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1Recent development of casing treatments for aeroengine compressors显示文摘Casing treatment is a mature stabilization technique which has been widely applied on aero-engines for modern aircrafts and turbo-chargers for automobiles. After the investigations of half century since the 1960 s, this technique has been well developed for various configurations with different effectiveness. From the perspective of stabilization mechanism, this paper roughly categorizes the configurations of casing treatment into two types: traditional ones which work by affecting the flow structure of blade tip region; a novel one named as Stall Precursor-Suppressed(SPS) casing treatment. The effectiveness of both types will be demonstrated for their applications on axial compressors and centrifugal compressors with uniform or distorted inlet. And the stabilization mechanism of casing treatments for regular types and SPS one will also be explained respectively. In addition, this review will summarize the methodologies of casing treatments with the numerical simulations for regular grooved configurations and the eigenvalue approach for SPS casing treatment.Looking forward to the future of compressor stabilization, casing treatment technique will still exist as a general and inexpensive option, and the exploration for its effectiveness and mechanism will be deeper with the development of computational fluid dynamics and advanced measurement techniques.Xiaofeng SUN Xu DONG Dakun SUN 2019Chinese Journal of Aeronautics2019,32,1:16
2An analysis of the Circumferential Grooves Casing Treatment for transonic compressor flow显示文摘The stall mechanism of the NASA Rotor 37 is investigated through the analysis of the critical flow structures near the stall under the transonic condition. The performance of the rotor with Circumferential Grooves Casing Treatment (CGCT) is also studied based on the Reynolds-Averaging Navier-Stokes approach. The study finds that stall margin improvement can be achieved without significant penalty on the efficiency for the two CGCT configurations applied. The effects of circumferential grooves on the critical flow structures are studied through the analysis of the tip leakage mass and momentum transport that further re-veal the CGCT mechanism.HUANG XuDong,CHEN HaiXin,SHI Ke & FU Song School of Aerospace,Tsinghua University,Beijing 100084,China 2010Science China(Physics,Mechanics & Astronomy)2010,53,2:7
3Containment of soft wall casing wrapped with Kevlar fabric显示文摘Aramid fabrics have been commonly used in the civil turbofan engine fan blade containment system for its excellent performance. To investigate the behavior and capability of soft wall containment casing, a series of fan blade released tests were conducted on the high-speed spin tester.The soft wall casing was fabricated by wrapping multiple layers of Kevlar49 plain woven fabric around a thin steel ring. Casings with different inner metal ring and outer fabric layers number were compared. The method of using the explicit dynamic software LS-DYNA to establish the finite element analysis model for the quantitative analysis of the containment process was developed and conducted. The simulation results are in good agreement with the test results. It is shown that the containment process of the soft wall casing can be divided into three impact stages. The casing with low-stiffness inner metal ring will get severe overall deformation and lose the structural integrity when it suffers the blade impact. Kevlar fabric layers will appear large bulge on outside surface and absorb the most impact dynamic energy of the high speed released fan blade. By summing up the results of the test and simulation, an empirical critical equation was derived to describe the relationship between the released blade dynamic energy and the Kevlar fabric thickness.Zekan HE Haijun XUAN Conger BAI Manli SONG Zhuoshen ZHU 2019Chinese Journal of Aeronautics2019,32,4:5
4Entropy Generation Analysis in a Mixed-Flow Compressor with Casing Treatment显示文摘Casing treatments(CT) can effectively extend compressors flow ranges with the expense of efficiency penalty. Compressor efficiency is closely linked to loss. Only revealing the mechanisms of loss generation can design a CT with high aerodynamic performance. In the paper, a highly-loaded mixed-flow compressor with tip clearance of 0.4 mm was numerically studied at a rotational speed of 30,000 r/min to reveal the effects of axial slot casing treatment(ASCT) on the loss mechanisms in the compressor. The results showed that both isentropic efficiency and stall margin were improved significantly by the ASCT. The local entropy generation method was used to analyze the loss mechanisms and to quantify the loss distributions in the blade passage. Based on the axial distributions of entropy generation rate, for both the cases with and without ASCT, the peak entropy generation rate increased in the rotor domain and decreased in the stator domain during throttling the compressor. The