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Analysis of the Flow Field and Impact Force in High-Pressure Water Descaling
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作者 Yue Cui Liyuan Wang +2 位作者 Jian Wu Haisheng Liu Di Wu 《Fluid Dynamics & Materials Processing》 EI 2024年第1期165-177,共13页
This study aims to improve the performances of the high-pressure water descaling technology used in steel hot rolling processes.In particular,a 2050 mm hot rolling line is considered,and the problem is investigated by... This study aims to improve the performances of the high-pressure water descaling technology used in steel hot rolling processes.In particular,a 2050 mm hot rolling line is considered,and the problem is investigated by means of a fluid–structure interaction(FSI)method by which the descaling effect produced by rolling coils with different section sizes is examined.Assuming a flat fan-shaped nozzle at the entrance of the R1R2 roughing mill,the outflow field characteristics and the velocity distribution curve on the strike line(at a target distance of 30–120 mm)are determined.It is found that the velocity in the center region of the water jet with different target distances is higher than that in the boundary region.As the target distance increases,the velocity of the water jet in the central region decreases.Through comparison with experimental results,it is shown that the simulation model can accurately predict the impact position of the high-pressure water on the impact plate,thereby providing a computational scheme that can be used to optimize the nozzle space layout and improve the slabs’descent effect for different rolling specifications. 展开更多
关键词 high pressure water descaling flow field analysis FSI target distance strike range
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A Hydrogen Iron Flow Battery with High Current Density and Long Cyclability Enabled Through Circular Water Management
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作者 Litao Yan Yuyan Shao Wei Wang 《Energy & Environmental Materials》 SCIE EI CAS CSCD 2023年第6期463-468,共6页
The hydrogen-iron(HyFe)flow cell has great potential for long-duration energy storage by capitalizing on the advantages of both electrolyzers and flow batteries.However,its operation at high current density(high power... The hydrogen-iron(HyFe)flow cell has great potential for long-duration energy storage by capitalizing on the advantages of both electrolyzers and flow batteries.However,its operation at high current density(high power)and over continuous cycling testing has yet to be demonstrated.In this paper,we discuss our design and demonstration of a water management strategy that supports high current and long cycling performance of a HyFe flow cell.Water molecules associated with the movement of protons from the iron electrode to the hydrogen electrode are sufficient to hydrate the membrane and electrode at a low current density of 100 mA cm^(-2)during the charge process.At higher charge current density,more aggressive measures must be taken to counter back-diffusion driven by the acid concentration gradient between the iron and hydrogen electrodes.Our water management approach is based on water vapor feeding in the hydrogen electrode,and water evaporation in the iron electrode,thus enabling the high current density operation of 300 mA cm^(-2). 展开更多
关键词 flow battery high current density operation HYDROGEN membrane hydration water management
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Enlarging Zn deposition space via regulating Sn-induced effective interface for high areal capacity zinc-based flow battery
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作者 Yuning Sun Siyu Zhang +5 位作者 Qiming Zhang Lantong Cui Pengfei Wang Yanbin Yin Qian Wang Qinzhi Lai 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2023年第11期579-586,I0012,共9页
Zinc-based flow batteries(ZFBs)have aroused great favor in large-scale energy storage due to the high security and low cost.However,the low areal capacity arising from the limited space for Zn plating hinders the furt... Zinc-based flow batteries(ZFBs)have aroused great favor in large-scale energy storage due to the high security and low cost.However,the low areal capacity arising from the limited space for Zn plating hinders the further development.Herein,a novel carbon felt-Sn-carbon felt sandwich host(CSCH)is designed and constructed.Benefiting from the strong chemical absorption and the dehydration effect on Zn(H_(2)O)_(6)^(2+),the Sn activation layer in the CSCH demonstrates the lowest comprehensive resistance for Zn deposition.Thus,Zn is induced to nucleate preferentially on the Sn activation layer,and grows towards the membrane,regulating the spatial distribution of Zn electrochemical deposits,which remarkably improves the areal capacity and cyclic stability of Zn anode.Consequently,the zinc-bromine flow batteries equipped with CSCH electrodes can achieve the ultra-high areal capacity of 120 mA h cm^(-2)at 80 mA cm^(-2),and run stably for 140 h with average energy efficiency of 80.3%in the extreme condition(80 mA cm^(-2),80 mA h cm^(-2)).This innovative work will inspire future advanced designs for high areal capacity electrodes in ZFBs. 展开更多
