Pub Date : 2023-09-27DOI: 10.15282/jmes.17.3.2023.3.0757
None Kamran Khan, Israr Ahmed
Gasketed bolted flange joints (GBFJ) are commonly used in various industries however, their failure could result in significant losses not only in terms of financial but human life as well. Most of the work present on the performance of the GBFJ involves simplified assumptions by neglecting the effect of bolt scatter. Also, there is a paucity of studies investigating the sealing performance of GBFJ under combined thermal transient and structural loading. In the present study, two different flange sizes of ANSI B16.5 pressure class 900 (4in. and 6in.) are evaluated, using a detailed three-dimensional finite element analysis (FEA). ASME bolt tightening scheme was applied for the preloading of the bolts. Higher bolts and gasket stresses were observed in the case of 6in. flange joint. Also, greater variation in bolt stresses (up to 18 % of the target value) was observed for the 6 in. model which may be due to higher number of bolts resulting in greater scattering phenomena. Both models were found to be safe under the structural loading. However, large relaxation in stresses was observed at high bulk temperature. The gasket stress in 4in. flange model was observed to be less than the minimum seating stress (69 MPa) at temperatures greater than 300 °C implying possible leakage. However, stresses in the 6in. model stayed within the safe limit throughout the thermal and structural loading due to higher bolt target stresses, resulting in its proper seating even at higher temperatures.
{"title":"Combined loading performance analysis of gasketed bolted flange joints with emphasis on bolt scattering","authors":"None Kamran Khan, Israr Ahmed","doi":"10.15282/jmes.17.3.2023.3.0757","DOIUrl":"https://doi.org/10.15282/jmes.17.3.2023.3.0757","url":null,"abstract":"Gasketed bolted flange joints (GBFJ) are commonly used in various industries however, their failure could result in significant losses not only in terms of financial but human life as well. Most of the work present on the performance of the GBFJ involves simplified assumptions by neglecting the effect of bolt scatter. Also, there is a paucity of studies investigating the sealing performance of GBFJ under combined thermal transient and structural loading. In the present study, two different flange sizes of ANSI B16.5 pressure class 900 (4in. and 6in.) are evaluated, using a detailed three-dimensional finite element analysis (FEA). ASME bolt tightening scheme was applied for the preloading of the bolts. Higher bolts and gasket stresses were observed in the case of 6in. flange joint. Also, greater variation in bolt stresses (up to 18 % of the target value) was observed for the 6 in. model which may be due to higher number of bolts resulting in greater scattering phenomena. Both models were found to be safe under the structural loading. However, large relaxation in stresses was observed at high bulk temperature. The gasket stress in 4in. flange model was observed to be less than the minimum seating stress (69 MPa) at temperatures greater than 300 °C implying possible leakage. However, stresses in the 6in. model stayed within the safe limit throughout the thermal and structural loading due to higher bolt target stresses, resulting in its proper seating even at higher temperatures.","PeriodicalId":16166,"journal":{"name":"Journal of Mechanical Engineering and Sciences","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135587091","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}
Pub Date : 2023-06-30DOI: 10.15407/pmach2023.02.033
V. H. Mykhailenko, Yevhen F. Lukianov, Olha I. Lukianova, Tamara S. Vitkovska, Oleksandr Ye. Khinievich
Water is considered as the working fluid of wet steam turbine units. The importance of a purposeful change in the thermophysical properties of water used for energy needs is indicated. A reagent-free method (transverse magnetic field of permanent magnets) of influence on water is proposed. Literature data on currently available papers dedicated to the study of water properties is presented. It is shown that the mechanisms of influence of external physical fields on the physicochemical and thermophysical properties of water have not been elucidated as of now. It is emphasized that the properties of distilled water during exposure and after exposure to physical fields are even less studied. The currently existing contradictions between theoretical ideas about the properties of water and experimental results are considered. It was found that currently there are no correct methods and equipment capable of indicating changes in water properties in real time. As a solution, the equipment and method of analyzing the optical density of distilled water is proposed. The shortcomings of most existing experimental works on the study of the influence of physical fields on the optical density of water are analyzed. The requirements for devices intended for measuring the optical density of distilled water are formulated. A stand was made and experimental work on the study of the dependence of the optical density of distilled water on the induction of a magnetic field that affects it was carried out. It is proved that the magnetic field affects the optical density of distilled water in the infrared range of wavelengths both in the direction of increase (4.1%) and in the direction of decrease (1.7%) depending on the induction of the magnetic field and the speed of water flow through the working section of magnetization device. A hypothesis explaining the obtained result is proposed.
