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momentum transfer on Underwater Shock Generation Induced by Pulsed Laser Irradiation with Thin Metal

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Open Journal of Fluid Dynamics 2016年第3期6卷 166-181页

作者： Rokhsan Ara Hemel Hiroyuki Hirahara Kento Takahashi Graduate School of Science and Engineering Saitama University Saitama Japan Faculty of Engineering Saitama University Saitama Japan

The present paper has investigated the momentum transport phenomena of underwater shock wave generation in terms of photo-acoustic wave with a very thin metal. The shock wave was induced by a pulsed-laser irradiation. In order to clarify the momentum transport mechanics in this phenomenon, we have been considered the momentum and energy transport from laser to metal, and metal to water. A numerical solution of thermo-elastic wave in metal has been obtained to estimate a fundamental gain of the longitudinal wave. Then, the underwater shock wave phenomena have been analyzed by adapting compressible fluid dynamics with suitable boundary condition between the solid and liquid. We had performed an experiment as well and observed the shock wave with optical system. The aim of the research is to estimate the underwater shock wave strength theoretically. The metal region was calculated by Laplace transformation of heat conduction and wave equations. The water region was simulated by MacCormack’s method. Some of boundary conditions have been examined and the acceleration condition has been adopted at the interface. The simulated results show a good agreement with experimental result, consequently the momentum transfer mechanism from longitudinal wave to underwater shock wave has been cleared in the present report.

关键词： momentum transfer Underwater shock wave Longitudinal wave

Investigating the Effect of Relative Width on momentum transfer between Main Channel and Floodplain in Rough Rectangular Compound Channel Sunder Varius Relative Depth Condition

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Open Journal of Geology 2016年第4期6卷 225-231页

作者： Shima Bahadori Mehdi Behdarvandi Askar Master’s Student Department of Offshore Structures Faculty of Marine EngineeringKhorramshahr University of Marine Science and Technology Khorramshahr Iran Assistant Professor Department of Offshore Structures Faculty of Marine EngineeringKhorramshahr University of Marine Science and Technology Khorramshahr Iran

Compound section is referred to a section the surface of which is made of several sub-sections with different flow characteristics. The difference in the hydraulic and geometry characteristics causes a complexity in flow hydraulic and creates an interaction between the main channel and floodplains, resulting in an apparent shear stress and a transverse momentum transfer. The amount of such a stress plays an important role in many river engineering measures [1]. Due to the flow complexity, the common approximate analytical methods are not enough to identify the flow profile. The FLOW3D Software with its great features in three-dimensional analysis of flow field is used as a tool to investigate the shear stress in a direct symmetrical compound rectangular channel. After the simulation of models, it is found that an increase in the relative width and relative depth parameters decreases the percentage of apparent shear stress and an increase in the relative roughness causes it to be increased [2].

关键词： Compound Channel momentum transfer Relative Roughness Relative Depth Relative Width

NUMERICAL SIMULATION OF HEAT,MASS AND momentum transferS IN METALLIC INGOTS AND PREDICTION OF MACROSEGREGATION

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Acta Metallurgica Sinica(English Letters) 1991年第7期4卷 37-41页

A continuum model and numerical methods were established for description of heat,mass and momentum transfers as well as macrosegregation formations in metallic *** simulation of temperature,composition and liquid flow fields during the solidification of an Al-4.5% Cu ingot were performed on an IBM personal *** model and numerical methods were verified through two experiments.

关键词： numerical simulation heat transfer mass transfer momentum transfer Al-Cu alloy macrosegregation

Near minimum-time feedback attitude control with multiple saturation constraints for agile satellites

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Chinese Journal of Aeronautics 2016年第3期29卷 722-737页

作者： Liu Xiangdong Xin Xing Li Zhen Chen Zhen Sheng Yongzhi School of Automation Beijing Institute of Technology National Key Laboratory of Complex System Intelligent Control and Decision Beijing Institute of Technology

Agile satellites are of importance in modern aerospace applications, but high mobility of the satellites may cause them vulnerable to saturation during attitude maneuvers due to limited rating of actuators, This paper proposes a near minimum-time feedback control law for the agile satellite attitude control system. The feedback controller is formed by specially designed cascaded sub-units. The rapid dynamic response of the modified Bang Bang control logic achieves the near optimal property and ensures the non-saturation properties on three-axis. To improve the dynamic performance, a model reference control strategy is proposed, in which the oniline near optimal attitude maneuver path is generated by the cascade controller and is then tracked by a nonlinear back-stepping controller. Furthermore, the accuracy and the robustness of the control system are achieved by momentum-based on-line inertial identification. The rapid attitude maneuvering can be applied for tasks including the move to move case. Numerical simulations are conducted to verify the effectiveness of the proposed control strategy in terms of the saturation-free property and rapidness.

