Numerical Investigations on Dynamic Stall Characteristics of a Finite Wing

The paper examines the dynamic stall characteristics of a finite wing with an aspect ratio of eight in order to explore the 3D effects on flow topology,aerodynamic characteristics,and pitching damping.Firstly,CFD methods are developed to calculate the aerodynamic characteristics of wings.The URANS equations are solved using a finite volume method,and the two-equation k-ωshear stress transport(SST)turbulence model is employed to account for viscosity effects.Secondly,the CFD methods are used to simulate the aerodynamic characteristics of both a static,rectangular wing and a pitching,tapered wing to verify their effectiveness and accuracy.The numerical results show good agreement with experimental data.Subsequently,the static and dynamic characteristics of the finite wing are computed and discussed.The results reveal significant 3D flow structures during both static and dynamic stalls,including wing tip vortices,arch vortices,Ω-type vortices,and ring vortices.These phenomena lead to differences in the aerodynamic characteristics of the finite wing compared with a 2D airfoil.Specifically,the finite wing has a smaller lift slope during attached-flow stages,higher stall angles,and more gradual stall behavior.Flow separation initially occurs in the middle spanwise section and gradually spreads to both ends.Regarding aerodynamic damping,the inboard sections mainly generate unstable loading.Furthermore,sections experiencing light stall have a higher tendency to produce negative damping compared with sections experiencing deep dynamic stall.

Three-dimensional stability calculation method for high and large composite slopes formed by mining stope and inner dump in adjacent open pits

The 2D limit equilibrium method is widely used for slope stability analysis.However,with the advancement of dump engineering,composite slopes often exhibit significant 3D mechanical effects.Consequently,it is of significant importance to develop an effective 3D stability calculation method for composite slopes to enhance the design and stability control of open-pit slope engineering.Using the composite slope formed by the mining stope and inner dump in Baiyinhua No.1 and No.2 open-pit coal mine as a case study,this research investigates the failure mode of composite slopes and establishes spatial shape equations for the sliding mass.By integrating the shear resistance and sliding force of each row of microstrip columns onto the bottom surface of the strip corresponding to the main sliding surface,a novel 2D equivalent physical and mechanical parameters analysis method for the strips on the main sliding surface of 3D sliding masses is proposed.Subsequently,a comprehensive 3D stability calculation method for composite slopes is developed,and the quantitative relationship between the coordinated development distance and its 3D stability coefficients is examined.The analysis reveals that the failure mode of the composite slope is characterized by cutting-bedding sliding,with the arc serving as the side interface and the weak layer as the bottom interface,while the destabilization mechanism primarily involves shear failure.The spatial form equation of the sliding mass comprises an ellipsoid and weak plane equation.The analysis revealed that when the coordinated development distance is 1500 m,the error rate between the 3D stability calculation result and the 2D stability calculation result of the composite slope is less than 8%,thereby verifying the proposed analytical method of equivalent physical and mechanical parameters and the 3D stability calculation method for composite slopes.Furthermore,the3D stability coefficient of the composite slope exhibits an exponential correlation with the coordinated development distance,with the coefficient gradually decreasing as the coordinated development distance increases.These findings provide a theoretical guideline for designing similar slope shape parameters and conducting stability analysis.

Dynamic Modelling of a Hybrid Variable Reluctance Machine Using the 3D Finite Element Method

This paper presents the work carried out to evaluate the dynamic performance of the Hybrid Variable Reluctance Motor (HVRM). The fourth-order Runge-Kutta integration algorithm was employed to solve the equations of the dynamic model, in conjunction with the three-dimensional finite element method. The 3D numerical data was calculated using Comsol Multiphysics, which accounts for the nonlinearity of the ferromagnetic material and the 3D nature of the HVRM. The outcomes of this study are precise and accurately predict the dynamic behaviour of the HVRM in terms of rotor position response, rotational speed and torque. The distinctive contribution of this work lies in the 3D numerical modelling of the HVRM and the subsequent evaluation and analysis of its dynamic operation. Analytical and numerical 2D studies are less resource-intensive and time-consuming, and are more straightforward and rapid to analyse and interpret. However, they are constrained in their capacity to examine spatial, volumetric interactions and intricate dynamics such as flux studies where three 3D effects cannot be disregarded, winding end effects and the configuration and positioning of the interposed permanent magnet.

