基于SolidWorks Flow Simulation的PCB测试设备机柜散热仿真分析

为了解决PCB测试设备在机柜中温度过高导致被测产品损坏的问题。根据实际应用场景,设计出一款具有散热高效、结构紧凑、制作成本低的PCB测试设备机柜。结合PCB检测设备整体结构对其所在的机柜进行结构设计和散热仿真分析。主要以4台PCB测试设备满载运行在机柜中散热情况为研究对象。根据实际结构,使用SolidWorks对机柜和测试设备简化仿真模型进行建模,将简化模型导入到SolidWorks Flow Simulation中对机柜进行散热仿真分析。通过分析计算得出散热的分布情况和测试设备关键地方的温升数值,判断机柜散热结构的散热情况是否与预期结果一致。试验结果表明:常温下,在机柜中4台PCB测试设备满载测试时检测区域最高温度达到28℃左右,能够可持续运行状态并保持稳定工作。通过试验验证,机柜的散热实际温度与其散热仿真结果相符,证实了该机柜散热结构设计的合理性以及正确性,并且确定机柜散热结构设计方案。

基于SolidWorks Flow Simulation的矿用烟雾传感器气室结构流体仿真分析

针对矿用烟雾传感器气室结构容易进水且烟雾进出困难、影响烟雾传感元件响应时间的问题,为改善烟雾传感器气室结构对探测元件的影响并提高其防水性能,通过SolidWorks Flow Simulation对3种不同夹角投影的开孔气室结构进行流体仿真分析,研究了不同夹角开孔影响的气流、水流分布特征及变化规律。结果表明:气室结构设计为60°夹角投影的开孔防水、进烟雾程度对传感元件的影响最小,能极大地提高烟雾传感元件的检测灵敏性。

基于SolidWorks Flow Simulation的离心风机内流场仿真研究

为掌握风送喷雾机的离心风机内部气流场分布状况,利用SolidWorks Flow Simulation软件对离心风机内流场进行仿真分析。通过对离心风机的模型创建、仿真参数的设定与调整实现模拟仿真过程,利用切面图、流动迹线图、表面图、XY图等不同方式分析离心风机内流场仿真结果,实现了离心风机内流场气流分布状态的直观呈现,为提升学生对SolidWorks设计软件的学习兴趣,培养学生用虚拟仿真方法分析问题提供了参考。

SolidworksFlow Simulation软件在农业机械逆向设计建模研究生课程教学中的应用与实践

针对“农业机械逆向设计建模”研究生课程教学中的应用与实践环节改革创新问题,通过运用Solidworks Flow Simulation软件对T35型轴流风机流体力学实例分析,详细讲解了数值仿真过程及仿真结果的输出与分析,讨论了在农业机械逆向设计建模研究生课程中引入Solidworks Flow Simulation软件的教学新方法。该方法以直观的理论模型为手段,注重提高学生的学习兴趣,有助于培养研究生的逆向设计建模和在解决实际农业工程问题过程中的创新能力。

基于Solidworks Flow Simulation的物料管道气力输送仿真研究

针对农业机械在教学过程中创新与改革困难的问题,利用Solidworks Flow Simulation软件对气力输送管道进行流场仿真分析,讲解了仿真软件的操作流程及仿真结果的分析方法,讨论了在农业机械教学过程中引入Solidworks Flow Simulation软件操作的教学新方法。以直观的模型仿真为手段,可有效锻炼学生的动手能力,提高学生的学习兴趣,有助于学生更好地了解农业机械,并培养学生解决实际农业工程问题的创新思维。

The Flow Simulation and Experimental Study of Low-Specific-Speed High-Speed Complex Centrifugal Impellers＊

Based on the Navier-Stokes equations and the Spalart-Allmaras turbulence model, three-dimensional turbulent flow in four low-specific-speed centrifugal impellers are simulated numerically and analyzed. The relative velocity distribution, pressure distribution and static pressure rise at the design point are obtained for the regular impeller with only long blades and three complex impellers with long, mid or short blades. It is found that the back flow region between long-blade pressure side and mid-blade suction side is diminished and is pushed to pressure side of short blades near the outlet of impeller at suction side by the introduction of mid, short blades, and the size of back flow becomes smaller in a multi-blade complex impeller. And the pressure rises uniformly from inlet to outlet in all the impellers. The simulated results show that the complex impeller with long, mid and short blades can improve the velocity distribution and reduce the back flow in the impeller channel. The experimental results show that the back flow in the impeller has an important influence on the performance of pump and a more-blade complex impeller with long, mid and short blades can effectively solve low flow rate instability of the low-specific-speed centrifugal pump.

