流速梯度对悬浮颗粒脉动强度的影响

从简化的颗粒运动方程出发，分析了在剪切流场中颗粒脉动强度和流体脉动强度之间的关系。结果表明，由于纵向时均流速的垂线分布梯度的作用，颗粒在两个方向上的脉动强度均可能超过相应的流体脉动强度。     

明渠挟沙水流的颗粒相平均速度及速度滑移

基于颗粒相动理学模型所确立的颗粒相基本方程和本构关系，导出了明渠挟沙水流中固液两相平均速度差的表达式，表明相间速度差与两相的垂向脉动强度、脉动切应力、水下重力、剪切升力、颗粒弛豫时间等有关，与两相沿流向脉动强度无关。运用水流速度的窦国仁公式，计算了颗粒相速度的垂线分布，分析了相间速度差的垂线分布特性，结果与试验资料吻合很好。表明相间速度差呈现出水面小、水底大的分布形式；细小颗粒的速度差近似为零，粗重颗粒的速度差明显、在固壁附近存在明显的极大值。     

水沙流中颗粒脉动特性

作者利用固液两相流中关于颗粒运动的动理论，对恒定均匀流条件下微观的颗粒速度分布函数变 化以及颗粒脉动强度的宏观特性变化进行了分析，得到了水沙流中颗粒沿纵向和垂向脉动强度变化的理论计算结果。经与水平管流中颗粒运动的实验结果比较，二者比较吻合，从而印证了理论的合理性。     

细颗粒悬沙浓度分布的影响因素分析

从颗粒运动的PDF(概率密度分布函数)输运方程出发建立颗粒相的质量、动量和脉动速度二阶矩方程。对明渠二维恒定均匀流，利用垂向动量方程导出了修正的泥沙扩散方程，表明颗粒脉动强度梯度、升力、有效重力和紊动扩散都影响悬沙运动。理论和数值分析了细颗粒泥沙的密度、粒径、浓度，挟沙水流的水深和剪切流速等因素对泥沙扩散系数和浓度分布形状的影响，并定量分析了细颗粒试验资料，表明传统扩散方程在粒径、剪切流速相对较大、水深和水沙密度比较小的流动中存在较大误差，需要修正。     

水平方管内固液两相流运动特性数值模拟

将周力行建立的k-ε-kp两相湍流模型引入固液两相流的研究中，对水平方管内挟沙 水流固液两相的时均特性、脉动特性以及颗粒密度分布进行了数值模拟。将计算结果与k-ε-Ap模型、动理论计算结果以及物理模型试验观测结果进行了比较，发现k-ε-k p模型数值计算和物理模型试验观测结果的一致性较好；和kεAp模型相比，由于考虑了颗粒相的湍动特性在固液两相流中的作用，k-ε-k-p两相湍流模型可以得到颗粒的脉动速度分布；和动理论相比，k-ε-kp模型无法准确地预测固相的垂向脉动速度，需要引入各向异性的两相流模型。     

非连续剪切面的剪切过程模拟

在各类边坡工程中，坡体的破坏失稳过程往往就是其内部非连续剪切面的剪切贯通过程，这类剪切面的综合抗剪强度与非连续剪切面的分布状态有关．采用颗粒离散元方法，利用颗粒流模拟软件PFC建立了非连续剪切面的平面环剪模型，并模拟了剪切过程．模拟结果反映出非连续剪切面的综合抗剪能力除了与抗剪强度强弱区比例有关，还与非连续的分布形态有关；剪切过程中的颗粒间接触关系和接触应力的变化反映出剪切面的剪切破坏过程．     

水涡轮机械中的湍流固—液两相流动及磨损研究

导出了固体颗粒在任意流场中运动的Ｌａｇｒａｎｇｉａｎ方程对此方程进行线性化，并求出了其颗粒运动方程的解析通解。使用颗粒运动方程数值求解和分析稀疏颗粒湍流场中固体颗粒的运动。建立了湍流固－液两相液的Ｋ－ε双方湍流模型，体积分数流模型，Ｅｕｎｌｅｒｉａｎ－Ｌａｇｒａｎｇｉａｎ混合湍流模型以及颗粒磨损模型，利用这些模型对一些水涡轮机械过流通道内的流动及固壁磨损进行了模拟，其预测结果与实验结果较为一致。     

水涡轮机械中的湍流固－液两相流动及磨损研究

导出了固体颗粒在任意流场中运动的Ｌａｇｒａｎｇｉａｎ方程，对此方程进行线性化，并求出了其颗粒运动方程的解析通解。使用颗粒运动方程数值求解和分析了稀疏颗粒湍流场中固体颗粒的运动。建立了湍流固－液两相流的Ｋ－ε双方程湍流模型、体积分数湍流模型、Ｅｕｎｌｅｒｉａｎ－Ｌａｇｒａｎｓｉａｎ混合湍流模型以及颗粒磨损模型，利用这些模型对一些水涡轮机械过流通道内的流动及固壁磨损进行了数值模拟，其预测结果与实验结果较为一致     

