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numerical analysis OF THE INFLUENCE OF THE TIP CLEARANCE FLOWS ON THE UNSTEADY CAVITATING FLOWS IN A THREE- D IMENSIONAL INDUCER

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Journal of Hydrodynamics 2009年第1期21卷 34-40页

作者： OKITA K. UGAJIN H. MATSUMOTO Y. RIKEN Saitama 351-0198 Japan IHI Corporation Yokohama 235-8501 Japan Department of Mechanical Engineering The University of TokyoTokyo 113-8656 Japan

To clarify the influences of the tip clearance flows on the unsteady cavitating flow, the three-dimensional unsteady cavitating flows through both the two-dimensional cascades and the three-dimensional inducer with and without tip clearance are performed numerically. The governing equations for the compressible fluid flow with the DES turbulence model are employed with the assumption of the isentropic process of liquid phase. The evolution of cavities is represented as the source/sink of vapor phase. The basic equations in the curve linear coordinate are solved by the finite difference method. As the results of the three-dimensional cavitating flows through the two-dimensional cascades, the tip clearance flows from the pressure side to the suction side of the blade produces the tip vortex cavitation, which affects the sheet cavitation on the leading edge of the next blade and enhances the blockage effect near the casing than the flows without tip clearance. On the other hand, in the case of the three-dimensional inducer, the large backflow cavitation is observed around the inlet of the inducer, where the cavities are developed on the casing by the tip clearance flows. The large pressure gradient between the non-cavitating pressure side and the cavitating suction side enhances the tip clearance flows. The calculation considering the tip clearance reproduces the developed cavitation region similar to that of experimental visualizations. Additionally, the backflow cavitation rotates with the speed slower than the rotation speed of the inducer. Then, the rotation of backflow cavitation causes the periodic fluctuation of the outlet pressure greater than that of the inlet pressure.

关键词： cavitation inducer tip clearance flow numerical analysis

numerical analysis and experimental validation of surface roughness and morphology in honing of Inconel 718 nickel-based superalloy

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Advances in Manufacturing 2023年第1期11卷 130-142页

作者： Chang-Yong Yang Zhi Wang Hao Su Yu-Can Fu Nian-Hui Zhang Wen-Feng Ding Jiangsu Key Laboratory of Precision and Micro-Manufacturing Technology Nanjing University of Aeronautics and AstronauticsNanjing210016People’s Republic of China College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and AstronauticsNanjing210016People’s Republic of China

Honing is an important technology for machining onboard system *** parts are usually made of difficult-to-machining materials,e.g.,Inconel 718 *** can improve the finishing accuracy and surface ***,the selection of the honing parameters was primarily based on the results of a large number of ***,the establishment of a reliable model is needed to predict the honed surface roughness and morphology,and offers a theoretical direction for the choice of *** the present study,a numerical simulation model was constructed for analysis of the honing process by *** oilstone,workpiece surface morphology and motion trajectory were discretized by Python,and the machined surface was obtained by trajectory ***,based on the statistical analysis of the surface topography of oilstone,the shape of grains was simplified and the surface topography of oilstone was built ***,the initial surface morphology of the workpiece was constructed and the trajectory of grains on the workpiece surface was analyzed,which showed the distribution of the removed ***,the plastic deformation of material was analyzed in the simulation *** critical depth of three stages of contact between grains and workpiece was calculated by the theoretical formula:scratching,ploughing and *** analyzing the distribution of bulge,the plastic deformation in ploughing and cutting stage was ***,the simulated results of honed surface roughness and morphology were validated and agreed reasonably well with the honing ***,the effects of honing process parameters,including grain size,tangential speed,axial speed,radial speed and abrasive volume percentage,on the surface roughness of the workpiece were analyzed by the simulation model.

关键词： numerical analysis Surface roughness Plastic deformation Morphology

numerical analysis and field monitoring tests on shallow tunnels under weak surrounding rock

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维普期刊数据库

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Journal of Central South University 2015年第10期22卷 4056-4063页

作者：刘建华刘晓明张永杰肖庭 School of Traffic and Transportation Engineering Changsha University of Science and Technology College of Civil Engineering Hunan University School of Civil Engineering and Architecture Changsha University of Science and Technology

The Jianpudong No. 4 tunnel is a shallow tunnel, which belongs to Shaoshan County scenic highway in Hunan province, China and whose surrounding rock is weak. According to its characteristics, the field monitoring tests and numerical analysis were done. The mechanical characteristics of shallow tunnels under weak surrounding rock and the stress-strain rule of surrounding rock and support were analyzed. The numerical analysis results show that the settlement caused by upper bench excavating accounts for 44% of the total settlement, and the settlement caused by tunnel upper bench supporting accounts for 56% of the total settlement. The maximum axial force of shotcrete lining is 177.2 k N, which locates in hance under the secondary lining. The maximum moment of shotcrete lining is 5.08 k N·m, which locates in the arch foot. The stress curve of steel arch has three obvious stages during the tunnel construction. The maximum axial force of steel arch is 297.4 k N, which locates in tunnel vault. The axial forces of steel arch are respectively 23.5 k N and-21.8 k N, which is influenced by eccentric compression of shallow tunnel and locates in hance. The results show that there is larger earth pressure in tunnel vault which is most unfavorable position of steel arch. Therefore, the advance support should be strengthened in tunnel vault during construction process.

