Coupled Modeling Method Research Articles

Thermo-flexible coupled dynamics of composite laminated plates based on absolute nodal coordinate formulation

In this paper, a thermo-flexible coupled dynamic model of composite laminates is established by Absolute Nodal Coordinate Formulation (ANCF). In order to solve the problem of mesh mismatch and precision inconsistency between the displacement and temperature fields in the traditional thermo-flexible coupled modeling method, the ANCF hybrid element with integrated temperature description is constructed to achieve a unified description of the displacement and temperature fields. A new ANCF thin shell element with thermal effects is proposed. Based on the first law of thermodynamics, the heat capacity matrix, thermal conduction matrix, blackbody radiation matrix, internal heat source vector, and heat flux density vector caused by solar radiation for the ANCF thin shell element considering thermal effects are derived. The dynamic equation of ANCF composite laminates under a unified description is derived, and its dynamic model is established. The thermo-flexible dynamic response of ANCF composite laminates under thermal conduction, space thermal radiation, and solar radiation is analyzed by numerical simulation. The simulation results reveal the evolution process of the transient temperature field and the phenomenon of thermal-induced vibration, thus confirming that the thermal effects have an important influence on the dynamic behavior of ANCF composite laminates. The research provides a theoretical basis for the ground test of solar panels.

Quantifying Volume Change in Porous Electrodes via the Multi-Species, Multi-Reaction Model

Automotive manufacturers are working to improve individual cell and overall pack design by increasing their performance, durability, and range, while reducing cost; and active material volume change is one of the more complex aspects that needs to be considered during this process. As the time from initial design to manufacture of electric vehicles is decreased, design work that used to rely solely on testing needs to be supplemented or replaced by virtual methods. As electrochemical engineers drive battery and system design using model-based methods, the need for coupled electrochemical/mechanical models that take into account the active material change utilizing physics based or semi-empirical approaches is necessary[1-9]. In this study[10], we illustrated the applicability of a mechano-electrochemical coupled modeling method considering the multi-species, multi-reaction model as popularized by Verbrugge[11-16] and Baker. To do this, validation tests were conducted using a computer-controlled press apparatus that can control the press displacement and press force with precision. The coupled MSMR volume change model was developed and its applicability to graphite and NMC cells was illustrated. The increased accuracy of the model considering the coupled MSMR volume change approach shows in the importance of accounting for individual gallery volume change behavior on cell level predictions. References T. R. Garrick, K. Kanneganti, X. Huang and J. W. Weidner, J Electrochem Soc, 161, E3297 (2014).T. R. Garrick, Y. Dai, K. Higa, V. Srinivasan and J. W. Weidner, Ecs Transactions, 72, 11 (2016).T. R. Garrick, K. Higa, S.-L. Wu, Y. Dai, X. Huang, V. Srinivasan and J. W. Weidner, J Electrochem Soc, 164, E3592 (2017).T. R. Garrick, X. Huang, V. Srinivasan and J. W. Weidner, J Electrochem Soc, 164, E3552 (2017).D. J. Pereira, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 166, A1251 (2019).D. J. Pereira, M. A. Fernandez, K. C. Streng, X. X. Hou, X. Gao, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 167, 080515 (2020).T. R. Garrick, J. Gao, X. Yang and B. Koch, J Electrochem. Soc., 168 (1) 010530 (2021)D. J. Pereira, A. M. Aleman, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 169, 020577 (2022).T. R. Garrick, Y. Miao, E. Macciomei, M. Fernandez and J. W. Weidner, J Electrochem Soc, 170, 100513 (2023).T. R. Garrick, M. A. Fernandez, M. Verbrugge, C. Labaza, R. Mollah, B. J. Koch, M. Jones, J. Gao, X. Gao and N. Irish, J. Electrochem. Soc., 170 060548 (2023)M. Verbrugge, D. Baker and X. Xiao, J Electrochem Soc, 163, A262 (2016).M. Verbrugge, D. Baker, B. Koch, X. Xiao and W. Gu, J Electrochem Soc, 164, E3243 (2017).D. R. Baker and M. W. Verbrugge, J Electrochem Soc, 165, A3952 (2018).D. R. Baker and M. W. Verbrugge, J Electrochem Soc, 167, 013504 (2019).D. R. Baker, M. W. Verbrugge and W. Gu, J Electrochem Soc, 166, A521 (2019).M. W. Verbrugge, X. Xiao and D. R. Baker, J Electrochem Soc, 167, 080523 (2020).