关键词 Zinc-based flow batteries high areal capacity Sn-induced deposition Zn deposition depth
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High-flow priapism due to bilateral cavernous artery fistulas treated by unilateral embolization:A case report
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作者 Guo Li Yi Liu +2 位作者 Hao-Yang Wang Fei-Zhou Du Zhi-Wei Zuo 《World Journal of Clinical Cases》 SCIE 2023年第1期225-232,共8页
BACKGROUND High flow priapism(HFP)is a rare type of priapism.Perineal trauma is the most common cause of HFP.Trauma-induced penile artery injury may lead to an arterial-cavernosal fistula,whereas persistent irregular ... BACKGROUND High flow priapism(HFP)is a rare type of priapism.Perineal trauma is the most common cause of HFP.Trauma-induced penile artery injury may lead to an arterial-cavernosal fistula,whereas persistent irregular arterial blood flow entering the corpora cavernosum can cause a persistent penile erection.The routine treatment of HFP focuses on addressing the abnormal penile erectile status and avoiding post-treatment erectile dysfunction.Interventional embolization is an important therapeutic modality for HFP,and bilateral embolization therapy is currently the most commonly used technique for patients with bilateral cavernous artery fistulas;however,unilateral embolization therapy has yet to be reported.CASE SUMMARY Herein,we report of the case of a 26-year-old Chinese male who presented with a persistent abnormal erection for 12 h after perineal impact injury.Medical history,cavernous arterial blood gas analysis and radiological examinations led to a diagnosis of HFP caused by bilateral cavernous artery fistulas.We performed routine conservative treatment(compression therapy and ice application)for the patient after admission;however,10 d later,his symptoms had not been relieved.After completion of the preoperative workup,right(severe side)selective perineal artery embolization was performed;the left cavernous artery fistula was left untreated.After postoperative continuation of conservative treatment for 72 h,the patient experienced complete penile thinning.The patient had no symptoms of erectile dysfunction over a follow-up period of 12 mo.CONCLUSION Compared with bilateral cavernous artery fistula embolization,we believe that unilateral cavernous artery fistula embolization can achieve positive clinical efficacy and reduce the risk of postoperative erectile dysfunction secondary to penile ischemia. 展开更多
关键词 high flow priapism Elective pudendal artery embolization Cavernous fistula Erectile dysfunction Case report
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Impact and Management under Extracorporeal Circulation of a Patient with Renal Insufficiency on Dialysis with a High-Flow Arteriovenous Fistula in the Cardiac Surgery Department of the Angers Teaching Hospital about a Case and Review of the Literature
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作者 Abdoulaye Kanté Bréhima Coulibaly +6 位作者 Mamadou Diakité Mamadou A. Keita Bakary Keita Drissa Traoré Nouhoum Ongoïba Patrice Binuani Christophe Baufreton 《Open Journal of Thoracic Surgery》 2023年第1期1-5,共5页
Arteriovenous fistulas have a substantial impact on systemic hemodynamics, however their effect on extracorporeal circulation is not well understood. We report our clinical observation on the management under extracor... Arteriovenous fistulas have a substantial impact on systemic hemodynamics, however their effect on extracorporeal circulation is not well understood. We report our clinical observation on the management under extracorporeal circulation of a patient with renal insufficiency with a high-flow arteriovenous fistula. This is a 59-year-old man who was referred to us for surgical treatment of ischemic coronary artery disease in a context of anuric chronic renal failure. Hypothermia at 32°C is started from the start in CEC due to hyperflow at the level of the arteriovenous fistula. We performed two coronary artery bypasses of the marginal and IVA via the two internal thoracic arteries. The patient is hemofiltered in order to avoid hyperkalaemia and possibly avoid fluid overload related to filling per CEC. The clamping time was 71 minutes and the SCC lasted 141 minutes. There was no homologous transfusion in the operating room. It turns out that the input/output balance is zero at the end of the CEC. The postoperative course was simple. 展开更多
