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Direct Generation of Intense compression waves in Molten Metals by Using a High Static Magnetic Field and Their Application

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Journal of Materials Science & Technology 2003年第1期19卷 5-9页

作者： QiangWANG SATORUKAWAI 等 KeyLaboratoryofNationalEducationMinistryforElectromageneticProcessingofMaterials NortheasternUniversityShenyang110004China DepartmentofMaterialsProcessingEngineering NagoyaUniveris

compression waves propagating through molten metals are contributed to degassing, accelerating reaction rate,removing exclusions from molten metals and refining solidification structures during metallurgical processing of materials. In the present study, two electromagnetic methods are proposed to generate intense compression wavesdirectly in liquid metals. One is the simultaneous imposition of a high frequency electrical current field and a staticmagnetic field; the other is that of a high frequency magnetic field and a static magnetic field. A mathematical modelbased on compressible fluid dynamics and electromagnetic fields theory has been developed to derive pressure distributions of the generated waves in a metal. It shows that the intensity of compression waves is proportional to thatof the high frequency electromagnetic force. And the frequency is the same as that of the imposed electromagneticforce. On the basis of theoretical analyses, pressure change in liquid gallium was examined by a pressure transducerunder various conditions. The observed results approximately agreed with the predictions derived from the theoreticalanalyses and calculations. Moreover, the effect of the generated waves on improvement of solidification structureswas also examined. It shows that the generated compression waves can refine solidification structures when they wereapplied to solidification process of Sn-Pb alloy. This study indicates a new method to generate compression wavesby imposing high frequency electromagnetic force locally on molten metals and this kind of compression waves canprobably overcome the difficulties when waves are excited by mechanical vibration in high temperature environments.

关键词： High static magnetic field compression wave Electromagnetic processing of materials Maeneto-hvdrodvnamics. Solidification process

Experimental research on the instability propagation characteristics of liquid kerosene rotating detonation wave

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Defence Technology（防务技术） 2020年第6期16卷 1106-1115页

作者： Quan Zheng Hao-long Meng Chun-sheng Weng Yu-wen Wu Wen-kang Feng Ming-liang Wu National Key Laboratory of Transient Physics Nanjing University of Science and TechnologyNanjing210094China

In order to study the instability propagation characteristics of the liquid kerosene rotating detonation wave(RDW),a series of experimental tests were carried out on the rotating detonation combustor(RDC)with *** fuel and oxidizer are room-temperature liquid kerosene and preheated oxygenenriched air,*** experimental tests keep the equivalence ratio of 0.81 and the oxygen mass fraction of 35%unchanged,and the total mass flow rate is maintained at about 1000 g/s,changing the total temperature of the oxygen-enriched air from 620 K to 860 *** different types of instability were observed in the experiments:temporal and spatial instability,mode transition and *** interaction between RDW and supply plenum may be the main reason for the fluctuations of detonation wave velocity and pressure peaks with ***,the inconsistent mixing of fuel and oxidizer at different circumferential positions is related to RDW oscillate *** phenomenon of single-double-single wave transition is *** the transition,the initial RDW weakens until disappears,and the compression wave strengthens until it becomes a new RDWand propagates *** increased deflagration between the detonation products and the fresh gas layer caused by excessively high temperature is one of the reasons for the RDC quenching and re-initiation.

关键词： Rotating detonation wave Liquid kerosene Oxygen-enriched air Instability propagation characteristics compression wave

Numerical Investigation of the Angle of Attack Effect on Cloud Cavitation Flow around a Clark-Y Hydrofoil

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 2947-2964页

作者： Di Peng Guoqing Chen Jiale Yan Shiping Wang College of Engineering Peking UniversityBeijing100871China College of Shipbuilding Engineering Harbin Engineering UniversityHarbin150001China

Cavitation is a prevalent phenomenon within the domain of ship and ocean engineering,predominantly occurring in the tail flow fields of high-speed rotating propellers and on the surfaces of high-speed underwater *** re-entrant jet and compression wave resulting from the collapse of cavity vapour are pivotal factors contributing to cavity ***,these phenomena significantly modulate the evolution of cavitation *** this paper,numerical investigations into cloud cavitation over a Clark-Y hydrofoil were conducted,utilizing the Large Eddy Simulation(LES)turbulence model and the Volume of Fluid(VOF)method within the OpenFOAM *** analysis of results obtained at different angles of attack is undertaken.A discernible augmentation in cavity thickness is observed concomitant with the escalation in attack angle,alongside a progressive intensification in pressure at the leading edge of the hydrofoil,contributing to the suction *** results can serve as a fundamental point of reference for gaining a deeper comprehension of cloud cavitation dynamics.

