019, 14(5): 70-76. doi: 10.19693/j.issn.1673-3185.01480
Abstract:
  Objectives  Establish a method capable of quickly calculating the flow velocity of an artesian circulating system, in order to optimize and compare multiple design schemes for key components of the sea water artesian circulating system.  Methods  Numerical simulation of the sea water artesian circulating system of a ship is done by using the RANS method and the SST k-ω turbulence model. Body force is used instead of main components to do numerical analysis. A method for finding the intersection point by using system characteristic curve and component performance curve is proposed, to identify the flow velocity points of sea water artesian circulating system.  Results  By comparing the operating condition points obtained by the body force method with those obtained by the component-hull combined calculation method, the calculation accuracy of body force is verified, so as to determine the flow velocity of the sea water artesian circulating system. The body force method is more convenient and less computationally intensive than the combined calculation method, therefore the body force method is more suitable for multi-scheme simulation analysis on system components.  Conclusions  The body force method can simplify the numerical simulation calculation and provide a reference for predicting the flow velocity and flow of the artesian circulating system of the ship.
Flow analysis and uniformity evaluation of the exhaust pipeline of a marine diesel engine
Benke Li, Bingyang Huang, Yanhua Li, Fucheng Nie, Xiaoming Ye
2019, 14(5): 77-84. doi: 10.19693/j.issn.1673-3185.01404
Abstract:
  Objectives  In a marine diesel engine, the SCR reactor's NOx conversion efficiency is effected by the flow field uniformity at the inlet. In order to optimize the design of the exhaust pipeline of the diesel engine and the improve the SCR reactor's conversion efficiency, the establishment of a reasonable evaluation system for the flow field uniformity at the inlet has great significance.  Methods  Based on the exhaust pipeline of a marine diesel engine, the flow properties of the exhaust pipeline were analyzed under the rated condition. Based on these results, the flow field uniformity at the inlet of the SCR reactor was evaluated by different evaluation indicators. Then, the otherness and applicability of different evaluation indicators were analyzed and compared.  Results  The results show that, the pressure loss at the bending and abrupt parts of the pipeline accounts for about 20% of that of the exhaust system, and the bending in front of the entrance of the SCR reactor has a great influence on the flow field uniformity of the entrance with the local maximum non-uniformity as high as 19.96%.  Conclusions  It can be concluded that, the inlet face of the SCR reactor should be kept at a distance from the bending and abrupt parts to improve the flow field uniformity at the inlet, and the uniformity index γ and the local maximum non-uniformity δ can more effectively evaluate the flow field uniformity at the inlet of the SCR reactor in the exhaust system of the marine diesel engine. The study in this paper provides an important reference for the reasonable evaluation of the uniformity of the flow field.
Analysis and optimization of resistance characteristics of submarine snorkel air-intake valve
Haibin Hu, Rui Zhou, Zhe Zhou, Yijun Liu
2019, 14(5): 85-89. doi: 10.19693/j.issn.1673-3185.01547
Abstract:
  Objectives  It is important to optimize the structure of the air-intake valve for submarine snorkel and reduce air intake resistance, which is of great significance to submarine energy saving and working safety.  Methods  The CFD method is used to simulate the resistance characteristics of the air-intake valve, and the accuracy of the calculation results is verified by experiments. The two parameters flapper stroke and the intake angle are adjusted and analyzed, and the related rules between the air-intake valve resistance and the structure are obtained.  Results  The research results show that the pressure loss of the air-intake valve gradually decreases with the increase of the flapper stroke. When the flapper stroke h is greater than 244 mm, continuing to increase the flapper stroke does not contribute much to the reduction of pressure loss. When the intake angle θ is greater than 65°, the air-intake valve pressure loss will rise sharply; when the intake angle is less than 65°, the angle change will have little effect on the pressure loss.  Conclusions  The research shows that the flapper stroke and the intake angle have important influence on the air-intake valve resistance characteristics. By structural optimization, the intake resistance of the air-intake valve is significantly reduced, and the results can be guidance for engineering design.