Quantifying Volume Change in Porous Electrodes Via the Multi-Species, Multi-Reaction Model

Automotive manufacturers are working to improve individual cell and overall pack design by increasing their performance, durability, and range, while reducing cost; and active material volume change is one of the more complex aspects that needs to be considered during this process. As the time from initial design to manufacture of electric vehicles is decreased, design work that used to rely solely on testing needs to be supplemented or replaced by virtual methods. As electrochemical engineers drive battery and system design using model-based methods, the need for coupled electrochemical/mechanical models that take into account the active material change utilizing physics based or semi-empirical approaches is necessary[1-8]. In this study, we illustrated the applicability of a mechano-electrochemical coupled modeling method considering the multi-species, multi-reaction model as popularized by Verbrugge[9-14] and Baker. To do this, validation tests were conducted using a computer-controlled press apparatus that can control the press displacement and press force with precision. The coupled MSMR volume change model was developed and its applicability to graphite and NMC cells was illustrated. The increased accuracy of the model considering the coupled MSMR volume change approach shows in the importance of accounting for individual gallery volume change behavior on cell level predictions. References T. R. Garrick, K. Kanneganti, X. Huang and J. W. Weidner, J Electrochem Soc, 161, E3297 (2014).T. R. Garrick, Y. Dai, K. Higa, V. Srinivasan and J. W. Weidner, Ecs Transactions, 72, 11 (2016).T. R. Garrick, K. Higa, S.-L. Wu, Y. Dai, X. Huang, V. Srinivasan and J. W. Weidner, J Electrochem Soc, 164, E3592 (2017).T. R. Garrick, X. Huang, V. Srinivasan and J. W. Weidner, J Electrochem Soc, 164, E3552 (2017).D. J. Pereira, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 166, A1251 (2019).D. J. Pereira, M. A. Fernandez, K. C. Streng, X. X. Hou, X. Gao, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 167, 080515 (2020).T. R. Garrick, J. Gao, X. Yang and B. Koch, J. Electrochem. Soc. (2021).D. J. Pereira, A. M. Aleman, J. W. Weidner and T. R. Garrick, J Electrochem Soc, 169, 020577 (2022).M. Verbrugge, D. Baker and X. Xiao, J Electrochem Soc, 163, A262 (2016).M. Verbrugge, D. Baker, B. Koch, X. Xiao and W. Gu, J Electrochem Soc, 164, E3243 (2017).D. R. Baker and M. W. Verbrugge, J Electrochem Soc, 165, A3952 (2018).D. R. Baker and M. W. Verbrugge, J Electrochem Soc, 167, 013504 (2019).D. R. Baker, M. W. Verbrugge and W. Gu, J Electrochem Soc, 166, A521 (2019).M. W. Verbrugge, X. Xiao and D. R. Baker, J Electrochem Soc, 167, 080523 (2020).

A new method to establish coupled multi-physics model of lubricated pin-hole oscillating pair

Under severe working conditions, about 10 % of the total engine friction loss originates from the piston pin-hole oscillating pair, significantly impacting the engine's reliability. Nevertheless, a systematic analysis encompassing the multi-physics environment (including lubrication, dynamics, and heat transfer) and their coupled behaviors is still lacking. A new coupled modeling method is proposed to achieve this, which can account for thermal deformation and frictional heat generation. All key components in this study are represented as three-dimensional flexible bodies, enabling a thorough characterization of the intricate secondary motions influencing lubrication. The method is applied to a lubricated oscillating pair test system, and a 1:1 simulation model is established. Experimental results also affirm its high accuracy. The model calculation results demonstrate that thermal deformation constrains pin secondary motions and increases axial load inhomogeneity. After factoring in fluid and asperity friction heat, the average friction coefficients at the small end hole (SEH) and pin base hole (PBH) increase by 1.8 % and 11.3 %, respectively. Furthermore, a parametric analysis is conducted, and the instantaneous friction coefficient curves under different loads/temperatures/frequencies are given. These findings can offer valuable insights into the tribological design of oscillating pairs.

