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THE TOPOGRAPHIC PARAMETER SENSITIVITY TO VORTICITY PROPAGATION AND TYPHOON TANGENTIAL VELOCITY CHANGES
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作者 余锦华 TC 《Journal of Tropical Meteorology》 SCIE 2005年第1期31-41,共11页
A high resolution shallow-water model is designed to study the roles which the topographical parameter and latitudinal basic flow play in the propagation of vortex Rossby waves and typhoon tangential velocity changes.... A high resolution shallow-water model is designed to study the roles which the topographical parameter and latitudinal basic flow play in the propagation of vortex Rossby waves and typhoon tangential velocity changes. With no latitudinal flow, the horizontal scale effects of island terrain on the vortex Rossby waves propagation show that the disturbance vorticity follows a clockwise island-circulating path more significantly, the local maximum wind speed amplitude reduces more sharply, the maximum mean azimuthally tangential wind spins down more substantially, when the topographic horizontal scale augments. With the latitudinal basic flow, the evolution of local wind and mean velocity are affected by the distance changes between TC and the terrain and the time length of topographic action: the local wind amplitude intensifies and the mean velocity diminishes while the distance is shortening; the opposite is true while TC is away from the terrain gradually. 展开更多
关键词 topography parameters vortex Rossby waves typhoon tangential velocity
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Estimation of the Radial Distribution of the Tangential Velocity in a Vortex Chamber 被引量:1
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作者 Akira OGAWA Tsuyoshi IKARI +1 位作者 Hiroyuki MURAKAMI Kouhei SATHO 《Journal of Thermal Science》 SCIE EI CAS CSCD 2009年第1期27-32,共6页
The estimation of maximum tangential velocity becomes a very important factor for the estimation of performancesof the vortex chamber. In this paper, a proposed flow model of how to estimate the maximum tangential vel... The estimation of maximum tangential velocity becomes a very important factor for the estimation of performancesof the vortex chamber. In this paper, a proposed flow model of how to estimate the maximum tangential velocity inthe special form of the vortex chamber is described in detail. The pressure drop basing upon the rapid expansion byflowing from the inlet pipe into the cyclone body is estimated as half of the dynamic pressure in the inlet pipe. 展开更多
关键词 Vortex chamber tangential velocity angular momentum flux Reynolds number
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Contributions of the Secondary Jet to the Tangential Velocity Distribution and to the Collection Efficiency of the Fixed Guide Vane Type Axial Flow Cyclone Dust Collector
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作者 Akira Ogawa Hideki Anzou +1 位作者 So Yamamoto Mituru Shimagaki 《Journal of Thermal Science》 SCIE EI CAS CSCD 2015年第6期503-509,共7页
In order to control the maximum tangential velocity V?m(m/s)of the turbulent rotational air flow and the collection efficiencyηc(%)using the fly ash of the mean diameter X R50=5.57?m,two secondary jet nozzles were in... In order to control the maximum tangential velocity V?m(m/s)of the turbulent rotational air flow and the collection efficiencyηc(%)using the fly ash of the mean diameter X R50=5.57?m,two secondary jet nozzles were installed to the body of the axial flow cyclone dust collector with the body diameter D1=99mm.Then in order to estimate V?m(m/s),the conservation theory of the angular momentum flux with Ogawa combined vortex model was applied.The comparisons of the estimated results of V?m(m/s)with the measured results by the cylindrical Pitot-tube were shown in good agreement.And also the estimated collection efficienciesηcth(%)basing upon the cut-size Xc(?m)which was calculated by using the estimated V?m(m/s)and also the particle size distribution R(Xp)were shown a little higher values than the experimental results due to the re-entrainment of the collected dust.The best method for adjustment ofηc(%)related to the contribution of the secondary jet flow is principally to apply the centrifugal effect?c(1).Above stated results are described in detail. 展开更多
关键词 Axial Flow Cyclone Dust Collector Maximum tangential velocity Cut-Size Particle Size Distribution Collection Efficiency Reynolds number Centrifugal Effect
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Estimations of the Maximum Tangential Velocity V_(θm) in the Vortex Core Region and also the Mean Rotational Velocity V_(oi) near the Concave Wall Surface in the Returned Flow Type Cyclone Dust Collector
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作者 Akira Ogawa 《Journal of Thermal Science》 SCIE EI CAS CSCD 2010年第6期553-560,共8页
There are many types of cyclone dust collectors for separating the fine solid and dust particles from gases in the various industries and also in the home used purposes. For estimating the power loss and the collectio... There are many types of cyclone dust collectors for separating the fine solid and dust particles from gases in the various industries and also in the home used purposes. For estimating the power loss and the collection efficiency, one of the most important factors is the maximum tangential velocity V0m in the vortex core region in the cyclone body. In order to determine V0~ by the simple method, it is useful to apply the mechanical balance of the angular momentum fluxes under the assumption of Ogawa combined vortex model which is composed of the quasi-forced vortex in the vortex core region and also the quasi-free vortex surrounded the vortex core region and also under the assumption of the introduction of equivalent length Heq corresponding to the cone spaces of the cyclone body and the dust bunker. On the other hand, the mean rotational velocity Voi near the concave wall surface is also estimated by the mechanical balance of angular momentum fluxes with the moment of viscous friction force. For confirming the general applications of the obtained equations, the returned flow types cyclones changed the throat diameter D3 are designed. The material of the cyclone is the transparent acrylic resin. Therefore the inner surface of the cyclone body can be regarded as smooth surface. The comparisons of the measured velocities V~ and Voi by a cylindrical Pitot tube are shown in good agreement with those of the proposed equations. The above stated results are described in detail. 展开更多
关键词 Cyclone Dust Collector Maximum tangential velocity Mean Rotational velocity Angular Momentum Flux Equivalent Length Surface Frictional Force Ogawa Combined Vortex Model Reynolds Number.
