Seven novice subjects participated in experiments of stick balancing on a linear track in the anterior-posterior (AP) and the medio-lateral (ML) directions. The goal of the experiments was to test how the depth perception in the subjects' AP direction affects balancing performance compared to balancing in the ML direction, where depth perception does not play a role. It is easier to balance longer sticks than shorter ones, therefore balancing performance is measured by the length of the shortest stick that subjects can balance. Subjects were found to be able to balance shorter sticks in the ML direction than in the AP direction: the ratio of the shortest stick lengths in the ML direction relative to the AP direction was in average 0.53. Thus, the additional challenge posed by depth perception in the AP direction is clearly observable. Additionally, repeated trials were carried out for 5 consecutive days to assess the development of balancing skill by using stabilometry analysis. The maximal balance time of the subjects significantly increased with the days of practice.
{"title":"The Critical Length is a Good Measure to Distinguish between Stick Balancing in the ML and AP Directions","authors":"Dalma J. Nagy, Tamás Insperger","doi":"10.3311/ppme.22937","DOIUrl":"https://doi.org/10.3311/ppme.22937","url":null,"abstract":"Seven novice subjects participated in experiments of stick balancing on a linear track in the anterior-posterior (AP) and the medio-lateral (ML) directions. The goal of the experiments was to test how the depth perception in the subjects' AP direction affects balancing performance compared to balancing in the ML direction, where depth perception does not play a role. It is easier to balance longer sticks than shorter ones, therefore balancing performance is measured by the length of the shortest stick that subjects can balance. Subjects were found to be able to balance shorter sticks in the ML direction than in the AP direction: the ratio of the shortest stick lengths in the ML direction relative to the AP direction was in average 0.53. Thus, the additional challenge posed by depth perception in the AP direction is clearly observable. Additionally, repeated trials were carried out for 5 consecutive days to assess the development of balancing skill by using stabilometry analysis. The maximal balance time of the subjects significantly increased with the days of practice.","PeriodicalId":43630,"journal":{"name":"PERIODICA POLYTECHNICA-MECHANICAL ENGINEERING","volume":" 46","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135241051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A large part of computational fluid dynamics (CFD) studies in hemodynamics concentrates on the berry-like bulgings on cerebral vessel walls, called intracranial aneurysms (IA). One technique is the calculation of particle paths, which can help understand important physiological processes like thrombus formation or drug propagation. The problem is that the particle paths can display chaotic nature even in simple flows, thus, investigating the effects of parameters on the particle paths is essential. The method used in this study consists of four steps. The first step is to voxelize the observed domain into a uniform voxel grid, the second step is to simulate the velocity flow field using the lattice-Boltzmann method, then to calculate one million particle paths using a fourth-order Runge-Kutta integrator. Lastly, the final step is the calculation of the relative perimeter, relative area and their ratio (P/A ratio) for each outlet when the particle release plane is colored according to the outlets the particles took. Five patient-specific cases were investigated. After a voxel size and integrator time step dependence study, the effect of the presence of the aneurysm sack and the particle release time within the heart cycle were assessed. Based on five geometries, the presence of the aneurysm sac increases the P/A ratio (which is a direct link to the chaotic nature of the particle paths), and when the particles are released near the peak and the decelerating phase of the heart cycle, the P/A ratio also significantly increases.