关键词 Coronaryartery by Pass Grafting high flow Arteriovenous Fistula Extracorporeal Circulation HYPOTHERMIA
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Shale oil development techniques and application based on ternary-element storage and flow concept in Jiyang Depression,Bohai Bay Basin,East China
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作者 YANG Yong 《Petroleum Exploration and Development》 SCIE 2024年第2期380-393,共14页
The ternary-element storage and flow concept for shale oil reservoirs in Jiyang Depression of Bohai Bay Basin,East China,was proposed based on the data of more than 10000 m cores and the production of more than 60 hor... The ternary-element storage and flow concept for shale oil reservoirs in Jiyang Depression of Bohai Bay Basin,East China,was proposed based on the data of more than 10000 m cores and the production of more than 60 horizontal wells.The synergy of three elements(storage,fracture and pressure)contributes to the enrichment and high production of shale oil in Jiyang Depression.The storage element controls the enrichment of shale oil;specifically,the presence of inorganic pores and fractures,as well as laminae of lime-mud rocks,in the saline lake basin,is conducive to the storage of shale oil,and the high hydrocarbon generating capacity and free hydrocarbon content are the material basis for high production.The fracture element controls the shale oil flow;specifically,natural fractures act as flow channels for shale oil to migrate and accumulate,and induced fractures communicate natural fractures to form complex fracture network,which is fundamental to high production.The pressure element controls the high and stable production of shale oil;specifically,the high formation pressure provides the drive force for the migration and accumulation of hydrocarbons,and fracturing stimulation significantly increases the elastic energy of rock and fluid,improves the imbibition replacement of oil in the pores/fractures,and reduces the stress sensitivity,guaranteeing the stable production of shale oil for a long time.Based on the ternary-element storage and flow concept,a 3D development technology was formed,with the core techniques of 3D well pattern optimization,3D balanced fracturing,and full-cycle optimization of adjustment and control.This technology effectively guides the production and provides a support to the large-scale beneficial development of shale oil in Jiyang Depression. 展开更多
关键词 Jiyang Depression continental shale oil reservoir space fracturing stimulation fracture network storage and flow theory 3D development high and stable production
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Study on Characteristics of a High-Precision Cold Gas Micro Thruster
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作者 Zhaoli Wang Changbin Guan +2 位作者 Xudong Wang Weijie Zheng Longfei Su 《Engineering(科研)》 2024年第1期38-45,共8页
In order to improve the reliability of the spacecraft micro cold gas propulsion system and realize the precise control of the spacecraft attitude and orbit, a micro-thrust, high-precision cold gas thruster is carried ... In order to improve the reliability of the spacecraft micro cold gas propulsion system and realize the precise control of the spacecraft attitude and orbit, a micro-thrust, high-precision cold gas thruster is carried out, at the same time due to the design requirements of the spacecraft, this micro-thrust should be continuous working more than 60 minutes, the traditional solenoid valve used for the thrusts can’t complete the mission, so a long-life micro latching valve is developed as the control valve for this micro thruster, because the micro latching valve can keep its position when it cuts off the outage. Firstly, the authors introduced the design scheme and idea of the thruster. Secondly, the performance of the latching valve and the flow characteristics of the nozzle were simulated. Finally, from the experimental results and compared with the numerical study, it shows that the long-life micro cold gas thruster developed in this paper meets the mission requirements. 展开更多
关键词 high-Precision Micro Thruster Performance flow Characteristic EXPERIMENT
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基于GO-FLOW法的某高速列车齿轮箱可靠性分析方法研究
