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1.
Investigation of oil-air two-phase mass flow rate measurement using Venturi and void fraction sensor 总被引：6，自引：0，他引：6
INTRODUCTION Accurate measurement of multiphase fluids flow rates in the petroleum industry is of great importance. The most reliable measurement technique for multi-phase flow is separating the mixture and using con-ventional devices for measuring single-phase flow. However, in many cases the separation is not practical from both technical and economical points of view. An alternative solution is the multiphase flow me-tering system, usually consisting of a combination of devices for ph… 相似文献
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INTRODUCTION Oil-water-gas multiphase mixed transport in oil pipe is extensively used in ocean oil industries. How to measure the volumetric fractions of oil-water-gas multiphase flow is an important subject of study in the oil industry. Related research work was started in the 1980s. The measurement of component ratios in multiphase flows using γ-ray attenuation was first suggested by Abouelwafa and Kendall (1980), and the technique has been used in many current com- mercial multiphase… 相似文献
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利用接收线圈和压电换能片2种传感器测得音叉受迫振动的速度、位移共振曲线,通过实验比较和理论分析,证明这2种传感器所测得的物理量并不相同,同时分析和验证了2种幅频曲线的区别。对影响位移共振曲线测量结果的阻尼系数进行讨论和分析,得出:用接收线圈做传感器测得的音叉共振曲线为速度共振曲线,而用压电换能片做传感器测得的音叉共振曲线为位移共振曲线。实验的研究有利于学生对受迫振动和共振概念的深入理解,也有利于对2种传感器的正确运用。 相似文献
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将信息处理技术引用到气固两相流参数检测中,初步探讨了应用数据融合技术及互相关技术进行固相颗粒界面平均速度的检测。采用两种方案确定上、下游传感器渡越时间,包括每对传感器采集的数据先进行互相关分析再进行数据加权融合,以及对所有传感器采集的数据先进行融合处理,再对其进行相关分析。通过对这两种信息处理方案进行仿真研究,得到稳定且正确的仿真结果。 相似文献
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Flow visualization and hot-wire measurement techniques were combined to investigate the influence of the size and number of tabs on jet flow field and vortex structure generation mechanism. Streamwise vortices generated by the tabs of different sizes and numbers were ob- served from the flow visualization images. Combined with flow visualization, hot-wire measurement gave a quantitative insight of the effect of various tabbed jet flows. Instantaneous two-component velocity signals （longitudinal and transverse velocity components） at different cross sections along radius direction and streamwise direction with different tabbed jet nozzles were measured using hot-wire anemometer. Average flow field parameters of tabbed jet flow such as mean velocity, turbulence intensity, vorticity were analyzed and the effects of tabs with different sizes and numbers were compared with that of circular no-tab jet flow. It is revealed that the generation of a series of counter-rotating quasi-streamwise vortices, azimuthal vortices and double-row azi-muthal vortex are the reasons for mixing enhancement of tabbed turbulent jet flow. 相似文献
6.
Experimental Study of Sediment Incipience Under Complex Flows 总被引：1，自引：0，他引：1
Sediment incipience under flows passing a backward-facing step was studied. A series of experiments were conducted to measure
scouring depth, probability of sediment incipience, and instantaneous flow velocity field downstream of a backward-facing
step. Instantaneous flow velocity fields were measured by using Particle Image Velocimetry (PIV), and an image processing
method for determining probability of sediment incipience was employed to analyze the experimental data. The experimental
results showed that the probability of sediment incipience was the highest near the reattachment point, even though the near-wall
instantaneous flow velocity and the Reynolds stress were both much higher further downstream of the backward-facing step.
The possible mechanisms are discussed for the sediment incipience near the reattachment point.
Partially supported by National Natural Science Foundation of China (No.10602017), Maritime Research Center and DHI-NTU Center
of Nanyang Technological University, Singapore. 相似文献
7.