{"title":"Investigating Particle Paths in Intracranial Aneurysms: A Parametric Study","authors":"Dániel Gyürki, György Paál","doi":"10.3311/ppme.23482","DOIUrl":"https://doi.org/10.3311/ppme.23482","url":null,"abstract":"A large part of computational fluid dynamics (CFD) studies in hemodynamics concentrates on the berry-like bulgings on cerebral vessel walls, called intracranial aneurysms (IA). One technique is the calculation of particle paths, which can help understand important physiological processes like thrombus formation or drug propagation. The problem is that the particle paths can display chaotic nature even in simple flows, thus, investigating the effects of parameters on the particle paths is essential. The method used in this study consists of four steps. The first step is to voxelize the observed domain into a uniform voxel grid, the second step is to simulate the velocity flow field using the lattice-Boltzmann method, then to calculate one million particle paths using a fourth-order Runge-Kutta integrator. Lastly, the final step is the calculation of the relative perimeter, relative area and their ratio (P/A ratio) for each outlet when the particle release plane is colored according to the outlets the particles took. Five patient-specific cases were investigated. After a voxel size and integrator time step dependence study, the effect of the presence of the aneurysm sack and the particle release time within the heart cycle were assessed. Based on five geometries, the presence of the aneurysm sac increases the P/A ratio (which is a direct link to the chaotic nature of the particle paths), and when the particles are released near the peak and the decelerating phase of the heart cycle, the P/A ratio also significantly increases.","PeriodicalId":43630,"journal":{"name":"PERIODICA POLYTECHNICA-MECHANICAL ENGINEERING","volume":" 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135241044","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Kornél Májlinger, Levente T. Katula, Balázs Varbai
Several correlations from the professional literature describing the shear and cross tension strength (STS and CTS) of resistance spot welded (RSWed) thin steel sheets were investigated. Some of them need chemical composition or weld nuggets strength hardness as input parameters, making them hardly applicable in the planning stage of the joints. Using STS and CTS data collected from over 250 papers, selected correlations were tested, whether they are applicable to predict the STS and CTS of the RSWed joints at the planning stage to help designers plan their static-loaded welds strength. Most correlations had limitations in the applicable base materials' tensile strength range. Therefore, new equations for STS and CTS are proposed, which can be used to plan in the 300–18900 MPa base metals tensile strength range for similar and dissimilar RSWed joints of thin steel sheets.
{"title":"Global Approach on the Shear and Cross Tension Strength of Resistance Spot Welded Thin Steel Sheets","authors":"Kornél Májlinger, Levente T. Katula, Balázs Varbai","doi":"10.3311/ppme.23184","DOIUrl":"https://doi.org/10.3311/ppme.23184","url":null,"abstract":"Several correlations from the professional literature describing the shear and cross tension strength (STS and CTS) of resistance spot welded (RSWed) thin steel sheets were investigated. Some of them need chemical composition or weld nuggets strength hardness as input parameters, making them hardly applicable in the planning stage of the joints. Using STS and CTS data collected from over 250 papers, selected correlations were tested, whether they are applicable to predict the STS and CTS of the RSWed joints at the planning stage to help designers plan their static-loaded welds strength. Most correlations had limitations in the applicable base materials' tensile strength range. Therefore, new equations for STS and CTS are proposed, which can be used to plan in the 300–18900 MPa base metals tensile strength range for similar and dissimilar RSWed joints of thin steel sheets.","PeriodicalId":43630,"journal":{"name":"PERIODICA POLYTECHNICA-MECHANICAL ENGINEERING","volume":"54 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135267666","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The dynamic spread of photovoltaic power plants in the global energy industry facilitates cost-effective and clean electricity generation. However, the intermittent nature of solar energy poses an increasing challenge from a system management point of view due to the fast-growing capacities. As a consequence, energy storage systems are increasingly important in this area, as they allow the efficient and flexible storage of excess electricity generated in the electricity system. Among various energy storage systems, the power-to-gas technology is becoming more and more important in the integration of weather-dependent renewable energy sources, as it can now provide an effective solution for increasing grid stability and scheduling efficiency, as well as enabling wide variety of application possibilities in the economy, for example in transport, industry or heating systems. The aim of the present research was to determine the potential amount of green hydrogen that can be produced by using the proton-exchange membrane technology, taking into account the climatic conditions in Hungary and the energy production potentials of photovoltaic power plants of given capacities. This is not only novel but also of practical use, as it provides important information about the integration of photovoltaic power plants and the power-to-gas technology to the actors of energy systems and the energy market and the decision-makers concerned. In addition to the vital economic aspects of the research, supporting the decisions of potential investors, it also contains important insights for market-related technological developments.