Three-dimensional spatial structure of the macro-pores and flow simulation in anthracite coal based on X-ray μ-CT scanning data

The three-dimensional(3 D) structures of pores directly affect the CH4 flow.Therefore,it is very important to analyze the3 D spatial structure of pores and to simulate the CH4 flow with the connected pores as the carrier.The result shows that the equivalent radius of pores and throats are 1-16 μm and 1.03-8.9 μm,respectively,and the throat length is 3.28-231.25 μm.The coordination number of pores concentrates around three,and the intersection point between the connectivity function and the X-axis is 3-4 μm,which indicate the macro-pores have good connectivity.During the single-channel flow,the pressure decreases along the direction of CH4 flow,and the flow velocity of CH4 decreases from the pore center to the wall.Under the dual-channel and the multi-channel flows,the pressure also decreases along the CH4 flow direction,while the velocity increases.The mean flow pressure gradually decreases with the increase of the distance from the inlet slice.The change of mean flow pressure is relatively stable in the direction horizontal to the bedding plane,while it is relatively large in the direction perpendicular to the bedding plane.The mean flow velocity in the direction horizontal to the bedding plane(Y-axis) is the largest,followed by that in the direction horizontal to the bedding plane(X-axis),and the mean flow velocity in the direction perpendicular to the bedding plane is the smallest.

Modified Saint-Venant equations for flow simulation in tidal rivers

Flow in tidal rivers periodically propagates upstream or downstream under tidal influence. Hydrodynamic models based on the Saint-Venant equations （the SVN model） are extensively used to model tidal rivers. A force-corrected term expressed as the combination of flow velocity and the change rate of the tidal fevel was developed to represent tidal effects in the SVN model. A momentum equation incorporating with the corrected term was derived based on Newton＇s second law. By combing the modified momentum equation with the continuity equation, an improved SVN model for tidal rivers （the ISVN model） was constructed. The simulation of a tidal reach of the Qiantang River shows that the ISVN model performs better than the SVN model. It indicates that the corrected force derived for tidal effects is reasonable; the ISVN model provides an appropriate enhancement of the SVN model for flow simulation of tidal rivers.

Parameter estimation in channel network flow simulation

Simulations of water flow in channel networks require estimated values of roughness for all the individual channel segments that make up a network. When the number of individual channel segments is large, the parameter calibration workload is substantial and a high level of uncertainty in estimated roughness cannot be avoided. In this study, all the individual channel segments are graded according to the factors determining the value of roughness. It is assumed that channel segments with the same grade have the same value of roughness. Based on observed hydrological data, an optimal model for roughness estimation is built. The procedure of solving the optimal problem using the optimal model is described. In a test of its efficacy, this estimation method was applied successfully in the simulation of tidal water flow in a large complicated channel network in the lower reach of the Yangtze River in China.

Debris flow simulation 2D(DFS 2D):Numerical modelling of debris flows and calibration of friction parameters

Debris flows are rapid mass movements with a mixture of rock,soil and water.High-intensity rainfall events have triggered multiple debris flows around the globe,making it an important concern from the disaster management perspective.This study presents a numerical model called debris flow simulation 2D(DFS 2D)and applicability of the proposed model is investigated through the values of the model parameters used for the reproduction of an occurred debris flow at Yindongzi gully in China on 13 August 2010.The model can be used to simulate debris flows using three different rheologies and has a userfriendly interface for providing the inputs.Using DFS 2D,flow parameters can be estimated with respect to space and time.The values of the flow resistance parameters of model,dry-Coulomb and turbulent friction,were calibrated through the back analysis and the values obtained are 0.1 and 1000 m/s^(2),respectively.Two new methods of calibration are proposed in this study,considering the crosssectional area of flow and topographical changes induced by the debris flow.The proposed methods of calibration provide an effective solution to the cumulative errors induced by coarse-resolution digital elevation models(DEMs)in numerical modelling of debris flows.The statistical indices such as Willmott's index of agreement,mean-absolute-error,and normalized-root-mean-square-error of the calibrated model are 0.5,1.02 and 1.44,respectively.The comparison between simulated and observed values of topographic changes indicates that DFS 2D provides satisfactory results and can be used for dynamic modelling of debris flows.

