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超高速充液旋压时轴向拉力和断管分析 被引量:4
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作者 汤勇 王莉 +3 位作者 周德明 张娟 王威 夏伟 《华南理工大学学报(自然科学版)》 EI CAS CSCD 北大核心 2001年第4期13-16,共4页
系统分析了超高速充液旋压内螺旋翅片过程中轴向拉力和断管倾向 .改善入口模区和旋压区管内 (外 )润滑条件 ,优化入口模和挡头结构 ,精确控制旋压量大小是减少轴向拉力及其断管倾向的主要措施 .旋压量增大时轴向拉力增大 ,当旋压量超过... 系统分析了超高速充液旋压内螺旋翅片过程中轴向拉力和断管倾向 .改善入口模区和旋压区管内 (外 )润滑条件 ,优化入口模和挡头结构 ,精确控制旋压量大小是减少轴向拉力及其断管倾向的主要措施 .旋压量增大时轴向拉力增大 ,当旋压量超过临界值时轴向拉力随旋压量增加而急剧增大 .入口模锥角对轴向拉力的影响十分明显 ,在入口模锥角13°时 ,轴向拉力最小 ,随着入口模锥角的增大或减少 ,轴向拉力均会增大 . 展开更多
关键词 充液旋压 超高速 内螺旋翅片铜管 轴向拉力 断管倾向 旋压量 旋压挤压
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GENERALIZED ENERGY CONSERVATION AND UNSTABLE PERTURBATION PROPERTY IN BAROTROPIC VORTEX
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作者 黄泓 张铭 《Journal of Tropical Meteorology》 SCIE 2006年第1期55-58,共4页
Based on a barotropic vortex model, generalized energy-conserving equation was derived and twonecessary conditions of basic flow destabilization are gained. These conditions correspond to generalizedbarotropic instabi... Based on a barotropic vortex model, generalized energy-conserving equation was derived and twonecessary conditions of basic flow destabilization are gained. These conditions correspond to generalizedbarotropic instability and super speed instability. They are instabilities of vortex and gravity inertial waverespectively. In order to relate to practical situation, a barotropic vortex was analyzed, the basic flow of which issimilar to lower level basic wind field of tropical cyclones and the maximum wind radius of which is 500 km.The results show that generalized barotropic instability depending upon the radial gradient of relative vorticitycan appear in this vortex. It can be concluded that unstable vortex Rossby wave may appear in barotropic vortex. 展开更多
关键词 INSTABILITY barotropic vortex Spiral bands generalized energy conservation vortex Rossby wave
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COMPARISON OF ON-LINE COUPLED AND CONSTANT TRANSFER SIMULATION METHODS FOR DIRECT RADIATIVE FORCING OF ANTHROPOGENIC SULFATE
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作者 吴涧 刘红年 +1 位作者 王卫国 刘罡 《Journal of Tropical Meteorology》 SCIE 2006年第1期87-88,共2页
1 INTRODUCTION Of three main methods for studying the radiative forcing of anthropogenic sulfate and climatic response on the regional scale, the first is, with given rates for transforming SO2 to sulfate, converting ... 1 INTRODUCTION Of three main methods for studying the radiative forcing of anthropogenic sulfate and climatic response on the regional scale, the first is, with given rates for transforming SO2 to sulfate, converting actually released SO2 into sulfate and acquiring the distribution of sulfate by computing transfer equations in the climate model. The second is obtaining the sulfate distribution through chemical reaction and transfer of matters in regional climate models online coupled with an atmospheric chemistry model that includes full chemical reactions for sulfides. The third is to put sulfate distribution data from GCM and its coupled atmospheric chemistry model to regional climate model, which is so called off-line coupled method. As shown in comparisons between the online and offline modeling on the regional scale, the radiative climate effect of sulfate shows large uncertainty due to significant influence from various methods. 展开更多
关键词 INSTABILITY barotropic vortex Spiral bands generalized energy conservation vortex Rossby wave
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Numerical analysis of thermal fluid transport behavior during electron beam welding of 2219 aluminum alloy plate 被引量:6
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作者 Cheng-cai LIU Jing-shan HE 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2017年第6期1319-1326,共8页
