A. M. Ummati, Chih-Shian Chen, Ren‐Zuo Wang, Chung-Yue Wang
Analysis of a single-span bridge with rubber bearing as the isolation system is performed under earthquakes. The conventional bridge seismic design requires the whole structure to be perfectly connected to avoid interrupting the transfer of earthquake energy from the ground through the bridge. A bridge with this typical design requires a high-cost construction due to the need for a huge section of the bridge to resist the earthquake force demand. Thus, many bridges in Taiwan are designed with a rubber bearing only put in between the column and girder without an anchor system. Thus, the bridge movement by rubber displacement is permissible, but the sliding displacement must be accommodated to limit the movement. The sliding displacement is the method to exploit the friction force provided by the sliding on the top and bottom interface of the rubber with the girder and column to dissipate the earthquake input energy transmitted to the structure. By involving the role of surface friction, the shear force transmitted to the structure can be reduced and the bridge performance optimized. General Functional Bearing Model (GFBM) analysis is a rubber bearing analysis which unmerges the function of friction and restoring force. In contrast with the conventional method, the rubber bearing designed with GFBM analysis may reduce the bridge stiffness and deck acceleration, and it is more convenient because only sliding displacement needs to be controlled. This research proposed GFBM analysis to simulate the rubber bearing that is reflected in the real conditions of bridges in Taiwan.
{"title":"Analysis of general functional bearing model in a single-span bridge to identify structure response and suitable friction coefficient under near- and far-fault earthquakes","authors":"A. M. Ummati, Chih-Shian Chen, Ren‐Zuo Wang, Chung-Yue Wang","doi":"10.1093/jom/ufac041","DOIUrl":"https://doi.org/10.1093/jom/ufac041","url":null,"abstract":"Analysis of a single-span bridge with rubber bearing as the isolation system is performed under earthquakes. The conventional bridge seismic design requires the whole structure to be perfectly connected to avoid interrupting the transfer of earthquake energy from the ground through the bridge. A bridge with this typical design requires a high-cost construction due to the need for a huge section of the bridge to resist the earthquake force demand. Thus, many bridges in Taiwan are designed with a rubber bearing only put in between the column and girder without an anchor system. Thus, the bridge movement by rubber displacement is permissible, but the sliding displacement must be accommodated to limit the movement. The sliding displacement is the method to exploit the friction force provided by the sliding on the top and bottom interface of the rubber with the girder and column to dissipate the earthquake input energy transmitted to the structure. By involving the role of surface friction, the shear force transmitted to the structure can be reduced and the bridge performance optimized. General Functional Bearing Model (GFBM) analysis is a rubber bearing analysis which unmerges the function of friction and restoring force. In contrast with the conventional method, the rubber bearing designed with GFBM analysis may reduce the bridge stiffness and deck acceleration, and it is more convenient because only sliding displacement needs to be controlled. This research proposed GFBM analysis to simulate the rubber bearing that is reflected in the real conditions of bridges in Taiwan.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":"1 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61541573","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
T. Kuraishi, Takuya Terahara, K. Takizawa, T. Tezduyar
In computational flow analysis with moving solid surfaces and contact between the solid surfaces, it is a challenge to represent the boundary layers with an accuracy attributed to moving-mesh methods and to represent the contact without leaving a mesh protection gap. The space-time topology change (ST-TC) method, introduced in 2013, makes moving-mesh computation possible even when we have contact between moving solid surfaces or other kinds of flow-domain TC. The contact is represented without giving up on high-resolution flow representation near the moving surfaces. With the ST-TC and other ST computational methods introduced before and after, it has been possible to address many of the challenges encountered in conducting this class of flow analysis in the presence of additional complexities such as geometric complexity, rotation or deformation of the solid surfaces and the multiscale nature of the flow. In this first part of a two-part article, we provide an overview of the methods that made all that possible. We also provide an overview of the computations performed for tire aerodynamics with challenges that include the complexity of a near-actual tire geometry with grooves, road contact, tire deformation and rotation, road roughness and fluid films.