{"title":"Effect of Magnetic Field on Optical Density of Distilled Water","authors":"V. H. Mykhailenko, Yevhen F. Lukianov, Olha I. Lukianova, Tamara S. Vitkovska, Oleksandr Ye. Khinievich","doi":"10.15407/pmach2023.02.033","DOIUrl":"https://doi.org/10.15407/pmach2023.02.033","url":null,"abstract":"Water is considered as the working fluid of wet steam turbine units. The importance of a purposeful change in the thermophysical properties of water used for energy needs is indicated. A reagent-free method (transverse magnetic field of permanent magnets) of influence on water is proposed. Literature data on currently available papers dedicated to the study of water properties is presented. It is shown that the mechanisms of influence of external physical fields on the physicochemical and thermophysical properties of water have not been elucidated as of now. It is emphasized that the properties of distilled water during exposure and after exposure to physical fields are even less studied. The currently existing contradictions between theoretical ideas about the properties of water and experimental results are considered. It was found that currently there are no correct methods and equipment capable of indicating changes in water properties in real time. As a solution, the equipment and method of analyzing the optical density of distilled water is proposed. The shortcomings of most existing experimental works on the study of the influence of physical fields on the optical density of water are analyzed. The requirements for devices intended for measuring the optical density of distilled water are formulated. A stand was made and experimental work on the study of the dependence of the optical density of distilled water on the induction of a magnetic field that affects it was carried out. It is proved that the magnetic field affects the optical density of distilled water in the infrared range of wavelengths both in the direction of increase (4.1%) and in the direction of decrease (1.7%) depending on the induction of the magnetic field and the speed of water flow through the working section of magnetization device. A hypothesis explaining the obtained result is proposed.","PeriodicalId":16166,"journal":{"name":"Journal of Mechanical Engineering and Sciences","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85475790","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}
Pub Date : 2023-06-30DOI: 10.15407/pmach2023.02.006
K. Avramov, B. Uspenskyi, I. Urniaieva, Ivan D. Breslavskyi
The authors derived a mathematical model of geometrically nonlinear vibrations of three-layer shells, which describes the vibrations of the structure with amplitudes comparable to its thickness. The high-order shear theory is used in the derivation of this model. Rotational inertia is also taken into account. At the same time, the middle layer is a honeycomb structure made thanks to additive FDM technologies. In addition, each shell layer is described by five variables (three displacement projections and two rotation angles of the normal to the middle surface). The total number of unknown variables is fifteen. To obtain a model of nonlinear vibrations of the structure, the method of given forms is used. The potential energy, which takes into account the quadratic, cubic, and fourth powers of the generalized displacements of the structure, is derived. All generalized displacements are decomposed by generalized coordinates and eigenforms, which are recognized as basic functions. It is proved that the mathematical model of shell vibrations is a system of nonlinear non-autonomous ordinary differential equations. A numerical procedure is used to study nonlinear periodic vibrations and their bifurcations, which is a combination of the continuation method and the shooting method. The shooting method takes into account periodicity conditions expressed by a system of nonlinear algebraic equations with respect to the initial conditions of periodic vibrations. These equations are solved using Newton's method. The properties of nonlinear periodic vibrations and their bifurcations in the area of subharmonic resonances are numerically studied. Stable subharmonic vibrations of the second order, which undergo a saddle-node bifurcation, are revealed. An infinite sequence of bifurcations leading to chaotic vibrations is not detected.