A two-dimensional mathematical model based on volume-of-fluid method is proposed to investigate the heat transfer,fluidflow and keyhole dynamics during electron beam welding(EBW)on20mm-thick2219aluminum alloy plate.In... A two-dimensional mathematical model based on volume-of-fluid method is proposed to investigate the heat transfer,fluidflow and keyhole dynamics during electron beam welding(EBW)on20mm-thick2219aluminum alloy plate.In the model,anadaptive heat source model tracking keyhole depth is employed to simulate the heating process of electron beam.Heat and masstransport of different vortexes induced by surface tension,thermo-capillary force,recoil pressure,hydrostatic pressure and thermalbuoyancy is coupled with keyhole evolution.A series of physical phenomena involving keyhole drilling,collapse,reopening,quasi-stability,backfilling and the coupled thermal field are analyzed systematically.The results indicate that the decreased heat fluxof beam in depth can decelerate the keyholing velocity of recoil pressure and promote the quasi-steady state.Before and close to thisstate,the keyhole collapses and complicates the fluid transport of vortexes.Finally,all simulation results are validated againstexperiments. 展开更多
关键词 heat transfer fluid flow keyhole dynamics electron beam welding mass transport VORTEX recoil pressure BACKFILLING
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Squeezing States of Magnons in a Ferromagnet
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作者 WANG Jun-Feng CHENG Ze 《Communications in Theoretical Physics》 SCIE CAS CSCD 2006年第4期745-748,共4页
In this paper, we conduct an investigation into magnon self-squeezing states in a ferromagnet. In these states, the quantum fluctuations of the spin components can be lower than the zero-point quantum fluctuations of ... In this paper, we conduct an investigation into magnon self-squeezing states in a ferromagnet. In these states, the quantum fluctuations of the spin components can be lower than the zero-point quantum fluctuations of the coherent states. Through calculating the expectation values of spin fluctuations we gain the condition of achieving magnon self-squeezing. We introduce the mean-field theory for dealing with the nonlinear interaction term of Hamiltonian of magnon system. 展开更多
关键词 self-squeezing state spin wave MAGNON quantum fluctuation
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High-Speed Numeral Filter in Impulse Voltage Measurement
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作者 Zheng Xiaodong Wu Weining +1 位作者 Huang Xinghan Wang Min 《Electricity》 2005年第3期37-41,共5页
Since the CPU of embed system has some limitation in operating speed, a new filter was put forward which implemented mountain template convolution by performing rectangle template convolution two times. It can obtain ... Since the CPU of embed system has some limitation in operating speed, a new filter was put forward which implemented mountain template convolution by performing rectangle template convolution two times. It can obtain time and frequency localization with computational complexity greatly reduced. This algorithm was applied to lightning waveforms (include chopped waveforms) parameter calculation. It simplifies the computation and the results pretreated by this algorithm are in accord with IEC1083-2 completely. It was applied in embed system successfully. Its capability in frequency restraining was researched. The validity of the algorithm was proved in theory when processing lightning waves. The standard sources and the processing results are consistent completely. 展开更多
关键词 CONVOLUTION numeral filter impulse wave time and frequency localization WAVELET
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Experimental Investigations of Micro Air Injection to Control Rotating Stall 被引量:6
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作者 Chaoqun Nie Zhiting Tong +2 位作者 Shaojuan Geng Junqiang Zhu Weiguang Huang 《Journal of Thermal Science》 SCIE EI CAS CSCD 2007年第1期1-6,共6页
Steady discrete micro air injection at the tip region in front of the first compressor rotor has been proved to be an effective method to delay the inception of rotating stall in a low speed axial compressor. Consider... Steady discrete micro air injection at the tip region in front of the first compressor rotor has been proved to be an effective method to delay the inception of rotating stall in a low speed axial compressor. Considering the practical application a new type of micro injector was designed and described in this paper, which was imbedded in the casing and could be moved along the chord. In order to verify its feasibility to other cases, such as high subsonic axial compressor or centrifugal compressor, some other cases have been studied. Experimental results of the same low speed axial compressor showed that the new injector could possess many other advantages besides successfully stabilizing the compressor. Experiments performed on a high subsonic axial compressor confirmed the effectiveness of micro air injection when the relative velocity at the blade tip is high subsonic. Meanwhile in order to explore its feasibility in centrifugal compressor, a similar micro injector was designed and tested on a low speed centrifugal compressor with vaned diffuser. The injected mass flow was a bit larger than that used in axial compressors and the results showed micro injection could also delay the onset of rotating stall in the centrifugal compressor. 展开更多