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作者 赫英凤 庞亚男 《自动化应用》 2024年第14期167-170,共4页
针对传统FTA无法对有反馈、多状态、有时序系统进行可靠性计算的问题,提出了一种基于GO-FLOW法的某型高速列车变速箱的可靠性分析方法。首先,根据齿轮箱的工作原理和结构逻辑,确定了操作符的类型并建立了齿轮箱系统的GO-FLOW图模型。其... 针对传统FTA无法对有反馈、多状态、有时序系统进行可靠性计算的问题,提出了一种基于GO-FLOW法的某型高速列车变速箱的可靠性分析方法。首先,根据齿轮箱的工作原理和结构逻辑,确定了操作符的类型并建立了齿轮箱系统的GO-FLOW图模型。其次,修正共因故障后计算齿轮箱成功概率并绘制齿轮箱的健康变化规律曲线。最后,对比GO-FLOW与FTA的分析结果可知,GO-FLOW法在齿轮箱健康评估应用中高效可行,且具有时序性。同时,该方法减少了计算量,为维修维护高速列车齿轮箱系统和提升其健康管理水平提供了一定的理论指导作用。 展开更多
关键词 高速列车 齿轮箱 可靠性分析 GO-flow FTA法 健康评估
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Flow behavior and microstructure of ZK60 magnesium alloy compressed at high strain rate 被引量:5
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作者 吴远志 严红革 +3 位作者 朱素琴 陈吉华 刘安民 刘先兰 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2014年第4期930-938,共9页
Flow behavior and microstructure of a homogenized ZK60 magnesium alloy were investigated during compression in the temperature range of 250-400 ℃ and the strain rate range of 0.1-50 s^-1. The results showed that dyna... Flow behavior and microstructure of a homogenized ZK60 magnesium alloy were investigated during compression in the temperature range of 250-400 ℃ and the strain rate range of 0.1-50 s^-1. The results showed that dynamic recrystallization (DRX) developed mainly at grain boundaries at lower strain rate (0.1-1 s^-1), while in the case of higher strain rate (10-50 s^-1), DRX occurred extensively both at twins and grain boundaries at all temperature range, especially at temperature lower than 350 ℃, which resulted in a more homogeneous microstructure than that under other deformation conditions. The DRX extent determines the hot workability of the workpiece, therefore, hot deformation at the strain rate of 10-50 s^-1 and in the temperature range of 250-350 ℃ was desirable for ZK60 alloy. Twin induced DRX during high strain rate compression included three steps. Firstly, twins with high dislocation subdivided the initial grain, then dislocation arrays subdivided the twins into subgrains, and after that DRX took place with a further increase of strain. 展开更多
关键词 ZK60 magnesium alloy high strain rate compression flow behavior MICROSTRUCTURE twin induced DRX
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Ultrasonic method for measuring water holdup of low velocity and high-water-cut oil-water two-phase flow 被引量:2
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作者 赵安 韩云峰 +2 位作者 任英玉 翟路生 金宁德 《Applied Geophysics》 SCIE CSCD 2016年第1期179-193,222,共16页
Oil reservoirs with low permeability and porosity that are in the middle and late exploitation periods in China's onshore oil fields are mostly in the high-water-cut production stage.This stage is associated with sev... Oil reservoirs with low permeability and porosity that are in the middle and late exploitation periods in China's onshore oil fields are mostly in the high-water-cut production stage.This stage is associated with severely non-uniform local-velocity flow profiles and dispersed-phase concentration(of oil droplets) in oil-water two-phase flow,which makes it difficult to measure water holdup in oil wells.In this study,we use an ultrasonic method based on a transmission-type sensor in oil-water two-phase flow to measure water holdup in lowvelocity and high water-cut conditions.First,we optimize the excitation frequency of the ultrasonic sensor by calculating the sensitivity of the ultrasonic field using the finite element method for multiphysics coupling.Then we calculate the change trend of sound pressure level attenuation ratio with the increase in oil holdup to verify the feasibility of the employed diameter for the ultrasonic sensor.Based on the results,we then investigate the effects of oildroplet diameter and distribution on the ultrasonic field.To further understand the measurement characteristics of the ultrasonic sensor,we perform a flow loop test on vertical upward oilwater two-phase flow and measure the responses of the optimized ultrasonic sensor.The results show that the ultrasonic sensor yields poor resolution for a dispersed oil slug in water flow(D OS/W flow),but the resolution is favorable for dispersed oil in water flow(D O/W flow) and very fine dispersed oil in water flow(VFD O/W flow).This research demonstrates the potential application of a pulsed-transmission ultrasonic method for measuring the fraction of individual components in oil-water two-phase flow with a low mixture velocity and high water cut. 展开更多
关键词 Oil-water two-phase flow low mixture velocity high water cut ultrasonic sensor water holdup
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High Flow TM直型无针密闭式输液接头与普通肝素帽在血液透析CVT中应用效果的对比性观察 被引量:1