基于SolidWorks Flow Simulation的热电制冷箱装配体安装架构的仿真优化

为了提高热电制冷箱的制冷性能,对市面上常见的热电(半导体)制冷箱进行分析,并对制冷箱的制冷装配体与箱壁之间的架构方式进行探究。采用仿真工具SolidWorks Flow Simulation对制冷箱的制冷装配体与箱壁之间的架构方式进行建模仿真。分析了重力、风扇方向、开槽尺寸、槽内所加支架等参数对半导体制冷箱制冷性能的影响规律,结果表明:制冷箱在开槽尺寸一定时,重力方向处于箱体尺寸最长边,风扇进气方向为吸气,槽内加对称支架,并对支架的4个侧面做尽可能多的圆形镂空处理,且圆越大越好,此时热电制冷箱的制冷性能最优。

Flow Simulation to Determine the Effects of Shrouds on the Performance of Wind Turbines

This paper describes a flow simulation model used to determine the effects of a shroud on the performance of a wind turbine. Also, it focuses on comparing the standard type of wind turbines— upwind turbine with three blades fixed on a horizontal axis—with a new type that is called a shrouded wind turbine. In addition, the two types of turbines are compared in terms of velocities profiles, pressure distribution and power output when applying four different velocities of winds: 10, 20, 30, 40 mph. Numerical values and graphs are highlighted in order to show the main differences between the shrouded turbine and the conventional one. Finally, a conclusion and some recommendations are provided to summarize the scope of this research and give a better prediction for a future optimal design of the shrouded turbines.

Application of Stochastic Fracture Network with Numerical Fluid Flow Simulations to Groundwater Flow Modeling in Fractured Rocks

The continuum approach in fluid flow modeling is generally applied to porous geological media, but has limited applicability to fractured rocks. With the presence of a discrete fracture network relatively sparsely distributed in the matrix, it may be difficult or erroneous to use a porous medium fluid flow model with continuum assumptions to describe the fluid flow in fractured rocks at small or even large field scales. A discrete fracture fluid flow approach incorporating a stochastic fracture network with numerical fluid flow simulations could have the capability of capturing fluid flow behaviors such as inhomogeneity and anisotropy while reflecting the changes of hydraulic features at different scales. Moreover, this approach can be implemented to estimate the size of the representative elementary volume (REV) in order to find out the scales at which a porous medium flow model could be applied, and then to determine the hydraulic conductivity tensor for fractured rocks. The following topics are focused on in this study: (a) conceptual discrete fracture fluid flow modeling incorporating a stochastic fracture network with numerical flow simulations; (b) estimation of REV and hydraulic conductivity tensor for fractured rocks utilizing a stochastic fracture network with numerical fluid flow simulations; (c) investigation of the effect of fracture orientation and density on the hydraulic conductivity and REV by implementing a stochastic fracture network with numerical fluid flow simulations, and (d) fluid flow conceptual models accounting for major and minor fractures in the 2 D or 3 D flow fields incorporating a stochastic fracture network with numerical fluid flow simulations.

Assessment of the Sensitivity of Streamflow Simulations to Changes in Patch Resolution Using GIS Based Hydro-Ecologic Model

Eight different patch configurations were investigated to analyze the effect of patch characterization/formation in streamflow simulation, using the Regional Hydro-Ecologic Simulation Systems (RHESSys) model. It is investigated for eight different patch configurations of a subcatchment of the Turkey Lakes Watershed, Ontario. The model’s hydrological parameters are calibrated for each of these patch configurations and the performance of the simulations is evaluated. Results indicate that both the nature of the flow simulation and the calibrated parameter values are sensitive to patch configuration. The best simulation results were obtained for the patch configuration with the highest spatial variation of climate, stream network and hillslope conditions across the subcatchment. Different patch configurations also lead to markedly different calibrations of the model’s hydrological parameters (54.26 < k < 119.13;and 1.02 < m < 2.28), which has implications for the physical interpretation and transferability of the calibrated parameter values.

Numerical Simulation of the Influence of Water Flow on the Piers of a Bridge for Different Incidence Angles

A two-dimensional mathematical model is used to simulate the influence of water flow on the piers of a bridge for different incidence angles.In particular,a finite volume method is used to discretize the Navier-Stokes control equations and calculate the circumferential pressure coefficient distribution on the bridge piers’surface.The results show that the deflection of the flow is non-monotonic.It first increases and then decreases with an increase in the skew angle.