关键词： Actuator saturation Attitude control Identification momentum transfer Satellites

EVALUATION OF STAGE-DISCHARGE RELATIONSHIP IN COMPOUND CHANNELS

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Journal of Hydrodynamics 2008年第1期20卷 81-87页

作者： MOHAGHEGH A. KOUCHAKZADEH S. College of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China Central Hydraulic Research Laboratory Water Engineering Department Tehran University KarajIran

Experimental results were compared with the computed results obtained from the nine most well-known methods for computation of discharge in a compound channel. The results demonstrate a high accuracy of the divided channel method with the horizontal division lines, while the length of division line is included within the calculation of the wetted perimeter. In addition, as relative depth increases, the results of the all methods converge to each other and also in case of steeper slopes in lower relative depths, more agreements between different calculated methods and experimental results were observed. Furthermore, the results show the effects of the maximum momentum transfer on the horizontal interface between the main channel and flood plains, while further angular distance from the horizontal interface toward the vertical interface between main channel and flood plains causes gradual decrease of momentum transfer effects.

关键词： compound channel momentum transfer division line flood plain

Experimental and numerical investigation on alternatives to sandy gravel

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Defence Technology（防务技术） 2024年第1期31卷 130-141页

作者： V.Denefeld H.Aurich Fraunhofer Institute for High-Speed Dynamics Ernst-Mach-Institut(EMI)Ernst-Zermelo-Str.479104FreiburgGermany Fraunhofer Institute for High-Speed Dynamics Ernst-Mach-Institut(EMI)Am Christianswuhr 279400KandernGermany

The NATO agreement STANAG 4569 defines the protection levels for the occupants of logistic and light armored *** Allied Engineering Publication,AEP-55,Volume 2 document outlines the test conditions for underbelly improvised explosive device(IEDs),which must be buried in water-saturated sandy *** use of sandy gravel has some drawbacks,for instance reproducibility,time consumption,and *** paper focuses on the investigation of four alternatives to sandy gravel,which could produce similar specific and cumulative impulses:a concrete pot filled with water,a concrete pot filled with quartz sand,a steel pot without filling and a concrete pot filled with glass spheres(diameter 200μm—300μm)and different water *** impulses are measured with a ring technology developed at the Fraunhofer EMI.A numerical soil model based on the work of Marrs,2014 and Fi serov a,2006 and considering the soil moisture was used to simulate the experiments with glass spheres at different water contents,showing much better agreement with the experiments than the classical Laine&Sandvik model,even for high saturation *** results can be used to create new test conditions at original scale that are more cost-effective,more reproducible and simpler to manage in comparison to the current tests carried out with STANAG sandy gravel.

关键词： Improvised explosive device(IED) Specific impulse momentum transfer Sandy gravel Glass spheres Numerical model Soil moisture

Hadronic Decays of the Spin-Singlet Heavy Quarkomium under the Principle of Maximum Conformality

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Chinese Physics Letters 2014年第5期31卷 31-34页

作者：樟琼联吴兴刚郑绪昌王声权付海冰方祯云 Department of Physics Chongqing University Chongqing 401331