{"title":"Computational flow analysis with boundary layer and contact representation: I. Tire aerodynamics with road contact","authors":"T. Kuraishi, Takuya Terahara, K. Takizawa, T. Tezduyar","doi":"10.1093/jom/ufac009","DOIUrl":"https://doi.org/10.1093/jom/ufac009","url":null,"abstract":"In computational flow analysis with moving solid surfaces and contact between the solid surfaces, it is a challenge to represent the boundary layers with an accuracy attributed to moving-mesh methods and to represent the contact without leaving a mesh protection gap. The space-time topology change (ST-TC) method, introduced in 2013, makes moving-mesh computation possible even when we have contact between moving solid surfaces or other kinds of flow-domain TC. The contact is represented without giving up on high-resolution flow representation near the moving surfaces. With the ST-TC and other ST computational methods introduced before and after, it has been possible to address many of the challenges encountered in conducting this class of flow analysis in the presence of additional complexities such as geometric complexity, rotation or deformation of the solid surfaces and the multiscale nature of the flow. In this first part of a two-part article, we provide an overview of the methods that made all that possible. We also provide an overview of the computations performed for tire aerodynamics with challenges that include the complexity of a near-actual tire geometry with grooves, road contact, tire deformation and rotation, road roughness and fluid films.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":"1 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61539735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The intracellular transport process plays an important role in delivering essential materials throughout branched geometries of neurons for their survival and function. Many neurodegenerative diseases have been associated with the disruption of transport. Therefore, it is essential to study how neurons control the transport process to localize materials to necessary locations. Here, we develop a novel optimization model to simulate the traffic regulation mechanism of material transport in three-dimensional complex geometries of neurons. The transport is controlled to avoid traffic jams of materials by minimizing a predefined objective function. The optimization subjects to a set of partial differential equation (PDE) constraints that describe the material transport process based on a macroscopic molecular-motor-assisted transport model of intracellular particles. The proposed PDE-constrained optimization model is solved in complex tree structures by using the isogeometric analysis. Different simulation parameters are used to introduce traffic jams and study how neurons handle the transport issue. Specifically, we successfully model and explain the traffic jam caused by the reduced number of microtubules (MTs) and MT swirls. In summary, our model effectively simulates the material transport process in healthy neurons and also explains the formation of a traffic jam in abnormal neurons. Our results demonstrate that both geometry and MT structure play important roles in achieving an optimal transport process in neurons.
{"title":"Modeling intracellular transport and traffic jam in 3D neurons using PDE-constrained optimization","authors":"Angran Li, Y. Zhang","doi":"10.1093/jom/ufac007","DOIUrl":"https://doi.org/10.1093/jom/ufac007","url":null,"abstract":"The intracellular transport process plays an important role in delivering essential materials throughout branched geometries of neurons for their survival and function. Many neurodegenerative diseases have been associated with the disruption of transport. Therefore, it is essential to study how neurons control the transport process to localize materials to necessary locations. Here, we develop a novel optimization model to simulate the traffic regulation mechanism of material transport in three-dimensional complex geometries of neurons. The transport is controlled to avoid traffic jams of materials by minimizing a predefined objective function. The optimization subjects to a set of partial differential equation (PDE) constraints that describe the material transport process based on a macroscopic molecular-motor-assisted transport model of intracellular particles. The proposed PDE-constrained optimization model is solved in complex tree structures by using the isogeometric analysis. Different simulation parameters are used to introduce traffic jams and study how neurons handle the transport issue. Specifically, we successfully model and explain the traffic jam caused by the reduced number of microtubules (MTs) and MT swirls. In summary, our model effectively simulates the material transport process in healthy neurons and also explains the formation of a traffic jam in abnormal neurons. Our results demonstrate that both geometry and MT structure play important roles in achieving an optimal transport process in neurons.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":"1 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61538939","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The interest for composites has constantly grown in recent years, especially in the aerospace and automotive industries, as they can be moulded in complex form and geometry, as well as exhibit enhanced engineering properties. Nevertheless, despite the accelerated diffusion of laminated composites, the design of these materials is often restrained by the lack of cost-effective modeling techniques. In fact, the existing numerical strategies allowing for cheap simulations of laminated structures usually fail to directly capture out-of-plane through-the-thickness stresses, which are typically responsible for failure modes such as delamination. In this context, a stress recovery approach based on equilibrium has been recently shown to be an efficient modeling strategy in the framework of isogeometric analysis. Since immersed approaches like the finite cell method have been proven to be a viable alternative to mesh-conforming discretization for dealing with complex/dirty geometries as well as trimmed surfaces, we herein propose to extend the stress recovery approach combining the finite cell method, isogeometric analysis and equilibrium to model the out-of-plane behavior of Kirchhoff laminated plates. Extensive numerical tests showcase the effectiveness of the proposed approach.
