低黏液体井筒携砂流动规律及特征流速实验

固体颗粒在井筒中的流动规律是石油工程领域中钻井携岩和携砂生产过程涉及到的基础性问题之一,其中的携砂（岩）流速是上述工程问题的主要设计参数之一。提出了井筒中固液携砂流动的3个特征流速,分别为静水沉速、悬浮流速和携砂流速,并给出了其界定方法。使用井筒携砂流动综合模拟实验装置进行了液体黏度为1-23 mPa·s、井筒倾角为45°-90°、石英砂和陶粒尺寸为0.05-1.5 mm、井筒内径为40-100 mm范围条件下的特征流速敏感性测试实验,得到了低黏度条件下静水沉速、悬浮流速、携砂流速随颗粒尺寸、流体黏度、井筒倾角、井筒直径、材料密度的定量敏感关系和规律。利用实验数据拟合了静水沉速、悬浮流速和携砂流速三者之间的经验关系。结果表明,在相同的条件下,液体流动对颗粒的悬浮流速约为颗粒在静水中沉降速度的80.43%,这与传统将静水沉速视为临界携砂流速的观点不同;合理携砂流速约为悬浮流速的3.73倍,可以达到快速携砂要求。针对现有直接根据静水沉速计算携砂流速所存在的问题,给出了一套利用3个特征流速完成合理携砂流量设计的流程和方法。

挡潮闸外迁对闸下水动力特征影响的概化模型研究

以苏北沿海的王港河口为原型,建立潮汐河口三维水动力概化数学模型,分别对挡潮闸迁移前、后的闸下水动力过程进行模拟。通过对比闸下潮位、流速及流向的特征变化,分析挡潮闸外迁的相关影响。结果表明:挡潮闸外迁后,闸下潮波变形现象减弱,涨、落潮历时趋于相近、不对称性减弱,有利于改善涨落潮流输沙不等现象;闸下水动力环境增强,平均流速增大,垂向各层流速的分布更加均匀,且表、底层流速比增大,有利于加强闸下冲刷、减轻淤积;闸门外迁对河口外的流速分布影响较小。上述结果可为类似的强潮流河口挡潮闸外迁论证以及外迁后的闸下淤积研究提供参考。

水平井不同倾角井筒临界携砂流速对比实验及其拟合应用

井筒中的携砂流速是石油工程领域携砂生产问题的主要设计参数之一,目前国内外学者针对垂直井的携砂流速研究较多,但对水平井中不同倾角井段的携砂流速变化规律及其影响因素关注较少。基于上述问题,针对井筒由水平至垂直的全倾角变化过程,使用携砂规律模拟实验装置进行了井筒倾角0°~90°、流体黏度1~50 m Pa·s、石英砂和陶粒颗粒尺寸0. 08~0. 4 mm、井筒内径40~100 mm条件下的井筒携砂流速对比实验,得到了不同井筒倾角下携砂流速与流体黏度、颗粒尺寸、颗粒密度、井筒内径的敏感性关系和携砂流速变化规律。使用实验数据拟合得到水平段、倾斜段、垂直段井筒携砂流速的经验模型,结果表明,在其他实验条件相同的情况下,井筒在0°,30°,45°,75°,90°时的携砂流速之比为1. 71∶3. 35∶2. 86∶2. 28∶1。基于实验现象与拟合结果,给出了修正现有特征流速的流程和方法,以完成合理的携砂流量设计。

CFD numerical simulation of flow velocity characteristics of hydrocyclone

A CFD based numerical simulation of flow velocity of hydrocyclone was conducted with different structural and operational parameters to investigate its distribution characteristics and influencing mechanism. The results show there exist several unsymmetrical envelopes of equal vertical velocities in both upward inner flows and downward outer flows in the hydrocyclone, and the cone angle and apex diameter have remarkable influence on the vertical location of the cone bottom of the envelope of zero vertical velocity. It is also found that the tangential velocity isolines exist in the horizontal planes located in the effective separation region of hydrocyclone. The increase of feed pressure has almost no effect on the distribution characteristics of both vertical velocity and tangential velocity in hydrocyclone, but the magnitude and gradient of tangential velocity are increased obviously to make the motion velocity of high density particles to the wall increased and to make the cyclonic separation effect improved.

