基于3种点焊模拟方式的帽型梁碰撞特性研究

帽型梁作为一种非常普遍的结构形式运用于不锈钢点焊车辆当中。利用有限元软件Ansys／Ls-Dyna分析了同一速度下3种不同点焊模拟方式对帽型梁变形过程、吸能特性以及法向力变化的影响。通过仿真结果与试验结果的比较,发现在保持其他条件不变的前提下,3种不同点焊模拟方式均能较好地模拟双帽型梁的屈曲变形情况,变形过程、吸能特性以及法向力变化曲线基本一致,为不锈钢点焊的整车碰撞仿真中点焊的模拟方式提供了可行性参考。     

振荡浮子式波浪能发电系统缓冲限位机构的设计分析

设计了一种适用于振荡浮子波浪能发电系统的限位装置,可防止因浮子振幅过大而造成系统损坏,同时起到防撞缓冲作用,保证系统的安全。首先阐述了系统的结构组成及设计过程,通过对比分析,确定了便于安装及拆卸的多弹簧均布缓冲形式;然后计算了不同波况下作用在浮子上的波浪力情况,得到随机波况下的最大波浪力;最后运用CATIA建立弹簧缓冲装置模型,仿真分析了弹簧的应力应变情况,并拟合得到弹簧的刚度,仿真结果表明,弹簧满足强度要求,能够实现缓冲限位的设计目标。     

机车吸能装置的研制

阐述了与机车车钩缓冲装置配合使用的吸能装置的总体设计、装车方案、主要技术参数、工作原理、仿真计算、样机试制及试验结果。     

越浪式波能发电装置的水力性能研究

越浪式发电装置的水力性能主要取决于装置的越浪量,对于越浪量的研究,以往文献的研究大部分集中于如何减少越浪对防波堤和海岸建筑的破坏,保障海上建筑的稳定。对于越浪式发电装置来说,最重要的就是研究如何使装置的越浪量达到最大,从而获得足够的能量。文章研究了在不同波况下装置的越浪量以及坡道压力分布。在试验水槽中对越浪式发电装置进行模型试验,通过分析试验结果,发现装置的越浪量基本符合Van der Meer越浪量模型,并给出了坡道在不同波况下受力的变化规律以及装置的水力效率。试验结果为研究越浪式装置的水力性能和结构稳定性分析提供了依据。     

自吸式飞灰取样器引射装置数值模拟

对自吸式飞灰取样器引射装置的工作原理进行分析,建立了简化的物理模型,并利用Fluent通用软件对引射装置进行数值模拟,研究了不同工况下烟气流量和被吸喷嘴喷口截面处与烟道内部形成压差的变化规律.模拟结果表明:在被吸喷嘴与拉法尔喷管进口距离d=18.5mm时,引射效率最佳.其研究结果为自吸式飞灰取样器引射装置的优化设计和现...     

一种多浮体铰接式波浪能装置的运动分析与俘获特性研究

基于线性势流理论，利用总模态法对多浮体铰接波浪能装置“海星号”在波浪中的运动开展水动力学系数计算；然后基于矢量力学建立多浮体刚体运动学方程，并结合几何约束条件开展动态响应计算，获得最优俘获效率和最优负载阻尼；最后比较并分析“海星”波浪能装置的多浮体俘获效率，获得“海星”多浮体做功的俘获特性。研究表明：“海星”波浪能装置的多浮体四向迎波设计可拓宽装置最优俘获频带宽度，提高装置整体俘获效率；正向迎波与背向迎波俘获波浪能方式相比，小周期情况下，正向吸波浮体俘获效率较高，随着周期增大，正向吸波浮体俘获效率开始降低，背向吸波浮体俘获效率开始增大，极大周期情况下，正向吸波浮体和背向吸波浮体俘获效率趋于一致且趋近于零。     

热网络法在发动机舱温度场仿真中的应用

对应用于温度场分析的热网络方法及基于热网络法的软件SINDA/FLUINT进行了介绍.利用热网络法和流体网络法对某发动机舱进行热仿真与热分析.建立了飞行器发动机舱各部件与其内外流体之间的网络关系及仿真模型,并进行耦合求解,得到此发动机舱各部件不同位置的温度分布,并对优化方案进行了仿真.其结果为发动机舱热分析及布局设计提供了参考.     