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作者 杨静 《现代诊断与治疗》 CAS 2017年第18期3340-3341,共2页
目的对比分析High Flow TM直型无针密闭式输液接头与普通肝素帽在血液透析中心静脉留置导管(CVT)中的应用效果。方法选取2014年8月~2016年10月我院肾内科住院治疗的血液透析患者100例。随机分为观察组和对照组各50例。观察组采用High Fl... 目的对比分析High Flow TM直型无针密闭式输液接头与普通肝素帽在血液透析中心静脉留置导管(CVT)中的应用效果。方法选取2014年8月~2016年10月我院肾内科住院治疗的血液透析患者100例。随机分为观察组和对照组各50例。观察组采用High Flow TM直型无针密闭式输液接头进行封管,对照组采用普通肝素帽进行封管。对比两组导管相关并发症及满意度。结果观察组导管相关并发症总发生率显著低于对照组,差异有统计学意义(P<0.05)。观察组满意度为98.0%,显著高于对照组的86.0%,差异有统计学意义(P<0.05)。结论 High Flow TM直型无针密闭式输液接头用于血液透析CVT患者有助于降低并发症发生,提高满意度,值得推广应用。 展开更多
关键词 中心静脉留置导管 high flow TM直型无针密闭式输液接头 普通肝素帽 并发症
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NONPARALLEL BOUNDARY LAYER STABILITY IN HIGH SPEED FLOWS 被引量:1
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作者 郭欣 唐登斌 沈清 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2008年第2期81-88,共8页
The parabolized stability equations (PSEs) for high speed flows, especially supersonic and hypersonic flows, are derived and used to analyze the nonparallel boundary layer stability. The proposed numerical technique... The parabolized stability equations (PSEs) for high speed flows, especially supersonic and hypersonic flows, are derived and used to analyze the nonparallel boundary layer stability. The proposed numerical techniques for solving PSE include the following contents: introducing the efficiently normal transformation of the boundary layer, improving the computational accuracy by using a high-order differential scheme near the wall, employing the predictor-corrector and iterative approach to satisfy the important normalization condition, and implementing the stable spatial marching. Since the second mode dominates the growth of the disturbance in high Mach number flows, it is used in the computation. The evolution and characteristics of the boundary layer stability in the high speed flow are demonstrated in the examples. The effects of the nonparallelizm, the compressibility and the cooling wall on the stability are analyzed. And computational results are in good agreement with the relevant data. 展开更多
关键词 high speed flow boundary layers nonparallelism parabolized stability equations
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Numerical and Experimental Investigation of High-efficiency Axial-flow Pump 被引量:50
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作者 SHI Weidong ZHANGDesheng GUAN Xingfan LENG Hongfei 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2010年第1期38-44,共7页
The experimental investigation of axial-flow pump has been rapidly developed to meet the needs of South-to-North Water Diversion Project of China. Owing to the boundary conditions of hub, blade tip clearance, much of ... The experimental investigation of axial-flow pump has been rapidly developed to meet the needs of South-to-North Water Diversion Project of China. Owing to the boundary conditions of hub, blade tip clearance, much of the physical phenomena and laws involved in this complex flow field can't be fully determined. The flow characteristics of the high efficiency axial-flow pump have been simulated by RNG k-e turbulence model and SIMPLEC arithmetic based on FLUENT software. Numerical results indicate that the data from the prediction show agreement with the experimental results, static pressure on pressure side of blades increases slightly at circumferential direction with radius increasing, and keep almost constant at the same radial while increasing gradually from inlet to exit on the suction side along flow direction at design conditions. The static pressure, total pressure and velocity at inlet, impeller outlet and vane outlet were measured by a five-hole probe, and a contrastive experiment was done to investigate the influence of hub leakage. The experimental results show that inlet flow is almost axial and the prerotation is very small at various conditions. The meridional velocity and circulation distribution are almost identical at impeller outlet at design conditions due to steady flow and high efficiency. The residual circulation exits at downstream of the guide vane, and the circumferential velocity component increases linearly from hub to tip at small flow rate conditions. Hub leakage in adjustable blades results in the decrease of the meridional velocity and circulation at blade exit near hub. The results of numerical simulation and experiments supply important flow structure information for the high-efficiency axial-flow pump. 展开更多
关键词 axial-flow pump flow field multi-conditions high efficiency PROBE hub leakage
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EFFECT OF TIP CLEARANCE ON PERFORMANCE AND FLOW FIELD OF SMALL SIZED HIGH SPEED CENTRIFUGAL FAN 被引量:2