{"title":"Bifurcations and Stability of Nonlinear Vibrations of a Three-Layer Composite Shell with Moderate Amplitudes","authors":"K. Avramov, B. Uspenskyi, I. Urniaieva, Ivan D. Breslavskyi","doi":"10.15407/pmach2023.02.006","DOIUrl":"https://doi.org/10.15407/pmach2023.02.006","url":null,"abstract":"The authors derived a mathematical model of geometrically nonlinear vibrations of three-layer shells, which describes the vibrations of the structure with amplitudes comparable to its thickness. The high-order shear theory is used in the derivation of this model. Rotational inertia is also taken into account. At the same time, the middle layer is a honeycomb structure made thanks to additive FDM technologies. In addition, each shell layer is described by five variables (three displacement projections and two rotation angles of the normal to the middle surface). The total number of unknown variables is fifteen. To obtain a model of nonlinear vibrations of the structure, the method of given forms is used. The potential energy, which takes into account the quadratic, cubic, and fourth powers of the generalized displacements of the structure, is derived. All generalized displacements are decomposed by generalized coordinates and eigenforms, which are recognized as basic functions. It is proved that the mathematical model of shell vibrations is a system of nonlinear non-autonomous ordinary differential equations. A numerical procedure is used to study nonlinear periodic vibrations and their bifurcations, which is a combination of the continuation method and the shooting method. The shooting method takes into account periodicity conditions expressed by a system of nonlinear algebraic equations with respect to the initial conditions of periodic vibrations. These equations are solved using Newton's method. The properties of nonlinear periodic vibrations and their bifurcations in the area of subharmonic resonances are numerically studied. Stable subharmonic vibrations of the second order, which undergo a saddle-node bifurcation, are revealed. An infinite sequence of bifurcations leading to chaotic vibrations is not detected.","PeriodicalId":16166,"journal":{"name":"Journal of Mechanical Engineering and Sciences","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76292033","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}
Pub Date : 2023-06-30DOI: 10.15407/pmach2023.02.016
S. Sklepus
A new numerical-analytical method for solving physically nonlinear bending problems of thin plates with complex shape made from materials that differently resist to tension and compression is developed. The uninterrupted parameter continuation method is used to formulate and linearize the problem of physically nonlinear bending. For the linearized problem, a functional in the Lagrange form, given on the kinematically possible displacement rates, is constructed. The main unknown problems (displacements, strains, stresses) were found from the solution of the initial problem, which was solved by the Runge-Kutta-Merson method with automatic step selection, by the parameter related to the load. The initial conditions are found from the solution of the problem of linear elastic deformation. The right-hand sides of the differential equations at fixed values of the load parameter corresponding to the Runge-Kutta-Merson scheme are found from the solution of the variational problem for the functional in the Lagrange form. Variational problems are solved using the Ritz method in combination with the R-function method, which allows to submit an approximate solution in the form of a formula – a solution structure that exactly satisfies the boundary conditions and is invariant with respect to the shape of the domain where the approximate solution is sought. The test problem for the nonlinear elastic bending of a square hinged plate is solved. Satisfactory agreement with the three-dimensional solution is obtained. The bending problem of the plate of complex shape with combined fixation conditions is solved. The influence of the geometric shape and fixation conditions on the stress-strain state is studied. It is shown that failure to take into account the different behavior of the material under tensile and compression can lead to significant errors in the calculations of the stress-strain state parameters.