Nonlocal thermomechanical coupled modeling method for two-dimensional rolling contact using a peridynamic approach

The development of thermomechanical coupled simulations for rolling contacts is challenging when the adjacent material is temperature-dependent or when there are cracks or other discontinuities on the contact surface. This paper proposes a novel thermomechanical coupled modeling method for rolling contacts using a nonlocal peridynamic (PD) approach. Fully coupled, ordinary state-based PD thermomechanical equations for the plane strain and plane stress cases are derived based on the strain-energy density, including thermal coupling terms, and detailed information on each parameter is provided. Subsequently, an algorithm for rolling thermal contacts in PD is proposed based on the penalty method. This study further provides a detailed modeling process and an algorithm for the proposed method based on a multi-rate time-integration scheme for numerical implementation. A typical two-dimensional (2D) wheel–rail rolling contact model is established to evaluate the performance of the proposed contact modeling method in wheel–rail thermal contact and to analyze the influence of temperature-dependent material and rail-surface cracks on the thermomechanical response. It is found that the contact stress and rail-surface temperature rise in the case of small creepages and temperature-independent materials are in good agreement with the analytical solution. In the case of large creepages, the mechanical and temperature results of using temperature-dependent materials and temperature-independent materials are quite different, and the frictional heat generated can cause martensitic transformation of adjacent materials. Rail-surface cracks cause a sharp increase in the contact stress and temperature rise near the cracks, and the high temperature also promotes crack growth.

Quantifying Volume Change in Porous Electrodes via the Multi-Species, Multi-Reaction Model

Automotive manufacturers are working to improve individual cell and overall pack design by increasing their performance, durability, and range, while reducing cost; and active material volume change is one of the more complex aspects that needs to be considered during this process. As the time from initial design to manufacture of electric vehicles is decreased, design work that used to rely solely on testing needs to be supplemented or replaced by virtual methods. As electrochemical engineers drive battery and system design using model-based methods, the need for coupled electrochemical/mechanical models that take into account the active material change utilizing physics based or semi-empirical approaches is necessary. In this study, we illustrated the applicability of a mechano-electrochemical coupled modeling method considering the multi-species, multi-reaction model as popularized by Verbrugge and Baker. To do this, validation tests were conducted using a computer-controlled press apparatus that can control the press displacement and press force with precision. The coupled MSMR volume change model was developed and its applicability to graphite and NMC cells was illustrated. The increased accuracy of the model considering the coupled MSMR volume change approach shows in the importance of accounting for individual gallery volume change behavior on cell level predictions.

An Effective Force-Temperature-Humidity Coupled Modeling for PEMFC Performance Parameter Matching by Using CFD and FEA Co-Simulation

High-performance proton exchange membrane fuel cell (PEMFC) vehicles are important for realizing carbon neutrality in transportation. However, the optimal power density of the fuel cell performance is difficult to achieve due to the internal complex operating conditions of a fuel cell stack. Moreover, there is a lack of effective models to solve the coupled multi-physical fields (force, temperature and humidity, etc.) in the PEMFC, particularly considering the gas diffusion layer (GDL) compression. Thus, a force-temperature-humidity coupled modeling method is introduced to evaluate the effects of key operating conditions for the fuel cell performance parameter matching. Firstly, the interfacial contact resistance and GDL porosity are obtained by a force-temperature coupled simulation using a finite element analysis (FEA) modeling, then the obtained results are introduced into a temperature-humidity coupled simulation using a computational fluid dynamics (CFD) modeling. An iteration algorithm is proposed to realize the force-temperature-humidity coupled simulation for the PEMFC performance. The main characteristics of the PEMFC performance parameters are revealed and the optimum matching criteria of the main performance parameters (temperature, stoichiometric ratio and relative humidity) are determined. The presented co-simulation method is significant and effective for realizing the PEMFC performance parameter matching condition, and it provides a design direction for an optimal power density of a fuel cell stack.