Seyed Sahand SEBTI Mohammad MASTIANI Hooshyar MIRZAEI Abdolrahman DADVAND Sina KASHANI Seyed Amir HOSSEINI 《浙江大学学报(A卷英文版)》2013,14(5):307-316
A comprehensive numerical study was conducted to investigate heat transfer enhancement during the melting process in a 2D square cavity through dispersion of nanoparticles. A paraffin-based nanofluid containing various volume fractions of Cu was applied. The governing equations were solved on a non-uniform mesh using a pressure-based finite volume method with an enthalpy porosity technique to trace the solid-liquid interface. The effects of nanoparticle dispersion in a pure fluid and of some significant parameters, namely nanoparticle volume fraction, cavity size and hot wall temperature, on the fluid flow, heat transfer features and melting time were studied. The results are presented in terms of temperature and velocity profiles, streamlines, isotherms, moving interface position, solid fraction and dimensionless heat flux. The suspended nanoparticles caused an increase in thermal conductivity of nano-enhanced phase change material (NEPCM) compared to conventional PCM, resulting in heat transfer enhancement and a higher melting rate. In addition, the nanofluid heat transfer rate increased and the melting time decreased as the volume fraction of nanoparticles increased. The higher temperature difference between the melting temperature and the hot wall temperature expedited the melting process of NEPCM. 相似文献
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CHANSONHubert GONZALEZCarlosA. 《浙江大学学报(A卷英文版)》2005,6(3):243-250
INTRODUCTION The stepped channel design has been used fomore than 3500 years. Greek and Minoan engineerswere probably the first to design an overflow steppedweir and stepped storm waterways respectively(Chanson, 2001). Later, Roman, Moslem, Mughaand Spanish designers used a similar technique. Thesteps increase significantly the rate of energy dissipation taking place on the channel face, reducing thesize of the required downstream energy dissipationand the risks of scouring. Rec… 相似文献
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研究目的：从实验及理论角度闸述边坡高扬程虹吸排水容易断流造成虹吸中断的原凶,并提供解决方案,实观虹吸排水的长期有效。创新要点研究方法重要结论：利用物理模型实验,结合理论解析推导,得到了高扬程虹吸排水管顶部流态特抓及其与管径的关系,解决了高扬程虹吸排水容易断流造成虹吸中断问题,保证了虹吸排水技术住边坡治理工程中的长期有效性。通过物理模型试验,揭示虹吸水流经过管顶区段的兰利,流型特征（见图4）;利用热力学理论推导,得到了虹吸水流绛过管顶区段由贴壁流向弹状流转变的临界管住,址公式（23）。管中形成气液共吲移动的完整掸状流是灾脱虹吸排水长期稳定的关键,虹吸水流绛过管硕区段由贴壁流向弹状流转变时存扯临界管仵。保讹边坡工群中虹吸排水长期稳定的管径以3．6mm为宜。 相似文献
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Employees are sometimes assigned tasks that lie outside their official role. Employees may perceive such extra-role tasks (ERTs) as unreasonable or illegitimate. Grounded in role theory and leader-member exchange (LMX) theory, we conducted two studies that examined how ERTs are associated with supervisor-employee relationship quality and how the ERT assignment is communicated. While supervisor-subordinate relationship quality was unrelated to the likelihood and frequency with which supervisors assign ERTs to employees, employees with low-quality relationships evaluated ERTs as more unreasonable than those in high-quality relationships. Study 1 showed that ERT messages that included a request (vs. command), acknowledgement, explanation, and appreciation were associated with higher quality LMX relationships. Study 2 found that ERT message characteristics influenced the perceived unreasonableness of the task for employees in high-quality relationships, suggesting employees in such relationships are particularly vulnerable to “job creep” and role expansion. 相似文献
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采用程序升温还原法制备了MoP/HZSM-5催化剂。在小型固定床反应装置上,考察了反应条件对催化裂化(50~100℃)汽油馏分芳构化降烯烃的性能影响。结果表明,在反应温度400℃、压力1.0MPa、液时空速1.0h-1、氢油体积比400∶1的条件下MoP/HZSM-5催化剂芳构化活性最佳,液相产品中芳烃质量分数为65.43%,烯烃质量分数为5.42%,液收为61.04%。 相似文献
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Ilkka Kauppinen 《Globalisation, Societies & Education》2014,12(4):498-519
The restructuring of European higher education (EHE) since the 1980s is a widely studied subject. However, this paper argues that previous studies have paid insufficient attention to the role of transnational policy-making groups in this complex and multilevel process. This argument is supported by focusing on how the European Round Table of Industrialists (ERT) has participated in this restructuring since the mid-1980s. This paper's focus is especially in two ERT documents that were published in the 1980s. The main finding is that the current restructuring of EHE reflects interests of the ERT that represents the emerging transnational capitalist class (TCC) at European level. 相似文献
15.
