生物柴油在船用低速机上的燃烧分析研究（英文）

To study the applicability of biodiesel in marine engines, this research investigated the performance, combustion characteristics, and emission characteristics of biodiesel(B100), diesel, and a 50% volume blend of the two fuels(B50) in a marine engine. This study was conducted on a 4-cylinder, 520 mm-bore, two-stroke, low-speed marine engine with a common rail fuel and exhaust gas charge system. The three fuels were tested at different loads from 25% – 100% with a step size of 25%. Results showe...     

高压共轨生物柴油混合燃料喷雾特性模拟研究

基于CONVERGE软件搭建了定容弹喷雾模型,采用试验和仿真相结合的方法对高压共轨生物柴油混合燃料喷雾特性进行研究,分析不同喷射压力、环境背压和喷孔直径下喷雾特性的影响规律。结果表明,燃油喷雾锥角在喷射压力和环境背压的关系规律上相同,喷射压力越高或者环境背压越大,喷雾锥角越大;喷射压力越大或者背压越低,燃油喷雾贯穿距越大,喷油压力为180 MPa时的喷雾贯穿距比120 MPa时的大8.75%,背压6 MPa时的喷雾贯穿距比2 MPa时的减小30%;喷雾贯穿距随喷孔直径的增大而增大,而喷雾锥角在前期受影响较小,趋于稳定时数值增大;油束前锋速度随着生物柴油含量的增加而增大;燃油喷射前期,喷油压力高的油束头部速度较大,喷射后期,喷油压力为130 MPa时的油束前锋速度比90 MPa时的小26.1%。     

生物柴油混合燃料预混合均一性实验研究

通过对生物柴油与0#柴油混合燃料B20(生物柴油体积含量为20%)的密度测试来进行生物柴油混合燃料预混合均一性实验研究。通过多种方法混合且在标定温度下进行试验,结果表明,生物柴油混合燃料B20的密度最接近于0#柴油的密度标准范围,混合均一性良好。     

纳米铝粉粒径对丁醇柴油基纳米流体燃料液滴蒸发特性的影响

通过丁醇柴油添加纳米铝颗粒,利用挂滴式实验装置研究纳米流体单液滴的蒸发特性.在蒸发炉内,比较含不同粒径为50、80、150 nm的纳米流体,环境温度分别为623、923 K.单液滴在923 K下的蒸发阶段可分为瞬态加热阶段、波动蒸发阶段和平衡蒸发阶段.而在623 K仅有瞬态加热阶段和平衡蒸发阶段;当环境温度为623 K时,液滴蒸发寿命随着纳米粒子的粒径增大而增大,且纳米粒子的加入抑制液滴的蒸发;环境温度为923 K下,粒子粒径为50 nm的纳米流体蒸发寿命最短.可见在高温下纳米粒子将促进液滴的蒸发,并且相对较小粒径的纳米粒子的促进作用更明显.     

缸内液喷LNG/柴油双燃料发动机燃烧特性研究

以L 21/31船用中速柴油机为原型,在不改变燃烧室结构的基础上将其改装成缸内液喷LNG/柴油双燃料发动机,利用AVL_FIRE软件展开三维数值模拟,研究此双燃料发动机的LNG替代率极限以及高替代率时的缸内燃烧及排放性能。研究结果表明：改装后双燃料发动机的LNG替代率极限为99.5%,当替代率大于99.5%时,LNG无法被引燃;在可以正常燃烧条件下,保持引燃柴油及液化天然气喷射正时和喷射时间间隔不变,随着液化天然气替代率的增加,液化天然气燃烧始点基本不变,缸内最大爆发压力和最高燃烧温度降低,NO、CO生成量和排放量降低。     

船舶醇类燃料发动机燃烧特性研究

目前阶段,高速发展的船舶行业一定程度上增加了对发动机的需求量。在船舶应用发动机航行的过程中,为保证与柴油机排放法规要求相适应,会借助多种处理方法,对发动机有害排放进行必要地控制。然而,柴油机所排放的有害氮氧化物以及微粒生成条件均存在诸多差异,且净化方法存在极大矛盾。在这种情况下,保证经济性的基础上减少柴油发动机氮氧化物以及微粒排放逐渐成为发动机领域的研究重点。特别是在资源与生态环境问题日益严重的情况下,醇类燃料得到了普及应用。本文结合当前国内能源资源的基本特点,新型清洁型代用燃料的发展可以不断改善船舶发动机燃烧特性,减少对于石油资源的依赖程度,更好地实现能源安全目标。     

缸内液喷LNG/柴油双燃料发动机燃烧特性

以L21/31船用中速柴油机为原型,在不改变燃烧室结构的基础上,将其改装成缸内液喷LNG/柴油双燃料发动机,利用AVL_FIRE软件展开三维数值模拟,研究此双燃料发动机的LNG替代率极限及高替代率时的缸内燃烧及排放性能。研究结果表明:改装后双燃料发动机LNG替代率极限为99.5%,当替代率大于99.5%时,LNG无法被引燃;在正常燃烧条件下,保持引燃柴油及液化天然气喷射正时和喷射时间间隔不变,随着液化天然气替代率的增加,液化天然气燃烧始点基本不变,缸内最大爆发压力和最高燃烧温度降低,进而降低NO、CO的生成量和排放量。     