关键词： tunnel engineering shallow tunnel weak surrounding rock numerical analysis field monitoring tests

numerical analysis of a Spiral-groove Dry-gas Seal Considering Micro-scale Effects

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Chinese Journal of Mechanical Engineering 2011年第1期24卷 146-153页

作者： WANG Bing ZHANG Huiqiang School of Aerospace Tsinghua University Beijing 100064 China Beijing 3E Enemy Key Laboratory Tsinghua University Beijing 100084 China

A dry-gas seal system is a non-contact seal technology that is widely used in different industrial ***-groove dry-gas seal utilizes fluid dynamic pressure effects to realize the seal and lubrication processes,while forming a high pressure gas film between two sealing faces due to the deceleration of the gas pumped in or *** is little research into the effects and the influence on seal performance,if the grooves and the gas film are at the *** paper investigates the micro-scale effects on spiral-groove dry-gas seal performance in a numerical solution of a corrected Reynolds *** Reynolds equation is discretized by means of the finite difference method with the second order scheme and solved by the successive-over-relaxation（SOR） iterative *** Knudsen number of the flow in the sealing gas film is changed from 0.005 to 0.120 with a variation of film depth and sealing *** numerical results show that the average pressure in the gas film and the sealed gas leakage increase due to micro-scale *** open force is enlarged,while the gas film stiffness is significantly decreased due to micro-scale *** friction torque and power consumption remain constant,even in low sealing pressure and spin speed *** this paper,the seal performance at different rotor face spin speeds is also *** proposed research clarifies the micro-scale effects in a spiral-groove dry-gas seal and their influence on seal performance,which is expected to be useful for the improvement of the design of dry-gas seal systems operating in the slip flow regime.

关键词： micro-scale effect spiral-groove dry-gas seal numerical analysis Reynolds equation

numerical analysis of Deteriorated Sub-sea Pipelines under Environmental Loads

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Chinese Journal of Mechanical Engineering 2015年第6期28卷 1163-1170页

作者： GüCüYEN Engin Department of Civil Engineering Faculty of Engineering Celal Bayar University

The significant point is the bidirectional interaction technique in FSI analysis while investigating subsea corrosion effect. By this way, pipe environment is accurately modelled and fluid effects are also considered. The effect of external corrosion defects on structural behaviour of a pipeline is studied by creating a nonlinear numerical model based on the finite element method according to ABAQUS analysis program. Corrosion losses of sections are obtained from experimental results and applied to the model. numerical model is formed by a span of sub-sea pipeline that is subjected to environmental loads. Seismic and wind-generated irregular wave loads are considered as environmental loads. Irregular wave is represented with equivalent eight regular waves via FFT. The pipe is modelled according to two different types which are non-corroded（intact） and corroded（deteriorated） to demonstrate corrosion effects on it. The visible type of corrosion in marine environment is named ‘pitting＇ corrosion, in which the material loss is locally interpenetrated over the surface. By considering this situation, the corroded and non-corroded pipes are modelled as 3D solid elements. The main point is revealing how the subsea corrosion affects the structural behaviour of pipelines on the basis of implementation of experimental results to a model structure due to changes of stresses and displacement.

关键词： offshore pipelines environmental loads corrosion numerical analysis

numerical analysis on Neutron Shielding Structure of ITER Vacuum Vessel

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Plasma Science and Technology 2008年第3期10卷 373-378页

作者：刘常乐武松涛郁杰盛道林 Institute of Plasma Physics Chinese Academy of Sciences Hefei 230031 China

The neutron shielding component of ITER （International Thermonuclear Experimental Reactor） vacuum vessel is a kind of structure resembling a wall in appearance. A FE （finite element） model is set up by using ANSYS code in terms of its structural features. Static analysis, thermal expansion analysis and dynamic analysis are performed. The static results show that the stress and displacement distribution are allowable, but the high stress appears in the junction between the upper and lower parts. The modal analysis indicates that the biggest deformation exists in the port area. Through modal superposition, the single-point response has been found with the lower rank frequency of the acceleration seismic response spectrum. But the deformation and the stress values are within the permissible limit. The analysis results would benefit the work in the next step and provide some reference for the implementation of the engineering plan in the future.