{"title":"Photovoltaic Energy Generation in Hungary: Potentials of Green Hydrogen Production by PEM Technology","authors":"Gábor Pintér, Henrik Zsiborács","doi":"10.3311/ppme.23333","DOIUrl":"https://doi.org/10.3311/ppme.23333","url":null,"abstract":"The dynamic spread of photovoltaic power plants in the global energy industry facilitates cost-effective and clean electricity generation. However, the intermittent nature of solar energy poses an increasing challenge from a system management point of view due to the fast-growing capacities. As a consequence, energy storage systems are increasingly important in this area, as they allow the efficient and flexible storage of excess electricity generated in the electricity system. Among various energy storage systems, the power-to-gas technology is becoming more and more important in the integration of weather-dependent renewable energy sources, as it can now provide an effective solution for increasing grid stability and scheduling efficiency, as well as enabling wide variety of application possibilities in the economy, for example in transport, industry or heating systems. The aim of the present research was to determine the potential amount of green hydrogen that can be produced by using the proton-exchange membrane technology, taking into account the climatic conditions in Hungary and the energy production potentials of photovoltaic power plants of given capacities. This is not only novel but also of practical use, as it provides important information about the integration of photovoltaic power plants and the power-to-gas technology to the actors of energy systems and the energy market and the decision-makers concerned. In addition to the vital economic aspects of the research, supporting the decisions of potential investors, it also contains important insights for market-related technological developments.","PeriodicalId":43630,"journal":{"name":"PERIODICA POLYTECHNICA-MECHANICAL ENGINEERING","volume":"38 7","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135273902","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Brahim Menacer, Sunny Narayan, Mostefa Bouchetara, Tawfiq Khatir, Pedro Daniel Urbina Coronado
Currently, modern internal combustion engines are receiving great attention due to their efficiency, particularly in response to the increasing limits imposed by environmental and emission legislation. Sound emissions of internal combustion engines are mainly caused by three sources of noise: combustion, mechanical and aerodynamic flow. The secondary motion of the piston plays a crucial role in the analysis of performance, noise, vibration and reliability of internal combustion engine (ICE). In the presented article, a mathematical simulation model has been developed by using of the GT-Suite software to study the rotational and lateral motion of the piston (called secondary motion) as well as the piston slap in ICE. This model takes into account the effect of variation in the major geometric parameters of the skirt design, such as the piston pin offset (P.P.O) and the length of the skirt. Furthermore, a combined model that accounts for the interplay between the secondary dynamics of the piston and the dynamic fluid lubrication has been developed. This model utilizes a mixed lubrication approach for the purpose of simulation. The results of this simulation have demonstrated that the variations in length of the skirt and the P.P.O have a considerable effect on piston secondary motion and tribological performances, and that the lateral motion of the piston is significantly influenced by the piston side force, which plays a crucial role in this behavior.
{"title":"Numerical Analysis to Investigate the Impact of Skirt Geometric Parameters on Secondary Piston Movement in a Single-cylinder Diesel Engine","authors":"Brahim Menacer, Sunny Narayan, Mostefa Bouchetara, Tawfiq Khatir, Pedro Daniel Urbina Coronado","doi":"10.3311/ppme.22459","DOIUrl":"https://doi.org/10.3311/ppme.22459","url":null,"abstract":"Currently, modern internal combustion engines are receiving great attention due to their efficiency, particularly in response to the increasing limits imposed by environmental and emission legislation. Sound emissions of internal combustion engines are mainly caused by three sources of noise: combustion, mechanical and aerodynamic flow. The secondary motion of the piston plays a crucial role in the analysis of performance, noise, vibration and reliability of internal combustion engine (ICE). In the presented article, a mathematical simulation model has been developed by using of the GT-Suite software to study the rotational and lateral motion of the piston (called secondary motion) as well as the piston slap in ICE. This model takes into account the effect of variation in the major geometric parameters of the skirt design, such as the piston pin offset (P.P.O) and the length of the skirt. Furthermore, a combined model that accounts for the interplay between the secondary dynamics of the piston and the dynamic fluid lubrication has been developed. This model utilizes a mixed lubrication approach for the purpose of simulation. The results of this simulation have demonstrated that the variations in length of the skirt and the P.P.O have a considerable effect on piston secondary motion and tribological performances, and that the lateral motion of the piston is significantly influenced by the piston side force, which plays a crucial role in this behavior.","PeriodicalId":43630,"journal":{"name":"PERIODICA POLYTECHNICA-MECHANICAL ENGINEERING","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135883782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The main focus of the current paper is the detection of vortices in fluid flow around a circular cylinder and a square cylinder, with an emphasis on the identification of the parameters used for vortex detection. The authors aim to enhance the practicality of an existing vortex detection method (Lagrangian-averaged vorticity deviation) by providing recommendations for the settings of the vortex detection parameters. The simulations were carried out using ANSYS Workbench 2022 R2, encompassing Reynolds numbers between 12 and 140, and angles of incidence from 0° to 45°. The vortex detection was performed using MATLAB R2020b. The paper provides a comprehensive description of the parameters involved in the detection process and their significance, as well as the implementation of the parameter identification. The study results in the determination of the suggested parameter ranges, and a comparative analysis of different vortex detection methods is also presented for the case of the circular cylinder.