一种基于弹簧振子的波浪发电装置

通过对波浪发电的现状、发展趋势以及波浪的特性进行分析,提出了一种采用弹簧振子作为动子的直线发电装置。通过对该装置自身结构进行简化分析并对其建立数学模型;根据线性波理论给出的波浪力与时间的关系建立数学模型的微分方程;在对该微分方程进行拉普拉斯(laplace)变换整理后再进行拉普拉斯反变换,得到发电机的动子与定子相对位移随时间的变化关系,进而得到发电装置的发电功率,并选取参数采用matlab软件进行仿真模拟,绘制位移-时间图和P-c-k关系曲线。结果表明,在设计参数下装置发电功率可达到78.6 W。     

岩锚梁混凝土施工期裂缝成因分析

针对岩锚梁混凝土结构施工期开裂问题,分析了产生混凝土不利应力的主要荷载,利用ANSYS、基于实测岩壁不均匀最大位移量进行了弹性有限元计算,并分析了计算结果.通过对岩锚梁有限元温度场和应力场的仿真计算与分析,获得了混凝土内的温度分布及其经时变化是引起开裂的主要原因.     

机车辅助变流器柜基于有限元的疲劳分析

以有限元法为基础,采用有限元软件ANSYS对某机车辅助变流器柜进行了静强度分析.采用MSC.Fatigue疲劳仿真软件,根据有限元应力结果、标准提供的疲劳载荷谱和材料S-N曲线用准静态法对结构的疲劳寿命进行了仿真计算,得到了两种不同安装方式下的柜体及安装梁在98%存活率下的总寿命分布.     

Model predictive control of sea wave energy converters – Part II: The case of an array of devices

This paper addresses model predictive control (MPC) of highly-coupled clusters of sea wave energy converters (WECs). Since each WEC is not only a wave absorber but also a wave generator, the motion of each WEC can be affected by the waves generated by its adjacent WECs when they are close to each other. A distributed MPC strategy is developed to maximize the energy output of the whole array and guarantee the safe operation of all the WECs with a reasonable computational load. The system for an array is partitioned into subsystems and each subsystem is controlled by a local MPC controller. The local MPC controllers run cooperatively by transmitting information to each other. Within one sampling period, each MPC controller performs optimizations iteratively so that a global optimization for the whole array can be approximated. The computational burden for the whole array is also distributed to the local controllers. A numerical simulation demonstrates the efficacy of the proposed control strategy. For the WECs operating under constraints explored, it is found that the optimized power output is an increasing function of degree of WEC–WEC coupling. Increases in power of up to 20% were achieved using realistic ranges of parameters with respect to the uncoupled case.     

Uncertainty in wave energy resource assessment. Part 2: Variability and predictability

The uncertainty in estimates of the energy yield from a wave energy converter (WEC) is considered. The study is presented in two articles. The first article considered the accuracy of the historic data and the second article, presented here, considers the uncertainty which arises from variability in the wave climate. Mean wave conditions exhibit high levels of interannual variability. Moreover, many previous studies have demonstrated longer-term decadal changes in wave climate. The effect of interannual and climatic changes in wave climate on the predictability of long-term mean WEC power is examined for an area off the north coast of Scotland. In this location anomalies in mean WEC power are strongly correlated with the North Atlantic Oscillation (NAO) index. This link enables the results of many previous studies on the variability of the NAO and its sensitivity to climate change to be applied to WEC power levels. It is shown that the variability in 5, 10 and 20 year mean power levels is greater than if annual power anomalies were uncorrelated noise. It is also shown that the change in wave climate from anthropogenic climate change over the life time of a wave farm is likely to be small in comparison to the natural level of variability. Finally, it is shown that despite the uncertainty related to variability in the wave climate, improvements in the accuracy of historic data will improve the accuracy of predictions of future WEC yield.     

