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Effects of temperature distribution and level on heat transfer on a rotating free disk

航空动力学报 2011年第6期26卷 1310-1320页

作者： ZHAO Xi xu guo-qiang LUO Xiang National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics School of Jet Propulsion Beijing University of Aeronautics and Astronautics Beijing 100191 China

In gas turbine engines,with the existence of the intense forced convection and significant buoyancy effects,temperature distribution and level on turbine or compressor disks affect the heat transfer characteristics *** this paper,numerical simulations were performed to analyze these influences for a free disk,with the laminar and turbulent flow *** influences of temperature distribution on the heat transfer were observed by using incompressible cooling air,and temperature profiles of nth order monomial and polynomial were assumed on the *** analysis revealed that the heat transfer for two flow states on the free disk is determined by the exponent n of the monomial profile when specifying the rotating Reynolds number;for an arbitrary polynomial profile,the local Nusselt number can be deduced from results of monomial *** study the effects of temperature level on heat transfer singly,monomial profiles were used and the local Nusselt number of compressible and incompressible cooling air were *** both for two flow states,the following conclusions could be drawn: the relative difference of local Nusselt number is mainly controlled by nondimensional local temperature difference,and almost independent of the monomial's coefficient C,exponent n and the rotating Reynolds ***,a correction method for heat transfer of the free disk is presented and verified computationally,with which the local Nusselt number,obtained with a uniform and low temperature profile,can be revised by arbitrary distribution and high temperature magnitude.

关键词： thermal boundary condition temperature boundary condition rotating disk free disk heat transfer

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海南岛西部近岸海域碎屑锆石U-Pb同位素年代学物源示踪及其地质意义

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科学技术与工程 2024年第16期24卷 6626-6641页

作者：曾广骅陈旸许国强梁定勇海南省海洋地质资源与环境重点实验室海口570206 海南省地质调查院海口570206 海南省海洋地质调查院海口570206 三亚水文地质工程地质勘察院三亚572000

海南岛西部近岸海域海砂资源丰富、经济价值巨大,对其物质来源却缺乏系统研究。为解决这一科学问题,为该区域海砂资源的开发利用提供科学依据,对海南岛西部近岸海域和昌化江入海口1 471粒碎屑锆石开展了U-Pb同位素年代学和微区元素地球... 详细信息

海南岛西部近岸海域海砂资源丰富、经济价值巨大,对其物质来源却缺乏系统研究。为解决这一科学问题,为该区域海砂资源的开发利用提供科学依据,对海南岛西部近岸海域和昌化江入海口1 471粒碎屑锆石开展了U-Pb同位素年代学和微区元素地球化学研究。海南岛西部近岸海域年龄范围在3.45 Ga~82 Ma,具有99、241、252 Ma 3个主要年龄峰值,以及113、155、325、357 Ma 4个次要年龄峰值;昌化江入海口具有2.3 Ga~96 Ma的年龄范围,存在101、244、254 Ma 3个主要年龄峰值,以及122、266、281、307、342 Ma 4个次要年龄峰值。结果表明:海南岛西部近岸海域沉积物以具有~99 Ma的显著年龄峰,并缺乏晋宁期、加里东期和喜山期年龄峰为识别标志,海南岛应是其主要物源区,区内丰富的海砂资源来源于海南岛内岩浆岩和沉积岩的风化剥蚀和搬运沉积;海南岛西部近岸海域与昌化江沉积物年龄峰值的差异,指示海南岛西部近岸海域沉积物并非单纯来源于近源昌化江输入,也在北部湾逆时针环流的作用下接受琼西南部河流的物源贡献;更新昌化江入海口的碎屑锆石年龄组成,新识别出的380~310 Ma年龄群,可作为昌化江流域物源的识别标志;本次碎屑锆石年龄频谱特征与海南岛经历的多次重要地质事件相吻合,有助于了解海南岛复杂的地质演化历史。

关键词：海南岛西部海域海砂碎屑锆石U-Pb同位素年代学物源示踪构造演化

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Numerical investigation of windage heating within shrouded rotor-stator cavity system with central inflow

