检索结果-南通市图书馆

Journal of Hydrodynamics 2019年第5期31卷 887-899页

作者： Bin Teng Hong-fei Mao De-zhi Ning Chong-wei Zhang State Key Laboratory of Coastal and Offshore Engineering Dalian University of TechnologyDalian 116024China

As a classical topic,the hydrodynamic forces on a submerged horizontal cylinder undergoing forced oscillation have been widely studied based on potential flow ***,the fluid viscosity and the flow rotation may play an important role when the oscillation amplitude of the circular cylinder is large,and large discrepancy will occur between the potential flow simulation and the experimental *** study focuses on the study of hydrodynamic forces on a submerged horizontal circular cylinder undergoing forced oscillation by means of a viscous fluid numerical wave tank(NWT)*** accuracy of the numerical model is validated against available experimental *** comparisons between the hydrodynamic forces on the circular cylinder predicted by the viscous fluid model and the potential flow model are conducted to show the viscous effects on the hydrodynamic *** the study on the flow fields,the mechanism of the viscous effects is explained by the vortex *** basic reason for the difference between the results based on the viscous fluid theory and the potential flow theory is revealed by analyzing the force components.

关键词： Submerged horizontal circular cylinder forced oscillation hydrodynamic forces vortex effect

Effect of cooling rate on microstructure and inclusion in non-quenched and tempered steel during horizontal directional solidification

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2019年第9期26卷 973-982页

作者： Hui Liu Zong-ze Huang Da-jiang Yu De-lin Hu Hong-gang Zhong Qi-jie Zhai Jian-xun Fu State Key Laboratory of Advanced Special Steel School of Materials Science and EngineeringShanghai UniversityShanghai 200072China State Key Laboratory of Development and Application Technology of Automotive Steels (Baosteel Group) Shanghai 201900China

In order to investigate the relationship between microstructure and MnS inclusion in non-quenched and tempered steel, and cooling rate during horizontal directional solidification, 49MnVS steel was used to conduct the experiments with a selfdesigned device. The mathematical effect of cooling rate on dendritic arm spacing and mean diameter of MnS particles (dMnS) were determined by using linear regression method. The results show that the length of dendrite from solid–liquid interface to end-solidification decreased with increasing the withdrawal velocity (#). dMnS has a similar value in the area of the steady directional solidification;the value of dMnS was 4.1, 3.6, 3.3, 2.8 and 2.3 lm at withdrawal velocity of 50, 75, 100, 150 and 200 lm/s, respectively. dMnS increased with reducing # or RC (interface cooling rate). MnS precipitated in the gaps between dendrites and was influenced by secondary dendritic arm spacing. Besides, a new concept of the ‘Precipitation Unit Space’(PUS) was proposed and the relationships between dMnS, VPUS (volume of PUS) and RC were obtained.

关键词： horizontal directional solidification Dendrite MnS Inclusion Cooling rate

Influence of horizontal Flow on Atrium in High-Rise Residential Building

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

湖南大学学报（自然科学版） 2009年第S1期36卷 15-18页

作者： LI Nian-ping,LI Jing,HE Dong-yue,ZHANG Min-hui,HOU Su-juan(College of Civil Engineering,Hunan University,Changsha,Hunan 410082,China) College of Civil Engineering Hunan University Changsha 410082 China

In this study a 10-storied residential building model was employed to clarify the ventilation characteristics of the atrium and the rooms,which were effected by the different forms of lateral *** experiment was conducted under the combined effect of wind force and thermal buoyancy,and the similarity requirements were *** results have shown that the different forms of lateral openings cause the different ventilation effect of the building,and also have some certain *** conclusions provide a theoretical foundation for how to use the ventilation of atrium better in high-rise residential building.

关键词： high-rise residential building atrium model experiment horizontal flow natural ventilation

LATERAL STABILITY OF ALTERNATIVE horizontal LEVITATION ELECTROMAGNETIC CONTINUOUS CASTING OF ALUMINIUM SHEET

在线全文

学校读者我要写书评

暂无评论

中国有色金属学会会刊：英文版 1998年第3期8卷 86-89页

作者： Deng, K Shen, M Ren, ZM Shanghai Univ Coll Mat Sci & Engn Shanghai 200072 Peoples R China Shanghai Univ Shanghai Inst Appl Math & Mech Shanghai 200072 Peoples R China

１ＩＮＴＲＯＤＵＣＴＩＯＮＡｌｔｅｒｎａｔｉｖｅｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｃｏｎｔｉｎｕｏｕｓｃａｓｔｉｎｇｉｓａｈｉｇｈｌｉｇｈｔｅｄｎｅｗｔｅｃｈｎｉｑｕｅ．Ｉｎｔｈｉｓｔｅｃｈｎｉｑｕｅｔｈｅｅｌｅｃｔ... 详细信息

１ＩＮＴＲＯＤＵＣＴＩＯＮＡｌｔｅｒｎａｔｉｖｅｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｃｏｎｔｉｎｕｏｕｓｃａｓｔｉｎｇｉｓａｈｉｇｈｌｉｇｈｔｅｄｎｅｗｔｅｃｈｎｉｑｕｅ．Ｉｎｔｈｉｓｔｅｃｈｎｉｑｕｅｔｈｅｅｌｅｃｔｒｏｍａｇｎｅｔｉｃｆｏｒｃｅｐｒ...