{"title":"Cost-effective and accurate interlaminar stress modeling of composite Kirchhoff plates via immersed isogeometric analysis and equilibrium","authors":"A. Patton, M. Carraturo, F. Auricchio, A. Reali","doi":"10.1093/jom/ufac005","DOIUrl":"https://doi.org/10.1093/jom/ufac005","url":null,"abstract":"The interest for composites has constantly grown in recent years, especially in the aerospace and automotive industries, as they can be moulded in complex form and geometry, as well as exhibit enhanced engineering properties. Nevertheless, despite the accelerated diffusion of laminated composites, the design of these materials is often restrained by the lack of cost-effective modeling techniques. In fact, the existing numerical strategies allowing for cheap simulations of laminated structures usually fail to directly capture out-of-plane through-the-thickness stresses, which are typically responsible for failure modes such as delamination. In this context, a stress recovery approach based on equilibrium has been recently shown to be an efficient modeling strategy in the framework of isogeometric analysis. Since immersed approaches like the finite cell method have been proven to be a viable alternative to mesh-conforming discretization for dealing with complex/dirty geometries as well as trimmed surfaces, we herein propose to extend the stress recovery approach combining the finite cell method, isogeometric analysis and equilibrium to model the out-of-plane behavior of Kirchhoff laminated plates. Extensive numerical tests showcase the effectiveness of the proposed approach.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":"1 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61539192","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Both surface ground motion and cavity stress concentration have always been considered in the designs of earthquake engineering. In this paper, a theoretical approach is used to study the scattering problem of circular holes under a scalene trapezoidal hill. The wave displacement function was obtained by solving the Helmholtz equation that meets the zero-stress boundary conditions by the variable separation method and the image method. Based on the complex function, the multipolar coordinate method and the region-matching technique, algebraic equations were established at auxiliary boundaries and free boundary conditions in the complex domain. Auxiliary circles were used to solve the singularity of the reflex angle at the trapezoidal corner. Then, according to the sample statistics, instead of the Fourier expansion method, the least-squares method was used to solve the undetermined coefficient of the algebraic equations by discrete boundaries. Frequency responses for some parameters were calculated and discussed. The numerical results demonstrate that the continuity of the auxiliary boundaries and the accuracy of the zero-stress boundary are good; the displacement of the free surface and the stress of the circular hole are related to the shape of the trapezoid, the position of the circular hole, the direction of the incident wave and the frequency content of the excitation. Finally, time-domain responses were calculated by inverse fast Fourier transform based on the frequency domain theory, and the results have revealed the wave propagation mechanism in the complicated structure.
{"title":"Scattering of a scalene trapezoidal hill with a shallow cavity to SH waves","authors":"Yingchao Sun, Zai-lin Yang, Lei Chen, Duanhua Mao","doi":"10.1093/jom/ufac010","DOIUrl":"https://doi.org/10.1093/jom/ufac010","url":null,"abstract":"Both surface ground motion and cavity stress concentration have always been considered in the designs of earthquake engineering. In this paper, a theoretical approach is used to study the scattering problem of circular holes under a scalene trapezoidal hill. The wave displacement function was obtained by solving the Helmholtz equation that meets the zero-stress boundary conditions by the variable separation method and the image method. Based on the complex function, the multipolar coordinate method and the region-matching technique, algebraic equations were established at auxiliary boundaries and free boundary conditions in the complex domain. Auxiliary circles were used to solve the singularity of the reflex angle at the trapezoidal corner. Then, according to the sample statistics, instead of the Fourier expansion method, the least-squares method was used to solve the undetermined coefficient of the algebraic equations by discrete boundaries. Frequency responses for some parameters were calculated and discussed. The numerical results demonstrate that the continuity of the auxiliary boundaries and the accuracy of the zero-stress boundary are good; the displacement of the free surface and the stress of the circular hole are related to the shape of the trapezoid, the position of the circular hole, the direction of the incident wave and the frequency content of the excitation. Finally, time-domain responses were calculated by inverse fast Fourier transform based on the frequency domain theory, and the results have revealed the wave propagation mechanism in the complicated structure.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":"1 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61539792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C. Ri, RyongSik O, Qianghfu Zhao, Chunghyok Chae, Yong-Seung Sin, Yong-Seung Sin