Study on Electromagnetic–Dynamic Coupled Modeling Method—Detection by Stator Current of the Induction Motors with Bearing Faults

Detecting motor bearing faults by stator currents is of great importance as it improves the adaptability of measurement means to different environments and reduces the number of sensors. Therefore, many studies have been conducted to investigate bearing faults by constructing motor models, most of which have used signal models to simulate the dynamics of the bearings. However, the signal model may be exposed to the issue that the nonlinearities in the bearing operation are neglected, thus oversimplifying the coupling effects between the electromagnetic and dynamics models. Hence, a coupled electromagnetic–dynamic modeling method for induction motors based on multiple coupled circuit theory and the rotor-bearing dynamics model is proposed in this study to implement the coupled simulation of electromagnetic and dynamic models. The air gap length and rotor velocity are used as coupled parameters for the calculation of stator–rotor mutual inductance and ball contact deformation, respectively. The simulation results show that the proposed model can effectively implement the electromagnetic–dynamic coupled and reflect the bearing fault characteristics in the current signal. Experiments were conducted on induction motors with typical winding configurations under laboratory conditions. The comparison results verify the effectiveness of the proposed modeling method.

An Improved Coupled Modeling Method for Coalbed Methane Extraction after Hydraulic Fracturing

This paper proposes an improved coupled modeling method for coalbed methane extraction after hydraulic fracturing. Based on the damage mechanics theory, we introduce a state damage variable to record the damage changes at different times and construct the coupling governing equations of the seepage field and solid mechanics field in the hydraulic fracturing process. Then, the results of hydraulic fracturing simulation are used as initial values to perform coupling modeling for coalbed methane extraction. The method is implemented by the combination of different modules in COMSOL to solve the state damage variable, displacement, and pressure. Additionally, two 2D numerical examples are used to verify the precision of this method, and a 3D coalbed methane extraction simulation is performed to analyze the extraction effects and the evolution characteristics of the permeability before and after hydraulic fracturing. Numerical examples show that the proposed coupling modeling method can not only simplify the calculation steps of the CwM method and reduce the numerical errors caused, but also characterize the damage, porosity, permeability, and extraction effect caused by hydraulic fracturing in coal seams with permeability anisotropy.

Effect of helical twist angle on the aerodynamic performance and blade dynamic characteristics of floating vertical axis wind turbines

Due to the low fluctuation of aerodynamic torque, the helical blade floating vertical axis wind turbine (FVAWT) is a promising optimization structure compared with the traditional straight blade FVAWT. The helical twist angle plays a significant role in wind turbine design and operation. In this research, the effect of the helical twist angle on the aerodynamic performance and blade dynamic characteristics are investigated. A slack coupled modeling method is applied to model a 5 MW helical blade FVAWT system. Verification is conducted in comparison with a rigid body code and ANSYS software. Then a comparative study is conducted under seven cases with helical twist angles of 0°, 60°, 90°, 100°, 110°, 120° and 150°. The results show that helical twist angles ranging from 90° to 120° could significantly restrain the fluctuation of aerodynamic torque and suppress blade deformation. The varying regularity of blade deformation under different cases is affected by both aerodynamic force and blade stiffness characteristics. In addition, for blade deformation, 1 P and its frequency multiplication, the sum and difference frequency components of 1 P and wave frequency are observed in the amplitude spectrum. For the design of the FVAWT, the natural frequency of the blade should be far from the above frequencies to avoid resonant vibration. This study could provide a feasible mathematical method for the dynamic modeling of helical blade FVAWTs. Additionally, the range of helical twist angles recommended in this paper can be referred to when designing a helical blade.