{"title":"Parameter Identification of the Lagrangian-averaged Vorticity Deviation Vortex Detection Method Through the Investigation of Fluid Flow Around Solid Bodies","authors":"Kinga Andrea Kovács, Esztella Balla","doi":"10.3311/ppme.22874","DOIUrl":"https://doi.org/10.3311/ppme.22874","url":null,"abstract":"The main focus of the current paper is the detection of vortices in fluid flow around a circular cylinder and a square cylinder, with an emphasis on the identification of the parameters used for vortex detection. The authors aim to enhance the practicality of an existing vortex detection method (Lagrangian-averaged vorticity deviation) by providing recommendations for the settings of the vortex detection parameters. The simulations were carried out using ANSYS Workbench 2022 R2, encompassing Reynolds numbers between 12 and 140, and angles of incidence from 0° to 45°. The vortex detection was performed using MATLAB R2020b. The paper provides a comprehensive description of the parameters involved in the detection process and their significance, as well as the implementation of the parameter identification. The study results in the determination of the suggested parameter ranges, and a comparative analysis of different vortex detection methods is also presented for the case of the circular cylinder.","PeriodicalId":43630,"journal":{"name":"PERIODICA POLYTECHNICA-MECHANICAL ENGINEERING","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136295423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Lawrance Gunaraj, Sam Paul, Jazeel Mohammed, Edwin Sudhagar, Titus Thankachan
Tool vibration in the boring process is the main concern because of the tool overhanging which leads to high tool wear, cutting force and cutting temperature. Interaction between machine dynamics and the metal cutting operation tool also results in tool vibration. The optimized cutting parameters will able to decrease tool vibration and in turn, increase the productivity in the manufacturing sector. In this study, statistical mathematical approaches to develop models for determining the impact of individual cutting parameters on cutting temperature, tool wear, cutting force, and tool vibration when hard boring AISI 4340 steels. During hard boring of AISI 4340 steel, the current investigation consisted of 27 run trials with three varying levels of cutting velocity, feed rate, and depth of cut and each of these variables was tested at three different levels. This work intends to simultaneous optimize statistical analysis such as Signal-to-Noise (S/N) ratio, Analysis of Variance (ANOVA) and Grey Relational Analysis (GRA). ANOVA and S/N ratio is used to identify the important cutting parameters on the single response optimization and GRA is used to optimize the multi-response optimization technique on cutting parameters. The results shows that both single and multi-response optimization technique shows the same optimized cutting parameter.