自由下落微粒流中气固两相流的数值模拟

在微粒流的自由下落过程中,环境空气会被卷吸到微粒流中,形成微粒羽流,有关微粒羽流与环境空气关系的基础理论及数值模拟研究文献相对较少。本文通过RNGk-ε模型对二维微粒羽流中的微粒与环境空气的耦合进行数值模拟,并讨论了微粒羽流速度分布、微粒羽流密度与羽流的流速变化关系,以及微粒羽流质量流对羽流流速的影响。

Turbulence regime near the forest floor of a mixed broad leaved/Korean pine forest in Changbai Mountains

The measurement and observation for this study were carried out by using a three-dimensional (u, v, w) Sonic anemometer (IAP-SA 485), at Forest Ecosystem Opened Research Station of Changbai Mountains (12828扙 and 4224?N, Jilin Province, P. R. China) in August 2001. The basic characteristics of turbulence, such as turbulence intensity, atmospheric stability, time scales, and convection state, near the forest floor were analyzed. It is concluded that the airflow near forest floor is characterized by high intermittence and asymmetry, and the active and upward movement takes the leading position. Near forest floor, the vertical turbulence is retained and its time scale and length scale are much less than that of u, v components. The eddy near forest floor shows a flat structure and look like a ’Disk’. Buoyancy plays a leading role in the generation and maintenance of local turbulence

基于质点运移模型的区域地下水循环规律研究——以陇东盆地为例

地下水循环规律研究是合理开发利用地下水资源的前提。选取陇东盆地泾河段作为研究对象,通过地下水模拟技术,确定了剖面上地下水流动方向,同时将水流系统划分为3个循环系统：局部循环系统、中间循环系统、区域循环系统。得出不同水流系统循环深度及循环宽度,3个循环系统深度依次为20-160m、160-700m、700-1 000m,循环宽度为3-8km、8-34km、34-70km。根据流速分布特征,将流速范围〉0.01m/d、0.005-0.01m/d、〈0.005m/d分别划分为强径流带、中等径流带、弱径流带。并对各径流带地下水运行更新时间进行计算,得出强径流带更新时间小于4 109a,中等径流带更新时间为4 109-24 657a,弱径流带更新时间大于24 657a。

重庆建峰天原乌江码头行洪能力影响分析

通过建立和验证平面二维水流数学模型,对重庆建峰天原工程乌江码头进行了多种水文组合下的行洪能力计算,获取了工程的过水面积占据率、最大雍水高度、雍水范围及流速特征值变化等成果,以研究其对乌江行洪能力的影响。结果表明,两工程的实施对防洪均不会产生明显影响。

EXPERIMENT ON FLOW CHARACTERISTICS OF SYNTHETIC JET DRIVEN BY PIEZOELECTRIC MEMBRANE

The characteristics of the flowfields of a synthetic jet actuator are experimentally investigated with the slot-nozzle driven by the piezoelectric membrane. The particle image velocimetry （PIV） and the hot-wire anemometer are utilized to measure the flowfields and the velocity profiles of the actuator with different actuating factors. Analytical results show that pairs of counter-rotating vortices are generated near the nozzle. With the development of the synthetic ject, the synthetic jet rapidly spreads in the slot-width direction; while in the slot-length direction, it contracts firstly and slowly spreads. The centerline velocity distribution has a up-down tendency varying with axial distances, and accelerates to its maximum at z/b= 10. The transverse velocity profile across the slot-width is centro-symmetric and self-similar. However, the velocity profiles across the slot-length are saddle-like near the nozzle. It shows that there are two resonance frequencies for the actuator. If the actuator works with the resonance frequency, the vorticity and the velocity of the synthetic jet are higher than those of other frequencies. Compared with the continuous jet, the synthetic jet shows special flow characteristics.

阶梯式消能在坝口河水库溢洪洞中的应用

为了减轻出口建筑物的消能压力和降低对下游河道的有害性冲刷,同时避免出口消能后的水体溶解气体过饱和,在山区泄水建筑物泄槽段可考虑布置阶梯,以加糙固体边界。基于坝口河水库溢洪洞原布置设计,通过水工模型试验,研究在第一泄槽段增设阶梯后,原反弧段末端(阶梯末端)以及消力池进口水流流速和动能的变化。成果表明:消力池进口水流流速和动能的降低,有效缓解了消力池内水体紊动,下游河道水体掺气明显减轻。

A calculation method for low dynamic vehicle velocity based on fusion of optical flow and feature point matching

Aming at the problem of the low accuracy of low dynamic vehicle velocity under the environment of uneven distribution of light intensity,an improved adaptive Kalman filter method for the velocity error estimate by the fusion of optical flow tracking and scale mvaiant feature transform(SIFT)is proposed.The algorithm introduces anonlinear fuzzy membership function and the filter residual for the noise covariance matrix in the adaptive adjustment process.In the process of calculating the velocity of the vehicle,the tracking and matching of the inter-frame displacement a d the vehicle velocity calculation a e carried out by using the optical fow tracing and the SIF'T methods,respectively.Meanwhile,the velocity difference between theoutputs of thesetwo methods is used as the observation of the improved adaptive Kalman filter.Finally,the velocity calculated by the optical fow method is corrected by using the velocity error estimate of the output of the modified adaptive Kalman filter.The results of semi-physical experiments show that the maximum velocityeror of the fusion algorithm is decreased by29%than that of the optical fow method,and the computation time is reduced by80%compared with the SIFT method.