peak entropy generation in rotor was mainly caused by the tip leakage flow and flow separations near the rotor leading edge for the mixed-flow compressor no matter which casing was applied. The radial distributions of entropy generation rate showed that the reduction of loss in the rotor domain from 0.4 span to the rotor casing was the major reason for the efficiency improved by ASCT. The addition of ASCT exerted two opposite effects on the losses generated in the compressor. On the one hand, the intensity of tip leakage flow was weakened by the suction effect of slots, which alleviated the mixing effect between the tip leakage flow and main flow, and thus reduced the flow losses;On the other hand, the extra losses upstream the rotor leading edge were produced due to the shear effect and to the heat transfer. The aforementioned shear effect was caused by the different velocity magnitudes and directions, and the heat transfer was caused by temperature gradient between the injected flow and the incoming flow. For case with smooth casing(SC), 61.61% of the overall loss arose from tip leakage flow and casing boundary layer. When the ASCT was applied, that decreased to 55.34%. The loss generated by tip leakage flow and casing boundary layer decreased 20.54% relatively by ASCT.ZHANG Qianfeng DU Juan LI Zhihui LI Jichao ZHANG Hongwu 2019Journal of Thermal Science2019,28,5:5
5Experimental study ofcasing wear under impact-sliding conditions显示文摘Theoretical analysis and field monitoring show that lateral vibration has very important effect on casing wear in deep & ultra-deep well drilling.The wear mechanism ofcasing under impact-sliding work conditions has been investigated and many experiments have been completed with a newly developed full-scale casing wear test machine.Test results present that adhesion wear,contact fatigue,and grinding abrasion are the main wear mechanisms under impact-sliding test conditions.The friction coefficient and linear wear rate ofthe casing rise obviously with an increase in impact load.And the larger the impact load,the rougher the worn surface ofthe casing.The linear wear rate decreased slightly but the average friction coefficient increased slightly with an increase in impact frequency under an impact load of2,500 N.Both the linear wear rate ofthe casing and the average friction coefficient increased substantially with an increase in impact frequency under an impact load of4,000 N.Under lower impact load conditions,grinding abrasion and contact fatigue are the main mechanisms ofcasing wear;under higher impact load conditions,adhesion wear and contact fatigue are the main mechanisms ofcasing wear.Shengli Chu Laibin Zhang Jianchun Fan Wenpei Zheng Huiyuan Yu 2009Petroleum Science2009,6,4:3
6Analysis on Collapse Strength of Casing Wear显示文摘Carrying capacity of the casing will reduce after the casing is worn, which seriously affects the subsequent well drilling, well completion, oil extraction and well repair. A lot of researches on calculation of casing wear collapse strength have been done, but few of them focus on collapsing failure mechanism, and influencing factors and law of collapse strength. So, significant difference between estimated value and actual value of collapse strength comes into being. By theoretical analysis, numerical simulation and actual test, the collapsing failure mechanism of casing wear as well as the influencing factors and laws of collapse strength are investigated, and the investigation results show that collapse of crescent casing wear belongs to 'three hinged' instability. The severely-worn position on the casing is yielded into the plastic zone first then deformed greatly, which causes the plastic instability of the whole structure. The casing wear collapse strength presents changes of exponent, power function and linear trend with the residual casing wall thickness, wear radius and axial load, respectively. When the flexibility is less than 10°/30 m, the borehole bending has less impact on casing collapse strength. Thus, the computation model for the casing wear collapsing strength is established by introducing wear radius coefficient and casing equivalent yield strength, at the same time, the model is tested. The test results show that the relative error for the computation model is less than 5%. The research results provide a basis for design of the casing string strength and evaluation of down-hole safety.LIANG Erguo LI Zifeng HAN Yong LI Guoqin GUO Peipei 2013Chinese Journal of Mechanical Engineering2013,26,3:3