The rotor system supported by the cylindrical roller bearings is widely used in various fields, such as aviation, space and machinery due to its importance. In study of the analysis of the vibration characteristics of the rotor system, it is important to accurately calculate the stiffness and damping of the cylindrical roller bearings. Therefore, in this paper, the dynamic characteristics of the simple rotor-bearing system were analyzed based on the new dynamic model of the rotor system considering the comprehensive stiffness and damping model of the cylindrical roller bearing. In consideration of the radial clearance of the cylindrical roller bearing, the radial load acting on the cylindrical roller bearing is derived and based on this, the Hertz contact stiffness model of the cylindrical roller bearing is obtained. After obtaining the oil film stiffness model of the cylindrical roller bearing according to the EHL theory, the comprehensive stiffness of the cylindrical roller bearing was calculated by combining the Hertz contact stiffness and the oil film stiffness of the cylindrical roller bearing. After a comprehensive damping model of the cylindrical roller bearing considering the radial clearance was created, a dynamic model of the simple rotor-bearing system was created based on the comprehensive stiffness and damping model of the cylindrical roller bearing. The dynamic characteristics of the simple rotor-bearing system were analyzed using the MATLAB program. The amplitude of the simple rotor-bearing system considering the comprehensive stiffness and damping was reduced by 18.2% compared to the case where it was not considered. This shows that the structure of the cylindrical roller bearing has a restraining effect on the unbalanced response of the rotor system.
{"title":"Dynamic analysis of the single rotor-bearing system considering the comprehensive stiffness and damping","authors":"C. Ri, RyongSik O, Qianghfu Zhao, Chunghyok Chae, Yong-Seung Sin, Yong-Seung Sin","doi":"10.1093/jom/ufac022","DOIUrl":"https://doi.org/10.1093/jom/ufac022","url":null,"abstract":"The rotor system supported by the cylindrical roller bearings is widely used in various fields, such as aviation, space and machinery due to its importance. In study of the analysis of the vibration characteristics of the rotor system, it is important to accurately calculate the stiffness and damping of the cylindrical roller bearings. Therefore, in this paper, the dynamic characteristics of the simple rotor-bearing system were analyzed based on the new dynamic model of the rotor system considering the comprehensive stiffness and damping model of the cylindrical roller bearing. In consideration of the radial clearance of the cylindrical roller bearing, the radial load acting on the cylindrical roller bearing is derived and based on this, the Hertz contact stiffness model of the cylindrical roller bearing is obtained. After obtaining the oil film stiffness model of the cylindrical roller bearing according to the EHL theory, the comprehensive stiffness of the cylindrical roller bearing was calculated by combining the Hertz contact stiffness and the oil film stiffness of the cylindrical roller bearing. After a comprehensive damping model of the cylindrical roller bearing considering the radial clearance was created, a dynamic model of the simple rotor-bearing system was created based on the comprehensive stiffness and damping model of the cylindrical roller bearing. The dynamic characteristics of the simple rotor-bearing system were analyzed using the MATLAB program. The amplitude of the simple rotor-bearing system considering the comprehensive stiffness and damping was reduced by 18.2% compared to the case where it was not considered. This shows that the structure of the cylindrical roller bearing has a restraining effect on the unbalanced response of the rotor system.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":"1 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61539958","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The stress intensity factors of a semi-infinite crack propagating with constant speed in an anisotropic elastic solid under a uniform stress wave loading are considered. The crack is assumed to start propagating at some arbitrary time after an obliquely incident plane stress wave strikes the crack tip. It is shown that the stress intensity factor of the propagating crack has the form of the product of a universal matrix function of the crack speed and an equivalent stationary crack stress intensity factor of t*, which is the time that would have elapsed since the incident wavestruck the crack tip if the crack tip had been always at its instantaneous position. The present result is a generalization of that obtained by Freund for isotropic materials.
