针对某型船板式冷却器B10海水管路频繁穿孔漏水问题,本文基于故障树分析理论,以故障海水管路的腐蚀环境、腐蚀形貌和腐蚀机理为层次,将可能导致海水管路穿孔漏水的各种因素作为底事件列出,通过逻辑联系形成上述问题管路的故障树模型.在逐一分析故障树各项底事件的发生原因和典型表现后,将故障原因定位为B10管路与冷却器钛合金板片之间发生异种金属电偶腐蚀,并进行了原理复现,以验证分析的正确性,最终提出包括增加电绝缘组件在内的一系列治理措施,在船上实施后,取得了较好的治理效果.该分析方法 可为各类舰船海水管路腐蚀问题的分析定位和治理防护提供借鉴.

随着红外探测技术的发展,水幕成为舰船红外隐身研究的焦点,而对于水幕降温与水雾遮蔽两种水幕效应对红外探测特性的影响及其内在的物理机制目前尚未形成统一的认识.针对舰船 8～14 μm波段的红外辐射问题,基于典型的壁式喷嘴建立壁式喷头试验系统,研究了不同喷射距离、不同喷射总流量以及不同温度钢板对壁式喷头的红外降温特性的影响.试验结果表明,当目标钢板处于中空区和中空区与覆盖区交界,红外降温速率分别为2.03℃/min和3.31℃/min,处于覆盖区时,喷射存在非重叠区和重叠区,非重叠区降温速率最大为 6.18℃/min,其同半径距离下的重叠区降温速率为 6.54℃/min,且此时重叠区的红外降温时长为 40 s,比非重叠区缩短了 32 s.喷射总流量的增加对钢板的降温表现出明显的增益性,并且钢板初始温度越高,壁式喷头对其的降温速率越快.此外,水幕内外的钢板温差最大可达 8.49℃,表明壁式喷头形成的水幕喷淋能有效遮掩钢板表面温度,降低舰船表面的红外可探测性,实现水幕喷淋隐身.该研究结果可对提高舰船的红外隐身性能提供技术参考.

为满足国际海事组织(IMO)最新公约要求,国际航行船舶需加装压载水处理装置防止生物入侵,所加设备要与船舶进行适应性匹配.根据大型舰船使命任务需求及压载水系统特点,结合压载水处理装置的安装要求,从管路系统改造设计和控制逻辑设计等方面对压载水处理装置加装的适应性进行分析,提出并详细论述压载水处理装置加装设计流程和方案.该方案施工工艺简单,在实际工程中得到顺利实施.实践结果表明,所提方案合理可行,满足相关规范要求,具有良好的建造经济性.

The trans-critical transition of multi-component sprays under the ECN Spray-A conditions has attracted extensive interest. However, the drastic change of critical points of multi-components makes this controversial. In this study, the trans-critical transition of sprays before and after the end of injection is evaluated by numerical methods, and new findings have been obtained. First, the robust and accurate thermodynamic equilibrium solver and multi-component droplet evaporation model were developed and implemented into the OpenFOAM. These models have been validated against the measured phase change diagram and isolated droplet evaporation rate. Then, the mixture critical temperatures of n-dodecane/nitrogen and multi-component diesel/nitrogen were calculated under a wide range of pressures based on the thermodynamic equilibrium solver. The mixture critical temperature decreases almost linearly with the increase of the pressure. Following that, extensive sprays of n-dodecane and multi-component diesel under high temperature and pressure conditions were simulated, and the predicted spray liquid penetrations were validated against the experimental data. The results found that the dilute sprays after the end of injection are more prone to transition to the supercritical mixing regime, while the trans-critical possibility of dense sprays before the end of spray decreases due to the cooling effect of extensive evaporation. Finally, the trans-critical transitions of multi-component diesel sprays before and after the end of injection were evaluated and compared with those of n-dodecane sprays. Due to the low mixture critical temperature and evaporation rate of diesel, its sprays are more likely to transition to the supercritical regime. Therefore, it can conclude that the dilute sprays after the end of injection cannot represent the thermodynamic state of dense sprays. Moreover, the multi-component diesel and n-dodecane sprays follow a different trans-critical transition pathway.