Slack coupled modeling method and dynamic analysis on floating vertical axis wind turbine with helical blades

The working performance of floating vertical axis wind turbine (FVAWT) with helical blades under complex ocean environment is greatly influenced by its dynamic characteristics. For better grasping the dynamic characteristics of helical blade FVAWT, a slack coupled modeling method is proposed in this paper. During the modeling process, the wind turbine system is divided into two configurations, which are connected through the transmission of large overall motion of the blade. Then the reliability of the proposed model is verified by validating the motions of floating foundation and deformations of blade, respectively. Afterwards, the dynamic characteristics of a 5 MW helical blade FVAWT are analyzed. Results show that the amplitude and the equilibrium position of floater motions are influenced by wave loads and wind loads, respectively. And the blade deformation is dominated by aerodynamic frequency components. In addition, the relative angle between orientation of blade section and direction of the wind are sensitive to the helical twist angle, which will lead to the phase difference of aerodynamic loads and the blade deformations between different sections. This study could provide a reasonable mathematical model on design and investigation of the helical blade FVAWT.

Effect of solid-state phase transformation on residual stress of selective laser melting Ti6Al4V

Residual stress in selective laser melting (SLM) is one of the key challenges in terms of precision control, success rate and the performance of deposited components. Ti6Al4V belongs to α+β titanium alloy, the residual stress of selective laser melted (SLMed) Ti6Al4V component maybe affected by solid-state phase transformation result from complex thermal history of SLM. In the present study, effect of solid-state phase transformation on residual stress of SLM Ti6Al4V was investigated. A coupled modeling method of thermo-metallurgical-mechanical considering solid-state phase transition is provided and validated by microstructure observation and residual stress measurements. Then the solid-state phase transformation strain was neglected in the validated model, the computed residual stress is used to investigate the effect of solid-state phase transformation strain on residual stress by comparing with experimental measurements. In addition, the influence of the difference in yield strength and thermal expansion coefficient between the original phase and the transition phase on the residual stress is discussed. It has been found that the residual stress of SLMed Ti6Al4V is related to the direction, the longitudinal residual stress is about twice transverse, and they are all tensile stresses. The microstructure and residual stress predicted by the simulation are in good agreement with the experimental measurements. The microstructure of SLM Ti6Al4V is mainly composed of martensite α', and the average error between the predicted longitudinal stress and measurement is 2.1%. The solid-state phase transformation has a stress relaxation effect during the SLM Ti6Al4V, predicted longitudinal and transverse residual stress exceeds the experimental measurement by up to 80.7% and 53.9%, when neglecting the solid-state phase transformation strain. The influence of the solid-state phase transformation of SLM Ti6Al4V on the residual stress is mainly determined by the volume change between the solid-state phases.

Free vibration analysis of a rotating graphene nanoplatelet reinforced pre-twist blade-disk assembly with a setting angle

This paper investigates the coupled modeling method and free vibration characteristics of a graphene nanoplatelet (GPL) reinforced blade-disk rotor system in which the blade has a pre-twist angle and setting angle. Based on the Kirchhoff plate theory and the Euler–Bernoulli beam theory, the theoretical model of the rotating blade-disk assembly is carried out accurately. The effective material properties of the blade and disk are assumed to vary continually along their thickness directions and are determined via the Halpin–Tsai micromechanics model together with the rule of mixture. The coupled equations of motion are derived in accordance with the Lagrange's equation. Then, the substructure modal synthesis method and the Galerkin method are employed to calculate the free vibration results of the rotor. Additionally, the effects of the rotating speed, GPL distribution pattern, GPL weight fraction, length-to-thickness ratio and length-to-width ratio of GPLs, inner and outer radius of the disk, and pre-twist angle per unit length, setting angle and length of the blade on free vibration characteristics of the rotating blade-shaft assembly are discussed in detail.