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Numerical simulation of the flow field in a dense-media cyclone 被引量:14
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作者 SHEN Li-juan HU Yan-feng +2 位作者 CHEN Jian-zhong ZHANG Peng DAI Hua-zhen 《Mining Science and Technology》 EI CAS 2009年第2期225-229,共5页
An analytical study of the flow and pressure fields inside a small-diameter dense-media cyclone is presented.The simulations were done with the help of the CFD software FLUENT.The following conclusions were reached:th... An analytical study of the flow and pressure fields inside a small-diameter dense-media cyclone is presented.The simulations were done with the help of the CFD software FLUENT.The following conclusions were reached:the tangential velocity tends to increase when moving from the center toward the exterior.The velocity then begins to decrease when the maximum velocity point is reached.The velocity field divides into two different sections;an inner swirling zone and an outer swirling zone.The axial velocity points down at the wall and gradually decreases toward the bottom.Continuing toward the bottom,the axial velocity passes through zero and then gradually increases in the opposite direction.In the cyclone's central zone,the pressure is negative and the suction of air allows an air column to be formed therein.At the center of the radial negative zone the pressure drops to its lowest value—phenomenon that has been verified by theoretical analysis.Some discrepancies between the observed data and the simulated data are noted when an analysis in made on a cyclone operating with either fresh water only or with water with added heavy particles. 展开更多
关键词 CYCLONE numerical simulation tangential velocity axial velocity pressure filed
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Particle dynamics in dense shear granular flow 被引量:8
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作者 Dengming Wang Youhe Zhou 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2010年第1期91-100,共10页
The particle dynamics in an annular shear granular flow is studied using the discrete element method, and the influences of packing fraction, shear rate and friction coefficient are analyzed. We demonstrate the existe... The particle dynamics in an annular shear granular flow is studied using the discrete element method, and the influences of packing fraction, shear rate and friction coefficient are analyzed. We demonstrate the existence of a critical packing fraction exists in the shear granular flow. When the packing fraction is lower than this critical value, the mean tangential velocity profile exhibits a rate-independent feature. However, when the packing fraction exceeds this critical value, the tangential velocity profile becomes rate-dependent and varies gradually from linear to nonlinear with increasing shear rate. Furthermore, we find a continuous transition from the unjammed state to the jammed state in a shear granular flow as the packing fraction increases. In this transforming process, the force distribution varies distinctly and the contact force network also exhibits different features. 展开更多
关键词 Shear granular flow - tangential velocity profile Critical packing fraction Force distribution - Jammed state
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Vortex mechanism in hydrocyclones
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作者 徐继润 刘正宁 +4 位作者 邢军 李新跃 黄慧 徐海燕 罗茜 《中国有色金属学会会刊:英文版》 CSCD 2001年第4期591-594,共4页
On the basis of analyzing the vortex characteristics, a new mechanism of the vortex formation in hydrocyclones is developed. The main concept of the mechanism is that the vortex flow in a hydrocyclone is resulted from... On the basis of analyzing the vortex characteristics, a new mechanism of the vortex formation in hydrocyclones is developed. The main concept of the mechanism is that the vortex flow in a hydrocyclone is resulted from the overlapping of container rotation and hole leakage. The model is then used to explain the compound distribution of free vortex and forced vortex, predict the similarity of tangential velocity at different input pressures, and make count of the principle of small hydrocyclone with lower cut size than large one. Meanwhile a new possible approach to a large hydro cyclone with lower cut size by minimizing or eliminating the air core is discussed briefly. 展开更多
关键词 HYDROCYCLONES tangential velocity vortex mechanism
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On the Pressure Drop and the Velocity Distribution in the Cylindrical Vortex Chamber with Two Inlet Pipes for the Control of Vortex Flow 被引量:3
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作者 Akira OGAWA Tutomu OONO +2 位作者 Hayato OKABE Noriaki AKIBA Taketo OOYAGI 《Journal of Thermal Science》 SCIE EI CAS CSCD 2005年第2期162-171,共10页
Vortex flow is applied to a cyclone dust collector, a vortex combustion chamber, and a vortex diode for vortex control. In order to apply the vortex flow to the industries, it is necessary to keep the stable flow cond... Vortex flow is applied to a cyclone dust collector, a vortex combustion chamber, and a vortex diode for vortex control. In order to apply the vortex flow to the industries, it is necessary to keep the stable flow condition and to estimate the response time of the transient flow process and also the intensity of the vortex flow. For control vortex flow, two types of vortex chamber with two inlet pipes were designed. One of them is to promote the vortex flow named as Co-Rotating Flow System and another one is to hinder the vortex flow named as Counter-Rotating Flow System. The pressure drops and the velocity distributions were measured for these vortex chambers. The estimation of the tangential velocity by the application of the angular momentum flux is compared with the measured velocity by a cylindrical Pitot-tube. The characteristics of the total pressure drop could be explained by introducing the circulation. 展开更多
关键词 vortex chamber tangential velocity total and local pressure drops angular momentum flux circulation.