{"title":"Optimization of Cutting Parameters for Hard Boring of AISI 4340 Steel Using Signal-to-Noise Ratio, Grey Relation Analysis and Analysis of Variance","authors":"Lawrance Gunaraj, Sam Paul, Jazeel Mohammed, Edwin Sudhagar, Titus Thankachan","doi":"10.3311/ppme.21729","DOIUrl":"https://doi.org/10.3311/ppme.21729","url":null,"abstract":"Tool vibration in the boring process is the main concern because of the tool overhanging which leads to high tool wear, cutting force and cutting temperature. Interaction between machine dynamics and the metal cutting operation tool also results in tool vibration. The optimized cutting parameters will able to decrease tool vibration and in turn, increase the productivity in the manufacturing sector. In this study, statistical mathematical approaches to develop models for determining the impact of individual cutting parameters on cutting temperature, tool wear, cutting force, and tool vibration when hard boring AISI 4340 steels. During hard boring of AISI 4340 steel, the current investigation consisted of 27 run trials with three varying levels of cutting velocity, feed rate, and depth of cut and each of these variables was tested at three different levels. This work intends to simultaneous optimize statistical analysis such as Signal-to-Noise (S/N) ratio, Analysis of Variance (ANOVA) and Grey Relational Analysis (GRA). ANOVA and S/N ratio is used to identify the important cutting parameters on the single response optimization and GRA is used to optimize the multi-response optimization technique on cutting parameters. The results shows that both single and multi-response optimization technique shows the same optimized cutting parameter.","PeriodicalId":43630,"journal":{"name":"PERIODICA POLYTECHNICA-MECHANICAL ENGINEERING","volume":"310 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135816917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In the field of industry, especially in the production areas, it is particularly important that the monitoring of assembly efficiency takes place in real-time mode, and that the related data-based estimation also works quickly and reliably. The Manufacturing Execution System (MES), Enterprise Resource Planning (ERP) and Customer Relationship Management (CRM) systems used by companies provide excellent support in data recording, processes, and storing. For Overall Equipment Effectiveness (OEE) data showing the efficiency of assembly lines, there is a regular need to determine expected values. This paper focuses on OEE values prediction with Multiple Linear Regression (MLR) as supervised machine learning. Many factors affecting OEE (e.g., downtimes, cycle time) are examined and analyzed in order to make a more accurate estimation. Based on real industrial data, we used four different methods to perform prediction with various machine learning algorithms, these were the cumulative, fix rolling horizon, optimal rolling horizon and combined techniques. Each method is evaluated based on similar mathematical formulas.
{"title":"Overall Equipment Effectiveness Prediction with Multiple Linear Regression for Semi-automatic Automotive Assembly Lines","authors":"Péter Dobra, J. Jósvai","doi":"10.3311/ppme.22302","DOIUrl":"https://doi.org/10.3311/ppme.22302","url":null,"abstract":"In the field of industry, especially in the production areas, it is particularly important that the monitoring of assembly efficiency takes place in real-time mode, and that the related data-based estimation also works quickly and reliably. The Manufacturing Execution System (MES), Enterprise Resource Planning (ERP) and Customer Relationship Management (CRM) systems used by companies provide excellent support in data recording, processes, and storing. For Overall Equipment Effectiveness (OEE) data showing the efficiency of assembly lines, there is a regular need to determine expected values. This paper focuses on OEE values prediction with Multiple Linear Regression (MLR) as supervised machine learning. Many factors affecting OEE (e.g., downtimes, cycle time) are examined and analyzed in order to make a more accurate estimation. Based on real industrial data, we used four different methods to perform prediction with various machine learning algorithms, these were the cumulative, fix rolling horizon, optimal rolling horizon and combined techniques. Each method is evaluated based on similar mathematical formulas.","PeriodicalId":43630,"journal":{"name":"PERIODICA POLYTECHNICA-MECHANICAL ENGINEERING","volume":"4 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-09-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88314031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The presented work focuses on the development of a novel method that can numerically describe the properties of metal matrix syntactic foam (MMSF) with low memory requirements and short computational times without losing the properties of the interior structure. In this paper, we propose a novel method that avoids using the homogenization technique and instead rearranges stiffness matrices and constructs specific substructures to perform the overall construction. The two-dimensional cases are discussed in order to focus on the methodology itself. First, the reductions and structural design with solid mesh structures were performed, and then the model was applied on structures filled with iron hollow spheres. So far, the method has been used to evaluate small deformations to see how suitable the subspace technique is for describing metal foams. Aluminum was used as the matrix material, as it is one of the most common materials for MMSFs. The optimal parameters were searched that resulted in the shortest running time for the given construction. Since in the proposed substructure technique only the displacement values at the boundary points are computed, a back-calculation step for each selected substructure was performed to see the interior deformations in the vicinity of an iron hollow sphere.
