高稳高效海上风电安装平台关键制造技术研究

海上风电作为可再生清洁能源之一,受到世界各国的高度重视与大力发展。我国将海上风电提升至解决能源危机、减缓气候变化、调整能源结构的国家战略高度,到2030年我国单位国内生产总值二氧化碳排放将比2005年下降65%以上,非化石能源占一次能源消费比重将达到25%左右。安装平台不足将是我国海上风电场无法如期建成投产的主要障碍。对自升自航式海上风电安装平台系列高端装备及其设计制造的三大技术难题——腿站立作业易“失稳”、大平台大跨距大倾覆力矩自升易“失控”、高空吊装巨型叶片逾百螺栓精准定位易“失准”,以及焊缝缺陷修复和局部裂纹损伤的激光锻造修复再制造进行了介绍,研制的具有不同规格的系列装备在中国、英国、丹麦、德国等国家的著名海上风电场建设应用情况良好。     

采用温控和碘吸收池技术的发射激光稳频技术

多普勒测风激光雷达通过分析系统回波信号的多普勒频移反演出风速，为提高风场探测精度，从稳频技术方面展开研究。在稳频过程中，分别采取措施消除激光频率的长期漂移和短期抖动。针对激光频率的长期漂移，设计并研制了种子激光器温控箱，通过水浴的控温方式大大减小了激光频率的长期漂移，将激光频率稳定在±50 MHz以内；针对激光频率的短期抖动，采用以碘分子吸收池为核心器件的稳频系统，通过半导体控温方式对碘分子吸收池精确控温，控温精度达0.03 ℃，提高了稳频精度，将激光频率进一步稳定在±8 MHz以内，满足±10 MHz以内的设计精度要求。通过搭建多普勒测风激光雷达系统，对发射激光稳频装置进行系统验证，连续4组风场观测结果表明:系统探测高度为17 km，绝大部分方差在4 m/s以下，满足测风激光雷达测量指标的要求。     

基于GA-BP的汽车风振噪声声品质预测模型

目前对于汽车风振噪声的优化研究主要以声压级（Sound pressure level，SPL）作为单一评价指标，既不能全面反映噪声的物理属性，也无法考虑人耳对噪声的主观认知过程。为准确评价风振噪声，引入声品质，运用大涡模拟（Large eddy simulation，LES）对风振噪声进行数值仿真，根据实车道路试验判断仿真的准确性；对仿真结果进行声品质客观评价与主观评价，综合声品质客观评价参数与声品质主观评价试验结果建立BP神经网络预测模型；利用遗传算法（Genetic algorithm，GA），进一步对BP神经网络的结构参数进行优化，建立GA-BP声品质预测模型。研究结果表明，GA-BP声品质预测模型在训练速度和预测精度上都优于BP神经网络预测模型。预测模型基于声品质主客观评价结果，其预测值可以代替传统的声压级评价指标，为风振噪声提供更为准确合理的评价。     

内含实体对H型垂直轴风力机气动性能的影响

以H型垂直轴风力机及其内含圆柱形实体为研究对象,对NACA0018翼型的五叶片H型垂直轴风力机的气动性能进行数值模拟和实验验证。分析8种不同直径的内含圆柱体,在内含实体截面积占风轮迎风面积之比分别为21.2%、50.0%和76.9%时,风力机风能利用率的峰值分别下降8.04%、20.7%及74.3%。结果表明：随着内含实体直径的增大,风能利用率的峰值逐渐减小,开始较为缓慢,达到一定值时快速下降。小直径内含实体主要影响叶片在下风区的转矩,对风能利用率的影响较小,而大直径内含实体还会影响叶片在上风区的转矩,其风能利用率迅速减小。对于内含固定直径的实体,比如在现有建筑物外侧安装风力机时,其风轮半径的选择需综合考虑风能利用率和风力机的建造成本两方面的因素。研究结果可为建筑物与垂直轴风力机进行有效结合以提高风能的利用提供参考。     