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A Structure-Preserving Numerical Method for the Fourth-Order Geometric Evolution Equations for Planar Curves
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作者 Eiji Miyazaki Tomoya Kemmochi +1 位作者 Tomohiro Sogabe Shao-Liang Zhang 《Communications in Mathematical Research》 CSCD 2023年第2期296-330,共35页
For fourth-order geometric evolution equations for planar curves with the dissipation of the bending energy,including the Willmore and the Helfrich flows,we consider a numerical approach.In this study,we construct a s... For fourth-order geometric evolution equations for planar curves with the dissipation of the bending energy,including the Willmore and the Helfrich flows,we consider a numerical approach.In this study,we construct a structure-preserving method based on a discrete variational derivative method.Furthermore,to prevent the vertex concentration that may lead to numerical instability,we discretely introduce Deckelnick’s tangential velocity.Here,a modification term is introduced in the process of adding tangential velocity.This modified term enables the method to reproduce the equations’properties while preventing vertex concentration.Numerical experiments demonstrate that the proposed approach captures the equations’properties with high accuracy and avoids the concentration of vertices. 展开更多
关键词 Geometric evolution equation Willmore flow Helfrich flow numerical calculation structure-preserving discrete variational derivative method tangential velocity
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Estimation of the Collection Efficiency of the AxialFlow Cyclone Dust Collector with the Fixed Guide Vanes 被引量:3
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作者 Akira OGAWA(Department of Mechanical Engineering, College of Engineering, Nihon University T-963, Tokusada,Tamura-machi, Kooriyama-shi, Japan)Tetzuya IWANAMI Hideki SHONO(Mikuni Comp., Japan) 《Journal of Thermal Science》 SCIE EI CAS CSCD 1997年第1期58-65,共8页
In order to estimate the cut-size Xc and the mechanically balanced particles in the axial flow cyclonewith the slit-separation method, the tangential velocity distributions were calculated by the finitedifference meth... In order to estimate the cut-size Xc and the mechanically balanced particles in the axial flow cyclonewith the slit-separation method, the tangential velocity distributions were calculated by the finitedifference method. In comparison of the calculated results of the total collection efficiency with theexperimental results, the calculated results showed a little higher than the experimental results due tothe re-entrainment of the collected particles by turbulence. The effect of the slit for promoting thecollection efficiency was not recognized. 展开更多
关键词 axial flow cyclone finite difference method eddy kinematic viscosity tangential velocity mechanically balanced particle collection efficiency particle size distribution
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Investigation of the Surface Vortex in a Spillway Tunnel Intake 被引量:1
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作者 王英奎 江春波 《Tsinghua Science and Technology》 SCIE EI CAS 2010年第5期561-565,共5页
The surface vortex in a spillway tunnel intake was investigated in a physical model of the Xiluodu hydropower station.The velocity fields were measured using the particle tracking velocimetry technique.The tangential ... The surface vortex in a spillway tunnel intake was investigated in a physical model of the Xiluodu hydropower station.The velocity fields were measured using the particle tracking velocimetry technique.The tangential velocity formula of the surface flow field was derived based on the Navier-Stokes equations,and this formula greatly improved the consistency between the numerical and experimental data.Also,the formula has the advantage of describing the tangential velocity more accurately than previous formulas.The current research is based on established engineering practices,and the results provide a valuable reference for actual projects designed to prevent and eliminate surface vortexes. 展开更多
关键词 surface vortex axisymmetric flow particle tracking velocimetry(PTV) tangential velocity
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