Numerical modeling of the effects of wave energy converter characteristics on nearshore wave conditions

Modeled nearshore wave propagation was investigated downstream of simulated wave energy converters (WECs) to evaluate overall near- and far-field effects of WEC arrays. Model sensitivity to WEC characteristics and WEC array deployment scenarios was evaluated using a modified version of an industry standard wave model, Simulating WAves Nearshore (SWAN), which allows the incorporation of device-specific WEC characteristics to specify obstacle transmission. The sensitivity study illustrated that WEC device type and subsequently its size directly resulted in wave height variations in the lee of the WEC array. Wave heights decreased up to 30% between modeled scenarios with and without WECs for large arrays (100 devices) of relatively sizable devices (26 m in diameter) with peak power generation near to the modeled incident wave height. Other WEC types resulted in less than 15% differences in modeled wave height with and without WECs, with lesser influence for WECs less than 10 m in diameter. Wave directions and periods were largely insensitive to changes in parameters. However, additional model parameterization and analysis are required to fully explore the model sensitivity of peak wave period and mean wave direction to the varying of the parameters.     

基于风电场海域海况的波能浮子阵列发电功率优化

[目的]为了响应国家集约用海,发展清洁能源,助力碳中和,对海上风电-波浪能装置多能融合模式进行初步分析,对波能浮子进行优化设计,以获得更高的功率输出。[方法]依据势流理论,对漂浮式风机平台-波能浮子阵列进行仿真计算,分析浮子的外形尺寸和固有周期对浮子的输出功率的影响。[结果]仿真结果表明：同一固有周期下,波能浮子越扁平,波能浮子阵列的总发电功率越大,且浮子的经济性差异很小。对于海况下,不同固有周期的波能浮子阵列经济性差异较大,因此要综合分析考虑。[结论]在已知海域海况条件下,可以通过对波能浮子固有周期和外形尺度进行优化设计,使波能浮子获得更高的功率输出,提高单位海域能量产出。     

Case study feasibility analysis of the Pelamis wave energy convertor in Ireland, Portugal and North America

The performance and economic viability of the Pelamis wave energy converter (WEC) has been investigated over a 20 year project time period using 2007 wave energy data from various global locations: Ireland, Portugal, USA and Canada. Previous reports assessing the Pelamis quote a disparate range of financial returns for the Pelamis, necessitating a comparative standardised assessment of wave energy economic indicators. An Excel model (NAVITAS) was created for this purpose which estimated the annual energy output of Pelamis for each location using wave height (H_s) and period (T_z) data, and produced financial results dependant on various input parameters. The economic indicators used for the analysis were cost of electricity (COE), net present value (NPV) and internal rate of return (IRR), modelled at a tariff rate of €0.20/kWh). Analysis of the wave energy data showed that the highest annual energy output (AEO) and capacity for the Pelamis was the Irish site, as expected. Portugal returned lower AOE similar to the lesser North American sites. Monthly energy output was highest in the winter, and was particularly evident in the Irish location. Moreover, the difference between the winter wave energy input and the Pelamis energy output for Ireland was also significant as indicated by the capture width, suggesting that Pelamis design was not efficiently capturing all the wave energy states present during that period. Modelling of COE for the various case study locations showed large variation in returns, depending on the number of WEC modelled and the initial cost input and learning curve. COE was highest when modelling single WEC in comparison to multiples, as well as when using 2004 initial costs in comparison to 2008 costs (at which time price of materials peaked). Ireland returned the lowest COE of €0.05/kWh modelling over 100 WEC at 2004 cost of materials, and €0.15/kWh at 2008 prices. Although favourable COE were recorded from some of the modelled scenarios, results indicated that NPV and IRR were not encouraging when using a €0.20/kWh tariff. It is recommended that a tariff rate of €0.30/kWh be considered for Ireland, and higher rates for other locations. In conclusion, Ireland had the most abundant wave energy output from the Pelamis. COE returns for Ireland were competitive for large number of WEC, even at peak costs, but it is recommended that careful analysis of NPV and IRR should be carried out for full economic assessment. Finally, a standardised method of COE reporting is recommended, using fixed WEC number or MW size, as well as standardised learning/production curves and initial costs, to facilitate confidence in investment decisions based on COE.     