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作者 曹人靖 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2005年第4期329-334,共6页
A centrifugal fan with the high speed and compact dimensions is studied numerically and experimentally. The centrifugal fan consists of a shrouded impeller rotating at 34 000 r/min with a small tip clearance 0.7 mm to... A centrifugal fan with the high speed and compact dimensions is studied numerically and experimentally. The centrifugal fan consists of a shrouded impeller rotating at 34 000 r/min with a small tip clearance 0.7 mm to the fixed outer casing. Computational models with/without the tip clearance are built and the κ-ω shear stress transport (SST) turbulence model and the unstructured mesh are applied to the numerical simulation for unsteady solutions. The overall performance is measured on a standard experimental bench and the major flow feature of each component inside the centrifugal fan is numerically investigated. In the presence of the tip clearance due to the difference of static pressure between leading and trailing edges of the clearance, i. e. , leading and trailing edges of the impeller, a strong return flow exists inside the clearance passage and re-circulates the main stream inside the impeller passage, and produces the strong flow interaction, thus changing the flow field and influencing the overall performance. 展开更多
关键词 small sized high speed centrifugal fan tip clearance flow field analysis
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ASYMMETRIC VORTICES FLOW OVER SLENDER BODY AND ITS ACTIVE CONTROL AT HIGH ANGLE OF ATTACK 被引量:16
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作者 邓学蓥 王延奎 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2004年第6期567-579,共13页
The studies of asymmetric vortices flow over slender body and its active control at high angles of attack have significant importance for both academic field and engineering area.This paper attempts to provide an upda... The studies of asymmetric vortices flow over slender body and its active control at high angles of attack have significant importance for both academic field and engineering area.This paper attempts to provide an update state of art to the investigations on the fields of forebody asymmetric vortices.This review emphasizes the correlation between micro-perturbation on the model nose and its response and evolution behaviors of the asymmetric vortices.The critical issues are discussed, which include the formation and evolution mechanism of asymmetric multi-vortices;main behaviors of asymmetric vortices flow including its deterministic feature and vortices flow structure;the evolution and development of asymmetric vortices under the perturbation on the model nose;forebody vortex active control especially discussed micro-perturbation active control concept and technique in more detail.However present understanding in this area is still very limited and this paper tries to identify the key unknown problems in the concluding remarks. 展开更多
关键词 asymmetric vortex flow control high angle of attack aerodynamics slender body
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The Flow Simulation and Experimental Study of Low-Specific-Speed High-Speed Complex Centrifugal Impellers* 被引量:28
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作者 崔宝玲 朱祖超 +1 位作者 张剑慈 陈鹰 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2006年第4期435-441,共7页
Based on the Navier-Stokes equations and the Spalart-Allmaras turbulence model, three-dimensional turbulent flow in four low-specific-speed centrifugal impellers are simulated numerically and analyzed. The relativ... Based on the Navier-Stokes equations and the Spalart-Allmaras turbulence model, three-dimensional turbulent flow in four low-specific-speed centrifugal impellers are simulated numerically and analyzed. The relative velocity distribution, pressure distribution and static pressure rise at the design point are obtained for the regular impeller with only long blades and three complex impellers with long, mid or short blades. It is found that the back flow region between long-blade pressure side and mid-blade suction side is diminished and is pushed to pressure side of short blades near the outlet of impeller at suction side by the introduction of mid, short blades, and the size of back flow becomes smaller in a multi-blade complex impeller. And the pressure rises uniformly from inlet to outlet in all the impellers. The simulated results show that the complex impeller with long, mid and short blades can improve the velocity distribution and reduce the back flow in the impeller channel. The experimental results show that the back flow in the impeller has an important influence on the performance of pump and a more-blade complex impeller with long, mid and short blades can effectively solve low flow rate instability of the low-specific-speed centrifugal pump. 展开更多