Large-scale marine equipment will overheat if it works for a long time and a cooling system is necessary to be established to ensure that the equipment works in a safe range of temperature. To meet the cooling requirements of a large-scale marine equipment, a model of seawater cooling system is established in FloMaster, and simulations under dynamic conditions are conducted. According to the temperature of the coolant (glycol solution) in the front or back of the room of the heat exchanger, the pump speed or valve opening is changed to realize automatic control of seawater flow. Three control schemes are proposed, and the control effects are evaluated by the response characteristics and operating characteristics of the system under variable working conditions using the FloMaster-Simulink co-simulation method. The results show that when the pump speed is controlled by both the open loop and closed loop, the best control effect and lower energy consumption can be achieved.

A transcritical multi-component evaporation and micro-explosion sub-model is suggested to investigate the micro-explosion of blended ethanol-diesel droplets under diesel engine-like conditions. A homogeneous theory is used to qualitatively predict the bubble generation, and the subsequent bubble growth leads to the final explosion. The evaporation rate under subcritical state is calculated by a multi-component diffusion sub-model along with an isothermal-isobaric flash. The finite thermal conduction and mass diffusion equations are solved inside the multi-component droplets. The transcritical transition is defined by the time instant that the droplet surface attains the mixture critical temperature, then the finite regression rate is controlled by the thermal diffusion, and the critical mixing surface moves continuously inward. The suggested model is validated against the experimental data. Based on the numerical results, the heat transfer rate in ambient and the superheat limit are found to be the predominated factors on the micro-explosion under low pressures. However, with accelerating pressure, the net result of competition among the evaporation rate, heating rate, transcritical transition, as well as the bubble growth rate determines the micro-explosion for small micron droplets (< 24 mu m). When the ambient temperature is higher than 1000 K, the enhanced regression rate caused by the transcritical transition makes the droplet lifetime too short to explode. Finally, the suggested sub-model is implemented into the OpenFOAM code. The spray of blended ethanol-diesel under diesel engine-like conditions is simulated, and the occurrence of micro-explosion is confirmed and found to show large effects on the spray characteristics.

The transcritical transition of the nonpolar hydrocarbon and highly polar alcohol mixtures from the subcritical to supercritical regime has not been yet well understood. In the present paper, based on molecular dynamics simulation, the nonequilibrium evaporation and transcritical transition processes of the n-heptane/ethanol mixtures are comprehensively investigated under various ambient conditions, and the development of the vapor-liquid interface is deeply analyzed. Under the sub critical condition, the increased ethanol concentration elevates the evaporation rate because of the decreased vapor pressure and increased thermal conductivity. However, under the supercritical condition, the effect of ethanol addition on the mixture temperature becomes slight due to the decreased difference of thermal conductivity between ethanol and n-heptane, but the preferential diffusion of ethanol is observed because of its higher diffusivity. In addition, it is found that the increase of ethanol broadens the vapor-liquid interface at moderately high pressure due to its higher volatility and thermal conductivity. Since the interfacial thickness affects the interfacial resistivities and evaporation characteristics in the hydrodynamic framework, the thickened interface indicates the more significant nonequilibrium effect in the vicinity of interface for the mixtures with large amounts of ethanol. Finally, the transcritical transition time decreases rapidly with the increased ambient pressure, and the descent gradient gradually decreases with the further increased pressure because the thermal conductivity becomes less sensitive to the pressure.

Spray simulations involve much effort in calibrating the empirical constants in the break-up model case-by-case to obtain good predictions for the target experiments. Most calibrations are based on the ideal-gas evaporation model for the evaporating sprays even under high-pressure conditions. The effect of droplet evaporation on the calibration of the break-up model is first evaluated, and an accurate multi-component evaporation model is suggested to reduce the dependency of the break-up constants on the ambient conditions and fuel types. First, a multi-component evaporation model with the real vapor-liquid equilibrium is introduced and implemented into the OpenFOAM-v6. Then, extensive sprays under a wide range of conditions are simulated by the typical ideal- and suggested real-gas frameworks, respectively. Since the ideal-gas evaporation model underestimates the droplet evaporation rate, especially for the multi-component sprays under high pressures, calibrating the breakup constants is needed to compensate the errors induced by the ideal-gas evaporation model. Even though the spray liquid penetration could be well reproduced through calibrating the constants in the KH-RT model, the droplet size is seriously underestimated. In contrast, the real-gas evaporation model can accurately predict the droplet evaporation rate, and the dependency of break-up constants on the ambient conditions is reduced. Finally, the comparison of n-dodecane and multi-component diesel sprays confirmed that the break-up constants for the multi-component spray simulation are more sensitive to the ambient conditions, and an accurate multi-component evaporation model can reduce this sensitivity.

