杭州大剧院风压分布的风洞试验研究

杭州大剧院外观造型新颖独特，由一个近似为椭球的双曲面屋盖和一个倒置的圆锥面玻璃幕墙相交形成大剧院的主体建筑的外轮廓．本文结合该主体结构的抗风设计要求，制作了1：200刚性模型进行结构表面脉动风压平均风压分布的风洞试验研究，详细介绍了风洞试验及数据处理方法，讨论了在不同风向角下椭球面屋盖和圆锥面玻璃幕墙的风压分布．为了便于整体结构设计，本文根据结构的实际情况对椭球面和圆锥面进行分块并给出相应的分块风压数据，最后根据各风向角下的风压分布特征给出了整体结构抗风设计的最不利风向角．     

THEORETICAL AND EXPERIMENTALRESEARCH ON DYNAMIC BEHAVIOR OF GUYED MASTS UNDER WIND LOAD

I. INTRODUCTION Wind-induced vibration is the critical factor for the safety of guyed masts. Many dynamic modelshave been proposed in the literature[1 , 2]. However, there are obvious de?ciencies in many of theseprevious works owing to the poor cabl…     

Interference effects of two and three super-tall buildings under wind action

Most previous investigations on interference effects of tall buildings under wind actions focused on the wind induced interference effects between two buildings,and the interference effects of three or more buildings have seldom been studied so far due to the huge workload involved in experiments and data processing.In this paper,mean and dynamic force/response interference effects and peak wind pressure interference effects of two and three tall buildings,especially the three-building configuration,are investigated through a series of wind tunnel tests on typical tall building models using high frequency force balance technique and wind pressure measurements.Furthermore,the present paper focuses on the effects of parameters,including breadth ratio and height ratio of the buildings and terrain category,on the interference factors and derives relevant regression results for the interference factors.     

Background oriented schlieren for flow visualisation in hypersonic impulse facilities

Experiments to demonstrate the use of the background-oriented schlieren (BOS) technique in hypersonic impulse facilities are reported. BOS uses a simple optical set-up consisting of a structured background pattern, an electronic camera with a high shutter speed and a high intensity light source. The visualization technique is demonstrated in a small reflected shock tunnel with a Mach 4 conical nozzle, nozzle supply pressure of 2.2 MPa and nozzle supply enthalpy of 1.8 MJ/kg. A 20° sharp circular cone and a model of the MUSES-C re-entry body were tested. Images captured were processed using PIV-style image analysis to visualize variations in the density field. The shock angle on the cone measured from the BOS images agreed with theoretical calculations to within 0.5°. Shock standoff distances could be measured from the BOS image for the re-entry body. Preliminary experiments are also reported in higher enthalpy facilities where flow luminosity can interfere with imaging of the background pattern. A version of this paper was presented at the 25th International Symposium on Shock Waves in Bangalore in July 2005.     

大型砂尘风洞中砂尘浓度测量与控制方法的研究

砂尘浓度指标严重影响砂尘风洞试验效果;在大型砂尘风洞中准确的测量及有效的控制砂尘浓度是砂尘风洞设备研制中的两个关键问题;针对动态试验工况环境中浓度传感器标定的问题,分析了浓度测量时标定参数与风速和浓度的关系,使用模型树算法建立了三者之间的关系模型,以此模型来预测各种动态情况下的标定参数;针对复杂环境下浓度动态控制问题,采用专家PID算法,提出了多回路控制系统结构和专家规则;工程实践表明该测量和控制方法满足了动态试验环境的需求,取得了良好效果;模型树算法和专家PID系统能有效的解决动态工况下砂尘浓度的测量与控制问题。     

Upstream porthole injection in a 2-D scramjet model

Injection from portholes upstream of the combustion chamber was investigated as a method of delivering fuel into a scramjet. This method reduces the viscous drag on a model by allowing a reduction in the length of the combustion chamber. At experimental enthalpies of 3.0 MJ/kg in the T4 shock tunnel, there was no evidence of combustion in the intake, either by shadowgraph or pressure measurements. Combustion was observed in the combustion chamber. A theoretical extension of these results is made to a hot wall scenario. Received 2 January 2001 / Accepted 3 August 2001     

用反向渐进结构优化方法研究洞室支护优化

洞室开挖支护的优化是在铁路隧道、矿山开挖、水电站建设中经常面对的课题,特别是研究洞室开挖支护拓扑优化有着重要的意义。本文利用近年来发展的渐进优化方法(ESO)的概念,提出了反向ESO方法的迭代格式,建立了洞室开挖支护优化的准则及其敏感度,研究了均匀地基不同地应力条件使得开挖卸荷产生的总应变能最小的最优支护拓扑。结果证明了反向ESO方法的适用性,最优支护拓扑大致成椭圆或者圆形,其主轴方向与最大主应力主轴方向相同。     

回转体表面条纹沟槽减阻水洞实验研究

本文在条纹沟槽表面减阻理论分析的基础上,对条纹沟槽表面回转体进行了大量的水洞实验研究。实验模型表面条纹沟槽采用直接加工方法,头部线型为双参数平方根圆头曲线,尾部线型为双参数尖尾曲线。实验结果分析表明,与相同形状、尺寸的光滑表面回转体相比,条纹沟槽表面回转体在一定速度范围内存在很好的减阻效果,最大减阻量超过6%,且在小攻角范围内减阻量基本稳定,对回转体升力特性也没有影响。对比不同尺寸条纹沟槽的减阻效果发现,降阻量不但随条纹沟槽宽度S变化,而且随来流速度U∞变化,即与无因次沟槽宽度S (文中近似取S =S.LRe2Ckx,其中k为总阻力Cx的修正因子)存在着一定的关系。对于V型条纹沟槽具有减阻效果的S 的范围在10到60之间。本文研究证明,条纹沟槽表面减阻技术在水下航行器设计领域有着很好的应用前景,同时文中所取得的研究成果对该技术的应用具有一定的促进作用。     

Numerical study of free-piston shock tunnel performance

A free-piston shock tunnel (FPST) is one of the most useful ground testing facilities for hypervelocity flow research of re-entry vehicles and scramjet engines. For an efficient operation with tuned piston motion, the design of facility and the comprehension of the physical phenomena in a FPST, a numerical simulation which can properly predicts the flow with actual losses is required. But there are few successful numerical methods which can simulate its overall performance. In the present study, numerical method was developed by using the KRC shock capturing scheme and by modeling the flow losses in suitable forms for a quasi-1D numerical computation. The present numerical results were compared with the data obtained in two different facilities, T4 and T5. The applicability of the present numerical method as a design tool is discussed briefly.This article was processed using Springer-Verlag T_EX Shock Waves macro package 1.0 and the AMS fonts, developed by the American Mathematical Society.     

Absolute intensity measurements of impurity emissions in a shock tunnel and their consequences for laser-induced fluorescence experiments

Absolute intensity measurements of impurity emissions in a shock tunnel nozzle flow are presented. The impurity emission intensities were measured with a photomultiplier and optical multichannel analyser and calibrated against an intensity standard. The various metallic contaminants were identified and their intensities measured in the spectral regions 290 to 330 nm and 375 to 385 nm. A comparison with calculated fluorescence intensities for predissociated laser-induced fluorescence signals is made. It is found that the emission background is negligible for most fluorescence experiments.This article was processed using Springer-Verlag T_EX Shock Waves macro package 1.0 and the AMS fonts, developed by the American Mathematical Society.