7Comparative study on bearing mechanism and design parameters of confined concrete arch joints in deep soft rock roadway显示文摘Square confined concrete arch is increasingly used in deep soft rock roadway support because of its advantages of high strength and construction convenience.However,the design of confined concrete arch in underground engineering still remains in experience-based method and lacks quantitative analysis.As a connecting component between arch sections,the connection joints have an important influence on the internal force distribution and failure mechanism of support arch.Therefore,a reasonable design of arch joints is the premise of rational support design.Taking Liangjia Coal Mine,a typical deep soft rock mine in China,as research background,this paper fully compared the most widely used joint types of confined concrete arch as analytical objects:flange joints and casing joints.The main failure modes of these two kinds of joints under bending moment are defined.Laboratory and numerical tests are carried out to study the mechanical characteristics of joints.Based on the M-θ curve,the influence law of different design parameters is analyzed,and the design principles of joints are proposed.The research results could provide a theoretical basis for the design and application of confined concrete arch in related projects.Wei Lu Qi Wang Bei Jiang Shuo Xu Bohong Liu Peng Zhang Zhenhua Jiang 2019International Journal of Coal Science & Technology2019,6,4:3
8Experimental investigation of Daqing Oilfield mudstone's creep characteristic under different water contents显示文摘In order to analyze mechanism of casing damage,the uniaxial compression experiment and creep experiment of interbedded mudstone samples from Sanan development area of Daqing Oilfield under different water contents were carried out.The changes of the mudstone's mechanical parameters and creep characteristics with the increment of water saturation were studied.The results indicate that the rock strength and elastic modulus decrease rapidly with the increment of water content,at the same time,the creep strain and creep strain rate of steady state increase with the increment of water content,and also the steady state creep strain rate is enhanced with the increment of deviatoric stress.Through the creep characteristic curves,a non-linear creep constitutive equation of mudstone considering the change of water contents is established,which will be used in future numerical analysis.黄小兰 刘建军 杨春和 陈剑文 2008Journal of Central South University2008,15,S1:3
9The fragmentation of D-shaped casing filled with explosive under eccentric initiation显示文摘With the technical development of new warhead designs and improvised explosive device protection,irregular casing filled with explosive has been paid more attention recently. In this paper, we studied the fragmentation of a type of D-shaped casing, which is a common asymmetric casing in the field of warhead design. Based on the radiograph technique, static explosive experiments were conducted with D-shaped casings under four different eccentric initiation ratios to explore their fragmentation. A numerical model was then established to simulate the dynamic response of D-shaped casing filled with explosive. The results of numerical simulation were found to agree well with the experimental data.According to the results of numerical simulation and experimental data, the dynamic responses of Dshaped casing were analyzed. The results of the current work pave way for the innovative design of new warhead and for further studying the dynamic response of asymmetric casing.Zhi-wei Guo Guang-yan Huang Wei Zhu Shun-shan Feng 2018Defence Technology(防务技术)2018,14,5:2
10A NEW TECHNIQUE—ELECTROMAGNETIC CENTRIFUGAL CASTING PROCESS显示文摘A new technique of centrifugal casting under electromagnetic field was firstly proposedand investigated.Taking a heat resisting alloy steel 25Cr20Ni and an Al-Cu alloyas examples,products,though their length,diameter and wall thickness are varied,re-vealed so superior macrostructures that the mechanical properties are much improved incomparison with conventional centrifugal casting.GE Yunlong YANG Yuansheng JIAO Yuning HU Zhuangqi Institute of Metal Research,Academia Sinica,Shenyang,ChinaGAO Yunyan JIA Guanglin Northeast University of Technology,Shenyang,China associate professor,Institute of Low Energy Nuclear Physics,Beijing Normal University,Beijing,100875,China 1993Acta Metallurgica Sinica(English Letters)1993,6,11:2
11Application of Stall Warning Approach with Stall Precursor-Suppressed Casing Treatment on a Two-Stage Compressor显示文摘A stall warning approach based on aero-acoustic theory is studied in this paper. For this stall warning approach, a parameter Rc is defined to measure the periodicity of the blade-passing signal. Signal simulation is used to investigate the mechanism of the stall warning approach. The results suggest that the value of Rc is influenced by the power of the perturbations. The experiments on a two-stage compressor indicate this stall warning approach can generate a warning signal several seconds before the stall. It is demonstrated in this paper that the stall warning approach can detect the distribution and evolution of stall precursors. According to the distribution of the stall precursors, the partial stall precursor-suppressed casing treatment is applied and realized a stabilization of compressor.XU Ruize SUN Dakun DONG Xu LI Fanyu SUN Xiaofeng LI Jia 2019Journal of Thermal Science2019,28,5:2