关键词 COMPRESSOR rotating stall air injection
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Experimental and Numerical Investigation on Compressor Cascade Flows with Tip Clearance at a Low Reynolds Number Condition 被引量:3
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作者 Hiromasa Kato Hideo Taniguchi +3 位作者 Kazunari Matsuda Ken-ichi Funazaki Dai Kato Guillaume Pallot 《Journal of Thermal Science》 SCIE EI CAS CSCD 2011年第6期481-485,共5页
High flow rate aeroengines typically employ axial flow compressors, where aerodynamic loss is predominantly due to secondary flow features such as tip leakage and comer vortices. In very high altitude missions, turbo-... High flow rate aeroengines typically employ axial flow compressors, where aerodynamic loss is predominantly due to secondary flow features such as tip leakage and comer vortices. In very high altitude missions, turbo- machinery operates at low density ambient atmosphere, and the recent trend toward more compact engine core inevitably leads to the reduction of blade size, which in turn increases the relative height of the blade tip clearance. Low Reynolds number fiowfield as a result of these two factors amplifies the relative importance of secondary flow effects. This paper focuses on the behavior of tip leakage flow, investigating by use of both experimental and numerical approaches. In order to understand the complex secondary flow behavior, cascade tests are usually conducted using intrusive probes to determine the loss. However relatively few experimental studies are pub- lished on tip leakage flows which take into account the interaction between a rotating blade row and its casing wall. Hence a new linear cascade facility has been designed with a moving belt casing in order to reproduce more realistic flowfield as encountered by a rotating compressor row. Numerical simulations were also performed to aid in the understanding of the complex flow features. The experimental results indicate a significant difference in the flowfield when the moving belt casing is present. The numerical simulations reveal that the leakage vortex is pulled by the shearing motion of the endwall toward the pressure side of the adjacent blade. The results highlight the importance of casing wall relative motion in analyzing leakage flow effects. 展开更多
关键词 COMPRESSOR tip leakage flow
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Effect of high negative incidence on the performance of a centrifugal compressor stage with conventional vaned diffusers
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作者 Ahti Jaatinen Aki Grnman +1 位作者 Teemu Turunen-Saaresti Jari Backman 《Journal of Thermal Science》 SCIE EI CAS CSCD 2011年第2期97-105,共9页
Three vaned diffusers, designed to have high negative incidence (-8°) at the design operating point, are studied experimentally. The overall performance (efficiency and pressure ratio) are measured at three rotat... Three vaned diffusers, designed to have high negative incidence (-8°) at the design operating point, are studied experimentally. The overall performance (efficiency and pressure ratio) are measured at three rotational speeds, and flow angles before and after the diffuser are measured at the design rotational speed and with three mass flow rates. The results are compared to corresponding results of the original vaneless diffuser design. Attention is paid to the performance at lower mass flows than the design mass flow. The results show that it is possible to improve the performance at mass flows lower than the design mass flow with a vaned diffuser designed with high negative incidence. However, with the vaned diffusers, the compressor still stalls at higher mass flow rates than with the vaneless one. The flow angle distributions after the diffuser are more uniform with the vaned diffusers. 展开更多
关键词 centrifugal compressor vaned diffuser efficiency PERFORMANCE flow field
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