The principle of maximum conformality （PMC） provides a way to eliminate the conventional renormalization scale ambiguity in a systematic way. By applying the PMC scale setting, all non-conformal terms in a perturbative series are summed into the running coupling, and one obtains a unique, scale-fixed prediction at any finite order. In this study, we make a detailed PMC analysis for the spin-singlet heavy quarkoniums decay （into light hadrons） at the next-to-leading order. After applying the PMC scale setting, the decay widths for all those cases are ahnost independent of the initial renormalization scales. The PMC scales for ηc and he decays are below 1 GeV; to achieve a confidential pQCD estimation, we adopt several low-energy running coupling models to carry out the estimation. By taking the MPT model, we obtain Г（ηc → LH） = 25.09 -4.28^＋5.52 MeV, F（ηb →LH） 14.34-0.84^＋0.92 feV, Г（hc →LH） = 0.54-0.04^＋0.06 MeV and Г（hb →LH） = 39.89-0.46^＋0.28 keV, where the errors are calculated by taking mc E[1.4OGeV, 1.60GeV] and mb C[4.50GeV, 4.70GeV]. These decay widths agree with the principle of minimum sensitivity estimations, in which the decay widths of ηc,b are also consistent with the measured ones.

关键词： QUARKONIUMS PRINCIPLE of maximum hardness CHARMONIUM momentum transfer FACTORIZATION (Mathematics)

Effects of impingement and friction of swirling air stream on prefilming airblast atomization of non-Newtonian fluids

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Journal of Harbin Institute of Technology(New Series) 2007年第1期14卷 119-123页

作者：贺文智李光明姜兆华索全伶 School of Environmental Science and Engineering Tongji University Dept.of Applied Chemistry Harbin Institute of Technology Chemical Engineering School Inner Mongolia Polytechnic University

Liquids to be broken up using a prefilming airblast atomizer are usually Newton liquids with relatively low *** in some industrial processes,such as spray drying,liquids to be atomized are high concentration suspensions or non-Newtonian fluids with high *** this paper,non-Newtonian fluids with viscosity up to 4.4 Pa·s were effectively atomized using a specially designed prefilming airblast *** atomizer enabled liquid to extend to a thickness-adjustable film and forced the atomizing air stream to swirl with 30° or 45° through gas distributors with spiral *** liquid film was impinged by the swirling air stream resulting in the disintegration of the film into *** sizes were measured using a laser diffraction *** improved four-parameter mathematical model was established to relate the Sauter mean diameter of drops to the atomization conditions in terms of power dependencies on three dimensionless groups:Weber number,Ohnesorge number and air liquid mass *** friction on the surface of the liquid film made by swirling air stream played an important role in the prefilming atomization at the conditions of low air velocity and low liquid *** this case,the liquid film was disintegrated into drops according to the classical wavy-sheet mechanism,thus thinner liquid films and high swirl levels of the atomizing air produced smaller *** the increase of the air velocity and the liquid viscosity,the effect of the friction on the prefilming atomization relatively weakened,whereas the impingement on the liquid film made by atomizing air stream in a direction normal to the liquid film and corresponding momentum transfer gradually strengthened and eventually dominated the disruption of liquid into drops,which induced that the initial thickness of the liquid film and the swirl of atomizing air stream exercised a minor influence on the drop sizes.

关键词： atomization prefilming atomizer non-newtonian fluids impingement friction momentum transfer

transfer and Reaction Performances of Selective Catalytic Reduction of NzO with CO over Monolith Catalysts

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Chinese Journal of Chemical Engineering 2013年第8期21卷 835-843页

作者：代成娜雷志刚王玉丽张润铎陈标华 State Key Laboratory of Chemical Resource Engineering Beijing University of Chemical Technology

This work tries to identify the relationship between geometric configuration of monolith catalysts, and transfer and reaction performances for selective catalytic reduction of N2O with CO. Monolith catalysts with five different channel shapes (circle, regular triangle, rectangle, square and hexagon), was investigated to make a comprehensive comparison of their pressure drop, heat transfer Nu number, mass transfer Sh number and N2O conversion. It was found that monolith catalysts have a much lower pressure drop than that of traditional packed bed, and for monolith catalysts with different channel shapes, pressure drop decreases in the order of regular triangle > rectangle > square > hexagon > circle. The order of Nu is in regular triangle > rectangle ≈ square > hexagon > circle, similar to that of Sh. N2O conversion follows the order of regular triangle > rectangular ≈ square ≈ circle > hexagon. The results indicate that chemical reaction including internal diffusion is the controlling step in the selective catalytic reduction of N2O removal with CO. In addition, channel size and gas velocity also have influence on N2O conversion and pressure drop.

关键词： selective catalytic reduction N2O conversion momentum transfer heat transfer mass transfer monolith catalysts mathematical modeling