{"title":"Bending of Plates with Complex Shape Made from Materials that Differently Resist to Tension and Compression","authors":"S. Sklepus","doi":"10.15407/pmach2023.02.016","DOIUrl":"https://doi.org/10.15407/pmach2023.02.016","url":null,"abstract":"A new numerical-analytical method for solving physically nonlinear bending problems of thin plates with complex shape made from materials that differently resist to tension and compression is developed. The uninterrupted parameter continuation method is used to formulate and linearize the problem of physically nonlinear bending. For the linearized problem, a functional in the Lagrange form, given on the kinematically possible displacement rates, is constructed. The main unknown problems (displacements, strains, stresses) were found from the solution of the initial problem, which was solved by the Runge-Kutta-Merson method with automatic step selection, by the parameter related to the load. The initial conditions are found from the solution of the problem of linear elastic deformation. The right-hand sides of the differential equations at fixed values of the load parameter corresponding to the Runge-Kutta-Merson scheme are found from the solution of the variational problem for the functional in the Lagrange form. Variational problems are solved using the Ritz method in combination with the R-function method, which allows to submit an approximate solution in the form of a formula – a solution structure that exactly satisfies the boundary conditions and is invariant with respect to the shape of the domain where the approximate solution is sought. The test problem for the nonlinear elastic bending of a square hinged plate is solved. Satisfactory agreement with the three-dimensional solution is obtained. The bending problem of the plate of complex shape with combined fixation conditions is solved. The influence of the geometric shape and fixation conditions on the stress-strain state is studied. It is shown that failure to take into account the different behavior of the material under tensile and compression can lead to significant errors in the calculations of the stress-strain state parameters.","PeriodicalId":16166,"journal":{"name":"Journal of Mechanical Engineering and Sciences","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87778930","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}
Pub Date : 2023-06-30DOI: 10.15407/pmach2023.02.024
Alexander Hirschl, Daniel Österreicher
Small wind turbines offer a complement to photovoltaic systems and are becoming an interesting solution in the wake of rising energy prices. The measurement results indicate that some locations on and around the building are not suited for installing wind turbines, while others show increased wind potential. Due to limited space, rooftop mounting is an interesting alternative to free mounting on a mast from a technical point of view. For this reason, the influence of roof shapes on the flow on and behind the building was measured and the performance of two different types of small wind turbines was investigated. The turbines assessed in the project are VertikonM with a vertical axis and helix-shaped rotor blades, and Superwind 1250 wind turbine with a horizontal axis and centrifugal force pitch control. The results showed that there is an average increase in wind speed of 0.2 m/s on gable roofs at hub height (7 m). In comparison, there is an increase of 0.4 m/s on flat roofs at hub height (7 m). In relation to the performance of the turbines, high turbulence on the roof seems to cancel out this effect. The performance of the horizontal axis small wind turbine has not increased in comparison with gable roof and free-standing mast. For the vertical-axis turbine, a power increase by a factor of 2.23 was achieved between free-standing mast and gable roof. Vertical wind flow above the gable roof was identified as the main cause for power increase. The experiment was conducted on the Lichtenegg energy research park (Lower Austria) and its results make it possible to better identify all effects that affect the turbine output power.
{"title":"Evaluation of the Influences of Different Roof Shapes on the Flow Properties and Performance of Small Wind Turbines","authors":"Alexander Hirschl, Daniel Österreicher","doi":"10.15407/pmach2023.02.024","DOIUrl":"https://doi.org/10.15407/pmach2023.02.024","url":null,"abstract":"Small wind turbines offer a complement to photovoltaic systems and are becoming an interesting solution in the wake of rising energy prices. The measurement results indicate that some locations on and around the building are not suited for installing wind turbines, while others show increased wind potential. Due to limited space, rooftop mounting is an interesting alternative to free mounting on a mast from a technical point of view. For this reason, the influence of roof shapes on the flow on and behind the building was measured and the performance of two different types of small wind turbines was investigated. The turbines assessed in the project are VertikonM with a vertical axis and helix-shaped rotor blades, and Superwind 1250 wind turbine with a horizontal axis and centrifugal force pitch control. The results showed that there is an average increase in wind speed of 0.2 m/s on gable roofs at hub height (7 m). In comparison, there is an increase of 0.4 m/s on flat roofs at hub height (7 m). In relation to the performance of the turbines, high turbulence on the roof seems to cancel out this effect. The performance of the horizontal axis small wind turbine has not increased in comparison with gable roof and free-standing mast. For the vertical-axis turbine, a power increase by a factor of 2.23 was achieved between free-standing mast and gable roof. Vertical wind flow above the gable roof was identified as the main cause for power increase. The experiment was conducted on the Lichtenegg energy research park (Lower Austria) and its results make it possible to better identify all effects that affect the turbine output power.","PeriodicalId":16166,"journal":{"name":"Journal of Mechanical Engineering and Sciences","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83907779","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}
Pub Date : 2023-06-30DOI: 10.15407/pmach2023.02.039
Liudmyla V. Kapitanova, Danylo S. Kirnosov, Viktor I. Riabkov