关键词 centrifugal pump low-specific-speed complex impeller flow simulation high speed experimentalstudy
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Residence time distribution of high viscosity fluids falling film flow down outside of industrial-scale vertical wavy wall: Experimental investigation and CFD prediction 被引量:5
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作者 Shichang Chen Lihao Zhang +2 位作者 Yongjun Wang Xianming Zhang Wenxing Chen 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2019年第7期1586-1594,共9页
The flow behavior of gravity-driven falling film of non-conductive high viscosity polymer fluids on an industrial-scale vertical wavy wall was investigated in terms of film thickness and residence time distribution by... The flow behavior of gravity-driven falling film of non-conductive high viscosity polymer fluids on an industrial-scale vertical wavy wall was investigated in terms of film thickness and residence time distribution by numerical simulation and experiment.Falling film flow of high viscosity fluids was found to be steady on a vertical wavy wall in the presence of the large film thickness.The comparison between numerical simulation and experiment for the film thickness both in crest and trough of wavy wall showed good agreement.The simulation results of average residence time of falling film flow with different viscous fluids were also consistent with the experimental results.This work provides the initial insights of how to evaluate and optimize the falling film flow system of polymer fluid. 展开更多
关键词 FALLING FILM flow high viscosity polymer fluid RESIDENCE time distribution FILM thickness Numerical simulation
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Control of Asymmetric Flow Fields of Slender Bodies at High Angle of Attack 被引量:4
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作者 明晓 顾蕴松 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2006年第2期168-174,共7页
The wind tunnel experiments is conducted to get inspiration for understanding the mechanism of the asymmetric flow pattern and developing an innovative flow control technique for a slender body at high angle of attack... The wind tunnel experiments is conducted to get inspiration for understanding the mechanism of the asymmetric flow pattern and developing an innovative flow control technique for a slender body at high angle of attack. The bi-stable situation of the side forces is observed, which could be easily switched by a tiny disturbances either from coming flow or from artificial disturbances at nose tip (including manufacturing defect). In turbulent flows the side forces switched randomly between positive and negative. There exists a hysteresis loop of side force with the rolling angle. A rod in front of the slender body is used to change the vortex pattern, which could be kept even the rod is moved out from the stream. A miniature strake attached to the nose tip of the model can be moved to different circumferential position. When the strake is stationary, the hysteresis loop disappears and the side force does not change with the turbulent fluctuation of coming flow. The results from dynamic measurements of section side force indicates that when the strake swung at lower frequency the side force can follow the cadence of the swinging strake. With increasing frequency, the magnitude of the side force decreases. At still high frequency, the side force diminishes to zero. If the strake is swinging, while the middle position can be changed to different circumferential angle Фs on either left or right side, the side forces can be changed proportionally with the angle Фs. On the basis of the experimental results, the mechanism of the asymmetry is discussed. 展开更多
关键词 high angle of attack asymmetric vortex pattern flow control
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High-flow nasal oxygen availability for sedation decreases the use of general anesthesia during endoscopic retrograde cholangiopancreatography and endoscopic ultrasound 被引量:10
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作者 Roman Schumann Nikola S Natov +4 位作者 Klifford A Rocuts-Martinez Matthew D Finkelman Tom V Phan Sanjay R Hegde Robert M Knapp 《World Journal of Gastroenterology》 SCIE CAS 2016年第47期10398-10405,共8页
