30万t FPSO船体码头抗台系泊设计

针对30万t FPSO码头舾装周期长,船体主尺度大,而码头前沿可用长度较短,台风季节码头系泊不利的问题,为解决该船体的临时系泊要求,以一30万t FPSO码头系泊设计为对象,设计FPSO在常规工况和台风工况2种不同工况下的码头系泊方案,建立2种方案下码头系泊的计算模型,分析船舶在风、流载荷下系泊缆绳的受力规律和设计方案...     

采用车厢底部出风的变频热泵空调在低温地区大巴车辆上的应用研究

纯电动大巴空调冬季制热是目前行业普遍关注的焦点问题,受大巴空调厂家技术影响,大部分电动空调热泵制热在环境温度0℃左右将无法启动,所以目前行业冬季制暖主要采用燃油炉或PTC加热方式。燃油炉与PTC加热能耗高,严重影响整车续航里程。热泵大巴空调可实现-15℃正常热泵制热,补气增焓技术可实现-25℃正常热泵制热。另外,在冬季制热时,暖风从上部的风道往下吹,大部分热风下不去,造成了车厢上部温度高,脚部温度过低,非常影响舒适性。通过从上部风口引一些风道到脚部的方式,提高车厢底部的热风循环,提高车厢热泵制热的舒适性,从而验证了大巴车厢底部出风对热泵空调制热效果的影响。综合上述,对热泵空调在低温地区冬季热泵制热效果及节能效果进行对比测试,通过对比热泵空调和电加热器的温升速率、耗电量和舒适性等参数,可得知热泵空调升温速度快、温控精度高、耗电量少,变频热泵空调更舒适、更节能。     

电价在风能和太阳能装机容量较高的国家会更高吗?(2019年数据)

该文将欧洲、亚洲和美洲20个不同国家的国内电价(P)与2019年的总发电量、装机容量以及风能和太阳能提供的实际能源(间歇型能源,VER)的各种组合进行比较,发现各国国内电价与间歇型能源的人均装机容量之间存在正相关关系,但比过去报道的在欧洲的关系要弱一些.与各国国内电价相关性最强的是风和太阳能在额定容量下连续工作的最大可...     

流水槽对客车风阻影响的仿真及试验

基于某中型发动机后置客车,建立整车的仿真模型分析流水槽导致整车风阻增加的流动机理,在此基础上提出圆弧型流水槽结构,并通过仿真和整车等速油耗试验进行验证。     

斜拉索涡激振动的被动自吸吹气流动控制

圆形斜拉索长细比大、阻尼及刚度小，因而其经常发生风致振动，尤其是涡激振动。涡激振动是一种限幅振动，其发生风速较低，因而斜拉索经常发生涡激振动现象，为此提出一种被动自吸吹气流动控制措施来抑制斜拉索涡激振动。通过节段模型气弹试验得到，被动吸吹气控制方法在套环间距适当下使得斜拉索涡激振动区间变窄，甚至可以完全抑制其发生涡激振动。通过分析斜拉索节段模型表面压力分布，得到被动自吸吹气能大幅度降低压力脉动值和脉动风荷载；且模型背风面的平均压力值的平台区也有所提升，表明平均阻力也有所减小。频谱分析表明：此控制方法改变了旋涡脱落模式及脱落强度。最后由尾流速度剖面可得，被动吸吹气流动控制方法缩小了模型尾流区宽度，尾流中的速度脉动也极大降低。折算风速为5.99时，对尾流速度时程做频谱分析可得，吸吹气控制方法能抑制住无控圆柱模型尾流中周期性交替脱落的旋涡。套环控制方法应用于三维柔性索性索模型上，能极大地降低柔性斜拉索的前三阶涡激振动幅值，同时发现套环间距越小，控制效果越强。     

Effect of wind speed variation on the dynamics of a high-speed train

The severe shaking due to wind speed variation in high-speed trains has a negative impact on driving safety and riding comfort. It is difficult to solve this problem by directly applying civil engineering technology because of the actual conditions. Therefore, set up a reasonable train operation plan considering the wind speed variation under strong winds is very important. In this study, a multi-body simulation model of a CRH2 high-speed rail vehicle is constructed, and the overturning coefficient is set as the safety limit, we established a crosswind model on the basis of measured wind speed curves and investigated the effect of the rate of wind speed changes, the duration of maximum wind speed and the variation of wind speed in different amplitude on the dynamics of the high-speed train. Considering the most critical wind speed variation conditions, the characteristic wind curve is obtained, which can be used as a reference to set up a reasonable train operation scheme considering the wind speed variation.     