The subject of research in the paper is the process of forming a criterion base to evaluate the effectiveness of carrying out modification changes in a transport category aircraft. The goal is to develop supporting criteria for making decisions regarding the expediency of modification changes, namely, during design, during production, and at the stage of its operation, at each stage of the life cycle of a new transport category aircraft. The complexity of the task lies in the need to develop a model for evaluation of the consequences of changing the aircraft for each stage separately, which would collectively determine the integral effectiveness of its modification. To evaluate the efficiency of basic aircrafts in operation, there are a number of economic indicators of their efficiency, in particular, the cost of an aircraft hour and the transportation of one ton of cargo per one kilometer, which are only partially taken into account when analyzing the efficiency of aircraft modifications, although in the case of aircraft transport category, specific cost criteria for the entire life cycle both for the base aircraft and for its modification is required. For their development, a method of estimating the cost of the entire life cycle of the aircraft is proposed, as well as a method of dividing modification changes according to the parameters of the upper level (PMD), which is used at the stage of designing the devices, and the lower level (PPO) for the operational stage. On the basis of and taking into account the specifics of the specified methods, indicators of additional labor costs that arise during the implementation of modification changes in the conditions of production and at the stage of aircraft operation have been developed. The proposed criteria take into account indicators of the transport efficiency of heavy aircraft modifications and the integral efficiency of the modification, taking into account the costs at all the main stages of the life cycle of the modification. The scientific novelty of the obtained results is as follows: the supporting criteria for the adoption of decisions regarding the expediency of modification changes at each stage of the life cycle of a new transport category aircraft are proposed, i.e. during design, under the conditions of production and at the stage of its operation. Such criteria will ensure the integral efficiency of the transport aircraft modification.
{"title":"Criterion Basis for Assessment of Transport Aircrafts Modifications by Cost Indicators","authors":"Liudmyla V. Kapitanova, Danylo S. Kirnosov, Viktor I. Riabkov","doi":"10.15407/pmach2023.02.039","DOIUrl":"https://doi.org/10.15407/pmach2023.02.039","url":null,"abstract":"The subject of research in the paper is the process of forming a criterion base to evaluate the effectiveness of carrying out modification changes in a transport category aircraft. The goal is to develop supporting criteria for making decisions regarding the expediency of modification changes, namely, during design, during production, and at the stage of its operation, at each stage of the life cycle of a new transport category aircraft. The complexity of the task lies in the need to develop a model for evaluation of the consequences of changing the aircraft for each stage separately, which would collectively determine the integral effectiveness of its modification. To evaluate the efficiency of basic aircrafts in operation, there are a number of economic indicators of their efficiency, in particular, the cost of an aircraft hour and the transportation of one ton of cargo per one kilometer, which are only partially taken into account when analyzing the efficiency of aircraft modifications, although in the case of aircraft transport category, specific cost criteria for the entire life cycle both for the base aircraft and for its modification is required. For their development, a method of estimating the cost of the entire life cycle of the aircraft is proposed, as well as a method of dividing modification changes according to the parameters of the upper level (PMD), which is used at the stage of designing the devices, and the lower level (PPO) for the operational stage. On the basis of and taking into account the specifics of the specified methods, indicators of additional labor costs that arise during the implementation of modification changes in the conditions of production and at the stage of aircraft operation have been developed. The proposed criteria take into account indicators of the transport efficiency of heavy aircraft modifications and the integral efficiency of the modification, taking into account the costs at all the main stages of the life cycle of the modification. The scientific novelty of the obtained results is as follows: the supporting criteria for the adoption of decisions regarding the expediency of modification changes at each stage of the life cycle of a new transport category aircraft are proposed, i.e. during design, under the conditions of production and at the stage of its operation. Such criteria will ensure the integral efficiency of the transport aircraft modification.","PeriodicalId":16166,"journal":{"name":"Journal of Mechanical Engineering and Sciences","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83546878","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}
Pub Date : 2023-06-28DOI: 10.15282/jmes.17.2.2023.4.0748
Gurubasavaraju Tharehalli mata, M. Muralidhar Singh
A key feature of magnetorheological fluid is its variability of rheological properties in which upon exposing this fluid, the viscosity of the fluid changes accordingly. Hence this nature can be implemented in various engineering applications. To understand its influence in a magnetorheological (MR) damper, it is essential to study the flow behaviour using computational and numerical methods. The main objective of this work is to estimate the influence of the external magnetic field on the fluid flow velocity inside the damper using magnetohydrodynamic analysis. Finite element analysis, magnetostatic analysis, and magnetohydrodynamic (MHD) analysis have been carried out to investigate the change in the shape of the velocity profile across the flow gap of the monotube MR damper under the various magnitude of magnetic force using the MHD module of ANSYS fluent software. The simulation is conducted by considering laminar, steady-state, and incompressible fluid flow. In finite element analysis, the magnitude of magnetic flux density (MFD) ‘B’ was evaluated at various direct currents. Later, obtained MFD has been applied perpendicular direction to the flow of MR fluid. The effective length of the fluid exposed to the MFD is taken as 2 mm to 28 mm in an overall flow length of 30 mm. The extracted results have shown that the fluid flow velocity reduces with an increase in the magnetic flux density. It has been observed that 10.42 % reduction in velocity upon increasing the magnetic flux density from 0.25 T to 1 T at 75 kPa pressure. The reason for a reduction in velocity is because of variation in the rheological properties of the fluid under the magnetic field, which is very much essential to produce a good damping effect in the MR damper.
