单层平面索网玻璃幕墙数值风洞风载荷分析

针对现行幕墙设计规范没有明确规定单层平面索网幕墙体系的风载荷计算的问题,以某大厦裙房幕墙为研究对象,用ADINA分析考虑流固耦合作用的玻璃 索网体系风振响应分析,并与通常采用的等效静风载荷方法得到的结构风效应比较.分析表明,对于非线性的索网玻璃幕墙结构,现行载荷规范采用的等效静风载荷方法会导致偏于不安全的设计计算结果.     

Petascale large eddy simulation of jet engine noise based on the truncated SPIKE algorithm

With the emergence of petascale computing platforms, high-fidelity computational aeroacoustics (CAA) simulation has become a feasible, robust and accurate tool that complements theoretical and empirical approaches in the prediction of sound levels generated by aircraft airframes and engines. Differentiating itself from the broader discipline of computational fluid dynamics, CAA is particularly challenging as it demands high accuracy, good spectral resolution, and low dispersion and diffusion errors from the underlying numerical methods. Large eddy simulation based on space-implicit high-order compact finite difference schemes has been shown to meet such stringent requirements. In this paper, we discuss a new, scalable parallelization scheme with a three-dimensional computational space partitioning. Unlike many traditional multiblock computational fluid dynamics (CFD) methods, our partitioning is non-overlapping. We use the truncated SPIKE algorithm to solve the governing equations accurately and limit one-sided biased differentiation to just the physical boundaries. We present experimental performance data collected on Kraken and Ranger, two near-petascale computing platforms.     

随机风速场的数值模拟及高层建筑风振控制

根据Davenport脉动风速谱, 采用AR模型(auto-regressive)法, 考虑竖向相关性、平稳的多变量随机过程以及它的互谱密度矩阵, 模拟生成具有随机性的脉动风速时程曲线和风速谱的功率谱密度. AR法模拟风速的功率谱密度函数与Davenport目标谱的比较表明AR法具有很高的精度和效率. 采用了建筑结构振动控制第2代标准规定的76层306m高钢筋混凝土结构的风振控制模型, 研究了风荷载作用下高层建筑动力响应的控制方法, 给出了模拟脉动风荷载作用下, 被动调谐质量阻尼器(TMD, tuned mass damper)控制和主动线性二次型Gauss(LQG, linear quadratic Gaussian)控制的控制结果.     

檐口构造对四坡低矮房屋屋面风压分布影响规律的数值模拟研究

基于日本东京工艺大学风洞试验数据,针对低矮四坡房屋展开研究,验证了RNG模型对四坡低矮建筑表面风压研究的可靠性.利用此模型深度研究檐口外伸长度与出挑高度对四坡低矮屋面表面风压的影响规律.结果表明:檐口的长度及出挑高度对屋面风压影响明显,当檐口外伸长度不变,随檐口竖向高度增加,迎风面风吸力随之增大,当檐口竖向高度不变,高度为0.5m、1.0m时,随着檐口外伸长度的增加,迎风面负风压减小,檐口外伸长度为1.5m,竖向高度为1.0m为最有利于房屋表面抗风设计,结论可为台风多发地区低矮民居设计提供建议.     

风洞天平实时载荷监测方法研究

针对当前风洞天平应用环境越来越复杂,但却缺乏有效的安全监测手段的现状,提出了一种基于应力叠加原理的风洞天平实时载荷监测方法;首先,分析天平受力情况,基于工程经验、天平应力集中位置以及应变计粘贴位置等因素划分危险载荷监测区域;其次,基于有限元方法对天平进行网格划分,计算载荷监测区网格节点的应力影响系数;最后,结合天平六元信号输出实时计算载荷监测区的节点应力值,并与有限元理论计算结果和静态校准加载结果进行对比验证;验证结果表明,有限元理论验证准度优于0.02%,静态校准加载验证阻力元准度优于10%,其余5元准度均优于4%;证明本方法具有较高的计算准度,能够满足风洞天平实时载荷监测的使用需求,具有较高的实际应用价值。     

压力平衡口对开口式汽车模型风洞驻室流场影响的数值仿真

为尽可能真实地建立汽车测试环境,对开口式汽车模型风洞驻室试验段流场品质进行数值仿真,研究在开设压力平衡口前后的流场品质,并对不同面积和形式的压力平衡口工况进行数值仿真,得到不同试验段内流场品质的计算结果.通过比较分析得出结论:有压力平衡口时,特别是压力平衡口的面积为140 m×140 m时,汽车模型风洞驻室试验段最有利于汽车性能测试.     

