固相颗粒在钻井筛筛面上运移的计算机模拟和试验

根据钻井筛动力学的基本原理,分析了钻井液中固相颗粒在非淹没状态下相对于振动筛面作后滑、抛掷、静止和前滑4种运动状态的动力学条件。在考虑筛箱运动轨迹、筛面倾角、振动方向角、抛掷指数和钻井液粘附阻力等参数对固相颗粒运移影响的基础上,建立了固相颗粒运移速度和位移的动力学方程。按方程模拟计算得到的固相颗粒运移速度与实测值相比,误差小,吻合较好。综合分析认为,钻井液固相颗粒在平动椭圆筛上的运移速度高于直线筛．在直线筛上的运移速度叉高于圆型筛。     

负压钻井振动筛的动力特性分析

在传统钻井振动筛的筛面下引入负压腔,设计了一种新型钻井振动筛。通过压差作用提高钻井振动筛的工作性能和钻井液的处理量。文中建立了筛箱振动模型,推导了加载负压后筛箱的运动轨迹。建立了在负压、非淹没条件下岩屑颗粒的受力模型,得到了负压钻井振动筛筛网上岩屑颗粒的抛掷运动规律。通过研究负压下不同大小岩屑颗粒抛掷运动的起跳情况,对负压参数进行优化。当负压压差为126Pa时,负压钻井振动筛具有较好的抛掷效率和工作性能。     

钻井液固相提纯用ZJS12振动筛参数确定

参照现有钻井液直线振动筛的技术参数,通过分析筛框运动机理和工作状态下钻井液固相粒度变化特征,对ZJS12振动筛的参数进行理论研究,得到满足ZJS12振动筛运动的动力学指标最优值,为今后振动筛的设计与改进提供重要的参数依据,也为提高钻头的二次钻切效率和减少钻井成本提供保障。     

连续循环筛网振网筛横向振动研究

连续循环筛网振网筛是最新提出的一种固控设备,其工作原理与传统筛分设备不同,研究其筛网横向振动规律,有助于其筛分效率的探讨。基于拉格朗日方程和达朗贝尔原理建立了连续循环筛网振网筛的横向振动数学模型,计算了其轨道上筛盘的横向振动理论幅值;建立连续循环筛网振网筛虚拟样机模型,对其运动过程进行了精确模拟。研究发现,连续循环筛网振网筛作双频振动,在一定范围内,随着隔振弹簧刚度变大,会有效抑制链传动多边形效应引起的横向振动,但是对由激振电机引起的横向振动基本无影响。     

可调式自同步概率筛的设计与研究

通过研究透筛概率理论,建立动力学模型和筛粒在筛面上的运动模型,得出:概率筛振幅的大小取决于偏心块的质量,振动方向角和筛体的计算质量以及抛掷指数应在3的附近选取.最后提出一种新型的裹胶变筛孔筛面,可以有效的缓解筛网的磨损、减轻筛网的堵塞.     

不同筛面形式振动筛颗粒运移的DEM模拟

建立了凸、凹和平直三种筛面形式的振动筛离散元筛分模型,并采用JKR湿颗粒接触模型模拟了钻井液振动筛上的颗粒运移与透筛特性。研究结果表明,平直筛面的振动筛的筛分能力良好,筛面上分固相颗粒具有运移速度快、分布均匀特点;凹形筛面筛分能力较差,固相颗粒容易在筛面凹部堆积;凸形筛面振动筛的筛分能力也弱于平直筛面的振动筛,固相颗粒也容易在筛面两侧堆积。研究结果对钻井振动筛设计和筛分能力评价具有重要参考意义。     