关键词： ITER vacuum vessel neutron shielding structure numerical analysis finite element method

numerical analysis of the self-heating effect in SGOI with a double step buried oxide

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Journal of Semiconductors 2011年第3期32卷 42-48页

作者：李斌刘红侠李劲袁博曹磊 Key Laboratory for Wide Band Gap Semiconductor Materials and Devices of Education School of MicroelectronicsXidian University

To reduce the self-heating effect of strained Si grown on relaxed SiGe-on-insulator（SGOI） n-type metal-oxide-semiconductor field-effect transistors（nMOSFETs）,this paper proposes a novel device called double step buried oxide（BOX） SGOI,investigates its electrical and thermal characteristics,and analyzes the effect of self-heating on its electrical *** the simulation of the device,a low field mobility model for strained Si MOSFETs is established and reduced thermal conductivity resulting from phonon boundary scattering is considered.A comparative study of SGOI nMOSFETs with different BOX thicknesses under channel and different channel strains has been *** reducing moderately the BOX thickness under the channel,the channel temperature caused by the self-heating effect can be effectively ***,mobility degradation,off state current and a short-channel effect such as drain induced barrier lowering can be well ***,SGOI MOSFETs with a thinner BOX under the channel can improve the overall performance and long-term reliability efficiently.

关键词： self-heating effect step BOX SGOI mobility model numerical analysis

numerical analysis of solid–liquid interface shape during largesize single crystalline silicon with Czochralski method

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Rare Metals 2017年第4期36卷 289-294页

作者： Ran Teng Qing Chang Yang Li Bin Cui Qing-Hua Xiao Guo-Hu Zhang National Engineering Research Center for Semiconductor Materials Beijing 100088 China General Research Institute for Nonferrous Metals Semiconductor Materials Co. Ltd Beijing 100088 China

numerical analysis is an effective tool to research the industrial Czochralski （CZ） crystal growth aiming to improve crystal quality and reduce manufactur- ing costs. In this study, a set of global simulations were carried out to investigate the effect of crystal-crucible rotation and pulling rate on melt convection and solid- liquid （SL） interface shape. Through analyses of the sim- ulation data, it is found that the interface deformation and inherent stress increase during the crystal growth process. The interface deflection increases from 7.4 to 51.3 mm with an increase in crystal size from 150 to 400 mm. In addition, the SL interface shape and flow pattern are sen- sitive to pulling rate and rotation rate. Reducing pulling rate can flat SL interface shape and add energy-consuming. Interface with low deflection can be achieved by adopting certain combination of crystal and crucible rotation rates. The effect of crystal rotation on SL interface shape is less significant at higher crucible rotation rates.

关键词： Czochralski method numerical analysis Pullrate Crucible rotation Crystal rotation Solid/liquidinterface shape

numerical analysis of matrix swelling and its effect on microstructure of digital coal and its associated permeability during CO_(2)-ECBM process based on X-ray CT data

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Petroleum Science 2023年第1期20卷 87-101页

作者： Hui-Huang Fang Zhang-Fei Wang Shu-Xun Sang Yan-Hui Huang School of Earth and Environment Anhui University of Science and TechnologyHuainanAnhui232001China Institute of Energy Hefei Comprehensive National Science CenterHefeiAnhui230000China Low Carbon Energy Institute China University of Mining and TechnologyXuzhouJiangsu221008China School of Resources and Geosciences China University of Mining and TechnologyXuzhouJiangsu221116China Jiangsu Key Laboratory of Coal-based Greenhouse Gas Control and Utilization China University of Mining and TechnologyXuzhouJiangsu221008China State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China

Matrix swelling effect will cause the change of microstructure of coal reservoir and its permeability,which is the key factor affecting the engineering effect of CO_(2)-ECBM *** Sihe and Yuwu collieries are taken as research ***,visualization reconstruction of coal reservoir is ***,the evolution of the pore/fracture structures under different swelling contents is ***,the influence of matrix phase with different swelling contents on permeability is ***,the mechanism of swelling effect during the CO_(2)-ECBM process is further *** results show that the intra-matrix pores and matrix-edge fractures are the focus of this study,and the contacting area between matrix and pore/fracture is the core area of matrix *** number of matrix particles decreases with the increase of size,and the distribution of which is isolated with small size and interconnected with large *** swelling effect of matrix particles with larger size has a great influence on the pore/fracture *** number of connected pores/fractures is limited and only interconnected in a certain *** the increase of matrix swelling content,the number,porosity,width,fractal dimension,surface area and volume of pores/fractures decrease,and their negative contribution to absolute permeability increases from 0.368% to 0.633% and 0.868%-1.404%,*** the increase of swelling content,the number of intra-matrix pores gradually decreases and the pore radius becomes shorter during the CO_(2)-ECBM *** matrix continuously expands to the connected fractures,and the width of connected fractures gradually *** the influence of matrix swelling,the bending degree of fluid flow increases gradually,so the resistance of fluid migration increases and the permeability gradually *** study shows that the matrix swelling effect is the key factor affecting CBM recovery,and the application of this effec

关键词： Matrix swelling CO_(2)-ECBM Absolutely permeability numerical analysis X-ray CT Qinshui Basin