Ship Design and Performance
Influence of multi-legged pose of the deep-sea crawling-swimming vehicle on the stability during cruising
Kang Zhang, Lei Wang, Wenjun Leng, Hong Chen
2019, 14(5): 90-97. doi: 10.19693/j.issn.1673-3185.01500
Abstract:
  Objectives  The deep-sea Crawling-Swimming Vehicle(CSV)is a new type of underwater robot, of which the multi-legged pose will change the distribution of the surrounding flow field and its center of gravity.  Methods  Based on the structural characteristics of the CSV, i.e. left-right symmetry, front-back approximate symmetry and up-down asymmetry, the maneuvering vertical plane motion equation of CSV was established and the corresponding stability criteria and critical speed were obtained. The hybrid mesh was used to compute the hydrodynamic coefficients of CSVs' pure heaving motion and pure pitching motion, and the results of computation were compared with the experimental results. According to the stability criterion, the static stability and dynamic stability of CSVs in three poses including the longitudinal expansion pose, lateral expansion pose and landing pose were judged, and main influence factors of motion stability were analyzed.  Results  The results show that CSVs in all three poses are in the state of static instability and relative dynamic stability. The design speed is lower than the critical speed, which can satisfy the requirement of linear stability. The static stability mainly depends on the position derivative related to vertical force. The static stability in lateral expansion pose is the best, while that in landing pose is the worst. The dynamic stability mainly depends on the position derivative related to vertical force, the initial height of stability center and the structure layout. The dynamic stability in lateral expansion pose is the worst, while that in landing pose is the best.  Conclusions  The hydrodynamic and stability laws of CSVs' multi-legged pose can better guide the design of control system and make it run safely.
Simulation analysis tentative scheme of drag reduction by additives in water cannon system
Peng Lin, Yimin Gao, Weihua Cai, Yijun Chen, Hongchao Chen
2019, 14(5): 98-105, 118. doi: 10.19693/j.issn.1673-3185.01430
Abstract:
  Objectives  In order to increase the range and flow rate of the water cannon system, drag reduction additive was introduced.  Methods  Firstly, the experimental results showed that the typical drag reduction additive was also effective for seawater system. Secondly, the hydraulic model of the water cannon system was established. Finally, an automatic two-stage drag reducer injection system with slotted sieve holes was put forward. During the operation of the water cannon system, the mixing and injection of the drag reducer was carried out alternately, and the plunger pump was used to add the drag reducer with the corresponding flow.  Results  The simulation studies show that the additives can increase the range of the water cannon by about 20% and increase the flow rate by about 8% during 15 minutes utility enhancement period.  Conclusions  Turbulent drag reduction by surfactant additives can improve the range and flow rate of water cannon for a short time with great application potential for the law enforcement vessel.
Analysis on combustion characteristics of pool fire in the confined space with horizontal ceiling openings
Bing Chen, Shiqi Zhang, Xunxian Shi, Changhai Li, Shouxiang Lu
2019, 14(5): 106-111. doi: 10.19693/j.issn.1673-3185.01503
Abstract:
  Objectives  The confined spaces such as the ship's engine room usually has a horizontal opening at the ceiling, and the particularity of the position and shape of the opening results in a significant difference between the combustion characteristics of the fire in such space and those of the building fire. In order to understand the fire characteristics of the horizontal ceiling opening of the ship's engine room,  Methods  the combustion characteristics of the fire such as the flame-extinguishing characteristics, flame shape and combustion rate in the confined space fire with a horizontal ceiling opening were experimentally studied by changing the ceiling opening area of the simulated test chamber and the size of the heptane oil pool,  Results  According to the reason for fire extinction, the development process of confined space fire are divided into "oxygen-lack extinguishing" mode caused by insufficient O2 concentration and "fuel-lack extinguishing" mode caused by depletion of combustibles. In the "oxygen-lack" mode, the flue gas mixture is entrained into the flame to participate in the combustion process. The critical O2 concentration for self-extinguishing of flame is between 13% and 16.5%, and the shape of the flame changes from a stable combustion shape to a state of being out of the oil pool and keeping moving. In the "fuel-lack" extinguishing mode, the flame is relatively stable in shape, and the combustion rate in the late combustion period is significantly increased due to boiling combustion.  Conclusions  The results show that the combustion characteristics of the fire in the confined space with ceiling opening are of great significance for understanding the development process of the cabin fire and provide theoretical support for the cabin fire suppression.
Influence of height of the air supply inlet on the smoke characteristics of the vertical single opening cabin fire during mechanical smoke exhaust
Jinshui Qiu, Guanglu Ren, Boyun Liu, Rumu Chen
2019, 14(5): 112-118. doi: 10.19693/j.issn.1673-3185.01542
Abstract:
  Objectives  In order to rationally formulate the smoke exhaust tactics and improve the smoke exhaust efficiency,  Methods  the smoke characteristics of vertical single opening cabin were studied by building a full-scale fire experimental platform. By setting different opening heights, the burning rate of fire source, and the visibility and temperature of the cabin during negative pressure smoke exhaust were measured and calculated. According to the measured heat release rate of the fire source, the temperature peak values of the experimental and simulated cabins were compared and analyzed by Fire Dynamics Simulator(FDS).  Results  It is proved that the height of air supply inlet should be set at about one-half of the total height under mechanical smoke exhaust conditions, at which height the visibility and temperature of the cabin decrease more rapidly.  Conclusions  The results of this paper have certain guiding significance for the formulation of mechanical smoke exhaust tactics in the vertical single opening cabin fire, and have also proved the reliability of FDS under such fire conditions.