{"title":"Crack propagation induced by a plane stress wave in a general anisotropic elastic material","authors":"Kuang-Chong Wu","doi":"10.1093/jom/ufac030","DOIUrl":"https://doi.org/10.1093/jom/ufac030","url":null,"abstract":"The stress intensity factors of a semi-infinite crack propagating with constant speed in an anisotropic elastic solid under a uniform stress wave loading are considered. The crack is assumed to start propagating at some arbitrary time after an obliquely incident plane stress wave strikes the crack tip. It is shown that the stress intensity factor of the propagating crack has the form of the product of a universal matrix function of the crack speed and an equivalent stationary crack stress intensity factor of t*, which is the time that would have elapsed since the incident wavestruck the crack tip if the crack tip had been always at its instantaneous position. The present result is a generalization of that obtained by Freund for isotropic materials.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":"60 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61540604","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Numerous engineering applications exist for the piezoelectric effect, which results from the electromechanical coupling between electrical and mechanical fields. In-plane vibrations of piezoelectric plates’ resonance frequencies and associated mode shapes have been thoroughly investigated. However, analytical solutions for in-plane-dominated vibrations of thick piezoelectric circular plates are limited. In this paper, higher-order plate theories for the in-plane-dominated vibration characteristics of piezoelectric circular thick plates under fully clamped and completely free boundary conditions are presented. The resonant frequencies and associated mode shapes were investigated based on two higher-order plate theories: second-order shear deformation plate theory and third-order shear deformation plate theory, as well as simplified third-order linear piezoelectric theory. Hamilton's principle was applied to derive equations of motion and boundary conditions. In the theoretical analysis, the resonant frequencies, associated mode shapes and distribution of electric displacements for various radius-to-thickness ratios were calculated. The numerical results obtained by the finite element method were compared with those obtained from theoretical analysis. Excellent agreement was found between the theoretical and numerical results for the thick piezoelectric circular plates.
{"title":"In-plane-dominated vibration characteristics of piezoelectric thick circular plates based on higher-order plate theories","authors":"Ming Ji, Yi-Chuang Wu, Chien-Ching Ma","doi":"10.1093/jom/ufac034","DOIUrl":"https://doi.org/10.1093/jom/ufac034","url":null,"abstract":"Numerous engineering applications exist for the piezoelectric effect, which results from the electromechanical coupling between electrical and mechanical fields. In-plane vibrations of piezoelectric plates’ resonance frequencies and associated mode shapes have been thoroughly investigated. However, analytical solutions for in-plane-dominated vibrations of thick piezoelectric circular plates are limited. In this paper, higher-order plate theories for the in-plane-dominated vibration characteristics of piezoelectric circular thick plates under fully clamped and completely free boundary conditions are presented. The resonant frequencies and associated mode shapes were investigated based on two higher-order plate theories: second-order shear deformation plate theory and third-order shear deformation plate theory, as well as simplified third-order linear piezoelectric theory. Hamilton's principle was applied to derive equations of motion and boundary conditions. In the theoretical analysis, the resonant frequencies, associated mode shapes and distribution of electric displacements for various radius-to-thickness ratios were calculated. The numerical results obtained by the finite element method were compared with those obtained from theoretical analysis. Excellent agreement was found between the theoretical and numerical results for the thick piezoelectric circular plates.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":"1 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61541027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Abstract The low-grade heat source thermoelectric system generates electricity using a working fluid at temperature lower than 100°C or gas at temperature lower than 250°C. The system is usually composed of binary (1 + 0.5 × 2) cycles. Positive net output power or high efficiency of the system can only be feasible after optimization. Most works focused on the cycle of working fluid and treated the power consumptions of the other cycles as constants. However, both cycles should be comprehensively considered in optimization, especially when power consumptions vary with working conditions. This research selected an organic Rankine cycle thermoelectric system for demonstration. A thermodynamic model conforming to the target system was built. The temperature of the heat source and the pressure at expander inlet were tailored using the genetic algorithm. The best efficiency is 1.89%, and the largest net output power is 5.80 kW. Both results are better than those (efficiency = 1.59% and net output power = 5.34 kW) from benchmarks under the highest temperature of heat source and inlet pressure among possible working conditions. Experimental results are provided for both validation of the model and confirmation of the superiority of optimization results.
