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排序方式: 共有5825条查询结果,搜索用时 15 毫秒
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目前国内外对钝尾缘翼型的研究主要集中于翼型的改进方式与二维气动性能的模拟,对钝尾缘翼型应用于风力机时对其性能影响的研究较少,然而钝尾缘翼型应用于风力机时由于旋转效应的存在叶素翼型之间会发生相互影响。为了更好的研究钝尾缘翼型,了解钝尾缘翼型对风力机性能的影响,对NREL 5MW风力机叶片内侧翼型进行对称钝尾缘修型,分析二维翼型气动性能,发现一定范围内,翼型的升力系数、升阻比均随尾缘厚度的增加而增大。对原风力机进翼型替换,模拟并对比两类风力机的性能,研究表明改型后风力机的输出扭矩高于原机,而且随风速增大改型风力机的优势变得越来越突出;然而在相同工况下,改型后风力机的轴向力也大于原机。 相似文献
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《International Journal of Hydrogen Energy》2022,47(29):13887-13899
We propose a self-sustaining power supply system consisting of a “Hybrid Energy Storage System (HESS)” and renewable energy sources to ensure a stable supply of high-quality power in remote islands. The configuration of the self-sustaining power supply system that can utilize renewable energy sources effectively on remote islands where the installation area is limited is investigated. It is found that it is important to select renewable energy sources whose output power curve is close to the load curve to improve the efficiency of the system. The operation methods that can increase the cost-effectiveness of the self-sustaining power supply system are also investigated. It is clarified that it is important for increasing the cost effectiveness of the self-sustaining power supply system to operate the HESS with a smaller capacity of its components by setting upper limits on the output power of the renewable energy sources and cutting the infrequent generated power. 相似文献
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《International Journal of Hydrogen Energy》2022,47(58):24569-24583
Hydrogen generation from renewable energy resources is considered as a suitable solution to solve the problems related to the energy sector and the reduction of greenhouse gases. The aim of this study is to provide an integrated framework for identifying suitable areas for the construction of wind farms to produce hydrogen. For this purpose, a combined method of Geographic Information System (GIS) and multi-criteria decision making (MCDM) has been used to locate the power plant in Yazd province. The GIS method in the present study consisted of two parts: constraints and criteria. The constraint section included areas that were unsuitable for the construction of wind farms to produce power and hydrogen. In the present study, various aspects such as physical, economic and environmental had been considered as constraints. In the criteria section, eight different criteria from technical aspects (including average wind speed, hydrogen production potential, land slope) and economic aspects (including distance to electricity grid, distance to urban areas, distance to road, distance to railway and distance to centers of High hydrogen consumption) had been investigated. The MCDM tool had been used to weigh the criteria and identify suitable areas. Analytic Hierarchy Process (AHP) technique was used for weighting the criteria. The results of AHP weighting method showed that economic criteria had the highest importance with a value of 0.681. The most significant sub-criterion was the distance to urban areas and the least significant sub-criterion was the distance to power transmission lines. The results of GIS-MCDM analysis had shown that the most proper areas were in the southern and central sectors of Yazd province. In addition, the feasibility of hydrogen production from wind energy had shown that this province had the capacity to generate hydrogen at the rate of 53.6–128.6 tons per year. 相似文献
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风电机组齿轮箱故障一直是风电场主要机械故障之一,其故障信息多是混有噪声的非平稳信号。为避免陷入对复杂的非线性信号求解,提出多种算法融合下的数字信息频率筛查处理方法。首先利用小波分析对高频信号的敏感性进行消噪,然后充分利用Hilbert-Huang变换对非平稳信号的分解和时频变换能力进行信号特征挖掘,在被干扰的非平稳信号里面找出故障对应频率。充分利用多种算法融合有效去除与主频率不相关的高频噪声,找出时域变换的边际谱。避免了直接分解含有高频信号的不确定性,降低了信号分解过程中回流成分,避免发生反射现象,完成对风电机组齿轮箱故障的非平稳信号频率筛查比对。通过对某机组进行故障实验,验证数字信息频率筛查方法的有效性。 相似文献
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《岩石力学与岩土工程学报(英文版)》2022,14(5):1556-1567
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. 相似文献
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《International Journal of Hydrogen Energy》2022,47(62):25880-25898
Hydrogen as an energy carrier can play a significant role in reducing environmental emissions if it is produced from renewable energy resources. This research aims to assess hydrogen production from wind energy considering environmental, economic, and technical aspect for the East Azerbaijan province of Iran. The economic assessment is performed by calculation of payback period, levelized cost of hydrogen, and levelized cost of electricity. Since uncertainty in the power output of wind turbines may affect the payback period, all calculations are performed for four different turbine degradation rates. While it is common in the literature to choose the wind turbine based on a single criterion, this study implements Multi-Criteria Decision-Making (MCDM) techniques for this purpose. The results of Step-wise Weight Assessment Ratio Analysis illustrates that economic issue is the most important criterion for this research. The results of Weighted Aggregated Sum Product Assessment shows that Vestas V52 is the most suitable wind turbine for Ahar and Sarab cities, while Eovent EVA120 H-Darrieus is a better choice for other stations. The most suitable location for wind power generation is found to be Ahar, where it is estimated to annually generate 2914.8 kWh of electricity at the price of 0.045 $/kWh, and 47.2 tons of hydrogen at the price of 1.38 $/kg, which result in 583 tons of CO2 emission reduction. 相似文献
10.
风力发电机组混凝土塔架结构非常复杂,塔门的存在对整体塔筒的力学特性有着不可忽视的影响,因此有必要进行门洞处水平承载力研究。参照《高耸结构设计规范》(GB50135-2006)、《烟囱设计规范》(GB50051-2013)和美国混凝土协会标准(ACI307-08)进行预应力混凝土塔架门洞处截面极限状态验算,对比了不同规范所采用的计算方法的优缺点。采用ANSYS建立了相应的预应力混凝土塔架有限元模型,对决定截面抗弯承载力的一个重要影响因素进行了数值研究,即受压区的半角系数α或ACI308-08标准中采用的中性轴角度α。结果表明,采用《高耸结构设计规范》并结合《混凝土结构设计规范》进行预应力混凝土塔架门洞截面处的承载力极限状态验算具有一定的借鉴性,与有限元模拟结果接近。 相似文献