AIM To examine whether high-flow nasal oxygen(HFNO) availability influences the use of general anesthesia(GA) in patients undergoing endoscopic retrograde cholangiopancreatography(ERCP) and endoscopic ultrasound(EUS) ... AIM To examine whether high-flow nasal oxygen(HFNO) availability influences the use of general anesthesia(GA) in patients undergoing endoscopic retrograde cholangiopancreatography(ERCP) and endoscopic ultrasound(EUS) and associated outcomes.METHODS In this retrospective study, patients were stratified into 3 eras between October 1, 2013 and June 30, 2014 based on HFNO availability for deep sedation at the time of their endoscopy. During the first and last 3-mo eras(era 1 and 3), no HFNO was available, whereas it was an option during the second 3-mo era(era 2). The primary outcome was the percent utilization of GA vs deep sedation in each period. Secondary outcomes included oxygen saturation nadir during sedation between periods, as well as procedure duration, and anesthesia-only time between periods and for GA vs sedation cases respectively.RESULTS During the study period 238 ERCP or EUS cases were identified for analysis. Statistical testing was employed and a P < 0.050 was significant unless the Bonferroni correction for multiple comparisons was used. General anesthesia use was significantly lower in era 2 compared to era 1 with the same trend between era 2 and 3(P = 0.012 and 0.045 respectively). The oxygen saturation nadir during sedation was significantly higher in era 2 compared to era 3(P < 0.001) but not between eras 1 and 2(P = 0.028) or 1 and 3(P = 0.069). The procedure time within each era was significantly longer under GA compared to deep sedation(P ≤ 0.007) as was the anesthesia-only time(P ≤ 0.001).CONCLUSION High-flow nasal oxygen availability was associated with decreased GA utilization and improved oxygenation for ERCP and EUS during sedation. 展开更多
关键词 Endoscopic ultrasound Endoscopic retrograde cholangiopancreatography ENDOSCOPY SEDATION ANESTHESIA OXYGENATION high flow nasal oxygen
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Detached-eddy simulation of flow around high-speed train on a bridge under cross winds 被引量:3
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作者 陈敬文 高广军 朱春丽 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第10期2735-2746,共12页
In order to describe an investigation of the flow around high-speed train on a bridge under cross winds using detached-eddy simulation(DES), a 1/8th scale model of a three-car high-speed train and a typical bridge mod... In order to describe an investigation of the flow around high-speed train on a bridge under cross winds using detached-eddy simulation(DES), a 1/8th scale model of a three-car high-speed train and a typical bridge model are employed, Numerical wind tunnel technology based on computational fluid dynamics(CFD) is used, and the CFD models are set as stationary models. The Reynolds number of the flow, based on the inflow velocity and the height of the vehicle, is 1.9×10~6. The computations are conducted under three cases, train on the windward track on the bridge(WWC), train on the leeward track on the bridge(LWC) and train on the flat ground(FGC). Commercial software FLUENT is used and the mesh sensitivity research is carried out by three different grids: coarse, medium and fine. Results show that compared with FGC case, the side force coefficients of the head cars for the WWC and LWC cases increases by 14% and 29%, respectively; the coefficients of middle cars for the WWC and LWC increase by 32% and 10%, respectively; and that of the tail car increases by 45% for the WWC whereas decreases by 2% for the LWC case. The most notable thing is that the side force and the rolling moment of the head car are greater for the LWC, while the side force and the rolling moment of the middle car and the tail car are greater for the WWC. Comparing the velocity profiles at different locations, the flow is significantly influenced by the bridge-train system when the air is close to it. For the three cases(WWC, LWC and FGC), the pressure on the windward side of train is mostly positive while that of the leeward side is negative. The discrepancy of train's aerodynamic force is due to the different surface area of positive pressure and negative pressure zone. Many vortices are born on the leeward edge of the roofs. Theses vortices develop downstream, detach and dissipate into the wake region. The eddies develop irregularly, leading to a noticeably turbulent flow at leeward side of train. 展开更多
关键词 detached-eddy simulation high speed train BRIDGE cross wind flow structure train aerodynamics
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