为了满足安全返港理念下的船舶设计要求,通过对某特种用途船实船设计案例的分析,按照设计流程剖析安全返港设计理念如何在船舶设计流程中体现.针对船舶动力系统设计提出满足安全返港要求的非对称式机舱布置型式,并在船舶保障系统设计中提出跨层式总管设计方法,还总结了多种通用的安全返港船舶设计方法.这些设计方法能满足安全返港规范对系统的设计要求,且其实用性和可靠性已得到实船验证,可为类似船型的设计提供参考.

：Stealth performance is an important combat skill indicator for contemporary ships, thus affecting the vitality of a ship directly.Infrared stealth is one of the main components of ship stealth and is one of the key points of stealth design of advanced warships in various countries.In order to study how the infrared stealth performance of a ship may be improved, its infrared point source characteristics for the 3-5 m band and its infrared face source characteristics for the 8-14 m band are analyzed.The infrared radiation suppression principle and design method commonly used in ships are evaluated for two kinds of infrared radiation sources.The study defines how various infrared stealth technologies can be effectively applied in ship design.This research can serve as a reference for the design of infrared stealth for a ship.

At present, water spray cooling is widely used in the fields of fire prevention and cooling as an economical and convenient method. In recent years, surface ships have been using water curtains for surface cooling and infrared stealth, which is becoming more and more common. The LECHLER nozzle used in the infrared stealth field of ships adopts the built-in type, featuring a mounting surface flush with the shell plate, which is suitable for ship stealth. It has a water pressure of 0.5Mpa and a water volume of 4m3/h, and the water spray covers a diameter of 7m. However, through observing the inside, the author found that there is a total pressure loss existing in many structures in the nozzle, which generally results in a loss of flow energy inside the nozzle, thereby reducing the spray coverage of the nozzle. In this paper, the structural optimization research of the nozzle is carried out, and the dual control conditions of inlet water pressure and water supply are proposed. The pressure loss and the coverage of water spray are analyzed by numerical simulation. The calculation shows that the total pressure loss is reduced from the original 47.5% to 10% with the optimized design. Under the premise of controlling the inlet water pressure and flow, the spray coverage is increased by 86.6%.

[Objectives] The high temperature gas discharged from the power systems of modern ships exerts a great influence on the reliable operation of high-precision electronic equipment on the deck and whether such operation units as carrier aircraft can operate safely. [Methods] The study of the temperature field above the deck of a certain type of ship is carried out using the numerical calculation software Fluent. Focusing on the classic wind direction and four different wind speeds, the motion of the high temperature gas and temperature distribution on the superstructure surface and three key sections is calculated and analyzed. [Results] The results show that in the 30 degree wind direction, Heliports No. 1 and 2 on the leeward side of the superstructure are always affected by high temperature gas, which poses a serious threat to safe takeoff and landing. At the same time, the superstructure area affected by the high temperature gas is greater at a lower wind speed, with a maximum affected area of 73 m2. [Conclusions] It is suggested that shipboard helicopters should avoid taking off and landing at Heliports No. 1 and 2 in the 30 degree wind direction. In addition, attempts should be made to avoid installing electronic equipment in areas greatly affected by high temperature gas.

为探索非轴对称静叶在压气机中应用的可行性及其对畸变流场的改善作用,采用非定常数值模拟方法,研究非轴对称静叶对均匀和畸变进口条件下压气机性能的影响,并对流场结构进行分析.结果表明:非轴对称静叶可以改善静叶端区流动,降低损失;畸变条件下,非轴对称压气机最高效率和压比高于轴对称压气机;非轴对称压气机稳定裕度较原型压气机有所提升.

为明确船舶货物转运通道内火灾的蔓延特性,利用FDS(Fire Dynamic Simulator)火灾模拟软件建立某船货物转运通道数值仿真模型并进行模拟仿真.根据仿真结果分析该通道内发生火灾时烟气的扩散情况,研究该区域温度及能见度的变化规律,获得通道内温度及能见度超出人员承受范围的时间.研究结果可为船舶发生火灾后人员疏散策略及消防预案的制定提供指导和理论依据.