An Elliptical Wind Field Model of Typhoons

An elliptical wind field model of typhoons is put forward based on the characteristics of the typhoon wind fields occurring in the Yellow Sea and Bohai Sea. By contrasting it with the circular typhoon wind field model, it is found that the elliptical model can adequately represent the real wind field and trace the process of a typhoon storm surge. The numerically simulated results of storm surges by using the elliptical model are in good agreement with the observations and markedly better than those by using the circular model.

Mapping the Wind Hazard of Global Tropical Cyclones with Parametric Wind Field Models by Considering the Effects of Local Factors

Tropical cyclones(TCs) cause catastrophic loss in many coastal areas of the world. TC wind hazard maps can play an important role in disaster management. A good representation of local factors reflecting the effects of spatially heterogeneous terrain and land cover is critical to evaluation of TC wind hazard. Very few studies, however,provide global wind hazard assessment results that consider detailed local effects. In this study, the wind fields of historical TCs were simulated with parametric models in which the planetary boundary layer models explicitly integrate local effects at 1 km resolution. The topographic effects for eight wind directions were quantified over four types of terrain(ground, escarpment, ridge, and valley),and the surface roughness lengths were estimated from a global land cover map. The missing TC parameters in the best track datasets were reconstructed with local regression models. Finally, an example of a wind hazard map in the form of wind speeds under a 100-year return period and corresponding uncertainties was created based on a statistical analysis of reconstructed historical wind fields over seven of the world's ocean basins.

A Model Study of Three-Dimensional Wind Field Analysis from Dual-Doppler Radar Data

A three-dimensional wind field analysis sollware based on the Beigng-Gucheng dual-Doppler weather radar system has been built, and evaluated by using the numerical cloud model producing storm flow and hydrometeor fields. The effects of observation noise and the spatial distribution of wind field analysis error are also investigated.

Non-Gaussian Lagrangian Stochastic Model for Wind Field Simulation in the Surface Layer

Wind field simulation in the surface layer is often used to manage natural resources in terms of air quality,gene flow(through pollen drift),and plant disease transmission(spore dispersion).Although Lagrangian stochastic(LS)models describe stochastic wind behaviors,such models assume that wind velocities follow Gaussian distributions.However,measured surface-layer wind velocities show a strong skewness and kurtosis.This paper presents an improved model,a non-Gaussian LS model,which incorporates controllable non-Gaussian random variables to simulate the targeted non-Gaussian velocity distribution with more accurate skewness and kurtosis.Wind velocity statistics generated by the non-Gaussian model are evaluated by using the field data from the Cooperative Atmospheric Surface Exchange Study,October 1999 experimental dataset and comparing the data with statistics from the original Gaussian model.Results show that the non-Gaussian model improves the wind trajectory simulation by stably producing precise skewness and kurtosis in simulated wind velocities without sacrificing other features of the traditional Gaussian LS model,such as the accuracy in the mean and variance of simulated velocities.This improvement also leads to better accuracy in friction velocity(i.e.,a coupling of three-dimensional velocities).The model can also accommodate various non-Gaussian wind fields and a wide range of skewness–kurtosis combinations.Moreover,improved skewness and kurtosis in the simulated velocity will result in a significantly different dispersion for wind/particle simulations.Thus,the non-Gaussian model is worth applying to wind field simulation in the surface layer.

Evaluation of a Micro-scale Wind Model's Performance over Realistic Building Clusters Using Wind Tunnel Experiments

The simulation performance over complex building clusters of a wind simulation model（Wind Information Field Fast Analysis model, WIFFA） in a micro-scale air pollutant dispersion model system（Urban Microscale Air Pollution dispersion Simulation model, UMAPS） is evaluated using various wind tunnel experimental data including the CEDVAL（Compilation of Experimental Data for Validation of Micro-Scale Dispersion Models） wind tunnel experiment data and the NJU-FZ experiment data（Nanjing University-Fang Zhuang neighborhood wind tunnel experiment data）. The results show that the wind model can reproduce the vortexes triggered by urban buildings well, and the flow patterns in urban street canyons and building clusters can also be represented. Due to the complex shapes of buildings and their distributions, the simulation deviations/discrepancies from the measurements are usually caused by the simplification of the building shapes and the determination of the key zone sizes. The computational efficiencies of different cases are also discussed in this paper. The model has a high computational efficiency compared to traditional numerical models that solve the Navier–Stokes equations, and can produce very high-resolution（1–5 m） wind fields of a complex neighborhood scale urban building canopy（～ 1 km ×1km） in less than 3 min when run on a personal computer.