水—沙两相流的激光多普勒分相测量和试验研究

探讨泥抄颗粒在水流中的悬浮运动机理和水、沙两相之间的相互作用，首先需要分别了解水流和泥沙颗粒的运动特性及相互关系。因此，怎样分相观测水流和泥抄颗粒的运动参数成为泥沙运动基本理论研兜的一十重要问题。本文集中介绍了利用激光多普勒技术分相测量水流和泥沙运动参数的基本原理和方法．以及利用常见的一维激光器(无声光频移)测量水流和颗粒垂向(垂直于水流运动方向)脉动速度的实验方法。使用该技术对水平方管内的水一沙两相流运动进行了试验观测，给出了两相速度、纵向及垂向湍流度，以及泥沙浓度的测量结果。     

高浓度固液两相流的运动特性研究

利用固体颗粒运动的动理论，通过改变颗粒浓度可以考察非粘性颗粒在水流中运动的典型微观和宏观运动特性。本文分别对微观的颗粒速度分布函数变化和由此衍生的诸如颗粒平均速度、颗粒脉动速度和单位体积颗粒数垂线分布等宏观变量的变化进了系统比较。研究结果表明：动理论能够比传统理论获得理详细的微观和宏观信息，也更适合研究高浓度固液两相流运动特性，颗粒运动微观和宏观特性在颗粒浓度超过一定阈值后会发生本质的变化，但临界颗粒浓度值（阈值）在不同的计算和实验条件下会有一定的差别。     

Vibration analysis of hydropower house based on fluid-structure coupling numerical method

By using the shear stress transport(SST)model to predict the effect of random flow motion in a fluid zone,and using the Newmark method to solve the oscillation equations in a solid zone,a coupling model of the powerhouse and its tube water was developed.The effects of fluid-structure interaction are considered through the kinematic and dynamic conditions applied to the fluid-structure interfaces(FSI).Numerical simulation of turbulent flow through the whole flow passage of the powerhouse and concrete structure vibration analysis in the time domain were carried out with the model.Considering the effect of coupling the turbulence and the powerhouse structure,the time history response of both turbulent flows through the whole flow passage and powerhouse structure vibration were generated.Concrete structure vibration analysis shows that the displacement,velocity,and acceleration of the dynamo floor respond dramatically to pressure fluctuations in the flow passage.Furthermore,the spectrum analysis suggests that pressure fluctuation originating from the static and dynamic disturbances of hydraulic turbine blades in the flow passage is one of the most important vibration sources.     

Experimental investigation of turbulent flows around high-rise structure foundations and implications on scour

Many studies have been undertaken to predict local scour around offshore high-rise structure foundations (HRSFs), which have been used in constructing the Donghai Wind Farm in China. However, there have been few works on the turbulent flow that drives the scour process. In this study, the characteristics of the turbulent flow fields around an HRSF were investigated using the particle image velocimetry technique. The mean flow, vorticity, and turbulence intensity were analyzed in detail. The relationship between the flow feature and scour development around an HRSF was elaborated. The results showed that the flow velocity increased to its maximum value near the third row of the pile group. The shear layer and wake vortices could not be fully developed downstream of the last row of the piles at small Reynolds numbers. The strong flow and turbulent fluctuation near the third piles explained the existence of a long-tail scour pattern starting from the HRSF shoulders and a trapezoidal deposition region directly downstream of HRSF. This laboratory experiment gains insight into the mechanism of the turbulent flow around HRSFs and provides a rare dataset for numerical model verifications.     

幂律流体在圆管内湍流流动剪切率的近似计算

根据剪切率和能量耗散率的定义，建立了幂律流体湍流剪切率与能量耗散率的关系式。参照文献上对不可压缩牛顿流体湍流能量耗散率的近似算法，提出了一种幂律流体管内湍流能量耗散率的近似算法，从而得到了幂律流体管内湍流剪切率的实用近似算式，再利用湍流剪切率与脉动流剪切率的关系即可得到脉动流剪切率。计算得到的湍流剪切率分布及其随流动特性指数变化的特征与已知规律相符。     

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

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

Turbulent flow structure at a 90-degree open channel confluence: Accounting for the distortion of the shear layer