直立圆柱体内孤立波载荷特性数值模拟（英文）

以三类内孤立波理论(KdV、eKdV和MCC)的适用性条件为依据,将内孤立波诱导上下层深度平均水平速度作为入口条件,采用Navier-Stokes方程为流场控制方程,建立了两层流体中内孤立波对直立圆柱体强非线性作用的数值模拟方法。结果表明,数值模拟所得内孤立波波形及其振幅与相应理论和实验结果一致,并且直立圆柱体内孤立波水平力、垂向力及其力矩数值模拟结果与实验结果吻合。直立圆柱体内孤立波载荷由波浪压差力、粘性压差力和摩擦力构成,其中摩擦力很小,可以忽略;对于水平力,其波浪压差力与粘性压差力量级相当,流体粘性的影响显著;对于垂向力,粘性压差力很小,流体粘性影响可以忽略。此外,直立圆柱体对内孤立波的波形及其诱导流场的影响很小,因此采用Morison公式和傅汝德—克雷洛夫力分别计算其内孤立波水平力和垂向力是可行的。     

钢带软管内压和弯曲研究（英文）

复合材料管已成为管道发展的热点和趋势。文中对钢带软管在同时受到内压和弯曲组合载荷作用下的力学性能进行了研究。基于建立的钢带软管的环向和径向力学平衡方程,提出了不同弯曲半径下该种类型管道的爆破压力理论计算方法。文中还进行了有限元数值模拟,并与理论计算结果对比分析,分析结果表明文中提出的爆破压力计算方法可作为此类管在同时受到内压及弯曲组合载荷作用下的通用算法,为解决此类工程问题提供重要参考。     

船用锅炉燃烧旋流器高温腐蚀和退化研究（英文）

The present paper investigated and analyzed swirler material consisting of mild steel which was subjected to service for the period of one year in a 30 MW marine boiler. Due to the presence of high temperatures in the furnace coupled with the corrosive marine environment swirler material showed accelerated degradation and material wastage. An investigation into the feasibility of manufacturing the existing swirler with an alternate material or coating the swirler material with a thermal barrier coating was undertaken. Based on their properties and performance, SS 304 and SS 316 were proposed as the replacement materials for the swirler. The other alternative of coating the existing swirlers with a form thermal barrier coating to observe for any improvement in their performance at elevated temperatures was also tested. Stellite, which is a Ni-Co based coating, was carried out on the MS samples and the same were exposed to same temperatures mentioned above. The performance of the available options was evaluated with respect to the grain structure of the material, the hardness value of the materials and deterioration at elevated temperatures. Investigation showed the proposed materials/ coatings like SS 304, SS 316 and Stellite coating revealed that SS 316 is the material best suited for high temperature application.     

聚氨酯夹层隔振特性及模型试验研究（英文）

The vibration isolation performances of typical hull structure with viscoelastic interlayer are analyzed according to wave theory,and the influences of interlayer Young’s modulus and length on the vibration reduction are discussed.The theoretical analysis shows that combination of polyurethane interlayer with blocking mass can enhance the vibration isolation performance and expand isolation frequency band.In order to verify the effectiveness of polyurethane interlayer,the model test of power cabin’s vibration is carried out.The test data shows that the reduction of 20–1 000 Hz variation acoustic level at hull shell is more than 5 dB.     

细长体出水空泡特性实验研究（英文）

Experimental studies are carried out with slender bodies vertically exiting out of the water using a high-speed camera. The mechanisms for the formation, development, and collapse of the cavity around the slender body are explored. The dynamic characteristics of the shoulder cavity and the trail cavity during the water-exit of low-speed bodies are analyzed for various water depths and initial velocities. The results show that the initial velocity has a great influence on the formation, development, and collapse of the cavity. The length and the thickness of the shoulder cavity vary non-linearly with the depth.     

螺旋桨空泡和噪声特性试验研究（英文）

本文通过螺旋桨空泡噪声模型试验,研究螺旋桨空泡和噪声特征,以及螺旋桨不同阶段空泡和噪声的关系,探究螺旋桨噪声产生及控制机理。建立了螺旋桨空泡和噪声同步测试方法,针对2400 TEU集装箱船螺旋桨开展模型试验。从螺旋桨模型试验结果分析得出:片空泡脱落形成梢涡空泡产生的噪声量级最高,且具有宽带特性,梢涡空泡噪声量级次之;模型状态下片空泡脱落形成梢涡空泡,以及独立的梢涡空泡引起的空泡噪声均在1 000 Hz附近存在明显峰值,对应实桨的峰值频率为50-60 Hz。     

使用LNG燃料的开放式轮渡安全系统设计（英文）

In this feasibility study, we investigate the viability of using Liquefied Natural Gas(LNG) fuel in an open type Ro-Ro passenger ferry and the associated potential challenges with regard to the vessel safety systems. We recommend an appropriate methodology for converting existing ships to run on LNG fuel, discuss all the necessary modifications to the ship's safety systems, and also evaluate the relevant ship evacuation procedures. We outline the basic requirements with which the ship already complies for each safety system and analyze the additional restrictions that must be taken into consideration for the use of LNG fuel. Appropriate actions are recommended. Furthermore, we carry out a hazard identification study. Overall, we clearly demonstrate the technical feasibility of the investigated scenario. Minimal modifications to the ship's safety systems are required to comply with existing safety rules for this specific type of ship.     