Effect 3D带我们进入GIF动画的三维世界

网页上的GIF动画非常精彩,但绝大多数都是平面动画,很少有三维的GIF动画,是不是制作这样的动画非常困难呢?笔者这就向大家介绍一款非常好用的三维GIF动画制作工具Effect 3D,它完全去除了传统3D程序的复杂性,并且提供最优质的3D效果与动画,只要点选功能中的缩图即可立即套用效果,十分方便简捷,大大提高了工作效率。

Effect 3D特效魔法箱功能多

在网页或 PowerPoint 简报中以图象来增强作品的吸引力是非常普遍的,不知大家有否考虑过插人一些立体图象或动画于作品之内呢!要自行制作立体图象或动画就并不容易,如要使用3D StudioMax 一类专业软件,需要钻研的时间可不短。对于普通用户来说,想简单快捷地制作自己喜欢的立体图象或动画,“Effcet3D 特效魔法箱”也许能够帮助大家。

3D deformation effect and optimal excavated design of surface mine

The three-dimensional （3D） deformation effect of the slope engineering under the step-by-step excavation for the Antaibao surface mine was analyzed using the FLAC^3D technique. An optimal excavated scheme with a relatively steeper slope angle of 47° instead of 30° was successfully implemented at the west wall in the geological section 73200 of the mine area, where the 3D effect of the nonlinear large deformation of the slope was taken into account. Based on the above research conclusion, put forward the countermeasures of shortening mining length, excavating by different regions, timely foot backfilling to protect the excavated slope, and monitoring and feedback adjustment by studying the nonlinear effect. The results show that these countermeasures are effective in controlling maximum deformation and increasing the stability of the slope.

3D Effects on Vortex-Shedding Flow and Hydrodynamic Coefficients of A Vertically Oscillating Cylinder with A Bottom-Attached Disk

Vortex-shedding flow induced by the vertical oscillation of a cylinder with bottom-attached disks of different diameter ratio Dd/Dc and thickness ratio td/Dc is studied by a 3D （three-dimensional） numerical model developed in this paper, and compared with the results obtained through 2D （two-dimensional） numerical model. The high-order upwind scheme is applied to stabilize the computation, and convergence is accelerated by the multi-grid method. Qualitative and quantitative analyses of the differences between the 2D and 3D simulation results reveal the 3D effect on the flow field characteristics and hydrodynamic coefficients of the vertically oscillating cylinder with a bottom-attached disk. The 3D effect on the fluid field is mainly reflected in the significance of three vortex-shedding patterns： ωx has a greater effect on the flow fields around the sharp edges relative to the vortices generated in the 2D simulation. In the slice along the axial orientation, the vortex effect of ωy along the radial axis is smaller than that of ωx along the circumferential direction, indicating the radial effect on the velocity more pronounced than the circumferential effect around the sharp edges of the disk. The rotational interaction ωz of the fluid in the horizontal plane during the heave motion is insignificant. Based on the 2D and 3D simulation results, the turning points that separate the increasing regimes of the added mass coefficient and damping ratio are identified. The dependence of the turning point on the diameter ratio Dd/Dc and thickness ratio td/Dc are discussed in detail.

Modeling and Rendering in the Three-Dimensional Effect in Rhino for Lady's High Boots

In recent years, the computer drawing technology that deals with three-dimensional (3D) design of footwear has become hot topics. Rhino is a kind of common and practical 3D design software with strong drawing and rendering graphics function, which is widely used to design industrial products. In this paper, through decomposition and modeling, modeling and drawing methods were analyzed in various parts of footwear by Rhino, as well as the smooth technology and adjustments to its profile curve by an example of lady's high boots. Finally, through a series introductions of rendering effects for footwear in color, light perception, grain characteristic, and 3D graphics, the main technical essential is achieved and difficulties in design of overall footwear styles are solved.

Site 0ccupancy of Alloying Elements and Their Effects on the D0_3 Phase Stability in Fe_3Al

The effects of ternary solutes Ti, Co, V, Cr, Ta, W and Mo on the D03 phase 5tability of Fe3Alintermetallics are investigated by tight-binding linear Muffin-tin orbitaI method. The predictedsite preference5 of these elements in Fe3AI are in agreement with the experimental observations.The calculated Iocal magnetic moment of Fe3AI is identical to the experimentaI. ln addition, itis found that the D03 phase stability of Fe3AI doped with Ti, V, Co and Cr depends on 'energygap- of energy band near Fermi level. while the D03 phase stability of Fe3AI doped with Ta, Wand Mo may be affected by Madelung energy.

3D STRESS LOCAL NONDESTRUCTIVE ANALYSIS IN THE MIDDLE PLANE OF A PLATE

The Isodyne technique based on the scattered light scanning from a thin laser beam can be used to obtain the information inside the loaded object at the room temperature nondestructively, so it is a very powerful technique in 3D stress analysis. The problems are how to interpret the information and how to get sufficient information from the few interference fringe. Birefringence phase shift technique can distinguish the fringe orders automatically and enrich the information in 256 gray levels between maxim and minim light intensity. The Isodyne birefringence phase shift method with an oblique incidence and equilibrium equation is presented, by which the 3D stresses in the middle plane of a plate with U shape notch are separated successfully. (Edited author abstract) 12 Refs.