A Coupled Thermomechanical Modeling Method for Predicting Grinding Residual Stress Based on Randomly Distributed Abrasive Grains

Abstract In this research, we propose a coupled thermomechanical modeling method for predicting grinding residual stress based on randomly distributed grains. In order to deal with the problem that the nominal grinding force is too small to generate the plastic deformation, we hold the opinion that grinding residual stress is totally derived from three factors: thermal stress, the nominal grinding force (pressure) over the entire grinding zone, and the equivalent plowing force just under the bottom of the abrasive wheel. Finite element model (FEM) simulation of the single-grain grinding (SGG) is conducted to obtain the critical plowing depth and the SGG force at an arbitrary cutting depth. Based on the randomly distributed abrasive grains, the equivalent grinding heat source model, the equivalent SGG plowing force model, and the equivalent nominal pressure model are all established. A 2D coupled thermomechanical model is established to simulate the grinding process for temperature fields and grinding residual stress fields. In addition, verification tests are conducted to validate the model. It turns out that the coupled model can accurately predict the multiphysical fields on both temperature and residual stress. Based on the simulation results of the model, the generation mechanism of grinding residual stress is quantitatively studied. This research provides a promising pathway to residual stress control of grinding.

CFD simulations of natural cross ventilation through an apartment with modified hourly wind information from a meteorological station

Natural ventilation in buildings can improve indoor air quality and thermal comfort and reduce air-conditioning use except for highly polluted area. Traditionally, the inflow boundary conditions for calculating natural ventilation used weather data from a meteorological station that is often in a suburb. The use of hour-by-hour wind velocity from the station may give rise to some errors because of the large time step. This investigation proposed a correlation method for converting the hour-by-hour wind velocity from a meteorological station to minute-by-minute velocity, using data measured on the rooftop of the building of interest. A CFD simulation with the coupled modeling method using the unsteady RNG k-ɛ model was performed to calculate airflow around the building and airflow in an apartment simultaneously. The computed outdoor wind velocity and indoor ventilation rate were compared with the corresponding experimental data. The results showed that the simulations calculated the outdoor wind velocity on the building rooftop and the cross-ventilation rate through the apartment with acceptable accuracy.

A polycrystal plasticity based thermo-mechanical-dynamic recrystallization coupled modeling method and its application to light weight alloys

Hot forming often has to be resorted when processing metals with limited room-temperature formability, such as aluminum, magnesium, etc. The temperature rise induced by plastic work, especially under high strain rates, can exert significant effect on mechanical response as well as dynamic recrystallization of deformed metals. In the present work, a polycrystal plasticity based thermo-mechanical-dynamic recrystallization (DRX) coupled approach is established by implementing thermo-mechanical effect in a VPSC-DRX model where a grain nucleation and growth model is implemented into the VPSC framework. The modeling parameters associated with various slip modes, temperatures and strain rates are calibrated by isothermal compression experiments, and then evolution functions of hardening and DRX related parameters with respect to temperature and strain rate are established. The integrated computation of plastic deformation, texture, grain size and temperature update in hot deformation of metals can be achieved. The proposed method is verified and then applied to simulate hot extrusion processes of magnesium alloy bars at three different ram speeds. The influences of ram speed on development of deformation texture and grain size are analyzed. The temperature rise due to plastic work enhances stress softening and stimulates grain growth, makes the macro/micro responses of materials no longer monotonically varied with strain rate.

Analysis of the effect of an electrically conductive die on electromagnetic sheet metal forming process using the finite element-circuit coupled method

Accurate calculation of electromagnetic parameters in electromagnetic forming (EMF) process is crucial for predicting the deformation behavior of metallic workpieces. Previous theoretical and numerical studies for EMF process with a die have assumed that the die near the workpiece is non-conductive. However, the simplified treatment could be invalid for the cases with a conductive die since an eddy current would also be induced in the die under transient magnetic fields, thus resulting in the change of electromagnetic force acting on the workpiece. In this work, a coupled finite element method and circuit simulation approach with an improved circuit model for analyzing the workpiece deformation is presented, in which the mechanical analysis of the workpiece is done using ANSYS, while the circuit analysis is performed using an improved current filament model. Numerical simulations have been carried out for two types of EMF process, revealing the potential effects of an electrically conductive die on the electromagnetic force distribution and workpeice deformation. The coupled modeling method and simulation results could be useful for better understanding EMF process and designing EMF systems.

