Three-dimensional Geometry Model Research Articles

A New Method to Three-dimensional Dual Medium Geometry Model Construction

Dual medium geometric model is widely used in soil and rock mass environment, which can only reflect the material exchange between cracks and matrix. The dual medium geometric model ignores the hydraulic relationship between the pores and cracks. The paper develops a new method to construct the three-dimensional dual medium geometry model. This method is completely written by Matlab scripting language, can describe the real spatial distribution state of fracture in bedrock. In the method, three-dimensional random fracture network geometric models with different parameters and three-dimensional porous media geometric models with Berlin Noise characteristics are constructed respectively, and then use the three-dimensional direct superposition method to construct the dual medium geometric model. The paper introduces the construction of three-dimensional random fracture network geometry model, three-dimensional porous media geometric model and the dual medium geometric model by direct superposition method. This research is of great significance to the construction of dual medium model and numerical simulation in related fields.

Numerical Simulation of the Aerodynamic Performance of A U-Shaped Sail

For a U-shaped sail that has been applied on real ships, we establish a three-dimensional sail geometry model using SolidWorks, and obtain its numerical simulation results under 10 different angles of attack using Fluent to numerically simulate its aerodynamic performance. By comparing the calculated results with the wind tunnel test results, the simulation model proved to be effective. Then the interference effects between the twin sails of the U-shaped sail were investigated by using the sail simulation model.

Electromagnetic Load Analysis During Plasma Disruption for HL-2M Tokamak Plasma-Facing Components

This paper studies electromagnetic (EM) loads during major disruptions and vertical displacement events by introducing a two-dimensional spatiotemporal plasma current attenuation filament profile derived from the DINA code. Three-dimensional geometry models of the HL-2M tokamak are established by ANSYS, including the plasma-facing components (PFCs), the vacuum vessel (VV), poloidal magnetic field/central solenoid magnetic field coils, and divertor. Eddy currents are induced with plasma current decay and flow into the PFC components. The interaction between eddy currents and magnetic fields generates enormous EM forces and torques. The halo current also flows into the VV and divertor components from the inner and outer target plates, the demo plate, and the cassette box. The halo current–induced EM loads are the most substantial forces in the inward radial and upward vertical forces for the VV and divertor. The simulation results provide a reference for the design and safety assessment of the magnetically confined tokamak HL-2M.

Comprehensive modeling and parametric analysis of Multi-Mission Radioisotope Thermoelectric Generator

Radioisotope thermoelectric generators (RTGs) have been widely used as a promising power source for space mission, in which the Multi-Mission RTG (MMRTG) is the state of the art type. However, due to the scarcity of the 238 P u fuel and associated cost concerns, there exists an imperative need to increase the efficiency of RTGs. This requires intuitive, detailed and accurate system property predictions of the RTG system. In this work, a comprehensive finite element model of the MMRTG has been developed, by using a commercial software, COMSOL Multiphysics, including a full-size three-dimensional geometry model, temperature dependent materials and the thermoelectric and radiation heat transfer multiphysics fields involved. The calculation results agree well with reported experimental and simulated values. Through the obtained detailed temperature and voltage distribution, thermal and power properties of the MMRTG are characterized and the effects of non-uniform distributions of temperature and power generated in each TE couple are revealed. At last, the parametric analyses of operation conditions, thermal environment and key design factors are performed and several salient findings have been obtained. Through the analysis results, the design parameters and working mechanisms of the MMRTG are clarified, which can help the design and optimization of the future hundred-watt RTG. • The comprehensive FEM method is first implemented in the MMRTG modeling and analysis. • The non-uniform distributions of temperature and power in TE modules are revealed. • Suitable load and sufficient thermal inventory ensure adequate power output. • The insensitivity of performance to ambient temperature expands MMRTG’s application.