Design and realization of a nearby lightning-electric field environment simulator
Ke Wang, Yantao Duan, Lihua Shi, Ruitao Huang, Hailin Chen
2019, 14(5): 119-123, 158. doi: 10.19693/j.issn.1673-3185.01498
Abstract:
  Objectives  Lightning can be extremely harmful to ships on the open seas. Especially with the large-scale application of electronic and electrical equipment and closed integrated masts, the lightning indirect effect on ships is becoming increasingly serious. In order to effectively carry out the lightning indirect effect test for shipborne electrical and electronic equipment,  Methods  a kind of nearby lightning-electric field environment simulator based on the principle of Marx generator was designed and realized in this paper. The simulator realized the peak cut-off of the impact high voltage by using the adjustable single chopping sphere gap, and established a simulated nearby lightning-electric field environment through the high voltage plate and the conductive ground plane.  Results  The test results show that the device has a cut-off time of less than 2 μs and a drop time of less than 0.09 μs, which can produce a pulsed electric field environment that meets the requirements of GJB 1389A-2005.  Conclusions  This paper can provide equipment support for the research on the indirect effect of the nearby lightning strokes on system electronic and electrical equipment based on GJB 8848-2016.
Ship Structure and Fitting
Study on theoretical calculation of quasi-static pressure for explosion in confined space
Weizheng Xu, Weiguo Wu
2019, 14(5): 124-130. doi: 10.19693/j.issn.1673-3185.01368
Abstract:
  Objectives  The process of explosion in confined space involves not only the propagation and reflection of shock waves, but also complex afterburning effect. The afterburning effect not only enhances the shock wave intensity, but also has a great influence on the final quasi-static pressure. In order to give a prediction of the quasi-static overpressure for explosion inside confined space,  Methods  a theoretical model for calculation of the peak valve of the quasi-static overpressure for confined explosions considering afterburning effects was proposed based on the analysis of chemical reactions and the law of conservation of energy. The results calculated by the model were then analyzed and compared with the literatures' as well as the empirical formulas' to verify the reliability and correctness of the proposed model.  Results  The results show that, the peak value of the quasi-static overpressure calculated by theoretical model is in good agreement with the results of the experimental measurement and from the empirical formulas in the literature; the Anderson's empirical formula is inapplicable to the confined explosion condition in case of a small mass volume ratio of less than 0.5 kg/m3, and the formula given in the reference [8] may not be extrapolated to the confined explosion conditions with a large ratio of greater than 8.87 kg/m3.  Conclusions  The study in this paper can provide a better understanding of the physical mechanism of the contribution of afterburning effect to quasi-static pressure, and provide some reference and guidance for the design of explosion-resistant structures and damage assessment.
Analysis on the damping characteristics of resonance changers based on the wave theory
Liangwei Li, Yao Zhao
2019, 14(5): 131-137. doi: 10.19693/j.issn.1673-3185.01445
Abstract:
  Objectives  Resonance Changer (RC) is an effective vibration damping device, which receives much attention in the field of longitudinal vibration control of marine shafting. As the RC's damping effect is closely related to the internal structural parameters,  Methods  an analytical formula of sound pressure propagation in RC was derived based on the wave theory, and the physical relationship between the internal structural parameters and its vibration mechanism was constructed for engineering design. Then, the influence of design parameters of RC's external pipes and cavity on system insertion losses and sound pressure level in broad band as well as the sensitivity were analyzed.  Results  The results show that, RCs can control the resonance peak of the main system well at its natural frequency.  Conclusions  Attention should be paid to the external pipe size of RCs when considering the feature line spectrum suppression, and to the external cavity size when considering the overall control of sound pressure level in broad band.