Experimental study on mitigating wind erosion of calcareous desert sand using spray method for microbially induced calcium carbonate precipitation

Wind erosion is one of the significant natural calamities worldwide, which degrades around one-third of global land. The eroded and suspended soil particles in the environment may cause health hazards, i.e. allergies and respiratory diseases, due to the presence of harmful contaminants, bacteria, and pollens. The present study evaluates the feasibility of microbially induced calcium carbonate precipitation (MICP) technique to mitigate wind-induced erosion of calcareous desert sand (Thar desert of Rajasthan province in India). The temperature during biotreatment was kept at 36 °C to stimulate the average temperature of the Thar desert. The spray method was used for bioaugmentation of Sporosarcina (S.) pasteurii and further treatment using chemical solutions. The chemical solution of 0.25 pore volume was sprayed continuously up to 5 d, 10 d, 15 d, and 20 d, using two different concentration ratios of urea and calcium chloride dihydrate viz 2:1 and 1:1. The biotreated samples were subjected to erosion testing (in the wind tunnel) at different wind speeds of 10 m/s, 20 m/s, and 30 m/s. The unconfined compressive strength of the biocemented crust was measured using a pocket penetrometer. The variation in calcite precipitation and microstructure (including the presence of crystalline minerals) of untreated as well as biotreated sand samples were determined through calcimeter, scanning electron microscope (SEM), and energy-dispersive X-ray spectroscope (EDX). The results demonstrated that the erosion of untreated sand increases with an increase in wind speeds. When compared to untreated sand, a lower erosion was observed in all biocemented sand samples, irrespective of treatment condition and wind speed. It was observed that the sample treated with 1:1 cementation solution for up to 5 d, was found to effectively resist erosion at a wind speed of 10 m/s. Moreover, a significant erosion resistance was ascertained in 15 d and 20 d treated samples at higher wind speeds. The calcite content percentage, thickness of crust, bulk density, and surface strength of biocemented sand were enhanced with the increase in treatment duration. The 1:1 concentration ratio of cementation solution was found effective in improving crust thickness and surface strength as compared to 2:1 concentration ratio of cementation solution. The calcite crystals formation was observed in SEM analysis and calcium peaks were observed in EDX analysis for biotreated sand.     

Assessment of offshore liquid hydrogen production from wind power for ship refueling

Green hydrogen from electrolysis has become the most attractive energy carrier for making the transition from fossil fuels to carbon-free energy sources possible. Especially in the naval sector, hydrogen has the potential to address environmental targets due to the lack of low-carbon fuel options. This study aims at investigating an offshore liquefied green hydrogen production plant for ship refueling. The plant comprises a wind farm for renewable electricity generation, an electrolyzer stack for hydrogen production, a water treatment unit for demineralized water production, and a hydrogen liquefaction plant for hydrogen storage and distribution to ships. A pre-feasibility study is addressed to find the optimal capacities of the plant that minimize the payback time. The model results show that the electrolyzer capacity shall be set equal to a value between 80% and 90% of the wind farm capacity to achieve the minimum payback times. Additionally, the wind farm capacity shall be higher than about 150 MW to limit the payback time to values lower than 11 years for a fixed hydrogen price of 6 €/kg. The Levelized Cost of Hydrogen results to be below 4 €/kg for a wide range of plant capacities for a lifetime of the plant of 25 years. Thus, the model shows that this plant is economically feasible and can be reproduced similarly for different locations by rescaling the different selected technologies. In this way, the naval sector can be decarbonized thanks to a new infrastructure for the production and refueling of liquified green hydrogen directly provided on the sea.     