Investigation of gravity influence on EOR and CO_(2) geological storage based on pore-scale simulation

Gravity assistance is a critical factor influencing CO_(2)-Oil mixing and miscible flow during EOR and CO_(2)geological storage.Based on the Navier-Stokes equation,component mass conservation equation,and fluid property-composition relationship,a mathematical model for pore-scale CO_(2) injection in oilsaturated porous media was developed in this study.The model can reflect the effects of gravity assistance,component diffusion,fluid density variation,and velocity change on EOR and CO_(2) storage.For nonhomogeneous porous media,the gravity influence and large density difference help to minimize the velocity difference between the main flow path and the surrounding area,thus improving the oil recovery and CO_(2) storage.Large CO_(2) injection angles and oil-CO_(2) density differences can increase the oil recovery by 22.6% and 4.2%,respectively,and increase CO_(2) storage by 37.9% and 4.7%,respectively.Component diffusion facilitates the transportation of the oil components from the low-velocity region to the main flow path,thereby reducing the oil/CO_(2) concentration difference within the porous media.Component diffusion can increase oil recovery and CO_(2) storage by 5.7% and 6.9%,respectively.In addition,combined with the component diffusion,a low CO_(2) injection rate creates a more uniform spatial distribution of the oil/CO_(2) component,resulting in increases of 9.5% oil recovery and 15.7% CO_(2) storage,respectively.This study provides theoretical support for improving the geological CO_(2) storage and EOR processes.

APPLICATION OF VIDEO ANAGLYPH MAKER FOR 3-D FLOW SIMULATION

In this article,the anaglyph video maker is employed for generating realistic 3-D flows and the software FlowAnimator is developed using that technology.Based on Microsoft Windows Presentation Foundation（WPF）,the real 3-D scene is set up and marker particles are distributed in it randomly in order to create a more natural flow scenario.The trajectory of the particle motion is calculated with Lagrangian description in 3-D space.During the simulation,the viewport can be changed in order to focus on different parts of the model by panning,zooming,rotating and inclination variation etc.Marker particles may appear in different shapes：spheres,tracking-balls,cylinders and ribbons in order to fit different flows.It is the first time that the video anaglyph technology is employed in the 3-D hydrodynamic simulation,which removes the obstacles for 3-D scenes to be rendered on a flat-panel display.

Numerical simulation of the flow field of a flat torque converter

A flexible flat torque converter was proposed to fulfill the requirement of miniaturization and power density maximization for automobiles.Constructed by two arcs joined by lines,the torus was designed directly from design path.The influence of flatness on the performance of the torque converter was evaluated.The software CFX and standard k-ε model were adopted to simulate the internal flow fields of the torque converter under different flatness ratios.The results indicated that the performance of the torque converter got worse as the flatness declined,but the capacity of pump increased.The efficiency and the torque ratio dropped slightly as the flatness ratio decreased.So the torque converter could be squashed appropriately to get high power density without too much efficiency sacrifice.But when the flatness ratio was below 0.2,there was a significant drop in the efficiency.

Incident Detection Method of Expressway Based on Traffic Flow Simulation Model

The expressway traffc incidents have the characteristics of high harmful, strong destructive and refractory.Incident detection can guarantee smooth operation of the expressway, reduce traffc congestion and avoid secondary accident by informing the accident, detection and treatment timely. In this paper, an incident detection method is proposed using the toll station data that takes into account the traffc ratio at the entrances and crossway in the network. The expressway traffc simulation model is improved and a simulation algorithm is established to describe the movement of the vehicles. A numerical example is experimented on the expressway network of Shandong province. The proposed method can effectively detect the expressway incidents, and dynamically estimate the traffc network states so as to provide advice for the highway management department.

Thermal Flow Simulation of Twin-Roll Casting Magnesium Alloy

In order to better understand twin-roll casting process,a 3D finite element method(FEM) simulation was carried out,based on the conditions of the pilot vertical twin-roll caster,to study the thermal flow and solidification behavior in the twin-roll casting process.The simulation results show that non-uniform temperature and velocity distribution near the side dam region are the main reason for causing non-uniform solidification and non-uniform deformation along the cast sheet width.Therefore,it is necessary to preheat the side dams or improve the design of nozzle to compensate the effect of side dams on the casting process.High quality magnesium sheets have been cast after improved the casting devices.