湍流模型对电源车车舱内流场及散热的影响

针对某静音型电源车车舱结构及其通风散热特点,建立了车舱内部计算流体力学(Computational Fluid Dynamics,CFD)仿真模型,通过设置各类解析条件,分别利用Standardk-ε,Realizablek-ε,Standardk-ω和SSTk-ω四种湍流模型仿真模拟了车舱内流场和车载柴油发电机组的温度场,并分别测试了两条垂直线的风速对流场仿真结果进行了评价,测试了柴油发电机组和消声器不同测点的温度值,分析了散热的仿真精度.结果表明:k-ε模型的数值模拟结果比k-ω模型更加贴近实测结果,表明Realizablek-ε模型的仿真精度最高,适合静音型电源车车舱结构.     

Strategy and Simulation of Adaptive RID for Distributed Dynamic Load Balancing in Parallel Systems

Dynamic load balancing schemes are significant for efficiently executing nonuniform problems in highly parallel multicomputer systems.The objective is to minimize the total exectuion time of single applications.This paper has proposed an ARID strategy for distributed dynamic load balancing.Its principle and control protocol are described,and te communication overhead,the effect on system stability and the performance efficiency are analyzed.Finally,simulation experiments are carried out to compare the adaptive strategy with other dynamic load balancing schemes.     

建筑物健康诊断两种风荷载传感器的设计与应用

介绍了建筑物风工程研究用的两种风荷载传感器. 种是采用MEMS技术的梁膜岛复合力敏结构压阻微差压敏感元件,用准齐平无应力微封装,适用于建筑物缩模风洞试验测试用的风荷载动态微型微压传感器.另一种是采用MEMS梁膜复合结构力敏芯片,考虑了减小雨水张力影响及冲击载荷伴生的振动影响及防雷保护而封装的复合风雨荷载,现场实测用的风...     

Effects of speed, load and damping on the dynamic response of railway bridges and vehicles

In this paper, the effects of various parameters influencing the dynamic response of railway bridges are investigated. A versatile and computationally efficient numerical model was developed for this purpose. The model incorporates three-dimensional multi-body train and finite element bridge subsystems. The corresponding equations of motion are integrated numerically by applying the Newmark’s method combined with a modified Newton-Raphson iterative procedure. The model was verified by comparisons with analytical and numerical solutions available in the literature and good agreement was found. A parametric analysis was carried out to establish the key variables influencing the dynamic response of railway bridges. The speed of the train, train-to-bridge frequency, mass and span ratios, as well as bridge damping were identified as significant variables. Vehicle damping was found to have negligible influence on bridge response. Particularly strong dynamic amplification was found for train with shortly and regularly spaced axles travelling at the critical speeds. Other general conclusions were drawn on the basis of the parametric study.     

弹性支撑下风电机组传动系统结构动力分析

考虑水平轴风力发电机组齿轮箱弹性支撑的柔性连接特性,基于集中质量思想和拉格朗日方法,建立风力发电机传动系统多体动力学模型,研究了齿轮箱弹性支撑对传动系统结构动力学特性的影响.利用动力学模型和模态分析方法,得到了由弹性支撑耦合到系统后的模态频率,并获取了在该模态激励下的模态动能分布.采用变参数方法进行传动系统模态对齿轮箱弹性支撑刚度变化的敏感性分析,利用模态叠加法进行齿轮箱体的动响应分析.数值求解结果和分析表明,考虑齿轮箱弹性支撑的传动系统某阶固有频率即为弹性支撑下齿轮箱体振动主模态;弹性支撑线刚度对传动系统低频率固有模态存在一定影响;齿轮箱体振动分析时应考虑1阶和2阶的低频模态较为合理.本研究工作对传动链系统方案可靠性设计和抑制传动链振动的加阻控制提供了一定理论基础.     

基于数值计算的高速列车气动阻力风洞试验缩比模型选取方法

为给高速列车气动阻力风洞试验模型选取提供更多的参考依据,通过计算流体力学(Computational Fluid Dynamics,CFD)方法,研究不同比例的高速列车缩比模型对气动阻力风洞试验结果的影响.首先,计算得到开口式风洞测试段的静压系数分布曲线,为高速列车气动阻力测量试验模型的长度选择以及摆放位置提供依据;其次,通过数值计算得到全尺寸模型列车在明线运行时,以及不同比例的模型列车在风洞中运行工况下的气动阻力信息,并从阻塞效应和雷诺数的变化,以及风洞试验段内静压分布的影响这3个方面对列车模型的气动阻力结果进行分析,得到在所研究风洞中较合理的列车缩比模型比例选取范围.这种以CFD为基础进行数值仿真,选取风洞试验中列车模型比例及试验测试位置的方法,为在地面交通工具风洞中进行高速列车模型气动阻力试验的缩比模型选取提供一定依据.     