关键词： Cloud cavitation re-entrant jet compression wave clark-Y hydrofoil

PRESSURE CHARACTERISTICS OF CAVITATION CONTROL BY AERATION

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Journal of Hydrodynamics 2005年第6期17卷 764-769页

作者： DONG Zhi-yong LU Yang-quan JU Wen-jie CAI Xin-ming DING Chun-sheng School of Civil and Architectural Engineering Zhejiang University of Technology Hangzhou 310032 China

This experimental investigation was systernatically conducted with the aid of a non-circulating water tunnel in the Hydraulics Laboratory at Zhejiang University of Tech nology in China, The test velocity is between 20m/s and 40m/ s. The least air concentration to prevent cavitation erosion lies between 1. 7% and 4. 5%. Pressure waveforms with and without aeration in cavitation and cavitation erosion regions were measured. Time-averaged pressure profiles with and without aeration were compared. Pressure characteristics cotresponding to least air concentration to prevent cavitation erosion in cavitation and cavitation erosion regions were analyzed.

关键词： pressure increase compression wave cavitation control by aeration least air concentration eavitation number

Laboratory study on the mechanical behaviors of an anisotropic shale rock

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Journal of Rock Mechanics and Geotechnical Engineering 2015年第2期7卷 213-219页

作者： Quan Gao Junliang Tao Jianying Hu Xiong(Bill) Yu Department of Civil Engineering Case Western Reserve University

Shale gas is becoming an important energy source worldwide. The geomechanical properties of shalerocks can have a major impact on the efficiency of shale gas exploration. This paper studied themineralogical and mechanical characteristics of a typical gas shale in Ohio, USA. Scanning electron microscope（SEM） with energy dispersive X-ray （EDX） analyses was employed to measure the microstructureand material composition of the shale rock. The anisotropic behaviors of shale rock, includingcompressive and tensile strengths, were experimentally measured. The characteristics of shale rock werealso studied by nondestructive wave speed measurements. The shale demonstrated strong anisotropicbehaviors with the tensile strengths perpendicular to the bedding plane around 300e360 times of thatparallel to bedding plane. Results of ultrasonic tests indicated that both compression and shear wavevelocities show strong anisotropic patterns. The compression wave speed was the smallest in the directionperpendicular to the bedding plane; while the shear wave speed was the smallest in the directionparallel to the bedding plane. The ratio of wave speed anisotropy is around 1.3e1.4 for compressionwave; the ratio of shear wave speed anisotropy is larger and more diverse compared with thecompression wave anisotropy. This might be related to the larger variability in the frictional adhesivestrength along bedding plane than the compressive adhesive strength. 2015 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting byElsevier B.V. All rights reserved.

关键词： Shale rock Anisotropy Shear wave compression wave

Formation, Propagation and Reflection of 1D Normal Shocks in Riemann Shock Tube

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Applied Mathematics 2022年第3期13卷 295-323页

作者： Karan S. Surana Jacob K. Kendall Celso H. Carranza Mechanical Engineering University of Kansas Lawrence USA

The purpose of this paper is to consider 1D Riemann shock tube to investigate the formation and propagation of compression waves leading to formation, propagation and reflection of 1D normal shocks using simplified mathematical models commonly used in the published work as well as using complete mathematical models based on Conservation and Balance Laws (CBL) of classical continuum mechanics and constitutive theories for compressible viscous medium derived using entropy inequality and representation theorem. This work is aimed at resolving compression waves, the shock structure, shock formation, propagation and reflection of fully formed shocks. Evolutions obtained from the mathematical models always satisfy differentiability requirements in space and time dictated by the highest order of the derivatives of the dependent variables in the mathematical models investigated. All solutions reported in this paper including boundary conditions and initial conditions are always analytic. Solutions of the mathematical models are obtained using the space-time finite element method in which the space-time integral forms are space-time variationally consistent ensuring unconditionally stable computations during the entire evolution. Solution for a space-time strip or slab is calculated and is time marched upon convergence to obtain complete evolution for the desired space-time domain, thus ensuring time accurate evolutions. The space-time local approximation over a space-time element of a space-time strip or slab is p-version hierarchical with higher-order global differentiability in space and time, i.e., we consider scalar product approximation spaces in which k = (k1, k2) are the order of the space in space and time and p = (p1, p2) are p-levels of the approximations in space and time. Model problem studies are presented for different mathematical models and are compared with solutions obtained from the complete mathematical model b

关键词： compression wave 1D Normal Shock Riemann Shock Tube Space-Time

THE EFFECT OF JOINT GEOMETRY PARAMETERS ON ULTRASONIC WELD-GUIDED MODES IN THICK STEEL PLATES

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THE EFFECT OF JOINT GEOMETRY PARAMETERS ON ULTRASONIC WELD-G...