City channels often have a smaller width-to-depth ratio in comparison to natural rivers due to the limited land availability. The penetration of the tributary into the main channel can cause the distortion of the shear layer. The main purpose of the present study is to investigate the mean and turbulent flow structure in the distorted shear layer in a discharge-adjustable plexiglass circulating flume. Three-dimensional velocities were collected and hydrodynamics and turbulence characteristics such as mean velocity field, turbulent kinetic energy, Reynolds shear stress, turbulence spectrum, and occurrence probabilities of quadrant events were analyzed. The results showed that a stronger helical cell was formed and extended for a longer distance downstream when the tributary channel had a higher flow rate than the main channel. The maximum Reynolds shear stress and the ejection and sweep events were mainly distributed at the middle zone of the water depth, rather than near the water surface, which were coincident with the shear layer as indicated by the turbulence kinetic energy. No obvious energy concentration was observed, and the power law relations for individual velocity components all had an exponent slightly larger than −5/3 in the flow frequency. The distortion of the shear layer resulted in an increase in occurrence probabilities of ejection and sweep events within the shear layer, which were related to the turbulence presenting vortices induced by wall. If the discharge ratio remained unchanged, an increase in the discharge of both channels resulted in an increase in some parameters, such as velocity, turbulent kinetic energy, and the absolute values of Reynolds shear stress, while the shear layer was distorted to a larger extent as the discharge of each channel decreased. All these results suggested that sediment transport, bed morphology and contaminant transport in the distorted shear layer at city channel confluences may differ significantly from that at natural river confluences.     

LARGE EDDY SIMULATION OF PARTICLE TRANSPORT IN FULLY DEVELOPED VERTICAL TURBULENT CHANNEL FLOW

Fully developed vertical turbulent channel flow with particle transport was investigated by use of Large Eddy Simulation (LES) approach coupled with dynamic the SubGrid Scale (SGS) model. It was assumed that the motion of each particle is followed in a Lagrangian frame of reference driven by the forces exerted by fluid motion and gravity under the condition of one-way coupling. The goal of this study is to investigate the effectiveness of the I.ES technique for predicting particle transport in turbulent flow and the behavior of particle-laden turbulent channel flow for three kinds of particles at different Stokes numbers. To depict the behavior of particle-laden turbulent channel flow, statistical quantities including particle fluctuation and fluid-particle velocity correlation, and visualization of the particle number density field were analyzed.     

丁坝坝头冲淤的三维数值模拟

本文对洪水条件丁坝近体的局部冲淤进行了三维数值模拟。开发了与全三维紊流模型连接计算的泥沙模型。泥沙推移质的计算考虑了床面坡度对推移质输沙率和临界启动剪切力的综合影响。模型经丁坝淹没绕流实验的充分验证。结果详尽讨论了局部冲刷随时间的动态变化过程和动平衡下的河床平面形态特征。     

旋流流动中的颗粒相非线性双尺度k_p-ε_p湍流模型

基于多尺度湍流的概念,建立了颗粒相的非线性双尺度k_p-ε_p湍流模型.利用该模型对旋流突扩室内的两相流动进行了数值模拟,并且将两相平均速度及脉动速度的模拟结果和实验数据以及颗粒相的单尺度k_p-ε_p两相湍流模型的结果做了对照.结果表明:对两相切向速度,两种模型具有相接近的模拟能力;但是对脉动速度及轴向速度,本模型的预报结果比单尺度两相模型所获得的结果有较大改进.     

A SECOND-ORDER MOMENT TURBULENCE MODEL FOR POWER LAW FLUID WITH PARTICLES

The USM-θ model of power law fluid for dense two-phase turbulent flow was developed, which combines the unified second-order moment model for two-phase turbulence with the particle kinetic theory for the inter-particle collision. This model was used to simulate the turbulent flow of power law fluid single-phase in pipe. It is shown that the USM ? θ model has better prediction result than the k f ? ε f?kp?εp?θ model. The USM ? θ model was then used to simulate the dense two-phase turbulent up flow of power law fluid with particles. With the increase of the flow exponent, the velocities of power law fluid and particles increase near the pipe centre. Comparison between the two-phase flow of power law fluid-particle and of liquid-particle indicates that the axial fluctuation velocity of fluid phase and particle phase in liquid-particle two-phase flow is smaller than that in the power law fluid two-phase flow, but the two-phase velocities of power law fluid-particle and liquid-particle are close to each other.     

平面湍流混合层流动的统计理论

本文提出了不可压缩粘性流体充分发展的湍流流动的逐级迭代法。此方法能有效地求解脉动速度的高阶关联函数，并修正平均速度和低阶关联函数的精度，应用此方法给出了平面湍流混合层流动的一级近似的二阶、三阶和四阶脉动速度的关联函数，并同实验结果进行了比较，两者符合得较好。