圆管流动水击压力波测量及水力计算

为探索水击现象的物理过程和机理,研制了自循环定常流动管路瞬态特性计算机控制试验装置,并利用该装置进行圆管流动水击压力波实验测量。用12只扩散硅压力传感器测定圆管流动水击压力波瞬态分布及最大、最小压力值,由试验数据拟合出水击波波形,揭示了水击压力波传播方式、特性及衰减规律。通过分析随机捕捉测量技术方法,理论上推断出测量数据达到可信精度。在归纳分析试验数据基础上,得出最大压力随关阀时间的关系曲线,对圆管流动直接水击等概念进行了探讨,用数值分析方法拟合出水击最大压力水力计算修正方程式。     

石油工程中偏心油管内液流失速水击特性分析

为了对石油工程中油管偏心时液流失速水击特性进行分析研究,并给注水、洗井等工艺提供借鉴,本文利用试验装置,结合PIV、瞬态压力测量系统,对偏心油管内液流失速的流场流线、速度、涡量特性以及压力场特性进行了分析。得出了如下结论:水击发生时,随着偏心距的加大,油管内、外壁压力易产生严重失衡,油管内液流速度衰减变慢;油套环内流速随油管内流速衰减而增加;小流道内流速随偏心距增大而减小;涡量随偏心距的增加而减小。     

环空泥浆流场的超声波测试及应用

本文介绍了超声波流速仪测试非牛顿流（如泥浆，水泥浆）流场的方法和特点，对牛顿流和非牛顿流在管内的速度分布剖面作了对比，用该仪器对石油钻井工程环空套管旋流器产生的螺旋衰减流场进行了测试分析。     

基于PIV的油中水滴速度的特征分析

分析水击谐波场作用下乳化油液分散相液滴的微观运动特征,探讨分散相液滴聚集、分散的临界条件,以控制实现油水的有效分离,为深入研究水击谐波的油水分离方法提供技术支撑。通过施加不同的激振力获取了相应的水击谐波场,利用PIV图像采集系统对油水混合液在水击谐波场作用下水滴的微观运动特征进行了研究。结果表明:在施加6N~12N激振力作用下,在水击谐波流场中分散相液滴在波节18.2mm附近产生的聚集涡流以及在波腹68.2mm附近发散产生的涡流比较明显;分散相液滴随着施加激振力的减小,轴向速度幅值增加,在实验管道的自由平面其径向速度幅值相对较大,而在实验管道底部幅值较小;分散相液滴的平均运动速度随着激振力的减小而减小,但其径向速度幅值总体增加,所以较小激振力的水击谐波场有利于提高油水分离效率。     

90°弯管中瞬变流特性的实验研究

本文对水击波在90°弯管内部的传播特性进行了测试,得出了弯管中不同部位水击压力的数值及其随流速的变化规律.     

水击谐波流场中乳化油液滴粒径的PIV测量

为了掌握乳化油液滴在水击谐波流场中的碰撞、破裂、聚集和变形等微观形态的变化规律,采用粒子图像测速(PIV)技术对水平方管中乳化油液滴的水击谐波流场进行了测量,分析了在水击谐波流场中,不同激振力作用下乳化油液滴的粒径变化。测量结果表明,在水击谐波流场作用下,乳化油液滴平均粒径的增长率随着激振力的减小而减小,随着作用时间的增大呈增加趋势,直至粒径处于一种动态平衡;乳化液滴随着激振力增大到达波节聚集位置的时间减少,可见增大水击谐波激振力有利于乳化液滴的聚集并合并为大尺度的液滴,从而有效地提高了水击谐波流场作用下的油水分离效果。     

套管-水泥环-地层多层组合系统受力特性分析

以弹性力学为基础,对套管-水泥环-地层多层组合系统在理想固井状况下受非均匀地应力和均匀内压时的受载特性进行了分析;并依据接触条件和连续条件建立了相应的线性代数方程组,得到了套管-水泥环-地层多层组合系统应力分布的解析解;研究了水泥环厚度、弹性模量、泊松比、套管层数变化对最内层套管外壁径向应力分布规律的影响,并讨论了上述因素对最内层套管外壁径向应力最大值及应力分布非均匀系数的影响。结果表明:上述因素对最内层套管外壁径向应力的分布均有影响;对于具体问题,应综合考虑组合系统的几何、力学参数确定上述参数的最优值。本文研究可为复杂地层套管柱设计及多层复合材料的抗外挤问题提供参考。     