Improved method in calculating the surface charge distribution of DC‐GIL insulators with 3D geometry models

Surface charge accumulation is an important issue when dealing with the insulation property of direct-current gas-insulated transmission lines with insulators. An improved method is introduced to calculate the surface charge distribution of insulators based on three-dimensional (3D) geometry models with high solution accuracy and computing efficiency. More than 90% of the computing memory and time are reduced by applying weak form partial differential equation (PDE) to the ion transport equation compared to adding artificial diffusion term. The computing memory and time are further reduced by 70% when removing the diffusion term from the ion transport equation, whereas the accuracy remains unchanged. Thus, the method of combining the modification of ion transport equation and the application of weak form PDE is suggested in calculating the surface charge of 3D geometry models. Finally, this method is applied in calculating the surface charge distribution of a ±200-kV basin-type insulator under thermal-electric coupled fields and a ±500-kV tri-post insulator. Results show satisfying accuracy and efficiency. It is concluded that the proposed method can be applied in analysing the charge accumulation and ion transport behaviour based on 3D models under various operating conditions.

Evaluating the Effect of Embedment Depth on Collapse Failure Analysis of Strip Foundation

Bearing ultimate capacity of shallow footing on uniform soil can be evaluated experimentally. However, analytical and experimental methods are difficult to analyze and predict complicated behaviour of soil beneath the footing collapse failure on layered soil. A strip footing on dense sand overlying soft clay of bearing capacity is computed utilizing the three-dimensional (3D) geometry model by finite element method analysis. The soil model of the Mohr-Coulomb failure criterion is selected in the assessment. The effect of embedment depth with ratio foundation width (B) to the top layer thickness (H) exposed to vertical point loading is evaluated for different strength properties of soil layers. The present results were verified from established analytical formula. It shows the ultimate bearing capacity on layered soils on a strip footing increase in width of the footing. Local shear failure mechanism is observed in one of all cases with most cases indicate general shear failure mechanism occur for layered soil of dense overlying soft clay.

Comparative Study on Fuel Assembly of Modular Gas-cooled Fast Reactor using MCNP and OpenMC Code

The design study of GFR concepts comprises neutronic analysis of fuel pin and fuel assembly. The Monte Carlo method has advantages in three-dimensional (3D) geometry modeling but requires a high computation time. In this research, the comparative study of Gas-cooled Fast Reactor (GFR) using the Monte Carlo code. The GFR feasibility design study will be carried out with natural uranium with plutonium as fuel cycle inputs. The Monte Carlo method simulates GFR model at full-scale and heterogeneous three-dimensional (3D) using Evaluated Nuclear Data File (ENDF/B-VIII.b5) nuclear data. The code of Monte Carlo methods will be used in this research are the Monte Carlo N - Particle (MCNP) and OpenMC. The comparison of the GFR fuel assembly calculation simulation results is made between the MCNP and OpenMC code. The equilibrium cycle configuration is used as the basis model for the comparisons. The comparison of MCNP and OpenMC code gives a good agreement in criticality calculation of GFR that achieves delta kinf less than 1%. The (U-Pu)N fuel is a good candidate to be chosen in GFR research that gives kinf more than 1.1 in fissile contain 10%Pu and has the highest thermal conductivity. The Zircaloy-4 is the best candidate for material cladding in GFR design that provides the highest kinf.

Analysis of shielding failure flash-over rate of collection lines of wind farms in mountainous areas

Aiming at the current situation of serious economic losses caused by lightning shielding on the collection lines of wind farms in mountainous areas. First, this paper uses the horizontal section location map of the collection line to extract the terrain parameters, Then use the catenary equation to determine the spatial position of the conductor and ground of any section of the collector line along the pitch direction, and obtain the height of the conductor and the ground to the ground. Finally, complete the modeling calculation analysis of the three-dimensional electrical geometry model (EGM) of the entire collection line. The calculation results show that, when the thunderstorm day, the arrangement of the collection line and the structure of the tower are the same, the SFFOR of the collection line of the wind farm in mountainous terrain is 0.487 times/100 km/year, and the plain terrain is 0.167 times/100 km/year, that is, mountainous area is 2.9 times of plain terrain; It is recommended to use double lightning protection poles with small protection angles on the collection lines of wind farms in mountainous areas, or install lightning arresters for poles that are prone to flashover to meet the design requirements of line lightning protection.