磁流变液的一个关键特征是其流变特性的可变性，在暴露该流体时，流体的粘度会相应变化。因此，这种性质可以在各种工程应用中实现。为了了解其对磁流变阻尼器的影响，有必要使用计算和数值方法研究其流动特性。本工作的主要目的是利用磁流体动力学分析估计外磁场对阻尼器内部流体流速的影响。利用ANSYS fluent软件中的MHD模块，进行了有限元分析、静磁分析和磁流体动力学(MHD)分析，研究了在不同大小的磁力作用下，单管磁流变阻尼器流过流隙的速度剖面形状的变化。模拟考虑了层流、稳态和不可压缩流体的流动。在有限元分析中，计算了不同直流电流下的磁通密度(MFD) ' B '的大小。然后，将得到的MFD垂直方向应用于MR流体的流动。在总流长为30毫米的情况下，流体暴露于MFD的有效长度为2毫米至28毫米。提取结果表明，流体的流动速度随着磁通密度的增大而减小。在75千帕压力下，当磁通密度从0.25 T增加到1 T时，速度降低10.42%。速度降低的原因是流体在磁场作用下的流变特性发生了变化，这对于磁流变阻尼器产生良好的阻尼效果是非常必要的。
{"title":"Magnetohydrodynamics analysis of magnetorheological fluid damper","authors":"Gurubasavaraju Tharehalli mata, M. Muralidhar Singh","doi":"10.15282/jmes.17.2.2023.4.0748","DOIUrl":"https://doi.org/10.15282/jmes.17.2.2023.4.0748","url":null,"abstract":"A key feature of magnetorheological fluid is its variability of rheological properties in which upon exposing this fluid, the viscosity of the fluid changes accordingly. Hence this nature can be implemented in various engineering applications. To understand its influence in a magnetorheological (MR) damper, it is essential to study the flow behaviour using computational and numerical methods. The main objective of this work is to estimate the influence of the external magnetic field on the fluid flow velocity inside the damper using magnetohydrodynamic analysis. Finite element analysis, magnetostatic analysis, and magnetohydrodynamic (MHD) analysis have been carried out to investigate the change in the shape of the velocity profile across the flow gap of the monotube MR damper under the various magnitude of magnetic force using the MHD module of ANSYS fluent software. The simulation is conducted by considering laminar, steady-state, and incompressible fluid flow. In finite element analysis, the magnitude of magnetic flux density (MFD) ‘B’ was evaluated at various direct currents. Later, obtained MFD has been applied perpendicular direction to the flow of MR fluid. The effective length of the fluid exposed to the MFD is taken as 2 mm to 28 mm in an overall flow length of 30 mm. The extracted results have shown that the fluid flow velocity reduces with an increase in the magnetic flux density. It has been observed that 10.42 % reduction in velocity upon increasing the magnetic flux density from 0.25 T to 1 T at 75 kPa pressure. The reason for a reduction in velocity is because of variation in the rheological properties of the fluid under the magnetic field, which is very much essential to produce a good damping effect in the MR damper.","PeriodicalId":16166,"journal":{"name":"Journal of Mechanical Engineering and Sciences","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43905441","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}
Pub Date : 2023-06-28DOI: 10.15282/jmes.17.2.2023.6.0750
L. K. Moey, Seng Keat Cheong, Md Akkik Al Zobaied, V. Tai, T. F. Go, P. L. Chong
An eave refers to an extension attached to the building roof to protect the interior space from direct solar radiation and improve the performance on cross ventilation. In this study, the impact of eave inclination angle and roof pitch of an isolated sawtooth roof building on cross ventilation were investigated. The eave configurations at either windward or leeward openings were included. 3D steady Reynolds-Averaged Navier-Stokes (RANS) equation in combination with the Shear-Stress Transport model (SST k-ω model) was used for the Computational Fluid Dynamics (CFD) simulations. Grid sensitivity study was carried out and the performance of cross ventilation was evaluated based on the non-dimensional velocity magnitude, spatial distribution of pressure coefficient as well as the ventilation rate of the building. For the simulation model with 55° roof pitch, it is observed that a region with high velocity magnitude formed on top of the leeward eave due