Three-dimensional Simulation Model Research Articles

Research on Non-Contact Voltage Measurement Method Based on Near-End Electric Field Inversion

Aiming at the problems of complex equations, low accuracy, and the strict measurement point layout requirements of the existing electric field integration method, a non-contact measurement method based on the inversion voltage of the near electric field is proposed. Firstly, the field source relationship is clarified, the connection between the spatial electric field and the voltage is derived, and a near-end electric field inversion method is proposed. Secondly, a three-dimensional simulation model of an overhead line is established using COMSOL finite element software, the three-dimensional spatial potential distribution of the overhead line is obtained, and the voltage is inverted and calculated. Finally, an overhead line simulation test platform was built, and MEMS electric field sensors were used for testing and verification. The results show that the maximum error of the three-phase voltage inversion of the proximal electric field measurement is 6.8%, and the error between the voltage obtained by the experimental inversion measurement and the reference voltage is less than 7.2%. The simulation and experimental results also verify the accuracy and feasibility of the inversion voltage of the proximal electric field. The results of this paper can lay a foundation for the practical application of small and miniaturized electric field sensors, and help in the construction and development of smart grids.

Research on the Vibration Characteristics of Pumped Storage Unit Stator Core Based on Fiber Optic Sensing

Stator core vibration (SCV) response of pumped storage units (PSU) can effectively reflect its operation status and provide reference for excitation winding inter-turn short circuit (ITSC) fault diagnosis. Considering that traditional piezoelectric acceleration sensors (PAS) are difficult to be installed on the stator core surface, this study proposes an online monitoring method based on fiber optic vibration sensing (FOVS). Firstly, this study derives the SCV response equations for the normal and ITSC states of the excitation winding, and obtains the vibration characteristic harmonics corresponding to each state. Secondly, a three-dimensional finite element simulation model of PSU with a generating capacity of 278 MVA is built, and the acceleration amplitude and characteristic frequency harmonics of the stator core are calculated to provide a reference for fiber optic vibration detection. Thirdly, this study focuses on the principle of modulation and demodulation of optical phase, builds an optical frequency-domain reflectometer (OFDR) - based FOVS system, and calibrates its sensitivity, amplitude and frequency characteristics as well as the lower detection limit. Finally, FOVS probes are installed on the surface of synchronous generator stator core to capture the vibration signals under different degrees of ITSC, and compared with the collected signals of PAS. The experimental results prove that the proposed method has obvious advantages in vibration monitoring in the low frequency band below 100 Hz.

Experimental and Simulation Research on the Vibration Characteristics of the Traction Motor of Medium and Low Speed Maglev Train under Electromagnetic Excitation

In a medium and low speed maglev train, the linear induction motor (LIM) is employed as the traction motor, during operation its vibration characteristics correlate with the dynamic performance and noise radiation characteristics of the train. This paper conducted tests and established a three-dimensional simulation model of the LIM in a medium and low speed maglev train, to study the motor vibration characteristics by comparative analysis between test and simulation. The analysis results showed that the electromagnetic excitation sources of the train appear in the high-frequency band, with the main characteristic frequencies of 497.33 Hz, 994.33 Hz, 1989.00 Hz, and 3977.67 Hz. The structural modal analysis and vibration harmonic response analysis of the motor showed that the 3rd, 8th, and 18th modal frequencies of the motor structure approximate the frequencies of the electromagnetic excitation sources. As a result, the motor generates resonance at 497.33 Hz and 994.33 Hz under that excitation. The validity of the simulation was confirmed by the corresponding tests. From the perspective of theory, experiment, and simulation, this research can contribute to the optimization of traction systems in the future design of medium and low speed maglev trains.