Unified Modeling Method for Large Space Structures Using Absolute Nodal Coordinate

A unified rigid-flexible coupled modeling method for large flexible space structures is proposed based on absolute nodal coordinate formulation (ANCF). The explicit formulas of gravitational potential energy and generalized gravitational force are developed, which are simple to use and apply to all ANCF elements. First, the shape functions of all kinds of ANCF elements are written as a unified form by using the Kronecker product. Then, the equations of motion are derived through Hamilton’s principle. A Taylor series expansion is adopted to obtain the explicit expression of gravitational potential energy. Also, a simplified model of the gravitational force is proposed to improve simulation efficiency. Finally, two case studies are presented to validate the proposed modeling method, including a two-dimensional Euler–Bernoulli beam in elliptic orbits and a thin plate in a circular orbit. The effects of orbital eccentricity on the orbital and attitude accuracies of the proposed method, the mutual effects between the attitude motion and structural vibrations, and the effects of the flexibility on the attitude controller of the beam are also investigated. Simulation results show that the proposed modeling method takes gravitational force as well as gravity gradient torque into account accurately. The simplified model is recommended because of its accuracy and time efficiency.

Analysis of flow distribution in plate-type core affected by uneven inlet temperature distribution

The flow and power distribution characteristics of plate-type fuel reactor core have been investigated in the present study. A reactor core thermal-hydraulic and neutronics coupled model was established using RELAP5-3D codes. The coupled modeling method was used to establish the thermo-hydraulic model, and the phenomenon of two-phase flow instability in a parallel two-channel system was used to verify the reliability of the method. Besides, the influence on power and flow distributions of uneven core inlet temperature was also studied by the application of coupled three-dimensional neutron-kinetics and thermal-hydraulics. The results show that, the coupled modeling method is reliable and can be used to establish the thermo-hydraulic model of a reactor core. By this method, both the effects of heating power and inlet temperature on flow distribution have been studied. The flow and power distributions of reactor core are inseparable and have a great effect on each other under the strong coupling of thermal-hydraulic and neutronics, but the non-uniformity of power distribution is greater than flow distribution. When reactor core inlet temperature distribution is uneven, reactor power peaking factor shifts to the low inlet temperature region, and flow peaking factor shifts to the high inlet temperature region. The effect of uneven core inlet temperature on flow distribution has a far greater impact than reactor power.

Performance Prediction of Gel Water Shutoff in Horizontal Wells Using a Newly Coupled Reservoir–Wellbore Model

Water shutoff is a commonly used method to mitigate the early breakthrough in horizontal wells. Gel is frequently used as an effective water shutoff agent in mature fields, especially for horizontal wells in recent years. However, the relevant water shutoff prediction model lacks the accurate physical description of the gelation phenomenon. Using the conventional model, which simply accounts for the gelation mechanisms, does not allow us to predict the horizontal wells performance correctly. In this paper, a newly coupled reservoir–wellbore model for horizontal wells gel water shutoff prediction is presented. A conventional gel simulator is used to simulate the gel injection process in the reservoir and then modified to predict the horizontal well performance after the treatment. The time-varying residual resistance factor model and viscosity model is developed to simulate the gel degradation process. Especially, the wellbore pressure drop calculation takes account for the non-Newtonian behavior during and after the gel injection. An explicit modular coupled scheme, which consists of reservoir modular and wellbore modular, is adopted to numerically predict the horizontal wells performance. The newly presented method not only simulates the gel injection process but also predict the water shut off performance in horizontal wells. A field horizontal water shutoff case prediction shows that the coupled modeling method can give satisfactory results to guide the water shutoff treatment.