关键词： stability horizontal continuous casting electromagnetic casting aluminium sheet

Analysis of the motion of small-scale ellipsoidal particles in a horizontal laminar flow field

在线全文

学校读者我要写书评

暂无评论

Particuology 2018年第5期16卷 44-51页

作者： Lin Yang Ji Zhang Han Yuan Ning Mei Marine Engineering College of Engineering Ocean University of ChinaQingdao 266100China

A particle movement model for a horizontal laminar flow field was established in this study,using a modified Basset-Boussinesq-Oseen equation for multiphase fluid dynamics,The motion of ellipsoidal and spherical particles in this flow field was compared to determine the differences in entrainment of ellipsoidal versus spherical *** theoretical results indicate that ellipsoidal particles move more rapidly and smoothly within the fluid than spherical particles under the same ***,this feature is enhanced,as the ellipsoidal degree of the particle *** on a dimensional analysis,flow experiments were carried out to verify the behavior of ellipsoidal versus spherical particles in *** our theoretical and experimental results show that ellipsoidal particles approach the fluid velocity more quickly than spherical *** work would need to address effects of velocity gradients and rotation on particle behavior.

关键词： Solid-liquid two-phase flow horizontal laminar flow Ellipsoidal particle Ellipsoidal degree Spherical particle Velocity distribution

Development of an Omni-Directional Shear horizontal Wave Transducer Based on a Radially Poled Piezoelec trie Ring

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2019年第1期32卷 29-39页

作者： Qiang Huan Mingtong Chen Ai-Kah Soh Faxin Li LTCS and Department of Mechanics and Engineering Science College of EngineeringPeking UniversityBeijing 100871China Center for Applied Physics and Technology Peking UniversityBeijing 100871China School of Engineering Monash University Malaysia47500 Bandar SunwayMalaysia

For the inspection of large plate-like structures,the omni-directional guided wave transducer-based system has been regarded as an effective tool since only a few transducers are required to cover the entire inspection area without blind *** comparison with Lamb waves,the shear horizontal(SH)wave is more promising because its fundamental mode is *** this work,we proposed an omni-directional SH wave piezoelec trie t ransducer(OSH-PT)based on a radially poled d24-mode PZT *** the finite element simulations and experiments were carried out to demonstrate its performance in generating and receiving SH°*** showed that the radially poled OSH-PT could generate single-mode SHo wave and receive SHo wave only over a wide frequency range from 70 to 200 *** obtained signal-to-noise ratio can reach up to 26 dB in generation and 24 dB in *** omni-directivity of this OSH-PT is also very good with the deviation only about 6%in both generation and reception of SHo *** its easy fabrication,low cost and superior performances,this proposed OSH-PT may promote the applications of SHo wave-based inspection in structural health monitoring and nondestructive testing.

关键词： Omni-directional Guided wave Shear horizontal wave Piezoelec trie t ransducer

Physical modeling of a sidetrack horizontal well production to improve oil recovery

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2002年第4期45卷 353-364页

作者：王家禄江如意 1. Research Institute of Petroleum Exploration and Development 100083 Beijing China

The scaling criteria of physical modeling of a horizontal well production are discussed. A scaled experimental model was designed and realized. The experiments of a sidetrack horizontal well production have been carried out in the system, and the production curve variation is analyzed. The oil recovery of a sidetrack horizontal well production is compared with that of a vertical well, and the effect of factors such as sidetrack drilling time, water driving rate and the length of horizontal section on oil recovery are discussed. The production of a horizontal well changed both the fluid flow direction and pressure distribution in the reservoir; as a result the remaining oil in the dead oil region is recovered, and the ultimate oil output is raised.

关键词： sidetrack horizontal well, physical modeling, improve oil recovery, remaining oil.