Simulations of Heat Transfer through Multilayer Protective Clothing Exposed to Flame

Abstract In this paper, the safety and thermal comfort of protective clothing used by firefighters was analyzed. Three-dimensional geometry and morphology models of real multilayer assemblies used in thermal protective clothing were mapped by selected Computer-Aided Design (CAD) software. In the designed assembly models, different scales of the resolution were used for the particular layers – a homogenization for nonwoven fabrics model and designing the geometry of the individual yarns in the model of woven fabrics. Then, the finite volume method to simulate heat transfer through the assemblies caused by their exposure to the flame was applied. Finally, the simulation results with experimental measurements conducted according to the EN ISO 9151 were compared. Based on both the experimental and simulation results, parameters describing the tested clothing protective features directly affecting the firefighter’s safety were determined. As a result of the experiment and simulations, comparable values of these parameters were determined, which could show that used methods are an efficient tool in studying the thermal properties of multilayer protective clothing.

Neutronic Analysis of Modular Gas-cooled Fast Reactor for 5-25% of Plutonium Fuel using Parallelization MCNP6 Code

Modular Gas-cooled Fast Reactor (GFR) is one of six advanced reactor concepts set by the generation IV international forum. Modular GFR has the potential for use actinide recycling and closed fuel cycle as well as applying fast reactor, using helium gas as the main coolant, high working temperature and low void reactivity effect. The neutronic analysis of nuclear reactor means behavior study of subatomic particles that interact with matter. In this paper, the feasibility of plutonium fuel in modular Gas-cooled Fast Reactor (GFR) was investigated. The Monte Carlo method has advantages in full-scale and heterogeneous three-dimensional (3D) geometry modeling using Evaluated Nuclear Data File (ENDF/B-VIII.b5) nuclear data but requires a highly computation time. Since the progress of high performance computing, the reactor physicist community began proposing to use Monte Carlo method for nuclear reactor simulation through the parallelization of calculations. The GFR feasibility design study will carried out with plutonium fuel as fuel cycle inputs with 5-25% of fissile contain. The most important neutronic parameters characterizing of GFR core are determined for beginning of life (BOL) and during burnup calculation conditions. The results of calculation series in parallel computing give the good agreement will be faster of calculation time when more threads. Materials of (U-Pu)C and (U-Pu)N fuel are the good candidates to be chosen in GFR research that give keff more than 1.2 in fissile contain 20%Pu. The variation fissile contain gives the linearity with keff. In depletion simulation, the core reactor still in critical during 20 years operation, burn up values linear with operation time and mass evolution of plutonium and uranium from start-up core to equilibrium core.

Design and manufacturing a small-scale radial-inflow turbine for clean organic Rankine power system

With growing on the energy demand and availability of the low-grade temperature heat source, the organic Rankine cycle as a power system can be efficiently utilized to generate electricity. The turbine design and its performance have the main impact on determining the system power and overall system efficiency. Therefore, design a small-scale organic Rankine system requires the development of an appropriate turbine. To achieve this aim, this work offers an innovative complete design method to develop a radial-inflow turbine for small-scale organic Rankine cycle power applications, which includes a preliminary design (i.e. one-dimensional design calculation phase) and a three-dimensional flow analysis using the computational fluid dynamic technique. A thermodynamic analysis of the organic Rankine cycle was integrated with the design methodology. Where the three-dimensional geometry model was built based on the thermodynamic and aerodynamic design, and then was imported into the ANSYS-CFX software to conduct viscous numerical simulations. The optimum design of the radial-inflow turbine was manufactured using a three-dimensional printing (pioneering) technique, and the experimental testing was conducted at off-design points to validate the turbine design.The evaluation of the turbine’s performance (efficiency and power) was presented under design and off-design points in terms of rotational speeds, expansion ratios, and inlet temperatures with five different organic fluids. The turbine numerical results showed that R600 as a working fluid has a higher predicted turbine efficiency of 78.32% and power of 4.8 kW with cycle thermal efficiency of 9.15% compared with 8.045% for R245fa. Depending on the experimental results at off-design points, the highest cycle thermal efficiency of 4.25% with a turbine efficiency of 45.22% was achieved. These results assured the precision of the proposed PD methodology at off-design points in making performance maps of the turbine.

