面流消能近底紊动流速特性的研究(面流消能试验研究之一)

本文主要论述了面流消能五种典型流态近底紊动流速特性,总结出了近底时均流速和紊动强度沿程变化规律,提出了近底紊动流速可能出现的最大瞬时值及相应位置的计算公式。面流消能工程的下游防冲设计中考虑的主要水力参数之一是,消能段近底流速紊动可能出现的最大瞬时值及其相应的部位,但目前国内外研究成果较少。笔者通过水工模型试验重点研究了面流消能各典型流态近底流速及其紊动纵向分量沿程的变化规律,并提出了计算公式,为优化面流设计提供科学依据。     

TURBULENCE TRANSPORT OF SURFACTANT SOLUTION FLOW DURING DRAG REDUCTION DEGENERATION

Turbulence transport of surfactant solution flow during drag reduction degeneration is investigated experimentally in a two-dimensional channel.Particle Image Velocimetry (P1V) system is used to take t...     

湍流流动及燃烧模拟研究进展

湍流流动往往伴随着燃烧过程。湍流燃烧现象广泛存在于自然界及诸多实际工程问题中，成为近几年的研究热点。现有的相关理论及模型纷繁复杂。本文对该领域研究进行了分类总结、综合评述。可对全面了解研究现状和进一步的发展前景提供方向性的指导和帮助。     

Stochastic aspects of bridge deck aeroelasticity under turbulent flow

Returning to an earlier frequency-domain analysis of the problem of long-span bridge response to ambient winds, the paper emphasizes the indispensable experimental information necessary to bring results into conformity with full-scale prototype action. Focus is placed upon the use of a sectional wind tunnel model under simulated turbulent flow as the prime source of this information, which consists principally of the flutter derivatives and the spectra of the wind forces, both obtained under turbulent flow. The effect of three-dimensional turbulence upon the flutter derivatives is observed to influence structural stability in a manner consistent with that observed in full-bridge wind tunnel models.     

A TVD SCHEME FOR INCOMPRESSIBLE FLOW COUPLED WITH DIFFERENT TURBULENCE MODLES ON A GROUND- MOUNTED SQUARE-RIB FLOW

A finite-difference Total Variation Diminishing (TVD) numerical simulation model for coupling the Reynolds Averaged Navier-Stokes (RANS) equations, pressure-relative continuity equation and various k-εturbulence models was developed to solve the incompressible flow based on the pseudo-compressibility method. The hyperbolicity of all these equations was studied and the discretization of the fully coupling equations with all the primal variables and source terms were made in this article. Numerical simulation for modeling the flow around a ground-mounted square rib was implemented and validated by comparing with the published wind tunnel experimental data. It is shown that such a numerical simulation method with a proper turbulence model has a very good accuracy to simulate the flow around a surface-mounted rib. It is concluded that the Renormalization Group (RNG) and Chen-Kim k-εturbulence models have much better ability to predict the characteristics of the vortex structure and flow separation than the standard k-εmodel.     

Experimental investigation of turbulent boundary layer flow with surfactant additives using PIV and PDA

Drag reduction of turbulent water flow with surfactant (CTAC) additives was experimentally investigated. By using PIV and PDA measurements, the spatial velocity distribution of surfactant solution flow was clarified in a two‐dimensional water channel. With an increasing Reynolds number, it was found that drag reduction of surfactant solution flow is enhanced within the region of drag reduction. However, in the region of post drag reduction, the drag‐reducing coefficient approaches one without surfactant when Reynolds number is increased. In the near‐wall region, velocity profiles of the drag‐reducing fluid are similar to, but not the same as, the laminar profiles of the Newtonian fluid. When compared to the case of water flow without surfactant, the velocity contour lines of the drag‐reducing fluid run approximately parallel to the wall. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(2): 99–107, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20047     

A NEW METHOD FOR SOLVING TURBULENT VELOCITY CORRELATION FUNCTIONS AND ITS APPLICATION TO THE CHANNEL FLOW

ＡＮＥＷＭＥＴＨＯＤＦＯＲＳＯＬＶＩＮＧＴＵＲＢＵＬＥＮＴＶＥＬＯＣＩＴＹＣＯＲＲＥＬＡＴＩＯＮＦＵＮＣＴＩＯＮＳＡＮＤＩＴＳＡＰＰＬＩＣＡＴＩＯＮＴＯＴＨＥＣＨＡＮＮＥＬＦＬＯＷＬｉｎＪｉａｎ－ｚｈｏｎｇ；ＷａｎｇＹｕ－ｚｈｉ（Ｄｅｐａｒｔｍｅｎｔ...     

抽水蓄能电站中水力干扰下的过渡过程及其稳定问题的研究

高水头抽水蓄能电站中，常采用一洞多机系统，所以机组之间水力联系紧密，本文建立了对水力干扰进行过渡过程计算所必须的既能进行大波动计算又可进入小波动的数学模型，并编制了计算程序，通过计算研究了部分机组停机过程中，其余机组在水力干扰下的过渡过程及稳定问题。     

粒子相的分类及对紊流场的作用

本文提出了两相流中粒子相颗粒粗、细和含量浓、稀的分类标准，并从两相流紊流基本方程出发，分析了粒子相对紊流场的作用，并导出了粒子相对紊动强度影响的计算式。     

可变后掠机翼变形机理及气动特性研究

在飞行器的设计开发过程中,机翼后掠角的改变可以使飞行器在各个飞行阶段均保持较优的性能。本文提出一种局部旋转式变后掠机翼,并设计了相应的驱动机构。将此变后掠方案结合两种不同翼型分别构建三维模型后,基于FLUENT及SA湍流模型,对两模型分别进行了外部绕流流场的数值模拟,分析机翼在不同攻角及飞行马赫数下的气动特性差异。分析结果表明,通过改变机翼的后掠角改变可以显著改变机翼升力系数、阻力系数及升阻比,提高飞行器对不同飞行环境的适应能力。