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航空动力学报 2014年第10期29卷 2402-2409页

作者： WANG Qian-shun ZHANG Da LUO Xiang xu guo-qiang National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics School of Engergy and Power EngineeringBeijing University of Aeronautics and Astronautics

The rotating disk surface temperature rise due to windage heating effect by numerically modeling the turbulent flow within a rotor-stator cavity which is available with a peripheral shroud and imposed through airflow was dealt *** windage heating may be defined as viscous friction heating caused by relative velocity differences across the boundary layers between the fluid and the rotating disk *** kinetic energy dissipation process could transform the rotating shaft power into thermal *** finite volume based solver,ANSYS/CFX was employed to numerically simulate this physical process by using the shear stress transport(SST)turbulence *** results include the rotating disk surface temperature axial distribution and tangential velocity distribution of the fluid *** velocity difference between the result obtained by particle image velocimetry(PIV)experiments and CFD simulation are within 5%.The adiabatic disk temperature rise can be calculated by the tangential velocity of disk and fluid in large gap ratio and turbulent *** temperature distribution results and those estimated via velocity differences are within 10%.

关键词： windage heating rotor-stator cavity system flow structure recovery temperature gap ratio

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Development and calibration of heat transfer coefficient sensor for rotational state

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航空动力学报 2011年第12期26卷 2684-2690页

作者： QUAN Yong-kai xu guo-qiang LUO Xiang ZHANG Da （School of Jet Propulsion Beijing University of Aeronautics and Astronautics Beijing 100000 China

A novel heat transfer coefficient sensor is introduced and the design,manufacture,and calibration are *** intended application of this instrument was on a high rotational speed test *** the experiments,the heat transfer coefficient sensor was calibrated under static state and rotational state *** calibration under the static state was accomplished in a pipe: the inside diameter(ID) was 0.048m and the total length was 4m,the distance between the sensor and the inlet of the pipe was 3.5m;the standard value was measured using a self-made *** calibration under the rotational state was accomplished using a rotating disc: the diameter and thickness of the stainless disc were 800mm and 25mm,respectively;the sensor was installed at the location of r=250mm;the rotating disc driven by a 30kW direct current motor can supply the maximum rotational speed of 3000r/*** standard value under rotational state was provided by an approximate empirical *** results show that the designed sensor can measure heat transfer coefficient directly under rotational state and static state with good accuracy and stability;the correlation factor of K are constant under static state and rotational state.

关键词： rotational state steady method heat transfer coefficient sentor calibration

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Flow characteristics in a rotor-stator cavity with cooling air inlet at low radius

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航空动力学报 2015年第4期30卷 775-783页

作者： CAI xu LUO Xiang ZHAO Xi xuguo-qiang CAI Jun National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics School of Energy and Power Engineering Beijing University of Aeronautics and Astronautics Beijing 100191 China Dalian Airforce Department of Information Network Communicaiton Non-Commissioned Office Academy Dalian Liaoning 116600 China Guizhou Aero-Engine Research Institute Aviation Industry Corporation of China Guiyang 550081 China

Experiments were conducted on a typical rotor-stator system where air entered through an annular slot at low radius and flowed out of the cavity axially through a rim seal between the rotor and the *** the seal in this rotor-stator system,the stationary shroud overlapped the rotating *** distributions at the stator surface and flow resistance coefficients of the rotor-stator cavity with a maximum gap of 67mm were measured under different dimensionless mass flow rates from 1.32×104 to 4.87×104 with a large range of rotational Reynolds numbers from 0.418×106 to 2.484×*** results show that pressure on the stator surface decreases with the increase of rotational Reynolds number when the dimensionless mass flow rate is below 1.3×104;when the dimensionless mass flow rate is above 3.034×104,the trend *** is the so-called"pressure inversion effect".However,dimensionless pressure does not show the same changes when rotational dynamic pressure is chosen as the *** resistance coefficient of the rotor-stator cavity is determined by the dimensionless mass flow rate and rotational Reynolds number;for practical application,the resistance coefficient can also be estimated by the turbulent flow parameter in the range of turbulent parameter from 0.1to 1.6.