Response analysis and effect evaluation of dynamic stabilization for ballasted track

Dynamic stabilization is a process of the railway lines that are newly built must go through before it is put into operation. This study investigates the characteristics of stabilizing operation on ballasted track and proposes methods for detecting and evaluating the state of the ballast bed in an attempt to improve the operation quality. Firstly, the influence mechanism of stabilization on the migration of ballast particles and the settlement of track panel from the macro and micro perspectives through the method of visual non-contact measurement by video images were demonstrated. A three-dimensional simulation model which the first wheelset of the tamping and stabilizing vehicle - ballasted track was established using the discrete element method and multi-flexible body dynamics coupling algorithm, and the logistic mathematical model for sleeper displacement and support stiffness of ballast bed was constructed. Furthermore, an innovative non-contact method for measuring the support stiffness of ballast bed under complex scenes was proposed. Results show that the ballast particles on the slope of the ballast bed are rearranged and gradually compacted by a movement mode of “vertical as the main direction and horizontal as the auxiliary” during the stabilizing operation. As the number of stabilizing operations increases, the settlement of the track panel gradually decreases, with a maximum attenuation amplitude of 44.9%. Comprehensively, the track panel achieves reasonable load distribution after the second stabilizing operation, and achieves the best effect with the relative growth rate of the two-point stiffness being 49.5%. Significantly, this study provides key theoretical basis for the scientific stabilizing operation and evaluation of ballast bed status of railway lines that are newly built.

A New Integrated Model for Simulating Adaptive Cycle Engine Performance Considering Variations in Tip Clearance

The low-fidelity simulation method cannot meet the requirements for predicting the performance of an adaptive cycle engine (ACE), especially when considering tip clearance variations in the compression and expansion systems. The tip clearances of the components of an ACE, such as the adaptive fan and turbine, vary drastically under different operating conditions. Though the tip clearance significantly impacts the engine’s performance, including its thrust and fuel consumption, variations in tip clearance are not considered in traditional ACE simulation models. This paper developed a new integrated model for predicting ACE performance, including multi-fidelity simulation models of the components and a newly developed, simplified model for predicting tip clearance. Specifically, the integrated model consists of a zero-dimensional (0D) engine performance simulation model, a three-dimensional (3D) adaptive fan numerical simulation model, a one-dimensional (1D) low-pressure-turbine (LPT) mean line model, and a multi-dimensional (MD) tip clearance prediction model. The integrated model solved the problem of considering the impact of tip clearance on an ACE and further improved the accuracy of thrust and fuel consumption predictions. Specifically, considering variations in the tip clearances under the design conditions, the differences in the thrust and specific fuel consumption (SFC) of the ACE are 1% and 0.3%, respectively. In conclusion, the integrated model provides a useful tool for evaluating the performance of an ACE while considering tip clearance variations.

Geometrical Characterisation of TiO2-rGO Field-Effect Transistor as a Platform for Biosensing Applications.

The performance of the graphene-based field-effect transistor (FET) as a biosensor is based on the output drain current (Id). In this work, the signal-to-noise ratio (SNR) was investigated to obtain a high-performance device that produces a higher Id value. Using the finite element method, a novel top-gate FET was developed in a three-dimensional (3D) simulation model with the titanium dioxide-reduced graphene oxide (TiO2-rGO) nanocomposite as the transducer material, which acts as a platform for biosensing application. Using the Taguchi mixed-level method in Minitab software (Version 16.1.1), eighteen 3D models were designed based on an orthogonal array L18 (6134), with five factors, and three and six levels. The parameters considered were the channel length, electrode length, electrode width, electrode thickness and electrode type. The device was fabricated using the conventional photolithography patterning technique and the metal lift-off method. The material was synthesised using the modified sol-gel method and spin-coated on top of the device. According to the results of the ANOVA, the channel length contributed the most, with 63.11%, indicating that it was the most significant factor in producing a higher Id value. The optimum condition for the highest Id value was at a channel length of 3 µm and an electrode size of 3 µm × 20 µm, with a thickness of 50 nm for the Ag electrode. The electrical measurement in both the simulation and experiment under optimal conditions showed a similar trend, and the difference between the curves was calculated to be 28.7%. Raman analyses were performed to validate the quality of TiO2-rGO.