船用燃气轮机动力装置替代燃料的热力学分析（英文）

The marine shipping industry faces challenges to reduce engine exhaust emissions and greenhouse gases(GHGs) from ships, and in particular, carbon dioxide. International regulatory bodies such as the International Maritime Organization and National Environmental Agencies of many countries have issued rules and regulations to drastically reduce GHG and emissions emanating from marine sources. This study investigates the possibility of using natural gas and hydrogen as alternative fuels to diesel oil for marine gas turbines and uses a mathematical model to assess the effect of these alternative fuels on gas turbine thermodynamic performance. Results show that since natural gas is categorized as a hydrocarbon fuel, the thermodynamic performance of the gas turbine cycle using natural gas was close to that of the diesel case. However, the gas turbine thermal efficiency was found to be slightly lower for natural gas and hydrogen fuels compared to diesel fuel.     

船用燃料中芳烃浓度对粒子排放的影响研究（英文）

The fuel sulfur content in marine fuels has been regulated in Sulfur Emission Control Areas(SECAs) since January 2015. However, other fuel characteristics are also believed to have an impact on particle emissions, particularly on the number of particles emitted. This study investigates the impact of the content of aromatics in fuel. To achieve fuel blends with concentrations of aromatics similar to those found in marine fuel oils, i.e. 20%–30% by volume(%vol.), normal diesel oil(4%–5% vol. aromatics) is doped with a mixture of aromatics. Emission measurements are conducted in test-bed engine facilities and particle emissions over a wide size range are analyzed. Results show a decreased number of particles emitted(or not change) with an increase in the aromatic concentration in fuel. This is because there is a reduction in the cetane number of the fuel with an increased aromatic content, which effects the combustion process and results in decreased particle formation. However, when ignition improver is used to increase the cetane number, particle emissions remain at a lower level than for normal diesel oil; thereby emphasizing the presence of other factors in the formation of particles.     

圆盘水面弹跳过程运动特性数值研究（英文）

本文基于CFD方法对圆盘撞水弹跳过程的运动特性进行了研究,对三种典型撞水运动状态进行了模拟,数值结果与文献中的试验结果吻合良好。基于计算结果,获得了圆盘可以成功弹跳的初始参数组合范围。圆盘弹跳过程中,前方会产生一股射流,其脱离圆盘的射出速度可以达到入水速度的两倍左右。随着圆盘自旋速度的增加,圆盘受到的流体动力逐渐增加,但速度衰减也随之逐渐增加。相对较小的初始倾角和入水角总是有利于圆盘撞水后的弹跳,但过小的初始倾角可能会不利于连续多次弹跳过程。对圆盘连续弹跳过程的数值模拟结果表明,圆盘运动路线并非一直向前,而是受自旋影响运动方向有一定程度的偏转,圆盘第一次撞水弹跳的高度和距离远大于后面几次的弹跳过程。     

均布外压下球形封头屈曲特性研究（英文）

This study aims to experimentally and numerically examine the buckling performances of stainless steel spherical caps under uniform external pressure. Three laboratory-scale caps were fabricated, measured, and tested. The buckling behaviors of these caps were investigated through experiments and three numerical methods, namely, nonlinear Riks algorithm, nonlinear bifurcation, and linear elastic analysis. The buckling of equal-radius caps was numerically analyzed with different methods to identify their applicability under different wall thicknesses. The results obtained from the nonlinear Riks algorithm are in good agreement with the experimental results, which means the nonlinear Riks algorithm can accurately predict the buckling performances of spherical caps, including the magnitude of critical buckling loads and the deformation of post-buckling modes. The nonlinear bifurcation algorithm is only suitable for predicting the buckling loads of ultra-thin or large-span caps, and the linear buckling method is inappropriate for predicting the buckling of metal spherical caps.     

海事能源转型:未来燃料和未来排放（英文）

The lifecycle greenhouse gas(GHG) emissions(Well-to-Wake) from maritime transport must be reduced by at least 50% in absolute values by 2050 to contribute to the ambitions of the Paris Agreement(2015). A transition from conventional fuels to alternative fuels with zero or lower GHG emissions is viewed as the most promising avenue to reach the GHG reductions. Whereas GHG and toxic pollutants emitted from the use of fossil fuels(heavy fuel oil(HFO) and marine gas/diesel oil(MGO/MDO)) are generally...