离心式污水泵叶轮磨损的数值模拟

针对离心污水泵内固液两相流动比较复杂的情况,用含沙水为工作介质,通过改变沙粒粒径和含沙水颗粒浓度的方法,对小粒径颗粒在离心污水泵内的流动进行了数值模拟。借助弄清内流场的速度、压力与颗粒分布,分析了粒径大小对泵内固体颗粒运动的影响和进口初始颗粒浓度对泵内压力和固相分布的影响,得出压力沿叶轮吸力面和压力面的分布规律以及固体颗粒沿叶片吸力面和压力面的分布规律,并在此基础上得出了离心污水泵叶轮的磨损特性。     

水力旋流器进料物性参数对其流场规律的影响

在水力旋流器的结构参数和操作参数一定的情况下,改变进料物性参数(包括固相密度、粒度及浓度),用粒子动态分析仪(PDA)对水力旋流器内固相颗粒运动规律进行测试。根据测试结果,探讨了进料固相物性对水力旋流器内固粒运动规律的影响,为水力旋流器的结构优化以及进一步推广应用提供了重要的理论基础。     

气垫防磨叶栅内固体颗粒的运动特性

从空气动力学的角度提出了“气垫防磨”理论，以气垫叶栅作为研究对象，从含尘风机气－固两相流动的规律出发，气相采用Simple算法，结合标准k-ε紊流模型，固相采用拉格朗日法，在不同的主流与射流速度比，不同的缝隙数和缝隙宽度等条件下，计算了固体颗粒在气垫作用下的运动情况，计算结果表明，气垫阻碍了粒子与壁面的撞击几率，在理论上论证了气垫防磨的可行性。     

硅系铁合金在钢包内作用规律的物理模拟研究

应用相似理论 ,模拟研究了出钢速度、铁合金密度和加入方式以及底吹气体等因素对包内流体循环流动和固相颗粒运动的影响。结果表明 ,流体在包内的循环流动方式和固相颗粒的动量大小是固相颗粒能否参与循环并延长固相颗粒在流体中作用时间的主要因素。     

Experimental Research on Salt-out Particle Motion and Concentration Distribution in a Vortex Pump Volute

The vortex pump is suitable for salt solution transportation. But the salt-out flow mechanism in the pump has not been understood fully. Salt-out layer formation and growth rate are closely related to crystal particle motion and concentration distribution. Study on the particle hydrodynamic characteristics in the pump volute becomes a key problem, because the crystal particles are mainly distributing in this zone after they enter the pump. Phase Doppler particle analyzer(PDPA) is used to measure the two-phase flow field in a model pump volute to get more understanding about the salt-out phenomenon. The crystal particle velocities are obtained in all three peripheral, radial and axial directions. Particle size and particle number density(PND) measurements are also performed in the experiment. Results are presented and discussed along the radial direction under different pump operating conditions, as well as various axial measurement positions. It is found that particle velocity gradient of peripheral component varies with the pump discharge. There is a turning point of relation between peripheral velocity component and discharge. Radial flow velocity curves look like a saddle shape and velocity magnitudes are changing greatly with the discharge. The non-equilibrium velocity feature between liquid and solid phase on this direction is also remarkable. Particles flow into the impeller at radial position R1, and the axial velocity component increases in this region. The particle size curve shows an open-up parabola distribution. The largest particles are distributing near the casing peripheral wall. As flow rate increases, accordingly PND increases. It also grows up in the axial-outward direction towards the suction cover. Crystal particle aggregation phenomenon can be revealed from the analysis of particle size and PND distribution, and the aggregation region is determined as well. Research results are helpful for optimal design of this kind of pump preventing salt-out.     

自由漂浮空间机械臂非完整运动规划的粒子群优化算法

带空间机械臂航天器系统在无外力矩作用时,系统相对于总质心的动量矩守恒而变为非完整系统,由于非完整约束的不可积性,非完整系统的运动规划与控制比一般系统要困难得多.针对这一问题,利用非完整特性研究自由漂浮空间机械臂的三维姿态运动规划问题,导出带空间机械臂的航天器三维姿态运动数学模型,并将系统的控制问题转化为无漂移系统的非完整运动规划问题.在运动规划中,引入Fourier基函数构成系统控制输入,对基函数的系数向量优化,提出一种应用粒子群优化的最优运动规划数值算法.数值仿真表明该方法对空间机械臂及航天器三维姿态运动的非完整运动规划是有效的.     