A three-dimensional model of primary thrombus formation based on fluid dynamics and level sets

In this paper, a three-dimensional (3D) multiscale model is proposed for the formation process of a primary thrombus. In the model, blood plasma is modelled by Navier–Stokes equations in macroscale because the blood plasma is seen as a continuous viscous fluid. The adhesion and aggregation of platelets are the main physiological processes of primary thrombus formation. As platelets and the primary thrombus are seen as rigid solids, these physiological processes are modelled in microscale according to the force related to the distance between the two solid bodies. We use level sets to represent the growth of the primary thrombus in 3D, and the multiscale model is applied to the 3D simulation of the primary thrombus formation. From numerical observations, the appearance of the formation process shows that it was affected by the change of blood-flow velocities. We can conclude that the appearance of the primary thrombus affects vascular blood flow.     

Ultimate load carrying capacity of the Lu Pu steel arch bridge under static wind loads

This paper investigates the ultimate load carrying capacity of the Lu Pu Bridge under static wind loads through the spatial finite element model. Both geometric and material nonlinearities are involved in the analysis. The Lu Pu Bridge is a long-span half-through-type steel arch bridge with a 550 m-long central span under construction in Shanghai, China. This will be the longest central span of any arch bridge in the world. Three load combinations are used in the ultimate load capacity analysis of the bridge. Combination I: combined dead and live loads over the entire bridge. Combination II: combined dead and wind loads. Combination III: combined dead load, wind load and live load over the entire bridge. Ultimate load capacity of the bridge is first investigated under load combinations I and II. Attention is paid mainly to investigate the load capacity of the bridge under load combination III. In the case of load combination III, the influences of several parameters (i.e., loading sequence, three components of wind loads and wind loads of individual bridge element) on the ultimate load capacity of the bridge are discussed. It is concluded that wind loads result in significant reduction in the ultimate load capacity when applied wind loads become large.     

风力发电机组机舱结构散热性能分析方法

为研究双馈式风力发电机组机舱结构散热性能,对风电领域通用的拟六面体形机舱进行简化建模,采用基于热影响排序的机舱模型简化准则和流 固耦合面网格加密准则进行建模,运用计算流体力学（Computational Fluid Dynamics,CFD）方法分析机舱内气流组织形态.提出一种基于热源扰动的气流组织均匀性评价新方法,解决无参照状态下机舱散热气流组织的孤本评价难题.采用该方法对典型的“下送尾排”式机舱气流组织形态进行分析和评价,分析结论与制造商的试验结论相符.     

基于遗传算法和BP神经网络的城区中长期电力负荷预测与分析

由于产业结构的调整、居民消费能力消费结构的变化和市场化等因素的影响,城区中长期电力负荷预测具有相当的难度。建立一个基于遗传算法和BP算法相结合的神经网络预测模型,以南昌市为例做实证,并与传统BP神经网络和模拟退火预测结果做对比,验证了该模型的准确性。最后对城区未来十几年的基本用电负荷进行了预测和分析。     

基于振动力和风力作用的服装动态仿真*

为了真实地模拟服装的动态效果,本文提出了一种四元数产生振动运动的方法。本文首先介绍了四元数产生振动运动的过程,然后给出基于随机噪声函数构建随机风场的过程,调节不同的仿真参数,仿真出裙子在重力、振动力、风力作用下的动态效果。实验结果表明,该方法获得了不错的动态服装仿真效果。     

基于气象无人机GPS/DR组合导航的单步长测风方法研究

针对气象无人机GPS／DR组合导航的特点,提出了一种利用位置构成的矢量三角形关系进行风场测量的新方法,并提出了单步长风场测量,最后对测量结果进行了仿真,结果表明：采用单步长测量时风速变化频率较高,能够将风场高频信号的变化特点反映出来,测量精度较高,均方差为4m／s。可以作为气象无人机测风的一种新方法。     

基于计算流体动力学的探空温度传感器太阳辐射误差修正方法

高空大气温度是天气预报和气候变化研究所需的关键观测资料,随着对防灾减灾和应对气候变化能力要求的提高,希望探空温度传感器的准确度达到0.1℃量级,而太阳辐射引起的误差可达3℃量级甚至更高,已成为制约探空温度观测精度提高的瓶颈.本文利用计算流体动力学(CFD)方法对探空温度传感器从地面到32 km高空不同气压和多种引线夹角以及太阳高度角条件下的辐射误差效应进行求解,获得了辐射误差—海拔高度曲线族.研究结果表明,引线夹角以及太阳高度角是太阳辐射误差的重要影响因子.海拔高度与太阳辐射误差之间呈现出随海拔高度的增加斜率不断增大的类抛物线关系.