Development of a novel point absorber in heave for wave energy conversion

This paper presents an advanced design methodology for electric power generation from the vast ocean wave energy. A novel single-buoy heaving device called wave energy converter (WEC) based on hydrostatic transmission (HST), or can be shortened as HSTWEC, is proposed to convert mechanical energy generated by ocean waves into electric energy. Modeling and simulations with both regular and irregular waves were then carried out to investigate working performances of the designed HSTWEC. The results showed that more than 78% of wave energy can be absorbed. In addition, an adaptive controller was designed to improve the performance of the suggested device. Effectiveness of the overall HSTWEC control system was finally proved by simulations.     

An investigation of the impacts of climate change on wave energy generation: The Wave Hub,Cornwall, UK

In this paper a generic methodology is presented that allows the impacts of climate change on wave energy generation from a wave energy converter (WEC) to be quantified. The methodology is illustrated by application to the Wave Hub site off the coast of Cornwall, UK. Control and future wave climates were derived using wind fields output from a set of climate change experiments. Control wave conditions were generated from wind data between 1961 and 2000. Future wave conditions were generated using two IPCC wind scenarios from 2061 to 2100, corresponding to intermediate and low greenhouse gas emissions (IPCC scenarios A1B and B1 respectively). The quantitative comparison between future scenarios and the control condition shows that the available wave power will increase by 2–3% in the A1B scenario. In contrast, the available wave power in the B1 scenario will decrease by 1–3%, suggesting, somewhat paradoxically, that efforts to reduce greenhouse gas emissions may reduce the wave energy resource. Meanwhile, the WEC energy will yield decrease by 2–3% in both A1B and B1 scenarios, which is mainly due to the relatively low efficiency of energy extraction from steeper waves by the specific WEC considered. Although those changes are relatively small compared to the natural variability, they may have significance when considered over the lifetime of a wave energy farm. Analysis of downtime under low and high thresholds suggests that the distribution of wave heights at the Wave Hub will have a wider spread due to the impacts of climate change, resulting in longer periods of generation loss. Conversely, the estimation of future changes in joint wave height-period distribution provides indications on how the response and power matrices of WECs could be modified in order to maintain or improve energy extraction in the future.     

鹰式二号波浪能装置的频域动态响应计算与负载优化设计

以鹰式二号波浪能发电装置为研究对象,基于捕获宽度达到最优为准则,通过对波浪中运动的装置建立频域运动方程,计算装置运动模态响应、获得最优负载阻尼和主要结构点受力等设计要素,并根据万山岛海域波浪条件开展能量转换系统负载设计、提供结构强度设计支持数据等。研究结果表明:在不同波况下装置获得捕获宽度对应的最优阻尼也不同;鹰式二号波浪能装置对于周期约2 s小周期波浪也具有良好的响应,捕获宽度达50%以上,在主要设计波况3~6 s最高捕获宽度达到300%,在万山岛海域波浪能试验场波况最高捕获宽度达到200%。     

同轴双浮体波能装置最优获能研究

该文以同轴双浮体波能装置为研究对象,通过理论分析建立运动方程,求解线性能量摄取(PTO)作用下的最优阻尼系数及最大输出功率。同时探究了装置能量捕获的影响因素及控制策略,提出一种具有普遍意义的最优获能估算公式。研究结果表明:双浮体波能装置可通过调节PTO阻尼力使得获能最大化,且较单浮体装置具有更宽的能量俘获频率范围;不同PTO控制策略及水体粘性阻尼均对该类装置获能影响显著。     

Modelling and simulation of a heaving wave energy converter based PEM hydrogen generation and storage system

The research on wave energy systems has been ongoing for decades. However, there are not many operational wave energy converters in use. The hydrogen energy systems also have a great potential. The proposed solution is to combine wave energy system with hydrogen energy system. The study provides details of simulation models and related simulation results. It is environmentally friendly, safe, feasible and effective. The results indicate that the proposed system model has a very high potential. With the use of low to medium energy density sea states, it is appears to be possible to generate (for DS1, DS2 and DS3, m_H2 = 350.8 kg, 623.9 kg and 2124 kg, respectively) a considerable amount of hydrogen in 20-min. The presented results include WEC motion properties, instantaneous and moving average value of other system parameters. The future promising simulations results indicate that next generation wave energy converter systems could be accompanied by hydrogen generation and storage systems.