钻柱在钻井液和井壁摩阻共同作用下的涡动

把旋转钻柱简化为一内外有流体的柔性转子系统，分析了在内外钻井液流体作用下的钻柱涡动行为。研究表明，钻柱内钻井液将影响钻柱的受力状况及运动形式，钻柱外钻井液使钻柱承受一个与其旋转运动速度同向的侧向力，加大了钻柱涡动行为；钻柱与井壁接触摩擦，使钻柱在低速时也发生涡动。建立和求解了内外钻井液对钻柱动压力的数学模型，探讨和描述了内外钻井液作用下钻柱涡动过程的动力学机理和运行规律，得到了钻柱涡动失稳的临界条件。     

A multi-field approach to modeling the dynamic response of cellular materials

A multi-field approach is developed for simulating the continuum-scale mechanical response of cellular materials. This approach departs from traditional methods used to model cellular materials, which focus almost exclusively on the mechanical response of the cellular solid, while essentially ignoring the fluids permeating these material systems. In the present work, conservation equations are derived in multi-field form, producing a coupled set of governing equations with source terms depending on gradients in the cellular solid stress, but also on gradients in the permeating fluid pressure and momentum exchange resulting from relative motion between the cellular solid and permeating fluid fields. The multi-field equations of motion are implemented in a standard finite-volume computational test bed and used to study the dynamic response of cellular material systems. The influence of various permeating fluids, along with the effects of aperture size, loading rate, and boundary conditions, also are examined. By incorporating an advanced constitutive model for cellular solids into a multi-field response formulation, a promising new approach for simulating the finite-strain dynamic response of cellular materials is offered. Results demonstrate that the permeating fluid can play a major role in the general response of cellular material systems, contributing to the overall load-carrying capacity of the materials and affecting rate dependence and signal propagation speeds. Furthermore, the results point to the usefulness of the multi-field formulation and provide evidence to suggest that any modeling approach developed for cellular materials gives a proper accounting of the pressure evolution and flow behavior of the fluids present in these material systems.     

仿生鱼鳍波动推进模式对游动性能影响的数值研究

仿生鱼鳍的波动运动有两种基本模式:振幅从前往后保持不变和振幅从前往后逐渐变化。通过比较仿生鱼鳍两种波动模式的特点,可以给利用仿生鱼鳍驱动的水下推进器选择合理的波动方式提供依据。基于计算流体动力学(computational fluid dynamics,CFD)技术建立两种波动模式的二维数学模型。比较分析了在相同的雷诺数及运动学参数(频率、波速和平均振幅)下两种波动模式形成的压力分布和平均推进力。给出了阻力系数随时间的变化规律。根据尾迹涡量场分布形式和涡量强度解释了两种波动模式之间存在差异的原因。从仿真结果可以看出:在相同的运动学参数下,振幅从前往后保持不变的鱼鳍波动模式产生更大的推进力,具有更高的游动稳定性。     

自适应机翼柔性翼肋的受控运动学规律研究

柔性自适应机翼技术采用了一种全新的材料/结构/功能一体化的设计思想,它是将传感单元、驱动单元、控制单元与机翼结构有机地结合,赋予机翼形状自适应等功能,从而改善飞机的飞行性能。本文根据DLR可变后缘自适应机翼概念,设计制造了这种自适应机翼的基本构件——柔性翼肋,分析了模型设计的关键参数,推导出了单输入驱动下柔性翼肋变形的运动学规律,并通过软件仿真和模型实验验证了柔性翼肋受控运动规律的正确性。     