关键词： cooling system rotor-stator system flow characteristics pressure distribution resistance coefficient

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Numerical simulation on a film-cooled rotating model with 30° injection holes

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航空动力学报 2010年第7期25卷 1443-1453页

作者： YANG Bin xu guo-qiang TAO Zhi DING Shui-ting WU Hong-wei National Key Laboratory of Science and Technology on Aero-Engines School of Jet Propulsion Beijing University of Aeronautics and Astronautics Beijing 100191 China

The flow and heat transfer characteristics were numerically investigated on a film cooling model under different rotating operating *** computational model was originated from the mid-span section of a typical turbine rotor with two rows of 14 staggered injection holes angled 30° both on the suction surface and pressure surface,and the flow through the coolant plenum and all the hole-pipes were resolved as a part of the computational domain by specifying the coolant mass flux in the *** computations primarily focus on under-standing the rotational effect on film cooling performance in mechanism research *** the present study,the Reynolds number(Re) based on mainstream velocity and injection hole diameter varied from 1835.5 to 5507.4,and the averaged blowing ratio(M) ranges of 0.5 to *** show that the coolant will move on to the high-radius locations near the suction and pressure surfaces due to the strong centrifugal effect,which leads to the decrease in adiabatic effectiveness *** discharge coefficients(Cd),on the pressure surface,are much higher than that on the suction surface under a given operating *** addition,the critical values of angular speed which represent the equilibrium of centrifugal force and Coriolis force near the pressure surface are also presented.

关键词： film cooling rotating adiabatic effectiveness heat transfer discharge coefficient

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A Case Study of Impact of FY-2C Satellite Data in Cloud Analysis to Improve Short-Range Precipitation Forecast

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Atmospheric and Oceanic Science Letters 2014年第6期7卷 527-533页

作者： LIU Rui-Xia CHEN Hong-Bin CHEN De-Hui xu guo-qiang Key Laboratory of Radiometric Calibration and Validation for Environmental Satellite National Satellite Meteorological CenterChina Meteorological Administration Laboratory for Middle Atmosphere and Global Environment Observation (LAGEO) Institute of Atmospheric PhysicsChinese Academy of Sciences Numerical Prediction Center China Meteorological Administration

Chinese FengYun-2C(FY-2C) satellite data were combined into the Local Analysis and Prediction System(LAPS) model to obtain three-dimensional cloud parameters and rain content. These parameters analyzed by LAPS were used to initialize the Global/Regional Assimilation and Prediction System model(GRAPES) in China to predict precipitation in a rainstorm case in the country. Three prediction experiments were conducted and were used to investigate the impacts of FY-2C satellite data on cloud analysis of LAPS and on short range precipitation forecasts. In the first experiment, the initial cloud fields was zero value. In the second, the initial cloud fields were cloud liquid water, cloud ice, and rain content derived from LAPS without combining the satellite data. In the third experiment, the initial cloud fields were cloud liquid water, cloud ice, and rain content derived from LAPS including satellite data. The results indicated that the FY-2C satellite data combination in LAPS can show more realistic cloud distributions, and the model simulation for precipitation in 1–6 h had certain improvements over that when satellite data and complex cloud analysis were not applied.

关键词： FY-2C satellite data cloud analysis precipitation forecast impact study

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Colo-colonic intussusception as a rare complication of colonoscopy with polypectomy: Two case reports

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World Journal of Gastrointestinal Surgery 2024年第6期16卷 1939-1947页

作者： Sai-Heng Xiang guo-qiang xu Department of Gastroenterology The First Affiliated HospitalZhejiang University School of MedicineHangzhou 310003Zhejiang ProvinceChina