Vapor-liquid two-phase flow and thermodynamic loss of multi-stage high temperature and pressure reducing valve based on evaporation model

A three-dimensional simulation model of multi-stage high temperature and pressure reducing valve (MSHTPRV) was established via the combination of Euler-Lagrange two-phase flow and droplet evaporation model. The simulation model was verified by a DN10 temperature and pressure reducing valve (TPRV) experiment. Then the vapor-liquid two-phase flow model with droplet evaporation was applied to the MSHTPRV. The complex flow and working performance of the MSHTPRV are demonstrated. The key influence of water spray parameters on the flow characteristics and thermodynamic loss was analyzed. The results show that the steam flow evolves the strong vortex in front of each stage orifice, and the droplet evaporates faster in the large vortex. The entropy production in MSHTPRV is mainly from the vortex motion and droplet evaporation. With the increasing of droplet diameter, the evaporation rate of droplet decreases, and the steam work capacity loss decreases. When the injection velocity of droplet exceeds the steam velocity, the evaporation rate of droplet can be increased. The increasing of injection temperature leads to the decreasing of steam work capacity loss. The latent heat of vaporization absorbed by the droplet is the main mechanism to reduce the steam temperature, and the evaporation of smaller droplet diameter can produce more steam work capacity loss.

Investigation on the pressure fluctuation of hydrogen Roots pump with a novel reflow structure for fuel cell vehicles

The hydrogen pump is an important component in the hydrogen circulation system of fuel cells. Excessive pulsation at the outlet of the pump is challenging when the Roots hydrogen pump is used, which has a negative impact on the operation performance. To reduce the impact of excessive fluctuations in the hydrogen circulation system, a new structure of reflow grooves is proposed in this paper, which connects the different chambers and adjusts the pressure using a diversion method. The internal flow of the two pumps was studied for comparison, using a three-dimensional simulation model established by Computational Fluid Dynamics (CFD) method. Results showed that the reflow grooves reduce the exhaust pressure and mass flow pulsations, which has a positive effect on the pressure stabilization of the hydrogen circulation system and the anode inlet pressure of the fuel cell stack, contributing to the long durability and stability of the fuel cell stack.

Hole-wall temperature characteristics in thick UD-CFRP drilling by different condition

ABSTRACT Due to the low thermal conductivity of CFRP and serious axial heat accumulation in dry drilling condition, the excessive cutting temperature simulation and suppression analysis have been the main research fields to analyze and improve borehole quality with the wide application of thick CFRP component in main load-carrying structures of aircraft. This paper proposed a three-dimensional drilling temperature simulation model to investigate the complex cutting temperature characteristics and predict the overheating area distribution during thick UD-CFRP drilling with dry condition and Boelube lubricant, thereby revealing its effects on occurrence of thermal-mechanical damages. Different from the previous drilling temperature simulation models, the material continuous removal process in this model was considered and discretized into finite chip layers removal process to model its effects on drilling heat transfer. Based on thermography method, a drilling temperature measurement experiment was conducted to validate the simulation model. Meanwhile, the overheating area distribution was predicted and the obvious reduction effects of ECL method on the overheating area ranges were confirmed. Moreover, the size of overheating area was proved to be a qualitative index of whether the hole wall subsurface damage at against fiber cutting zone is serious or not.