{"title":"Application of Substructure Techniques to Syntactic Metal Foams in a Finite Element Environment","authors":"Márió Kovács, Balázs Pere, I. Orbulov","doi":"10.3311/ppme.22313","DOIUrl":"https://doi.org/10.3311/ppme.22313","url":null,"abstract":"The presented work focuses on the development of a novel method that can numerically describe the properties of metal matrix syntactic foam (MMSF) with low memory requirements and short computational times without losing the properties of the interior structure. In this paper, we propose a novel method that avoids using the homogenization technique and instead rearranges stiffness matrices and constructs specific substructures to perform the overall construction. The two-dimensional cases are discussed in order to focus on the methodology itself. First, the reductions and structural design with solid mesh structures were performed, and then the model was applied on structures filled with iron hollow spheres. So far, the method has been used to evaluate small deformations to see how suitable the subspace technique is for describing metal foams. Aluminum was used as the matrix material, as it is one of the most common materials for MMSFs. The optimal parameters were searched that resulted in the shortest running time for the given construction. Since in the proposed substructure technique only the displacement values at the boundary points are computed, a back-calculation step for each selected substructure was performed to see the interior deformations in the vicinity of an iron hollow sphere.","PeriodicalId":43630,"journal":{"name":"PERIODICA POLYTECHNICA-MECHANICAL ENGINEERING","volume":"27 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73381586","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The energy consumption of mechanical ventilation in buildings needs to be reduced. An efficient way to achieve this goal is to reduce the hydraulic resistance of the ventilation duct system elements, for example, that of sudden expansions. Ventilation ducts and pipe fittings are frequently of rectangular cross-section. The present paper investigates a passive flow control method in order to reduce the loss coefficient of a square-to-square sudden expansion, where the loss-reducing appendages are short guide vanes, termed as miniflaps, placed at the step edge of the sudden expansion. The turbulent flow is examined numerically using the generalized k-ω model of the Ansys Fluent software for different area ratios of the sudden expansion, miniflap lengths, and miniflap angle setups. The Reynolds number is kept constant at 1.08·105. Based on the results of the numerical simulations, the loss coefficient of the sudden expansion can be reduced by ~20–25% for an optimum miniflap angle between 9° and 12°. Increasing the length of the miniflaps leads to a greater reduction of the loss coefficient up to a miniflap length of 0.3 dh1, where dh1 is the upstream hydraulic diameter of the duct.
{"title":"Parameter Study of a Loss Reducing Passive Flow Control Method in a Square-to-square Sudden Expansion","authors":"E. Lukács, J. Vad","doi":"10.3311/ppme.22389","DOIUrl":"https://doi.org/10.3311/ppme.22389","url":null,"abstract":"The energy consumption of mechanical ventilation in buildings needs to be reduced. An efficient way to achieve this goal is to reduce the hydraulic resistance of the ventilation duct system elements, for example, that of sudden expansions. Ventilation ducts and pipe fittings are frequently of rectangular cross-section. The present paper investigates a passive flow control method in order to reduce the loss coefficient of a square-to-square sudden expansion, where the loss-reducing appendages are short guide vanes, termed as miniflaps, placed at the step edge of the sudden expansion. The turbulent flow is examined numerically using the generalized k-ω model of the Ansys Fluent software for different area ratios of the sudden expansion, miniflap lengths, and miniflap angle setups. The Reynolds number is kept constant at 1.08·105. Based on the results of the numerical simulations, the loss coefficient of the sudden expansion can be reduced by ~20–25% for an optimum miniflap angle between 9° and 12°. Increasing the length of the miniflaps leads to a greater reduction of the loss coefficient up to a miniflap length of 0.3 dh1, where dh1 is the upstream hydraulic diameter of the duct.","PeriodicalId":43630,"journal":{"name":"PERIODICA POLYTECHNICA-MECHANICAL ENGINEERING","volume":"1 1","pages":""},"PeriodicalIF":1.3,"publicationDate":"2023-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84208339","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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