Numerical Simulation of Wind Field Characteristics around Two Adjacent High-Rise Buildings

This paper based on Reynolds-averaged Navier-Stokes equations standard ?model [1];the surface pressure on the wind field around two adjacent high-rise buildings was numerically simulated with software Fluent. The results show that with the influence of adjacent high-rise building, numerical simulation is a good way to study the wind field around high-rise building and the distribution of wind pressure on building’ surface. The pressures on the windward surface are positive with the maximum at 2/3 H height and have lower values on the top and bottom. The pressures on the leeward surface and two sides were negative. Due to the serious flow separation at the corner of building’s windward, the wind field has a high turbulent kinetic energy.

VARYING SEASONS' MESOSCALE WIND FIELD CIRCULATION IN HAINAN ISLAND

Using a one-level numerical diagnostic model, the features of surface wind fields in Hainan Island and Leizhou Peninsula and maritime area around it are studied. In the experiments with prevailing synoptic situation for varying seasons there are obvious deflection flows, terrain slope drafts, convergence lines, sea/land breeze and mountain/valley breeze, and difference in season accounts for the features found in the mesoscale distribution.The complex terrain and seatland distribution in the area is shown to be the important cause for the formation of varying mesoscale circulation, and close relationships between local climatic distribution feature and mesoscale circulation are then revealed.

Improvement of wind field hindcasts for tropical cyclones

This paper presents a study on the improvement of wind field hindcasts for two typical tropical cyclones, i.e., Fanapi and Meranti, which occurred in 2010. The performance of the three existing models for the hindcasting of cyclone wind fields is first examined, and then two modification methods are proposed to improve the hindcasted results. The first one is the superposition method, which superposes the wind field calculated from the parametric cyclone model on that obtained from the cross-calibrated multi-platform （CCMP） reanalysis data. The radius used for the superposition is based on an analysis of the minimum difference between the two wind fields. The other one is the direct modification method, which directly modifies the CCMP reanalysis data according to the ratio of the measured maximum wind speed to the reanalyzed value as well as the distance from the cyclone center. Using these two methods, the problem of underestimation of strong winds in reanalysis data can be overcome. Both methods show considerable improvements in the hindcasting of tropical cyclone wind fields, compared with the cyclone wind model and the reanalysis data.

Probabilistic Model for Wind Speed Variability Encountered by a Vessel

As a result of social awareness of air emission due to the use of fossil fuels, the utilization of the natural wind power resources becomes an important option to avoid the dependence on fossil resources in industrial activities. For example, the maritime industry, which is responsible for more than 90% of the world trade transport, has already started to look for solutions to use wind power as auxiliary propulsion for ships. The practical installation of the wind facilities often requires large amount of investment, while uncertainties for the corresponding energy gains are large. Therefore a reliable model to describe the variability of wind speeds is needed to estimate the expected available wind power, coefficient of the variation of the power and other statistics of interest, e.g. expected length of the wind conditions favorable for the wind-energy harvesting. In this paper, wind speeds are modeled by means of a spatio-temporal transformed Gaussian field. Its dependence structure is localized by introduction of time and space dependent parameters in the field. The model has the advantage of having a relatively small number of parameters. These parameters have natural physical interpretation and are statistically fitted to represent variability of observed wind speeds in ERA Interim reanalysis data set.

风雨场中海上风机气动性能数值模拟研究

随着风力发电项目的不断发展,外部的降雨环境会对海上风机的气动性能造成一定的影响。以NREL-5MW型海上风机为研究对象,采用标准k-ε湍流模型建立数值模型,对比分析其在风场与风雨场中的气动性能,探讨了风雨共同作用对风机整体结构气动性能的影响规律。结果表明:降雨时风机结构的迎风面雨滴分布比例最高,虽然风机整体受到雨荷载占风荷载的比例较小,但是塔架受到的雨荷载占到塔架受到的风荷载的10%,作用力不能忽视。并且降雨也会降低风机的发电效率以及使叶片产生自振,影响其工作稳定性,需确保节点连接质量和强度。

桅杆结构有限元模型修正与参数敏感性研究

基于台风“圆规”激励下的实测加速度响应识别了深圳356 m高气象梯度观测塔的模态参数,结合带精英策略的快速非支配排序遗传算法(NSGA-Ⅱ)对气象塔有限元模型进行修正。结果表明:气象塔模态非常密集,且纤绳模态的参与程度较为显著。气象塔X向和Y向的基频分别为0.614 Hz和0.603 Hz,其前3阶弯曲模态阻尼比在1%~2%之间。塔身密度、纤绳弹模对塔身模态频率和振型有显著影响,高层纤绳的线质量和塔身弹模对其也有一定影响,但纤绳张力的影响较低。气象塔有限元模型修正后的风致响应高于修正前,并更接近实测结果,验证了修正模型的准确性。