Research on the impact of tuyere parameters on the states of hydrogen-rich blast furnace

It is critical to reveal the change in tuyere parameters for the efficient consumption of coal particles and natural gas in the lower zone of the blast furnace. Combined with the actual size and injection conditions of the blast furnace for natural gas utilization, the three-dimensional simulation model involving the tuyere, two lances, raceway and blowpipe is built to explore the influence of the tuyere diameter, tuyere length and inclination angle of tuyere on the difference of flow, temperature, gas concentration and fuel reaction in the tuyere and raceway. The research outcomes show that the change of tuyere diameter has the most significant influence on the gas velocity in the three conditions. The high-temperature district in the computational domain increases gradually with the diameter of the tuyere. However, the result is contrary to the increase of the length and inclination angle of the tuyere. Besides, when the diameter, length and inclination angle increase, the burnout of pulverized coal has a trend of decreasing, increasing and increasing, respectively. To obtain a better fuel combustion effect, it is recommended that the diameter of the tuyere should not exceed 160 mm, the length of the tuyere should not exceed 530 mm, and the inclination angle of the tuyere should not exceed 7° under the current operating conditions.

Study of a three-dimensional model simulation of a speed amplified flux switching linear generator for wave energy conversion and its design optimization in the ocean environment

This paper introduces a novel design of a speed amplified flux switching linear generator for the power take-off unit of an ocean wave energy converter. The design incorporates several innovative features, including semi-closed stator iron cores, four coil phases shifting, and a fixed pulley wheel mechanism. These enhancements aim to increase the generator's output power and reduce its cogging force. The fixed pulley wheel mechanism effectively doubles the relative speed of the translator with respect to the stators.The scientific originality of this work lies in the development of a comprehensive design methodology for wave energy converters, specifically focused on optimizing the power take-off design under different ocean environments. The proposed approach combines analytical techniques, hydrodynamic boundary element analysis, 3D electromagnetic finite element modeling, and machine learning methods. By synergistically employing these methods, the authors achieve an efficient and effective power take-off design.To facilitate the optimization process, a three-dimensional electromagnetic finite element model of the flux switching linear generator is developed. This model is refined and optimized to maximize the output power while minimizing the cogging force, using a regular sinusoidal wave motion as the excitation input.The experimental results confirm that the proposed flux switching linear generator outperforms conventional permanent magnet linear generators in terms of power output performance. Furthermore, the model is used to simulate and predict the generator's power output under various ocean environments, considering the hydrodynamics of the wave energy converter.In summary, this manuscript presents a significant contribution to the field of flux switching electromagnetic linear generator based wave energy harvesters. The novel generator design and the comprehensive design methodology offer valuable insights and advancements in the development of efficient wave energy converters.

Parameter characterization of HT-PEMFC stack with a non-isothermal 3D model

This paper proposes a methodology for characterizing electrochemical parameters in non-isothermal three-dimensional (3D) simulation models of fuel cell stacks. The proposed methodology involves utilizing only easily measurable construction and non-invasive operational data. In order to achieve a reasonable computational cost, an iterative method developed on various 3D computational domains is combined with a genetic algorithm optimization technique. The effectiveness of the methodology is demonstrated through its application on a real scale 40-cell high temperature PEM fuel cell (HTPEMFC) stack, with the results indicating good agreement between the model and experimental data. This approach has the potential to significantly reduce the computational cost of optimizing fuel cell designs while still maintaining accuracy.

Effect of post-welding coating process on the organization and properties of MIG-welded T-joints of 6063-T6 aluminum alloy

Abstract With the rapid development of the precision industry, aluminum alloy structural parts have been widely used. However, in the welding process of aluminum alloy, there are problems such as welding deformation and weld tumor defects due to the special physical characteristics of aluminum alloy. Therefore, this paper mainly focuses on 6063-T6 aluminum alloy as the research object to analyze the effect of the coating process on the organizational properties of MIG welded T-joints of 6063-T6 aluminum alloy. First, based on the Simufact welding finite element analysis platform, the establishment of a three-dimensional welding simulation model, the simulation calculations and test results for comparison, the peak temperature and temperature change trend of each measurement point between the two. Secondly, according to the T-joint welding process, welding numerical simulation of 6063-T6 aluminum alloy rear compartment structural parts to obtain the rear compartment assembly welding residual stress is mainly concentrated in the vicinity of the weld. Finally, the impact of welding current on the organization and properties of T-shaped welded joints of 6063-T6 aluminum alloy was discussed. The results show that the coating process has a good strengthening effect on the mechanical properties of welded joints. Compared with the pre-coating process, the welded joint tensile strength increased by 14.93%, and the welding coefficient of 73% of the parent material heat-affected zone microhardness increased by 21.82% compared to the pre-coating process. In this paper, the finite element theory of the coating process and MIG welding, T-joint organization between the found welding heat-affected zone after the coating process can make Mg, and Si atoms continue to be enriched, and mechanical properties strength is enhanced.

