一种风力发电机的尾迹识别方法

本发明提供一种风力发电机的尾迹识别方法,先采集试验风力发电机的所有流场数据,然后对流场数据通过差分方法进行求导计算,得到速度梯度张量,然后再计算出流场每个点上的流动不变量数据；对已知的数据进行分析,并按预定标准将收集的数据分为强湍流和弱湍流；以流动不变量数据作为输入量,以强湍流和弱湍流数据作为学习对象,通过机器学习算法软件生成一个识别器；将需要识别流场的不变量数据输入识别器,然后根据预定标准将符合强湍流的数据区域绘出,即得到产生当前需要识别流场的风力发电机的尾迹区域。本发明使用了现代计算机科学中的大数据分析方法,只需要提供充分的数据,而不需要加入其他人为干涉,可以保证计算结果的客观性

湿法粉碎辅助溶剂提取葡萄皮渣中多酚的研究

通过正交试验,优化分析确定湿法粉碎辅助溶剂提取葡多酚的最佳工艺条件。通过单因素试验研究了粉碎时间、固液比、乙醇体积分数、提取温度和时间对葡多酚产量的影响,利用正交试验优化得出各因素的最佳条件:粉碎时间30 s、料液比1∶20(m/v)、乙醇体积分数60%、提取温度60℃、提取时间1.5 h,在该条件下葡多酚产量可达到64.26 mg GAE/g,IC_(50)(DPPH)值为59.08 mg/L。</p

Large-eddy simulation on the similarity between wakes of wind turbines with different yaw angles

This work is dedicated to studying the similarity between wakes of wind turbines with different yaw angles and tip speed ratios under different turbulent inflows using large-eddy simulations with actuator surface models. Simulation results show that wake characteristics from cases with different yaw angles overlap with each other when normalized properly, which include the streamwise variations of the wake deflection, the centreline velocity deficit, the widths of the wakes, the standard deviations of instantaneous wake centre positions and the instantaneous wake widths. Different scalings are proposed for the streamwise velocity deficit and the transverse velocity. The similarities observed between cases with different yaw angles and the different scalings suggest that it is proper to -12ompose the wake of a yawed wind turbine into a streamwise wake and a lateral wake deflection, which is critical for developing analytical models. The mean of the instantaneous wake widths and the mean of the instantaneous centreline streamwise velocity are observed as being smaller than those of the time-averaged wake. These quantities are then related by using two analytical expressions proposed in this work. The observed similarities together with the proposed analytical expressions provide a better understanding of wakes of yawed wind turbines and can be employed to develop physics-based dynamic wake models

溶剂类型对葡萄籽多酚提取及抗氧化活性的影响

葡萄籽是一种富含多酚类物质的葡萄酒工业副产物,提取得到的多酚可作为抗氧化活性物质,被广泛应用于食品、药品和化妆品行业。试验分别选择单一纯溶剂(水、甲醇、乙醇和丙酮)及混合溶液(70%甲醇、70%乙醇、70%丙酮和酸性乙醇),提取葡萄籽中的多酚,并对提取物中多酚类物质进行深入分析比较。结果表明,混合溶剂比纯溶剂提取效果好,其中70%丙酮溶液综合提取效果最好,葡萄籽提取物(GSE)中总酚含量为601.93 mg&middot;g~(-1)GSE,是水提取物的近4倍;原花青素的含量为661.38 mg&middot;g~(-1) GSE,是水提取物的近7倍;其中儿茶素作为主要的活性物质其含量为31.32 mg&middot;g~(-1) G...</p

Large Eddy Simulation of Wind Turbine Wakes in Forest Terrain

In this study, large eddy simulation was employed to investigate the influence of the forest canopy on wind turbine wakes. Nine forest case studies were carried out with different vertical distributions of leaf area density (LAD) and values of leaf area index (LAI). It was found that the wake in forest canopies recovers at a faster rate when compared with the flat terrain. An interesting observation was the significant reduction in turbulence kinetic energy (TKE) in the lower part of the wake above the forest in comparison with the inflow TKE, which occurred for a wide range of turbine downstream positions. The increase of TKE, on the other hand, was mainly located in the region around the top tip. Analyses of the power spectral density showed that the increase in TKE happened at a certain range of frequencies for the forest canopy cases and at all the examined frequencies for the flat case. Wake meandering was also examined and was found to be of a higher amplitude and a lower dominant frequency for the forest cases compared with the flat case. In terms of the influence of forest canopy parameters, the LAI was found to have an impact greater than the vertical distribution of LAD. Specifically, the wake added TKE and wake added Reynolds shear stress were found to be approximately the same for cases with the same LAI, regardless of the vertical distribution of LAD

Review of Turbine Parameterization Models for Large-Eddy Simulation of Wind Turbine Wakes

Wind turbine parameterization models, which are often employed to avoid the computational cost of resolving the blade aerodynamics, are critical for the capability of large-eddy simulation in predicting wind turbine wakes. In this paper, we review the existing wind turbine parameterization models, i.e., the actuator disk model, the actuator line model, and the actuator surface model, by presenting the fundamental concepts, some advanced issues (i.e., the force distribution approaches, the method for velocity sampling, and the tip loss correction), and their applications to utility-scale wind farms. Emphasis is placed on the predictive capability of different parameterizations for different wake characteristics, such as the blade load, the tip vortices and hub vortex in the near wake, and the meandering of the far wake. The literature demonstrated the importance of taking into account the effects of nacelle and tower in wind turbine wake predictions. The predictive capability of the actuator disk model with different model complexities, which is preferred in wind farm simulations, is systematically reviewed for different inflows and different wind turbine designs. Applications to wind farms show good agreements between simulation results and measurements

野樱莓多酚提取剂对多酚抗氧化活性和可浓缩性的影响

多酚所具有的保健作用逐渐被人们所认识,含有丰富多酚类化合物的野樱莓(Aronia melanocarpa)也逐渐受到关注。高效提取野樱莓中总多酚是其高值化利用的重要途径。本文对比研究了利用酸性乙醇、乙醇和纯水3种提取剂对野樱莓中总多酚的提取效果。结果表明,酸性乙醇具有最高的多酚提取率,而以纯水作为提取剂其多酚提取量只有酸性乙醇的28.77%。对多酚抗氧化活性(去除DPPH自由基的能力)研究发现,水提多酚的抗氧化活性高于乙醇和酸性乙醇提取的多酚。酸性乙醇、乙醇和纯水提取的多酚去除DPPH自由基的VC当量比值为100∶76.10∶70.83。将3种提取液减压浓缩至原体积的10%后,多酚的抗氧化活性...</p