控压钻井环空卡森流体两相螺旋流轴向速度研究

考虑控压钻井环空气液两相流参数、钻井液周向与轴向运动等因素,本文提出了控压钻井环空卡森流体两相螺旋流柱坐标理论模型;通过新疆玛湖油田区块具体实例,分析了摩阻压降、屈服应力、环空外径、空隙率等对控压钻井两相螺旋流轴向速度的影响。结果表明:控压钻井环空卡森流体两相螺旋流流核及流速峰值向钻杆壁面靠近,距离环空内壁与钻杆外壁中心点的偏度可达8.36%;由于柯特流及钻井液动粘切力下降的影响,随杆转速和管径增大,卡森流体最大速度峰值在轴向的分布向环空壁面移动;随屈服应力的增大,流核宽度呈现增大趋势,当钻井液屈服应力为1.9Pa时,卡森流体流核宽度约为19.3mm;随控压钻井环空内空隙率增大,气液两相的粘度下降,螺旋流的轴向速度峰值呈增大趋势。分析螺旋流轴向速度分布可为控压钻井井口回压加载及环空流速控制提供帮助。     

液压换向阀的耦合水击振动特性研究

以某型舵机操纵液压换向阀为例,运用特征线法,对其由于自激振动以及启闭动作产生水击诱发非线性耦合振动现象的机理进行理论分析,获得换向阀水击振动的动态特性.通过实验验证,换向阀控制口水击压力幅值与计算结果偏差为2.87%,且压力变化趋势与计算结果基本一致.该结果可为掌握液压系统的振动特性、采取振动控制措施以及换向阀的设计和改进提供理论依据.     

水击驻波场中分散相颗粒的运动分析

根据水击在管段内形成的驻波场现象,分析了流体内分散相颗粒受到的驻波作用力;运用李雅普诺夫稳定判据研究了颗粒积聚与分离的机理;考虑到颗粒运动方程的严重刚性而很难进行数值求解,采用相空间和非对称分析方法获得了分散相颗粒的运动轨迹近似解,并进行了实验验证。结果表明:水击驻波场中分散相颗粒的受力方程中惯性项对颗粒初始运动速率的影响不可忽略;在水击驻波波节的±λ/4范围内,分散相颗粒经过一定的时间会发生积聚,其运动速度呈对称分布,最大速度出现在3λ/8位置处;随着分散相颗粒粒径和密度等物性参数以及水击驻波的频率和连续相初始速度的增大,颗粒达到平衡位置的时间呈减小趋势,且连续相的初始速度对颗粒到达波节时间的影响显著。     

用管轴流速确定动脉中血液振荡流的速度剖面

本文通过求解圆管内血液振荡流的基本方程，求得圆管内血液流的速度与压力梯度之间的关系式，文章提出一种利用管轴外流速计算管内压力梯度，进而确定血液振荡流动速度分布的方法，该方法用于检测活体血管内血液振荡流的速度剖面，具有操作简单，精度较高的优点，最后，以人体颈动脉为例，讨论血液周期振荡流的速度分布特征，发现在任意时刻，除了邻近管壁速度迅速降为零之外，沿管截面速度分布相当均匀，呈现出与定常流不同的速度分布特征。     

WATER HAMMER PRESSURE OF HYDRAULIC LIFTING PIPELINE IN DEEP-SEA MINING PILOT SYSTEM

深海采矿系统可能由于突然停泵、断电或机械故障等引起提升管道中流体速度瞬间变化, 导致管道内压力剧烈变化, 这种水击现象对管道破坏极大. 基于固液两相流体连续性原理和动量定理, 推导出含粗颗粒的固液两相流体管道水击压力的计算公式. 采用深海采矿中试系统参数, 模拟计算不同水体流速、不同流体浓度以及不同管径条件下的水击压力. 分析结果表明, 流速、体积浓度和管径是影响水击压力的重要因素, 其中, 流速影响最大. 研究结果可为深海采矿系统工程设计提供依据.     

非对称槽道中涡旋波的特性研究

利用PIV流场显示技术，对振荡流体在非对称槽道中涡旋波的产生、发展和消失的规律进 行了实验研究和分析，测得了涡旋波流场的速度矢量图，阐明了涡旋波流场周期性变化的特 点. 结合涡动力学方程，深入分析并揭示了做周期性运动的流体能在槽道中产生波的特性这 一规律，从中发现：流体周期变化的非定常性和不对称的槽道结构是形成涡旋波流动的主要 因素. 本文对涡旋波流场中各个旋涡的速度分布和涡量进行了测量和计算，分析了涡旋波 强化传质的机理，并研究了Re数对涡旋波流动的影响     

Flow field characterization of a jet and vortex actuator

 An actuator, which produces several different flow fields that may be used for active flow control, is characterized in still air using flow visualization and velocity measurements. The primary actuator-induced flow fields are: free jets, wall jets, and vortex flows. The non-dimensional parameters governing these actuator-induced flows are developed. For the vortex-flow regime, the operational range of the actuator increases as it’s size decreases without a significant decrease in either the actuator induced velocity or vortex core size. The velocity scaling is developed for the vortex flow and suggests that the optimum actuator efficiency occurs at a Stokes number of approximately 7.9 for the range of parameters surveyed. In a turbulent, zero pressure gradient boundary layer, measurements made just downstream of the actuator (when operated in the vortex mode) indicate a vortical disturbance is generated in the boundary layer. Received: 2 September 1998/Accepted: 9 January 1999     