{"title":"Realization and optimization of a binary cycle power generating system using a low-grade heat source","authors":"Wun-Hao Yang,Pin-Cheng Hou,Wei-Hung Shih,Sung-Wei Hsu,Yu-Bin Chen","doi":"10.1093/jom/ufac014","DOIUrl":"https://doi.org/10.1093/jom/ufac014","url":null,"abstract":"Abstract The low-grade heat source thermoelectric system generates electricity using a working fluid at temperature lower than 100°C or gas at temperature lower than 250°C. The system is usually composed of binary (1 + 0.5 × 2) cycles. Positive net output power or high efficiency of the system can only be feasible after optimization. Most works focused on the cycle of working fluid and treated the power consumptions of the other cycles as constants. However, both cycles should be comprehensively considered in optimization, especially when power consumptions vary with working conditions. This research selected an organic Rankine cycle thermoelectric system for demonstration. A thermodynamic model conforming to the target system was built. The temperature of the heat source and the pressure at expander inlet were tailored using the genetic algorithm. The best efficiency is 1.89%, and the largest net output power is 5.80 kW. Both results are better than those (efficiency = 1.59% and net output power = 5.34 kW) from benchmarks under the highest temperature of heat source and inlet pressure among possible working conditions. Experimental results are provided for both validation of the model and confirmation of the superiority of optimization results.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":"4 1","pages":"166-175"},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138536399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the process of oil and gas extraction, a system that uses a pump and reversing mechanism to achieve high-efficiency export of gas–liquid mixture is devised. A gas–liquid ejector is fitted in the front of the device to boost pressure inside the tank in order to store more gas in the tank under a given volume. To meet the working conditions of gas–liquid high-efficiency transport device and obtain a larger outlet pressure and better ejection performance, this paper investigates the effect of outlet pressure, ratio of throat inlet area to nozzle outlet area and nozzle contraction angle on the ejection performance of gas–liquid ejector, and simulations using the computational fluid dynamics approach. At the same time, an experiment platform is built for testing. The research findings show that the ejection gas flow rate and ejection ratio of gas–liquid ejector decrease with the increase of the outlet pressure; as the ratio of throat inlet area to nozzle outlet area increases, the ejection gas flow rate and the ejection ratio of gas–liquid ejector increase first and then decrease. Different nozzle diameters correspond to different optimal area ratios; under the specified working parameters, with the increase of the nozzle contraction angle, the ejection gas flow rate and injection ratio of the gas–liquid ejector increase first and then decrease, and there is an optimal nozzle contraction angle.
{"title":"Research on performance optimization of gas–liquid ejector in multiphase mixed transportation device","authors":"Junyou Zhao, Xin Wei, Junyan Zou, Yaning Zhang, Jiafeng Sun, Zhongping Liu","doi":"10.1093/jom/ufac001","DOIUrl":"https://doi.org/10.1093/jom/ufac001","url":null,"abstract":"In the process of oil and gas extraction, a system that uses a pump and reversing mechanism to achieve high-efficiency export of gas–liquid mixture is devised. A gas–liquid ejector is fitted in the front of the device to boost pressure inside the tank in order to store more gas in the tank under a given volume. To meet the working conditions of gas–liquid high-efficiency transport device and obtain a larger outlet pressure and better ejection performance, this paper investigates the effect of outlet pressure, ratio of throat inlet area to nozzle outlet area and nozzle contraction angle on the ejection performance of gas–liquid ejector, and simulations using the computational fluid dynamics approach. At the same time, an experiment platform is built for testing. The research findings show that the ejection gas flow rate and ejection ratio of gas–liquid ejector decrease with the increase of the outlet pressure; as the ratio of throat inlet area to nozzle outlet area increases, the ejection gas flow rate and the ejection ratio of gas–liquid ejector increase first and then decrease. Different nozzle diameters correspond to different optimal area ratios; under the specified working parameters, with the increase of the nozzle contraction angle, the ejection gas flow rate and injection ratio of the gas–liquid ejector increase first and then decrease, and there is an optimal nozzle contraction angle.","PeriodicalId":50136,"journal":{"name":"Journal of Mechanics","volume":"77 1","pages":""},"PeriodicalIF":1.7,"publicationDate":"2022-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"61538926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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