台风“艾克”(2008)的海面风场模型研究

台风风场模拟的准确性对台风风场后报工作具有重要意义,目前通过参数模型构建台风边界层的海面风场是较快速且常用的方法之一。以2008年侵入墨西哥湾的大西洋第8号台风“艾克”为例,选取多种参数模型对比研究台风风场模拟的效果。实验结果表明,台风风场模型的选择对台风风场模拟效果具有显著影响。采用Jelesnianski-1风廓线模型即可较好地再现“艾克”台风风场的时空特征;此外,具有可变系数的Holland等气压模型风场和Miller等风廓线模型风场则具有较好的适用性,通过调整可变系数使得参数风场的风廓线贴合实际台风案例。整体而言,基于理想模型的参数风场能基本反映台风核心区域的海面风场特征,但对外围背景风场模拟效果不甚理想,而分析及再分析风场数据则能较好地反映台风外围的背景风场,因此采用参数风场与分析及再分析风场融合的方式构建台风风场,可显著提高台风“艾克”风场的数值模拟效果。

山区高速公路不同深度路堑的积雪堆积规律

山区高速公路在风雪气象条件下极易形成较为严重的风吹雪灾害,造成雪阻和断通,其中路堑深度对路面积雪产生重要影响,但现在具有针对性的研究较少。利用大缩尺比(1∶10)的现场模型试验方法,分析了8 m深度全路堑周围的风速和积雪分布规律。使用现场模型试验结果验证数值模型,并进一步研究了不同深度全路堑、迎风半路堑和背风半路堑周围风场以及积雪沉积的形成机理。结果表明:风吹雪作用下,路堑内风速与雪深变化趋势呈负相关;全路堑以及背风半路堑的深度在小于和大于2 m时,路面积雪的主控因素分别为中央分隔带护栏和路堑边坡;迎风半路堑的深度与路面积雪堆积量之间呈正比关系,路堑边坡是影响路面积雪的主导因素,也可采用分离式路基断面形式减少路面的积雪沉积量及雪害的危害程度。研究成果可为风吹雪多发区高速公路路堑的设计和雪害防治提供有益参考。

考虑台风动态过程的电网故障路径分析方法

随着全球气候的变化,台风等极端自然灾害频发,电力系统难以承受大停电事故带来的后果,研究台风灾害下电网故障路径的准确推演方法,对降低停电损失、提高灾后恢复能力有重要意义。该文选取台风导致的高故障概率元件作为初始故障集,综合考虑台风动态路径导致的线路故障概率指标和交流潮流分析得到的潮流波动关联性指标,判断出下级故障元件;若该过程中不满足风险约束条件,还需采用GPU并行加速最优潮流计算,进行下级故障的最小切负荷计算,最后可以得到台风动态路径影响下的树状故障演变路径。通过IEEE39节点系统算例进行分析和验证,说明了电力系统的故障路径与强台风的动态路径之间的强相关性,验证了所提算法的有效性和加速效果。

变长度加油软管系统动力学建模及运动特性分析

空中加油过程中,软管锥套受复杂气流干扰发生飘摆运动,同时在受油机的撞击作用下可产生甩鞭现象,严重制约了空中加油的成功率及安全性。为了研究软管锥套系统的运动特性,基于绝对节点坐标方法建立变长度软管动力学模型。同时考虑软管材质的阻尼特性、加油吊舱卷盘机构的收放运动、加油过程中存在的紊流及尾涡等风场环境,根据多体系统动力学建模理论,获得软管复杂风场下加油锥套系统动力学模型。利用有限元分析软件ANSYS仿真及Simulink数值计算对软管平稳拖曳状态下锥套的下沉量进行模拟,同时将锥套平稳拖曳阻力Simulink数值结果与NASA公开数据资料进行比较,说明所提建模方法的准确性和可行性。通过数值仿真,确定了不同飞行高度/飞行速度下加油软管的稳定拖曳状态,分析了不同对接速度下软管甩鞭动力学特性,验证了不同测力反馈点对甩鞭抑制效果的影响。