Improved thermodynamic and aerodynamic design method and off‐design performance analysis of a radial inflow turbine for ORC system

Radial inflow turbine is one of the crucial components of organic Rankine cycle (ORC) system, which has great impact on the performance of system. R245fa was selected as the working fluid to recycle the waste heat source with a temperature of 350 to 400 K. The genetic algorithm (GA) was employed in thermodynamic design to optimize the 10 key design parameters, which are needed in aerodynamic design of the ORC turbine. Isotropic efficiency was the fitness function of 10 key variables in GA. The three-dimensional geometry model was built based on the thermodynamic and aerodynamic design and then was imported into the commercial software ANSYS-CFX to conduct viscous numerical simulation. Based on the three-dimensional simulation, the off-design performance in different mass flow rate, static inlet temperature coupled with different rotational speed was investigated respectively. The results show that at design condition, the maximum efficiency deviation is only 2.5% with the rotational speed variations among the range of 10%, so the radial inflow turbine designed in this research possesses great off-design performance.

On a three-dimensional constitutive model for history effects in skeletal muscles

An exceptional property of skeletal muscles that distinguishes them from other soft tissues is their ability to contract by generating active forces, which in turn are initiated by an electrochemical trigger. Some of these so-called active material properties are generally characterised using isometric contraction experiments at various muscle lengths. In this context, experimental observations revealed that unlike the widespread assumption in muscle modelling, reaction forces indeed depend on so-called history effects, which can be classified into force enhancement and force depression. For the experimental settings of force enhancement, two subsequent isometric contractions are interrupted by an isokinetic extension. The isometric reaction force is increased after the isokinetic extension with respect to a reference measurement, while in the case of force depression, isokinetic shortening is responsible for forces below a certain isometric reference measurement. Most theoretical investigations of force enhancement and force depression use one-dimensional models to simulate the force response considering muscle deformation to be homogeneous. In contrast, the aim of the present study is to analyse history effects in skeletal muscle tissue using a three-dimensional geometry model of the whole muscle-tendon unit. Therefore, a purely phenomenological approach is presented. The model is implemented in the finite element framework to analyse history effects for the boundary value problem of the entire three-dimensional muscle-tendon geometry. The constitutive model shows good agreement with the experimental data. Furthermore, the simulations reveal information about the inhomogeneous stretch distributions within the muscle tissues.

Control of spontaneous combustion of coal in goaf at high geotemperatureby injecting liquid carbon dioxide: inertand cooling characteristics of coal

The spontaneous combustion of coal in goaf at high geo temperatures is threatening safety production in coalmine. The TG-DSC is employed to study the variation of mass and energy at 4 atmospheres (mixed gases of N2, O2 and CO2) and heating rates (10°C/min) during oxidation of coal samples. The apparent activation energy and pre-exponential factor of coal oxidation decrease rapidly with increasing theCO2 concentration. Furthermore, its reaction rate is slow, its heat released reduces. Based on the conditions of 1301 face in the Longgucoalmine, a three-dimensional geometry model is developed to simulate the distributions stream field and temperature field and the variation characteristics ofCO2 concentration field after injecting liquidCO2. The results indicate that oxygen reached to depths of˜120m in goaf, 100m in the side of inlet air, and 10m in the side of outlet air before injecting liquidCO2. After injecting liquidCO2for 28.8min, the width of oxidation and heat accumulation zone is shortened by 20m, and the distance is 80m in the side of working face and 40˜60m in goafin the direction of dip affected by temperature.

Parametric modeling of three-dimensional geometry of warp-knitted loop based on variation of process parameters

The purpose of this study is to develop a parametric 3-D loop model for warp-knitted structures which can predict loop geometry with variation of process parameters. Firstly, a process matrix of warp-knitted structure and a matrix including 3-D coordinates of date points were, respectively, developed. Then, based on internal stress analysis, an algorithm were suggested which can calculate the process parameter into 3-D coordinates of date points in geometric model of warp-knitted loop. Moreover, loop model were improved by space curve fitting based on piecewise cubic Hermite interpolating polynomial (CHIP). Furthermore, the developed parametric loop model was programmed with software of Matlab2014, and four test samples with different process parameters were simulated. The accuracy of the proposed model was verified by between simulations and micrographs, as well as agreement between predicted run-in values and the measured ones. It is confirmed that 3-D geometry of warp-knitted loop can be well predicted by the proposed parametric loop model.