Prediction of regular wave loads on a fixed offshore oscillating water column-wave energy converter using CFD

In this paper,hydrodynamic wave loads on an offshore stationary-floating oscillating water column(OWC)are investigated via a 2D and 3D computational fluid dynamics(CFD)modeling based on the RANS equations and the VOF surface capturing scheme.The CFD model is validated against previous experiments for nonlinear regular wave interactions with a surface-piercing stationary barge.Following the validation stage,the numerical model is modified to consider the pneumatic damping effect,and an extensive campaign of numerical tests is carried out to study the wave-OWC interactions for different wave periods,wave heights and pneumatic damping factors.It is found that the horizontal wave force is usually larger than the vertical one.Also,there a direct relationship between the pneumatic and hydrodynamic vertical forces with a maximum vertical force almost at the device natural frequency,whereas the pneumatic damping has a little effect on the horizontal force.Additionally,simulating the turbine damping with an orifice plate induces higher vertical loads than utilizing a slot opening.Furthermore,3D modeling significantly escalates and declines the predicted hydrodynamic vertical and horizontal wave loads,respectively.

Numerical study on 3D effect and practical design in shield tunneling

In practice,different design methods are used in solving geotechnical problems depending on the type of issue such as the tunneling,braced excavation,or bearing capacity of a foundation,that is,the basic mechanism of the design method differs depending on the problems even for the same ground.A numerical analysis using the finite element method has recently become familiar owing to an improved computing performance;however,it is not widely used in the design of geotechnical problems including tunnel excavation owing to the reliability of the constitutive model of the ground material.If a constitutive model of soils can properly express the properties of the ground material,a numerical analysis will play a vital role in solving the geotechnical problems.In this paper,the current state of a numerical analysis and its applicability in tunnel design are discussed.Herein,the simulation of the ground behavior during tunnel excavation is carried out using sandy and clay ground parameters for shallow and deep tunnel excavations.This paper is mainly focused on the effects of tunnel excavation under three-dimensional(3D)conditions,as well as the current design method.Non-linear 2D and 3D finite element analyses have been conducted,in which the elastoplastic sub-loading tij model has been used as a constitutive model of the soil.The performance and acceptability of the constitutive model have already been proven to reproduce the results of various model tests on different geotechnical problems such as the tunneling,braced excavation,and bearing capacity of a foundation,as well as the measured field data.It was found that a 2D finite element analysis where the rate of stress release is considered,can be used for the prediction of the ground deformation and surface settlement;however,it does not provide rational information in the prediction of tunnel lining forces such as the stress,bending moment,and axial force,which emphasize the necessity of a 3D analysis with a proper construction process in a tunnel design.

Construction strategies for a NATM tunnel in Sao Paulo, Brazil, in residual soil

Due to the fast growth of urban areas worldwide,the demand for tunnels in developed areas is increasing.The design and construc-tion of those tunnels are complex because of their shallow depths and their interaction with existing aboveground and buried structures,which results in rather limited allowable ground deformations induced by the tunnel excavation and support.In tropical regions,residual porous soils near the surface are common.Those soils are highly deformable;thus,tunneling may induce large ground deformations that may damage nearby structures.The new Austrian tunneling method(NATM)and the sprayed concrete lining(SCL)technique are being widely employed in several big cities in tropical regions,but little research has been conducted to assess the induced ground deformations in residual soils,common in tropical areas.This paper provides insight into this issue.A well-documented metro tunnel in Sa˜o Paulo,Brazil,in a residual red porous clay,was analyzed using 3D finite element method(FEM).The behavior of the residual red porous clay was approximated by an advanced constitutive soil model calibrated with triaxial tests on intact samples extracted at the site.Predictions of the tunnel deformations during construction matched the field data.The calibrated model was then used to explore the tunnel per-formance under different construction strategies.The influence of partial face excavation,unsupported span length,support stiffness and pipe roof umbrella were assessed.The numerical results showed that partial face excavation was effective to reduce ground deformations ahead of the face of the tunnel and to improve face stability;however,the settlements behind the face increased because of the delay in closing the primary lining.The installation of a stiffer liner closer to the face reduced the ground deformations significantly.The pipe roof umbrella was the most effective technique to reduce the ground deformations around the tunnel;however,the numerical results did not consider deformations that could be induced by the drilling and grouting operations.The results shown in this paper provide both qual-itative and quantitative information about the ground deformations induced by NATM tunneling in residual porous soils,that could help designers and contractors choose the optimum support and construction methods to minimize ground deformations.