Experimental study on critical heat flux in bilaterally heated narrow annuli

Critical heat flux (CHF) experiments using deionized water as working fluid have been conducted in a range of pressure from 0.6 to 4.2 MPa, mass flow velocity from 60 to 130 kg/m² s and wall heat flux from 10 to 90 kW/m² for vertical narrow annuli with annular gap sizes of 0.95 and 1.5 mm. We found that the CHF, occurring only on the inside tube, or on the outside tube or on both tubes of the annular channel, depends on the heat flux ratio between surfaces of the outside and inside tubes. The CHF, occurring on the surface of the inside tube, reaches the maximum value under the pressure of 2.3 MPa while it occurring on the surface of the outside tube keeps increasing with the increase of the pressure. The CHF, occurring on the inside or outside tubes, increases with the increase of the mass flow velocity and the annular gap size; and decreases with the increase of critical quality and the other tube wall heat flux. Empirical correlations, which agree quite well with the experimental data, have been developed to predict the CHF occurring on surfaces of the inside or outside tubes of the narrow annular channel on the conditions of low pressure and low flow.     

Effect of the conical-shape on the performance of vortex tube

The present study focuses on the effect of conical shape in the cold side of the Ranque-Hilsch vortex tube which is shown to have a considerable influence on the system performance. A vortex tube is a simple circular tube with no moving parts which is capable to divide a high pressure flow into two relatively lower pressure flows with temperatures higher and lower than the incoming flow. A three-dimensional computational fluid dynamic model is used to analyse the mechanisms of flow inside a vortex tube. The SST turbulence model is used to predict the turbulent flow behaviour inside the vortex tube. The geometry of a vortex tube with circumferential inlet slots as well as axial cold and hot outlet is considered. Performance curves temperature separation versus cold outlet mass fraction are calculated for a given inlet mass flow rate and varying outlet mass flow rates.     

改进的特征线方法及过载对水锤效应影响分析

传统特征线方法对过载作用下的水锤计算具有局限性，无法为水锤防护提供可靠性指导。本文在考虑过载效应和动态摩阻的基础上，提出了改进的特征线方法，该方法能准确模拟过载作用下水锤最大压力峰值及水锤波的衰减特性。基于该方法，建立了过载作用下水锤效应数学模型，通过分析结果与CFD数值仿真及实验数据对比，验证了改进特征线方法的正确性。分析结果表明，在恒定过载作用时，阀门位置的流体压力随过载量的增加而增大，且管轴向过载的影响大于横向过载；关阀过程受到瞬时过载作用时，过载效应对水锤最大压力峰值影响显著，而对关阀后水锤波的传播和衰减影响较小；同时，分析了过载效应下关阀特性和流体密度等参数对水锤效应的影响规律。     

单柱单锥型液—液旋流分离管内流场的LDV诊断

应用二维激光多普勒仪（ＬＤＶ）对一种单柱单锥型液－液旋流分离管内流场进行了测量,考察了流量、溢流比、压力比和气芯等参数对流场的影响。测量结果表明：切向速度分布呈典型的Ｒａｎｋｉｎｅ涡结构,沿轴向衰减很少,表明所用锥角是合适的;因该旋流管的水力直径较大,切向速度的总体水平较低,由于对了离特性带来了不利影响。此外,没有观察到切向速度分布的的双峰分布现象。轴向速度的总体水平较低,尤其是在锥形管的上游更为     

Structure and evolution of the airflow generated by a slender body entry near a tube

When a slender body moving forward in open air enters into a confined region, two important unsteady aerodynamic phenomena are generated. An exiting flow is created with a direction opposite to the body movement and inside the confined region, a compression wave is formed. Generation mechanism of compression wave have been extensively studied but so far, no detailed investigation of the exiting flow has ever been reported. The experimental study presented in this paper was undertaken to gain insight into the structure and the evolution of the exit-flow. Experiments were conducted with an axisymmetric apparatus and the explored range of the moving body speed was 5–50 m/s. The study focused on the influence of the body speed and the body nose geometry on the flow. It was shown that the air ejected from the tube entrance generates an annulus jet accompanied by a vortex ring. The vortex development was clarified using laser sheet visualizations associated with unsteady pressure and velocity measurements at the tube entrance. It is constituted by four phases, the pre-vortex phase, the vortex development phase, the vortex convection phase and the vortex breakdown phase. The duration of each of these steps was found to be independent of both the studied parameters in a non-dimensional time scale. Furthermore, neither the body speed nor the nose geometry induced significant changes on the vortex ring evolution, except for extreme conditions (low body speed, V_M.B.<15 m/s, and/or very long nose geometry, L_nose/D_M.B.>6). The evolution of the vortex ring was compared to that of ‘classical’ vortex ring generated at a tube exit by a piston motion with large non-dimensional stroke length. Main similarities and differences were discussed in the paper. In particular, the formation number of vortex ring observed in our experiments was found to be significantly smaller.