河北、湖北、四川三省畜禽养殖场粪污样品中硒、钼含量的调查

目的 调查河北、湖北、四川三省畜禽养殖场粪污样品中硒、钼的含量。方法 采集河北、湖北、四川三省206个养殖场的422个样品, 干清粪和水泡粪样品经过65 ℃烘干至恒重后, 粉碎或研磨, 过0.25 mm样品筛, 进行微波消解处理后, 赶酸定容至50 mL容量瓶中, 用电感耦合等离子质谱仪对硒、钼元素进行测定。污水样直接进行微波消解处理后, 赶酸定容至50 mL容量瓶中, 用电感耦合等离子质谱仪对硒、钼元素进行测定。结果 3个省份的猪场、鸡场和牛场的干清粪样品中不同程度的检出了硒或钼的含量; 污水样品和水泡粪样品中均未检出硒和钼的含量。结论 河北、四川、湖北三省养猪场、养鸡场和养牛场的粪污再利用过程中可能会对环境造成一定的污染, 应当进行相应处理后再进行利用。     

Effect of hydrogen enrichment and electric field on lean CH4/air flame propagation at elevated pressure

Electric assisted combustion for hydrogen enriched hydrocarbons may even extend the lean burn limit and provide the further improvement on combustion stability. This study investigates the effect of hydrogen enrichment and DC electric field on lean CH₄/air flame propagation. Electric field inside the chamber was generated by mesh and needle electrodes. Effect of hydrogen enrichment on the ion mole fraction in the flame was discussed based on reaction mechanism included neutral and ion reactions. The flame propagation images, flame displacement speed were used to evaluate the combined influences of hydrogen enrichment and electric field on propagating flame. Results showed that the hydrogen addition would increase positive ions mole fraction and the peak value is mainly determined by H₃O⁺. This would be due to that CH increases with hydrogen fraction, which is the main species in the initial reaction for the ion reactions. Electric field effect about flame propagation was suppressed with hydrogen addition due to the competition between the increment in ion mole fraction and the decrement in flame time. Electric assisted combustion is more evident at leaner conditions and elevated pressure. The ratio of ionic wind velocity to flow velocity may be the determined factor to predict the electric field effect about propagating flame. The tendency based on this ratio is in accordance with the experimental results for various hydrogen fraction and equivalence ratio at elevated pressure.     

小孔间距布局对厢体气膜减阻效果的影响

为研究小孔间距布局对厢体气膜减阻效果的影响,通过优化厢体模型结构设计一种被动式气膜发生器,在渗流小孔直径1 mm、小孔与厢体表面倾斜度90°不变的情况下,通过模拟风洞实验测试厢体表面有渗流和无渗流喷出时小孔纵向间距为1.1～3 mm和小孔横向间距为1.1～5 mm的厢体模型所受到的总阻力。结果表明:小孔纵向间距的变化对厢体表面气膜减阻效果的影响很小;随着小孔横向间距的增加,厢体表面气膜减阻效果先增大后减小,且在小孔横向间距1.1～3 mm范围内减阻效果最佳;在主流速度和渗流速度比值相等的情况下,气膜减阻效果随着主流速度和渗流速度的增大而减小。     

复杂地形下风力机尾流数值模拟研究和激光雷达实验对比

以CFD数值计算和实验相结合的方法,对处于中国西南某多山地区陆上风电场的尾流特性进行研究,验证不同数值方法在复杂地形的适用性。首先采用2台激光雷达,测量目标风力机一个月内的自由来流风速和尾流廓线,在地形上坡加速效应下,不同大气稳定度下目标风力机的自由来流风速廓线均呈负梯度。然后分别采用经典致动盘和改进致动盘法,模拟目标风力机在主风向下的尾流发展。不同于只有风速与压降关系的经典致动盘法,改进致动盘法更考虑了叶片几何和气动参数(尺寸信息、攻角、桨距角、升阻力系数等)。通过与后置激光雷达尾流测试结果对比,这2种基于CFD技术的数值模拟方法,计算网格相同,计算时间相当,且均能较好地模拟因为复杂地形而引起的尾流偏转;其中改进致动盘的尾流形状与激光雷达相似,速度亏损也更接近激光雷达结果。因此,改进致动盘法更适合于复杂地形条件下风场模拟,较好平衡了计算的效率与精度。