潮汐河段糙率n的计算分析

针对平原河道糙率计算方法,探讨受潮汐影响的宽浅河段糙率计算。以长江河口段为例,分析潮周期内流量变化过程以及流速沿水深分布特征,选取落潮稳定时段,利用流速垂线分布特征及Einsten断面综合糙率计算方法计算河道糙率。利用明渠非恒定流圣维南方程,推算涨落潮历时过程中计算河段逐时河道糙率n,分析非恒定流量变化d Q/dt对糙率影响,反映了潮汐河段河道糙率变化特征,分析其落潮过程中,随水位降落洲滩水深植被等影响下河道糙率的变化情况,采用落潮稳定期天然实测资料,进行代表性断面测点垂线流速分布特征,综合糙率计算法和河道水力计算推求糙率法,分析确定河道糙率。

Characteristics of nonlinear internal waves observed in the northern South China Sea

The South China Sea(SCS) is one of the most active areas of internal waves.We undertook a program of physical oceanography in the northern South China Sea from June to July of 2009,and conducted a 1-day observation from 15:40 of June 24 to 16:40 of June 25 using a chain of instruments,including temperature sensors,pressure sensors and temperature-pressure meters at a site(117.5°E,21°N) northeast of the Dongsha Islands.We measured fluctuating tidal and subtidal properties with the thermistor-chain and a ship-mounted Acoustic Doppler Current Profiler,and observed a large-amplitude nonlinear internal wave passing the site followed by a number of small ones.To further investigate this phenomenon,we collected the tidal constituents from the TPXO7.1 dataset to evaluate the tidal characteristics at and around the recording site,from which we knew that the amplitude of the nonlinear internal wave was about 120 m and the period about 20 min.The horizontal and vertical velocities induced by the soliton were approximately 2 m/s and 0.5 m/s,respectively.This soliton occurred 2-3 days after a spring tide.

Analysis of internal tidal characteristics in the layer above 450 m from acoustic Doppler current profiler observations in the Luzon Strait

The characteristics of internal tides in the upper layer of the Luzon Strait are investigated on the basis of direct-observation current data recorded on April 25 and September 26, 2008 by an acoustic Doppler current profiler. Spectral analysis and energy estimation show that the diurnals and semidiurnals carry most of the energy of internal tides. Values of the depth-integrated total energy E for the three frequency bands of diurnal, semidiurnal, and high frequencies are 31, 6.9, and 3.4 kJ. m, respectively. Near-inertial peaks are only present in the baroclinic component. The behavior of typical tidal frequencies （i.e., O1, K1, M2, MK3, and M4） and the near-inertial frequency is basically consistent with linear internal wave theory, which predicts E＋（ω）/E_（ω）=（ω-f）2/（ω＋f）2 at depths above 66 m, while not all prominent tidal components coincide well with the relation of the linear internal wave field at other depths. Examinations of depth structures of the baroclinic tides and temporal variations show that the surface tides and internal tides are both of mixed type, having diurnal inequality and spring-neap fortnight periods. The K1 and O1 tides have comparable cross- and along-shelf components, while the M2 and S2 tides propagate toward the shelf in the northern South China Sea as wave beams. The amplitude and phase of internal tides vary with time, but M2 and S2 tides appear to have structures dominated by the first mode, while the K1 and O1 tides resemble second-mode structures. The minor to major axis ratios are close to expected values of flω in the thermocline.

Mechanisms of suspended sediment restoration and bed level compensation in downstream reaches of the Three Gorges Projects(TGP)

River basin reservoir construction affects water and sediment transport processes in downstream reaches. The downstream impact of the Three Gorges Projects （TGP） has started to become apparent： （1） reduction in flood duration and discharge, and significant reduction in sediment load. Although there was some restoration in downstream sediment load, the total amount did not exceed the pre-impoundment annual average; （2） in 2003-2014 the d 〉 0.125 mm （coarse sand） load was restored to some degree, and to a maximum at Jianli Station, which was mainly at the pre-impoundment average. After restoration, erosion and deposition characteristics of the sediment was identical to that before impoundment. The degree of restoration during 2008-2014 was less than during 2003-2007; （3） after TGP im- poundment, there was some restoration in d 〈 0.125 mm （fine sand） sediment load, however, it was {ower than the pre-impoundment average; （4） due to riverbed compensation, the d 〉 0.125 mm sediment load recovered to a certain degree after impoundment, however, the total did not exceed 4400x104 t/y. This was mainly limited by flood duration and the average flow rate, and was less affected by upstream main stream, tributaries, or lakes. Restoration of d 〈 0.125 mm suspended sediment was largely controlled by upstream main stream, tributaries, and lakes, as well as by riverbed compensation. Due to bed armoring, riverbed fine suspended sediment compensation capability was weakened; （5） during 2003-2007 and 2008-2014, Yichang to Zhicheng and upper Jingjiang experienced coarse and fine erosion,lower Jingjiang experienced coarse deposition and fine erosion, Hankou to Datong had coarse deposition and fine erosion, and Chenglingji and Hankou was characterized by coarse deposition and fine sand erosion in 2003-2007, and coarse and fine erosion in 2008-2014. This difference was controlled by flood duration and number at Luoshan Station.