BACKGROUND Colonoscopy is the most frequently used diagnostic and therapeutic tool for the treatment of colorectal *** the complication rate is low,it can be potentially *** is a rare and severe complication often associated with *** a handful of post-colonoscopy intussusception cases have been reported,making this study a valuable addition to the medical *** SUMMARY Case 1:A 61-year-old man underwent colonoscopy with polypectomy for chronic abdominal *** patient experienced abdominal pain 11 hours later but was still discharged after pain *** was readmitted due to recurring *** tomography(CT)showed colo-colonic *** conservative management and attempts at endoscopic reduction failed;therefore,laparoscopic right hemicolectomy was *** examination revealed tubular adenomas in the polyps and inflammation in the resected *** 2:A 59-year-old woman underwent colonoscopy with polypectomy for a polyp in the transverse *** experienced upper abdominal pain,fever,nausea,and vomiting 9 hours after the *** CT and blood tests revealed a colo-colonic intussusception near the hepatic flexure and an elevated white blood cell *** attempts at endoscopic reduction failed and conservative treatment showed no *** underwent successful laparoscopic reduction and recovered *** examination of the resected polyp revealed *** Post-colonoscopy intussusception in adults is rare,and polypectomy may contribute to its *** diagnosis is crucial,with prompt CT examination serving as *** excluding malignancies,conservative management and reduction of intussusception should be considered before surgical bowel resection.

关键词： Intussusception Colonoscopy Polypectomy Complication Case report

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Double-balloon enteroscopy for obscure gastrointestinal bleeding: A single center experience in China

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World Journal of Gastroenterology 2010年第13期16卷 1655-1659页

作者： Chen, Li-Hua Chen, Wen-guo Cao, Hai-Jun Zhang, Hong Shan, guo-Dong Li, Lin Zhang, Bing-Ling xu, Cheng-Fu Ding, Kai-Li Fang, Ying Cheng, Ying Wu, Chen-Jiao xu, guo-qiang Zhejiang Univ Dept Gastroenterol Affiliated Hosp 1 Coll Med Hangzhou 310003 Zhejiang Peoples R China Zhejiang Univ Chinese Med Dept Gastroenterol Affiliated Hosp 1 Hangzhou 310003 Zhejiang Peoples R China Dongyang Peoples Hosp 1 Dept Gastroenterol Jinhua 322100 Zhejiang Peoples R China Zhejiang Univ Dept Endoscopy Ctr Affiliated Hosp 1 Coll Med Hangzhou 310003 Zhejiang Peoples R China

AIM: To evaluate the diagnostic value of double-balloon enteroscopy (DBE) for obscure gastrointestinal bleeding (OGIB). METHODS: The data about 75 OGIB patients who underwent DBE in January 2007-June 2009 in our hospital were retrospectively analyzed. RESULTS: DBE was successfully performed in all 75 patients without complication. Of the 75 patients, 44 (58.7%) had positive DBE findings, 22 had negative DBE findings but had potential bleeding at surgery and capsule endoscopy, etc . These 66 patients were finally diagnosed as OGIB which was most commonly caused by small bowel tumor (28.0%), angiodysplasia (18.7%) and Crohn’s disease (10.7%). Lesions occurred more frequently in proximal small bowel than in distal small bowel (49.3% vs 33.3%, P = 0.047). CONCLUSION: DBE is a safe, effective and accurate procedure for the diagnosis of OGIB.

关键词： Double-balloon enteroscopy Capsule endoscopy Obscure gastrointestinal bleeding Diagnosis

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Divergent defluorocarboxylation of α-CF_(3) alkenes with formate via photocatalyzed selective mono-or triple C-F bond cleavage

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Science China Chemistry 2024年第1期67卷 368-373页

作者： Xing-Yu Wang Pei xu Wen-Wen Liu Hao-qiang Jiang Song-Lei Zhu Dong guo xu Zhu Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy School of PharmacyXuzhou Medical UniversityXuzhou 22100China

Unprecedented divergent synthesis of gem-difluorovinylacetic acid and glutaric acid derivatives fromα-CF_(3)alkenes with formate as the carbonyl source was *** reaction can undergo selective mono-or triple C-F bond cleavage by simply switching the photocatalyst and hydrogen atom transfer(HAT)catalyst under visible-light-induced conditions at room *** acts as both the C1 source and the reductant through the generation of CO_(2)^(·-)species,which underwent Giese radical addition to electron-deficient alkenes to trigger the consecutive C-F bond cleavage and carboxylation process.

关键词： C-F bond activation defluorocarboxylation carbon dioxide radical anion visible light

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