Multi-scale, multi-dimensional binocular endoscopic image depth estimation network

During invasive surgery, the use of deep learning techniques to acquire depth information from lesion sites in real-time is hindered by the lack of endoscopic environmental datasets. This work aims to develop a high-accuracy three-dimensional (3D) simulation model for generating image datasets and acquiring depth information in real-time. Here, we proposed an end-to-end multi-scale supervisory depth estimation network (MMDENet) model for the depth estimation of pairs of binocular images. The proposed MMDENet highlights a multi-scale feature extraction module incorporating contextual information to enhance the correspondence precision of poorly exposed regions. A multi-dimensional information-guidance refinement module is also proposed to refine the initial coarse disparity map. Statistical experimentation demonstrated a 3.14% reduction in endpoint error compared to state-of-the-art methods. With a processing time of approximately 30fps, satisfying the requirements of real-time operation applications. In order to validate the performance of the trained MMDENet in actual endoscopic images, we conduct both qualitative and quantitative analysis with 93.38% high precision, which holds great promise for applications in surgical navigation.

Simulation and analysis of hot cylindrical flow forming process of titanium alloy

The spinning process of cylindrical titanium alloy parts was studied using a three-dimensional model and finite element simulation. The forming conditions and stress changes under different spinning process parameters have been analyzed. Based on the numerical simulation test, the blank’s state in the processing process is analyzed and predicted, providing a process reference for the spinning trial.

Modeling and simulation of a pipeline leak detection using smart inspection ball

Recently, pipelines have replaced more carbon-intensive transportation methods making them more environmentally friendly for transporting energy and water supplies. However, pipelines can pollute the air, water, soil, and climate when they leak, causing economic, and environmental damage. Pipeline online monitoring provides data analysis and suitable controlling strategies to contain the risk. This paper proposes a three-dimensional numerical model simulation taking advantage of the fluids moving through pipelines at specific speeds. The transport speeds depend on many conditions, such as pipe diameter, the pressure through which the fluid is being transported, and other factors, such as terrain's topography and viscosity of the fluid. Under these conditions, the inspection approach uses a self-charging movable ball. The sensors inside the ball capture data as it travels through the pipe. The simulation focuses on spherical flow and pipe noise with and without leakage based on the COMSOL software platform. The paper shows the effect of several parameters, including leak location, sensor placement, ball diameter, sound pressure level propagation along a pipe and around the sphere, velocity, and temperature distribution that give the background for future smart ball design in a promising practical pipeline test project.

Modeling and simulation of a pipeline leak detection using smart inspection ball

Recently, pipelines have replaced more carbon-intensive transportation methods making them more environmentally friendly for transporting energy and water supplies. However, pipelines can pollute the air, water, soil, and climate when they leak, causing economic, and environmental damage. Pipeline online monitoring provides data analysis and suitable controlling strategies to contain the risk. This paper proposes a three-dimensional numerical model simulation taking advantage of the fluids moving through pipelines at specific speeds. The transport speeds depend on many conditions, such as pipe diameter, the pressure through which the fluid is being transported, and other factors, such as terrain's topography and viscosity of the fluid. Under these conditions, the inspection approach uses a self-charging movable ball. The sensors inside the ball capture data as it travels through the pipe. The simulation focuses on spherical flow and pipe noise with and without leakage based on the COMSOL software platform. The paper shows the effect of several parameters, including leak location, sensor placement, ball diameter, sound pressure level propagation along a pipe and around the sphere, velocity, and temperature distribution that give the background for future smart ball design in a promising practical pipeline test project.