Design and study on dynamic vibration absorber of fluid-conveying pipes based on the receptance method
Lin Zhang, Huafeng Li, Yong Chen, Tao Zhang, Yangjian Ding
2019, 14(5): 138-144. doi: 10.19693/j.issn.1673-3185.01394
Abstract:
  Objectives  The fluid-conveying pipes may vibrate under external excitation. In order to reduce the vibration of the fluid-conveying pipes and study the vibration-reduction characteristics of the Dynamic Vibration Absorber(DVA),  Methods  the receptance matrix of the multi-degree-of-freedom (DOF)system of the additional spring-mass system was derived based on the passive modification method in the receptance method, and the zero assignment of the target DOF in the multi-DOF system was performed to suppress the corresponding vibration under the target DOF. On this basis, a DVA was designed and applied to the fluid-conveying pipes for experiments to verify its vibration-reduction effect.  Results  The results show that the designed DVA can well absorb the vibration at the target frequency, and the vibration reduction is better for a larger tuned mass when the target frequency is the same.  Conclusions  Such DVA is convenient to install and has a wide application range, which can provide a certain reference for pipe vibration reduction research.
Weapon, Electronic and Information System
Optimal scheduling of aviation support resources for carrier based aircrafts based on integer linear programming
Dali Tan, Yunfei Wang, Lianfei Yu, Cheng Zhu
2019, 14(5): 145-151. doi: 10.19693/j.issn.1673-3185.01493
Abstract:
  Objectives  In order to optimize the scheduling of the aviation support resources for carrier based aircrafts,  Methods  a mixed integer linear programming model for optimal scheduling of aviation support resources was established based on integer linear programming method and according to the serial, parallel and flexible characteristics of the carrier based aircraft group's aviation support process as well as the take-off sequence of the carrier based aircraft. The mixed integer linear programming solver of CPLEX and the improved differential evolution algorithm were used to solve the resource scheduling model. Taking the support process of Gerald R. Ford-class aircraft carrier based fleet as an example, the simulation calculation was carried out.  Results  The calculation results show that both the mixed integer linear programming solver of CPLEX and the improved differential evolution algorithm can be used to solve the problem. There are differences in solving accuracy and convergence speed. The calculation method needs to be selected according to actual output scale and computing demand.  Conclusions  The optimal scheduling model of aviation support resources can effectively guide the optimal scheduling of aviation support resources.
Spatial positioning method based on visual measurement for carrier-based aircraft
Jiaming Liu
2019, 14(5): 152-158. doi: 10.19693/j.issn.1673-3185.01470
Abstract:
  Objectives  The spatial position of carrier-based aircraft on the deck is required before take-off. Visual measurement is a high-precision and high-efficiency automated measurement method.  Methods  Therefore, a spatial positioning scheme for the carrier-based aircraft based on visual measurement is proposed in this paper. Firstly, the "Visual Measurement System-Deck Plane" relative position calibration method is introduced; secondly, based on the collinear relationship of "Visual Measurement Camera-Imaging Center-Fuselage Cooperation Logo", the position of the cooperation logo relative to the visual measurement system is calculated; finally, on this basis, the fuselage fixed cooperation logo is identified as a position transfer relay station to obtain the non-visual environment "Visual Measurement System-Airborne Inertial Navigation" transfer measurement model.  Results  The results of the visual measurement experiments show that the target spatial positioning result based on visual measurement is better than 0.3 m.  Conclusion  This scheme is expected to enable more carrier-based aircraft sorties to obtain spatial positioning information with higher precision before take-off.
Analysis on convergence time of gyrocompass azimuth alignment
Dongxu He, Lei Ge, Xin Zhang, Xinle Zang
2019, 14(5): 159-166. doi: 10.19693/j.issn.1673-3185.01522
Abstract:
  Objectives  In order to research the convergence characteristics and parameter setting of compass azimuth alignment better, and analyze the influence of gyro constant drift and initial azimuth error on the convergence time of gyrocompass azimuth alignment,  Methods  the frequency domain response of gyro constant drift and initial azimuth error in the system was obtained by using the designed gyrocompass azimuth alignment system. Then the time domain response function was obtained by inverse Laplace transform, and the convergence time of the time domain function was analyzed.  Results  The analysis results show that the convergence time of gyrocompass azimuth alignment is related to the designed second order damped oscillation period, and is also related to the gyro constant drift and the initial azimuth misalignment. The convergence of gyrocompass azimuth alignment is judged by the error band of 0.01°. When the gyro drift is less than 0.05(°)/h, the gyrocompass azimuth alignment will converge in 0.9 damped oscillation periods at most. When the initial azimuth misalignment is less than 5°, the gyrocompass azimuth alignment will converge in 1.4 damped oscillation periods at most. The smaller the two factors are, the faster the gyrocompass azimuth alignment converges. When both of them work together, the initial azimuth error plays a major role in the control of the convergence time, and the gyro constant drift has a little influence on the convergence time. At last, the correctness of the analysis results in this paper is verified by numerical simulation.  Conclusions  The analytical method in this paper provides a theoretical reference for controlling the convergence time of the gyrocompass azimuth alignment and the parameter setting.