Productivity analysis of a fractured horizontal well in a shale gas reservoir based on discrete fracture network model

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2019年第3期31卷 552-561页

作者： Yu-long Zhao Nan-ying Li Lie-hui Zhang Rui-han Zhang State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum University Chengdu 610500 China Southwest Oil and Gas Branch SINOPEC Chengdu 610041 China

The treatment of horizontal wells with massive hydraulic fracturing technology is important for the economical development of shale gas reservoirs, but sometimes is complex because of the induced fractures during the fracturing process. The studies of the fluid flow characteristics in such formations are rare. In this study, a numerical method based on a finite element method (FEM) is developed for the productivity analysis of a horizontal well in a shale gas reservoir with complex fractures. The proposed method takes into account the adsorbed gas and the complex hydraulic fracture branches. To make the problem more tractable, the dimension of the fracture system is reduced from 2-D to 1-D based on the discrete fracture network (DFN) model. The accuracy of the new method is verified by comparing its results with those obtained by the Saphir commercial software. Finally, the productivity of the fractured horizontal wells in shale gas reservoirs with complex fractures systems is evaluated and analyzed. Results show that if a well is produced with a constant bottomhole pressure, the well productivity is much increased due to the existence of fracture branches that can increase the stimulated reservoir volume (SRV). In addition, the number of hydraulic fractures (Nf) and the fracture halMengths (Lf) have an important influence on the well's productivity. The larger the values of Nf,Lf,the greater the well productivity will be. The existence of adsorbed gas can markedly improve the well productivity, and the greater the Langmuir volume, the greater the productivity will be. The conclusions drawn by this study can provide a guidance for the development of unconventional shale gas reservoirs.

关键词： Fractured horizontal well discrete fracture network (DFN) model finite element method (FEM) productivity analysis shale gas reservoir

Geostrophic Spirals Generated by the horizontal Diffusion of Vortex Stretching in the Yellow Sea

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Advances in Atmospheric Sciences 2019年第2期36卷 219-230页

作者： Xiangzhou SONG Rui Xin HUANG Dexing WU Fangli QIAO Guansuo WANG Physical Oceanography Laboratory Ocean University of China State Oceanic Administration Ministry of Natural Resources Department of Physical Oceanography Woods Hole Oceanographic Institution First Institute of Oceanography State Oceanic Administration

horizontal velocity spirals with a clockwise rotation(downward looking) rate of 1.7?m^(-1), on average, were observed in the western and northern Yellow Sea from December 2006 to February 2007. With the observed thermal wind relation,the beta-spiral theory was used to explain the dynamics of spirals. It was found that the horizontal diffusion of geostrophic vortex stretching is likely to be a major mechanism for generating geostrophic spirals. Vertical advection associated with surface/bottom Ekman pumping and topography-induced upwelling is too weak to support these spirals. Strong wind stirring and large heat loss in wintertime lead to weak stratification and diminish the effects of vertical advection. The cooling effect and vertical diffusion are offset by an overwhelming contribution of horizontal diffusion in connection with vortex stretching. The Richardson number-dependent vertical eddy diffusivity reaches a magnitude of 10^(-4) m^2 s^(-1) on average. An eddy diffusivity of 2870 m^2 s^(-1) is required for dynamic balance by estimating the residual term. This obtained value of 10-4 m^2 s^(-1) is in good agreement with the estimation in terms of observed eddy activities. The suppressed and unsuppressed diffusivities in the observation region are 2752 and 2881 m^2 s^(-1), respectively, which supports a closed budget for velocity rotation.

关键词： geostrophic spirals horizontal diffusion vortex stretching and surface cooling effect

Wave uplift force on horizontal panels: a laboratory study

在线全文

学校读者我要写书评

暂无评论

Journal of Oceanology and Limnology 2019年第6期37卷 1899-1911页

作者： LIU Qingjun SUN Tianting WANG Dengting WEI Zhangping Nanjing Hydraulic Research Institute Nanjing 210029China College of Harbour Coastal and Off shore Engineering Hohai UniversityNanjing 210098China Key Laboratory of Port Waterway&Sedimentation Engineering of MOTNanjing 210029China Department of Civil Engineering Johns Hopkins UniversityBaltimoreMD 21218USA

Accurate estimation of wave uplift force is essential to the designs of reliable coastal and marine *** presents a series of laboratory work here on the impact of regular waves on horizontal panels,from which an empirical formula to estimate accurately the wave uplift force on panels is *** laboratory measurements show that the wave uplift force depends mainly on the incident wave height,the wave period,the wave length,the panel width,and the clearance between the subsurface of the panel and the still water *** these factors,the impact of the panel width on uplift forces is relatively *** shows that the relative panel width(i.e.,the ratio of panel width to wave length)plays a more important role in estimating the wave uplift *** on our comprehensive laboratory measurements,we further developed an empirical formula to compute wave uplift force on horizontal panels through dimensionless *** with other empirical formulas,this formula uses dimensionless variables of clear physical meanings,thus can describe the interaction between waves and the panels in a better *** addition,the efficiency of the formula to estimate wave uplift force on horizontal panels is verified against existing ***,the findings in this study shall be useful for understanding the mechanism of wave uplift force on horizontal panels and numerical model validation.

关键词： laboratory experiment wave-structure interaction horizontal panels wave uplift force empirical formula