12Influence of longwall mining on the stability of gas wells in chain pillars显示文摘Longwall mining has a significant influence on gas wells located within longwall chain pillars.Subsurface subsidence and abutment pressure induced by longwall mining can cause excessive stresses and deformations in gas well casings.If the gas well casings are compromised or ruptured,natural gas could migrate into the mine workings,potentially causing a fire or explosion.By the current safety regulations,the gas wells in the chain pillars have to be either plugged or protected by adequate coal pillars.The current regulations for gas well pillar design are based on the 1957 Pennsylvania gas well pillar study.The study provided guidelines for gas well pillars by considering their support area and overburden depth as well as the location of the gas wells within the pillars.As the guidelines were developed for room-andpillar mining under shallow cover,they are no longer applicable to modern longwall coal mining,particularly,under deep cover.Gas well casing of failures have occurred even though the chain pillars for the gas wells met the requirements by the 1957 study.This study,conducted by the National Institute for Occupational Safety and Health(NIOSH),presents seven cases of conventional gas wells penetrating through longwall chain pillars in the Pittsburgh Coal Seam.The study results indicate that overburden depth and pillar size are not the only determining factors for gas well stability.The other important factors include subsurface ground movement,overburden geology,weak floor,as well as the type of the construction of gas wells.Numerical modeling was used to model abutment pressure,subsurface deformations,and the response of gas well casings.The study demonstrated that numerical models are able to predict with reasonable accuracy the subsurface deformations in the overburden above,within,and below the chain pillars,and the potential location and modes of gas well failures,thereby providing a more quantifiable approach to assess the stability of the gas wells in longwall chain pillars.Peter Zhang Heather Dougherty Daniel Su Jack Trackemas Berk Tulu 2020International Journal of Mining Science and Technology2020,30,1:2
13Effects of longwall-induced stress and deformation on the stability and mechanical integrity of shale gas wells drilled through a longwall abutment pillar显示文摘This paper presents the results of a comprehensive study conducted by CONSOL Energy, Marcellus Shale Coalition, and Pennsylvania Coal Association to evaluate the effects of longwall-induced subsurface deformations on the mechanical integrity of shale gas wells drilled over a longwall abutment pillar.The primary objective is to demonstrate that a properly constructed gas well in a standard longwall abutment pillar can maintain mechanical integrity during and after mining operations. A study site was selected over a southwestern Pennsylvania coal mine, which extracts 457-m-wide longwall faces under about 183 m of cover. Four test wells and four monitoring wells were drilled and installed over a 38-m by84-m centers abutment pillar. In addition to the test wells and monitoring wells, surface subsidence measurements and underground coal pillar pressure measurements were conducted as the 457-m-wide longwall panels on the south and north sides of the abutment pillar were mined by. To evaluate the resulting coal protection casing profile and lateral displacement, three separate 60-arm caliper surveys were conducted. This research represents a very important step and initiative to utilize the knowledge and science obtained from mining research to improve miner and public safety as well as the safety and health of the oil and gas industries.Daniel W.H.Su 2017International Journal of Mining Science and Technology2017,27,1:1
14Effect of longwall-induced subsurface deformations on shale gas well casing stability under deep covers显示文摘This paper presents the results of a 2017 study conducted by the National Institute for Occupational Safety and Health(NIOSH), Pittsburgh Mining Research Division(PMRD), to evaluate the effects of longwall-induced subsurface deformations within a longwall abutment pillar under deep cover. The 2017 study was conducted in a southwestern Pennsylvania coal mine, which extracts 457 m-wide longwall panels under 361 m of cover. One 198 m-deep, in-place inclinometer monitoring well was drilled and installed over a 45 m by 84 m center abutment pillar. In addition to the monitoring well, surface subsidence measurements and underground coal pillar pressure measurements were conducted as the 457 m-wide longwall panel on the south side of the abutment pillar was being mined. Prior to the first longwall excavation, a number of simulations using FLAC3D^(TM) were conducted to estimate surface subsidence, increases in underground coal pillar pressure, and subsurface horizontal displacements in the monitoring well. Comparisons of the pre-mining FLAC3D simulation results and the surface, subsurface,and underground instrumentation results show that the measured in-place inclinometer casing deformations are in reasonable agreement with those predicted by the 3D finite difference models. The measured surface subsidence and pillar pressure are in excellent agreement with those predicted by the 3D models.Results from this 2017 research clearly indicate that, under deep cover, the measured horizontal displacements within the abutment pillar are approximately one order of magnitude smaller than those measured in a 2014 study under medium cover.Daniel W.H.Su Peter Zhang Mark Van Dyke Todd Minoski 2019International Journal of Mining Science and Technology2019,29,1:1