Vortex Tube: A Comparison of Experimental and CFD Analysis Featuring Different RANS Models

The Ranque–Hilsch vortex tube represents a device for both cooling and heating applications. It uses compressed gas as drive medium. The temperature separation is affected by fluid flow behaviour inside the tube. It has not been sufficiently examined in detail yet and has the potential for further investigation. The aim of this paper is to compare results of numerical simulations of the vortex tube with obtained experimental data. The numerical study was using computational fluid dynamics (CFD), namely computational code STAR-CCM+. For the numerical study, a three-dimensional geometry model, and various turbulence physics models were used. For the validation of carried out calculations, an experimental device of the vortex tube of identical geometrical and operating conditions was created and tested. The numerical simulation results have been obtained for five different turbulence models, namely Standard k-ε, Realizable k-ε, Standard k-ω, SST k-ω and Reynolds stress model (RSM), were compared with experimental results. The most important evaluation factor was the temperature field in the vortex tube. All named models of turbulence were able to predict the general flow behaviour in the vortex tube with satisfactory precision. Standard k-ε turbulence model predicted temperature distribution in the best accordance with the obtained experimental data.

Construction process of a three-dimensional roadway geometry map for autonomous driving

This paper presents a construction process of the three-dimensional roadway geometry map for an autonomous driving system. The presented process focuses on the post-processing and the three-dimensional roadway geometry modelling algorithms. The post-processing algorithm refines the raw Global Positioning System position data by combining the novel three-dimensional roadway geometry model which originated from the construction engineering of roadways and vehicle motion data from onboard sensors using a Rauch–Tung–Striebel smoother. The three-dimensional geometry modelling algorithm approximates the road geometry information described in three-dimensional point clouds into a mathematical curve model based on the B-spline. An adaptive curve refinement method using dominant points was applied to the road modelling algorithm. This dominant-point-based refinement method can reduce the number of knots and the number of control points of the B-spline road model while maintaining the desired accuracy of the roadway map. Also, since the dominant-point refinement method considers a road shape factor, such as the curvature and the arc length, for the road modelling, it is more efficient than the previous B-spline road modelling algorithms. The proposed map generation algorithm was verified and evaluated through experiments in various test conditions. The experimental results show that the presented construction process of the three-dimensional roadway geometry map can provide sufficient accuracy, reliability and efficiency for applications of autonomous driving systems in comparison with those of other roadway map construction processes.

Numerical simulation of thermal runaway and inhibition process on the thermal polymerization of styrene

In order to achieve safer operating conditions of styrene polymerization process and effective inhibition of runaway reaction, computational fluid dynamics (CFD) technology is applied to simulate the thermal polymerization of styrene. A three-dimensional geometry model of the stirred reactor is established with a tool of SolidWorks. The computational model is carried out with a commercial CFD code (FLUENT). The effect of the viscosity, the impeller speed, the temperature probe location and the diluent addition location are investigated. The simulation results indicate that the three-dimensional model is useful for revealing the distribution of temperature and divergence of thermal runaway and inhibition process on the thermal polymerization of styrene.

Temperature Distribution of Three-Dimensional Photovoltaic Panel by Using Finite Element Simulation

The low electricity performance of a photovoltaic (PV) panel has been concerned in the PV application system. The effect of environmental and operating condition was affected the performance of the PV panel. In this research work, the main objective is to perform a three-dimensional geometry model of monocrystalline silicon PV panel with and without cooling system by using finite element method. In the case of a cooling system, the effect of the Direct Current (DC) fan flow rate on the temperature distribution of PV panel was investigated. The electrical behaviour of this PV panel is obtained based on the average temperature of the PV panel obtained and average solar irradiance from site location. According to the experimental results, PV panel with cooling system can be significant to provide better performance than the PV panel without cooling system in the same environmental condition. For the effect of flow rate of DC fan in the PV panel with cooling system, the performance of this PV panel has been improved as increasing in flow rate of DC fan.

Thermodynamic Simulation on the Performance of Twin Screw Expander Applied in Geothermal Power Generation

A three-dimensional (3D) geometry model of twin screw expander has been developed in this paper to measure and analyze geometric parameters such as groove volume, suction port area, and leakage area, which can be described as functions of rotation angle of male rotor. Taking the suction loss, leakage loss, and real gas effect into consideration, a thermodynamic model is developed using continuity and energy conservation equation. The developed model is verified by comparing predicted results of power output and internal efficiency with experimental data. Based on the model, the relationship between mass flow rate through inlet port and leakage path with rotation angle of male rotor as well as effects of the inlet parameter and operating parameter on the performance of the expander are analyzed.