The effect of water on coking and heat transfer inhomogeneity of supercritical aviation kerosene in a curved mini-channel

Water addition to aviation kerosene draws increasing attention in increasing heat sink and suppressing coke formation for regenerative cooling of scramjet engines. However, the effect of water on flow, reaction and heat transfer, particularly the thermal inhomogeneity in curved cooling channel is rarely reported. In the present study, the effect of water on coking and heat transfer inhomogeneity characteristics of China aviation kerosene, RP-3 studied in a uniformly heated curved mini-channel. A transient three-dimensional numerical simulation model with hybrid pyrolysis and steam reforming reactions of RP-3 is established and validated. The results show that there exists serious mass and thermal stratification in the curved mini-channel due to secondary flow and species diffusion. Specifically, RP-3 and water are diffused to concentrate at the bottom heating wall surface while coke deposition and light gaseous species, e.g., H2, CH4, CO are concentrated at the top heating wall surface. The thermal difference between the top and bottom heating walls is significant. Temperature and coke content of the top heating wall are much higher than those of the bottom heating wall. The gas film and coke deposition formed at the top heating wall surface lead to serious heat transfer deterioration. Therefore, the heat transfer coefficient at the bottom wall of the curved channel is much higher than that of the top wall. Water addition enhances secondary flow and thus exacerbates the coking and heat transfer inhomogeneity in the curved cooling channel. With water content increasing from 0 to 15 wt%, the secondary flow velocity increases by 288.2%, the conversion of RP-3 increases by 114.8% and the average coke content on the heating walls decreases by 40%. Meanwhile, the average heat transfer coefficient increases by 33.9% at the bottom heating wall but decreases by 18.0% at the top heating wall with the increase of water content.

Influence of plasticity and vibration isolators on an underground floating slab track using finite element analysis

The floating slab track (FST) is largely viewed as the most efficient structure for mitigating the vibrations caused by underground railway systems. This paper presents a study on the dynamic behavior of the FST subjected to train-induced vibrations using a finite element approach. A three-dimensional simulation model of an FST was analyzed under a moving load. The effects of material plasticity of underground strata and concrete damaged plasticity of the floating slab were analyzed. A comparison between the vibration attenuation of the steel-spring isolator (SSI) and polyurethane pad (PUP) was performed. The load was moved at constant speeds ranging from 90 to 324 km/h using a pressure-loaded moving block. The results were analyzed in the form of four general output parameters. A slight vibration attenuation was observed when plastic material properties were included in the simulation model. The PUP was more effective in reducing vibrations at FST than SSI by a vibration transfer mechanism.

Numerical Study of the Local Scouring Process and Influencing Factors of Semi-Exposed Submarine Cables

Local scouring might result in the spanning of submarine cables, endangering their mechanical and electrical properties. In this contribution, a three-dimensional computational fluid dynamics simulation model is developed using FLOW-3D, and the scouring process of semi-exposed submarine cables is investigated. The effects of the sediment critical Shields number, sediment density, and ocean current velocity on local scouring are discussed, and variation rules for the submarine cables’ spanning time are provided. The results indicate that three scouring holes are formed around the submarine cables. The location of the bottom of the holes corresponds to that of the maximum shear velocity. The continuous development of scouring holes at the wake position leads to the spanning of the submarine cables. The increase in the sediment’s critical Shields number and sediment density, as well as the decrease in the ocean current velocity, will extend the time for maintaining the stability of the upstream scouring hole and retard the development velocity of the wake position and downstream scouring holes. The spanning time has a cubic relationship with the sediment’s critical Shields number, a linear relationship with the sediment density, and an exponential relationship with the ocean current velocity. In this paper, the local scouring process of semi-exposed submarine cables is studied, which provides a theoretical basis for the operation and maintenance of submarine cables.