15Study on forward modeling of through-casing resistivity logging显示文摘Through-casing resistivity logging (TCRL) is a new kind of logging method for formation evaluation,reservoir monitoring and saturation changes tracking. In this paper,the basic principle of TCRL is de-tailed,and the modified transmission line equation method (MTLEM) is first proposed in China. The MTLEM has been employed to simulate the responses of TCRL,on the basis of which,the effects of formation resistivity,cement and casing on the responses of TCRL are analyzed,and the signals in-duced in different formations are also calculated,which can help the design of TCRL tool and data processing and interpretation in China.GAO Jie1,LIU FuPing2,BAO DeZhou3,CHENG Xi3 & ZHANG YuLing4 1 China University of Petroleum,Beijing 102249,China 2 Beijing Institute of Graphic Communication,Beijing 102600,China 3 China Petroleum Logging CO. LTD.,Xi’an 710021,China 4 China National Logging Corporation,Beijing 100101,China 2008Science China Earth Sciences2008,51,S2:1
16Study on the Effects of Flow in the Volute Casing on the Performance of a Sirocco Fan显示文摘The flow at the exit from the runner blade of a centrifugal fan with forward curved blades (a sirocco fan) sometimes separates and becomes unstable. We have conducted many researches on the impeller shape of a sirocco fan, proper inlet and exit blade angles were considered to obtain optimum performance. In this paper, the casing shape were decided by changing the circumferential angle, magnifying angle and the width, 21 sorts of casings were used. Performance tests, inner flow velocity and pressure distributions were measured as well. Computational fluid dynamic calculations were also made and compared with the experimental results. Finally, the most suitable casing shape for best performance is considered.Tsutomu ADACHI Naohiro SUGITA Satoshi OHOMORI 2004Journal of Thermal Science2004,13,3:1
17Deep Drilling Technology of China显示文摘DeepDrillingTechnologyofChinaNiRongfu(DrillingBureau,CNPC)Keywords:Drillingtechnology,Deepwell,Engineeringdesign,Casingprogra...Ni Rongfu(Drilling Bureau, CNPC) 1995China Oil & Gas1995,2,1:0
18Design and research of gas-tight wedge dovetail tapered thread joint显示文摘Dovetail thread has a unique structure and characteristics. This paper describes different dovetail threads,and provides detailed descriptions of structure,performance characteristics,and processing and measurement methods of a wedge dovetail tapered thread,which is used in OCTG joints. A full-engagement wedge dovetail tapered thread joint that is highly gas-tight was designed and subjected to finite element method analysis,and the results show an even stress distribution in the joint. To verify the actual performance of these joints,the highest IV tubing test standard,ISO 13679: 2002 CAL,was used in a make-up/break-out test and combined loading test. No galling or gas leakage occurred in these tests,which confirms that the structure of the designed joint demonstrates reasonable and excellent performance.ZHAN Xianjue WANG Li 2019Baosteel Technical Research2019,13,1:0
19Horizontal aquifer movement induced by groundwater pumping and its applications to the analysis of some geological disasters显示文摘HorizontalaquifermovementinducedbygroundwaterpumpinganditsapplicationstotheanalysisofsomegeologicaldisastersQING-LIANGWANG(王...王庆良 王文萍 梁伟锋 刘练 1997Acta Seismologica Sinica(English Edition)1997,10,4:0
20基于数据挖掘和元模型的离心压缩机机匣多目标优化(英文)显示文摘Casing treatment(CT) has the potential to extend the stable operating range of a centrifugal compressor.A multi-objective optimization method is proposed to optimize the CT of centrifugal compressors. The method consists of Kriging metamodel, Genetic Algorithm(GA), data-mining techniques and CFD code. Firstly, data-mining techniques are used to analyze the initial design space. The correlations between design variables and objectives are extracted,resulting in a refined design space. Then, the global optimization of CT is conducted by GA based on data-mining results. After optimization, the performance of the centrifugal compressor shows a considerable improvement over the whole speed line. The isentropic efficiency increases by 2.05%, and the stall margin improves by 7.11%. Finally, the mechanism behind the performance improvement is further clarified by detailed flow analysis.李孝检 刘正先 左盼 2018风机技术2018,60,6:0
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