基于二极管箝位级联拓扑变流器的直驱风电用变流技术

直接驱动型风力发电系统需要全功率变流器作为与电网的接口，多电平变流器的应用得到了广泛关注。二极管箝位五电平级联H桥拓扑，结合了二极管箝位型多电平和级联H桥多电平的优势，只需较少的箝位二极管和独立直流电源，即可进一步提高输出电压等级；使用移相变压器和12脉波整流器作为输入电路.可以方便地应用在使用多相永磁同步发电机的直驱风电系统中。基于拓扑提出了消谐波SPWM和载波相移SPWM相结合的调制方法，能够方便地对二极管箝位级联拓扑进行控制，可以进一步提高等效载波频率，减小器件损耗和滤波器体积。仿真和实验结果证实了所采用的拓扑及其控制方法的有效性。     

凝汽式汽轮机转速调节的动态分析

针对船舶发电用凝汽式汽轮机转速的动态响应建立了数学模型，采用Matlab／Simulink软件进行了仿真计算，并运用该软件设计了汽轮机转速调节系统动态分析的图形用户界面，在一定的简化和假设基础上对汽轮机转速调节的动态特性进行了一般性分析及理论上的探讨。     

基于船用燃气轮机外特性的建模方法

针对动力系统稳态、动态特性研究,旨在预报快速性、操纵性和机动性这一特点,借助生产厂家的燃气轮机外特性曲线,先将图形数字化,然后在MATLAB/Simulink仿真环境下,运用二维线性插值法,二维非线性插值法,曲面拟合法,神经网络法分别对燃气轮机的外特性进行了数学建模。运用中值法对建模结果即数学模型进行了检验,比较了上述四种方法的优缺点,指出了每种方法使用中的注意事项,适用场合。上述建模方法亦适用于舰船动力装置其它部件外特性的建模与仿真。     

Wind-induced mesoscale circulation off the Ebro delta, NW Mediterranean: a numerical study

It is well known that the general circulation on the Catalan continental slope is dominated by a quasi-permanent southwestward geostrophic jet associated to the so-called Catalan front [Millot, C., 1987. Circulation in the western Mediterranean sea. Oceanol Acta 10, 143–149; Font, J., Salat, J., Tintoré, J., 1988. Permanent features of the circulation in the Catalan Sea. Oceanol. Acta 9, 51–57]. On the continental shelf, however, the flow is modified by the action of friction which enhances also other nonlinear interactions. Several authors have hypothesized that the shelf circulation is anticyclonic north of the Ebro delta [Salat, J., Manriquez, M., Cruzado, A., 1978. Hidrografia del golfo de Sant Jordi. Campaña Delta (Abril 1970). Investigación Pesquera 42 (2), 255–272; Ballester, A., Castellví, J., 1980. Estudio hidrográfico y biológico de las plataformas continentales españolas: I. Efecto de los efluentes de una planta de energía nuclear en el Golfo de San Jorge (Febrero 1975–Octubre 1976). Informes Técnicos del Instituto de Investigaciones Pesqueras 76, 70 pp.]. A quasi-3D finite element code based on the shallow-water equations has been used to explore the effect of several mechanisms which might be responsible for such a local circulation pattern, and in particular of wind. The obtained numerical results suggest that the basic anticyclonic structure of the mean flow is controlled by the bathymetry and that the clockwise-rotating mean flow pattern is not a permanent circulation feature. It is seen that the characteristic local wind stress fields—computed through interpolation of the records of a local network of meteo stations—may ‘enhance' or ‘delete' the anticyclonic gyre depending on the sign of their relative vorticity. According to the analysis of a 2-yr record of local wind data, the net contribution of wind events with a duration longer than 24 h is to reinforce the anticyclonic circulation (over 70% of these wind fields supply negative relative vorticity to the study area).