基于多级油泵的现场要求,提出了集多参量检测与控制为一体的多级油泵测控系统。从阐述多级油泵的结构和工作原理入手,确定了以数字信号处理器TMS320LF2812为控制核心的总体方案,设计了流量、压力等参数的检测电路和IGBT的驱动保护电路,给出了相应的软件。结果表明,该测控系统可以以一定的准确度实现压力、瞬时流量、累积流量的测量,也可对三相异步电动机进行变频控制,从而达到调节异步电动机转速、进而调节多级油泵流量和压力的目的。该系统具有结构紧凑、成本低、工作安全可靠、性能优良等特点。 相似文献
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气泡对声传播影响的研究 总被引：1，自引：0，他引：1
姚文苇 《陕西教育学院学报》2008,24(1):107-109
以气泡壁处声压和径向振动速度为边界条件,研究气泡对声传播的影响;给出了含气泡介质内声速的表达式,得到了声速随气泡体积分数及声波频率的变化图。表明：声波频率一定时,声速随着气泡体积分数增大而减小;气泡体积分数一定时,频率增大对声速的影响较小。 相似文献
17.
李睿 《湖北第二师范学院学报》2012,(8):4-6
利用蒙特卡罗方法,采用计算机模拟研究粒径呈连续分布的一维颗粒气体在均匀加热机制下的速度分布特性。研究表明颗粒气体的速度分布不再遵从高斯分布。系统的颗粒速度分布偏离高斯分布的程度及各个组分之间颗粒速度分布的差异程度受到颗粒的非弹性恢复系数及粒子粒径分布宽度的影响。 相似文献
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This paper discusses the principle and mathematical method to measure the phase fractions of multiphase flows by using a dual-energy gamma-ray system. The dual-energy gamma-ray device is composed of radioactive isotopes of 241Am and 137Cs with emission energies of 59.5 keV and 662 keV respectively. A rational method to calibrate the absorption coefficient was introduced in detail. The statistical error has been analyzed on the basis of the accurate absorption coefficient which enables determination phrase fractions almost independent of the flow regime. Improvement has been achieved on the measurement accuracy of phase fractions. 相似文献
19.
INTRODUCTION The imaging and measurement of multiphase flows has received much attention in recent years, largely because of a need in the oil industry to measure the mass flow rates of oil, water and gas in production pipelines, and the ability to see through objects and make quantitative measurements of the enclosed ma- terials and structures has wide range of applications. However, measurement over a wide range of flow regimes and the ability to very accurately measure the mass flow rat… 相似文献
20.
In this paper, an electrical resistance tomography（ERT） imaging method is used as a classifier, and then the Dempster-Shafer＇s evidence theory with fuzzy clustering is integrated to improve the ERT image quality. The fuzzy clustering is applied to determining the key mass function, and dealing with the uncertain, incomplete and inconsistent measured imaging data in ERT. The proposed method was applied to images with the same investigated object under eight typical current drive patterns. Experiments were performed on a group of simulations using COMSOL Multiphysics tool and measurements with a piece of porcine lung and a pair of porcine kidneys as test materials. Compared with any single drive pattern, the proposed method can provide images with a spatial resolution of about 10% higher, while the time resolution was almost the same. 相似文献