大型浅水湖泊高时空分辨率风场特征数值模拟研究:以巢湖为例

【目的】大型浅水湖泊的风场是影响湖泊流场、水体富营养化和藻华运移聚集规律的关键因素之一,仅依托气象站点的观测数据难以有效捕捉湖面风场在空间和时间上的快速变化。为精细刻画湖泊高频变化风场,辨识其时空变化特征,【方法】以巢湖为研究对象,综合利用气象观测数据、全球再分析数据集和地理静态数据,通过中尺度天气预报模式和地理空间分析技术,模拟分析巢湖地区2019年高时空分辨率的风场变化过程。【结果】结果显示:巢湖区域风速由东向西、由南向北、由湖面向陆面逐渐减弱;湖面主导风向为东风和偏东风,主导风速为二级至四级,湖面平均风速在11月最大,12月次之,5月最小,不同季节湖面平均风速由大到小依次为冬季、秋季、夏季和春季。【结论】结果表明:巢湖在白天(夜晚)出现冷(暖)湖效应,其风场在早上6时和夜晚23时出现陆风和湖风转换;西半湖受湖陆风和城市热岛影响显著,在夏季会出现明显的环湖湖风锋,其湖风锋穿透内陆距离约4.7~9 km;东半湖受山谷风影响显著,在东南部山脉以东湖区易形成低风速区,在湖口附近受狭管效应易形成高风速区。通过研究成果可进一步认知巢湖区域风场特征,为巢湖水生态环境治理提供技术支撑。

基于空分天线的雷达大气目标探测技术研究

为了拓展新型中间层-平流层-对流层(Mesosphere-Stratosphere-Troposphere, MST)雷达测风工作模式,提高测风数据的时间分辨力,基于全相关分析(Full Correlation Analysis, FCA)方法与大气散射模型,设计了一种应用于MST雷达的空分天线(Spaced-Antenna, SA)测风模式。通过大气散射模型结合雷达实际阵面分布与工作参数产生仿真时域信号,讨论了不同相关函数、相关函数拟合方法以及MST雷达不同天线尺度对雷达测风结果的影响。为验证测风模式的有效性,将信噪比(Signal to Noise Ratio, SNR)不同的测风结果与模型中风场真值进行比较。研究结果表明,新的测风模式仿真计算得到的风速、风向结果精度较高,符合雷达实际探测要求。

台风和台风模型研究综述

我国东南沿海及近海区域风能资源丰富,但也是受台风严重影响的区域。认识台风结构,并探究和预测台风高发区域的风场特征,对海上风电场的运行安全至关重要。首先详细阐述了台风的成因以及结构特征,在此基础上,总结参数台风风场模型的原理以及关键参数,并对风场模型中各关键参数进行了详细阐释。台风风场模型应用范围广,但仍需要进一步完善和验证以提高预测准确性,便于更好地服务工程实际。

风沙区高等级公路设施与路基高度耦合对气流动力学和蚀积特征的影响

[目的]揭示风沙地区不同高度高等级公路附属设施对过境风沙流的扰动效应,分析不同高度与公路设施影响下的公路路面积沙程度,为公路工程设计和穿沙公路防护措施的制定提供理论依据。[方法]采用了计算流体力学(CFD)数值模拟方法,将普通公路作为对照,对比分析不同路基高度和公路设施组合对近地表过境气流的影响,并通过野外实测数据进行验证。[结果]公路设施显著影响了路基过境气流,导致公路形成减速区,不同高度路基产生多样性的水平气流速度变化。当路基高度在1~2 m之间时,气流扰动较弱,有助于断面输沙;当路基高度在3 m高度时,气流扰动较强,不利于断面输沙。气流穿过护栏和中央隔离带时,气流从护栏下方经过,风速增加,护栏背风侧最大风速的距离随着路基高度的增加呈现先增加再减小的变化趋势,路基高度在0,1,2,3 m时,最大风速距离分别为10,20,25,20 cm。随后在护栏背风侧与上层气流合并,尾流持续扩散,形成减速区,过境气流在该区域发生衰减,沙粒颗粒产生沉积,最高积沙高度11.5 cm,积沙宽度4~4.5 m。[结论]路基高度和公路附属设施是影响公路沿线沙害的主要因素。路基高度对气流到达路基上方的风速产生显著影响,而护栏和防眩网的存在可能在背风侧形成弱风区,从而导致公路上的沙堆积,存在潜在危险。

基于SWAN模型下的马拉博油罐区深水波浪条件分析

在深水波浪条件下,油罐区的稳定性和安全性都面临着极大的挑战,对所在海域的风与波浪耦合作用的波浪分析变得至关重要。本文基于第三代海浪数值模型SWAN,依据CCMP和CFSR数值风场资料,建立南大西洋海浪后报数据集。通过与尼日利亚拉格斯外海Bonga站和纳米比亚卡拉斯外海Kudu站的实测数据资料进行对比,验证了数据集的合理性。并对赤道几内亚马拉博外海深水波浪条件进行分析,为后续油罐区项目建设提供数据参考。