水平井钻柱涡动特性数值分析与试验

根据转子动力学和流体力学理论,建立了水平井钻柱涡动的动力学方程,分析了钻柱自重、井壁摩阻、钻井液流速等因素对水平井钻柱涡动的影响规律,阐释了诱发水平钻柱涡动产生的机理及边界条件。基于自主研制的水平井钻柱动力学试验装置,采用数值模拟和试验研究相结合的方法,分析了钻压、转速、流体速度等参数对钻柱涡动轨迹和涡动速度的影响规律。研究结果表明：在钻柱的远钻头段不会发生涡动,但是转速达到阈值后,近钻头段便会出现涡动现象,并且随着钻压和转速的增加,其涡动轨迹幅值也在增大;而近钻头段的涡动方向并不是始终如一的,存在正反两个方向的涡动,并且随着转速的增大,还会出现“半频涡动”现象;另外,钻井液的存在及其流动速度的增大都不会改变钻柱现有的运动状态,仅小幅增加其运动范围。研究成果对水平井钻井工艺参数的选定有一定的借鉴作用。     

离心压缩机内固粒运动规律与冲蚀磨损的数值模拟

针对离心压缩机叶轮的冲蚀磨损问题,利用FLUENT中离散相模型、质量冲蚀率模型,对压缩机内部不同粒径的固体颗粒的运行轨迹、运动速度、偏聚浓度及造成的叶片冲蚀率的分布进行了数值模拟。结果表明:粒径为5~20μm的绝大部分的固体颗粒流经大叶片压力面附近流道;固体颗粒在运动到叶片前缘过程中速度迅速升高,在压力面腹侧会有所减小,后缘处重新升高;大叶片后缘根部固体颗粒浓度高、运行速度快,冲蚀磨损严重,且固体颗粒直径越大对大叶片压力面造成的冲蚀磨损越严重。     

Solid-liquid mixture flow through a slim hole annulus with rotating inner cylinder

An experimental study was conducted to study solid-liquid mixture upward hydraulic transport of solid particles in vertical and inclined annuli with rotating inner cylinder. Lift forces acting on a fluidized particle play a central role in many important applications, such as the removal of drill cuttings in horizontal drill holes, sand transport in fractured reservoirs and sediment transport, etc. Annular fluid velocities varied from 0.4 m/s to 1.2 m/s. Effect of annulus inclination and drill pipe rotation on the carrying capacity of drilling fluid, particle rising velocity, and pressure drop in the slim hole annulus have been measured for fully developed flows of water and of aqueous solutions of sodium carboxymethyl cellulose (CMC) and bentonite, respectively. For higher particle feed concentration, the hydraulic pressure drop of mixture flow increases due to the friction between the wall and solids or among solids. This paper was recommended for publication in revised form by Associate Editor Gihun Son Sang-Mok Han received a B.S. degree in Mechanical Engineering from Sung-kyunkwan University in 2001. He then went on to receive his M.S. degrees from Sungkyunkwan University in 2003. He is a candidate for Ph.D. from 2006 to the present at the School of Mechanical Engineering at Sungkyunkwan University in Suwon, Korea. His research interests are in the area of Multi-phase flow and drilling. Nam-Sub Woo received a B.S. degree in Mechanical Engineering from Sungkyunkwan University in 1997. He then went on to receive his M.S. and Ph.D. degrees from Sunkyunkwan University in 1999 and 2007, respectively. Dr. Woo is currently a Senior Researcher at the Fire & Engineering Services Research Center at Korea Institute of Construction and Technology in Goyang, Korea. Dr. Woo’s research interests are in the area of fluid dynamics and plant engineering. Young-Kyu Hwang received a B.S. degree in Mechanical Engineering from Sungkyunkwan University in 1977. He then went on to receive his M.S. from University of Wis-consin at Madison in 1980 and Ph.D. degrees from State Uni-versity of New York at Buffalo in 1984, respectively. Dr. Hwang has served as a Professor, from 1984 to the present at the School of Mechanical Engineering at Sungkyunkwan University in Suwon, Korea. His research interests are in the area of drilling hydraulics, molecular gas flow and hydrodynamic instability.