to the higher roof pitch and presence of the leeward eave. Results also indicated that the building model with 90° leeward eave and 55° roof pitch has the highest increment in ventilation rate which is 7.16%. On the other hand, the building model with 90° windward eave has the highest pressure coefficient because more blockage of airflow is caused by a steeper roof as the roof pitch of the building increases. Furthermore, the building model with 90° leeward eave shows a larger region with negative pressure at the leeward façade indicating higher airflow leaving the leeward opening. Therefore, the airflow behavior and characteristic are both dependent on the roof pitch and eave inclination angle for a naturally ventilated building.
{"title":"Impact of eave and roof pitch on cross ventilation for an isolated building with sawtooth roof","authors":"L. K. Moey, Seng Keat Cheong, Md Akkik Al Zobaied, V. Tai, T. F. Go, P. L. Chong","doi":"10.15282/jmes.17.2.2023.6.0750","DOIUrl":"https://doi.org/10.15282/jmes.17.2.2023.6.0750","url":null,"abstract":"An eave refers to an extension attached to the building roof to protect the interior space from direct solar radiation and improve the performance on cross ventilation. In this study, the impact of eave inclination angle and roof pitch of an isolated sawtooth roof building on cross ventilation were investigated. The eave configurations at either windward or leeward openings were included. 3D steady Reynolds-Averaged Navier-Stokes (RANS) equation in combination with the Shear-Stress Transport model (SST k-ω model) was used for the Computational Fluid Dynamics (CFD) simulations. Grid sensitivity study was carried out and the performance of cross ventilation was evaluated based on the non-dimensional velocity magnitude, spatial distribution of pressure coefficient as well as the ventilation rate of the building. For the simulation model with 55° roof pitch, it is observed that a region with high velocity magnitude formed on top of the leeward eave due to the higher roof pitch and presence of the leeward eave. Results also indicated that the building model with 90° leeward eave and 55° roof pitch has the highest increment in ventilation rate which is 7.16%. On the other hand, the building model with 90° windward eave has the highest pressure coefficient because more blockage of airflow is caused by a steeper roof as the roof pitch of the building increases. Furthermore, the building model with 90° leeward eave shows a larger region with negative pressure at the leeward façade indicating higher airflow leaving the leeward opening. Therefore, the airflow behavior and characteristic are both dependent on the roof pitch and eave inclination angle for a naturally ventilated building.","PeriodicalId":16166,"journal":{"name":"Journal of Mechanical Engineering and Sciences","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44773177","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}
Pub Date : 2023-06-28DOI: 10.15282/jmes.17.2.2023.2.0746
M. Varun, S. Subhani, R. Senthil Kumar
Solar-powered desalination is a quick and easy way to make drinking water. Numerous solar distillation systems have been investigated for various parameter modifications based on local resource availability. In this work, a solar still with a modified stepped basin is investigated to raise the rate of internal evaporation and, therefore the output yield of the solar still. Stepped basin solar stills are taken into consideration for the study since they are very effective because the water's surface exposure to radiation is greater. Thus, increasing the rate of internal water evaporation enhances the rate of convective heat transfer between the evaporating and condensing surfaces, leading to improved and consistent output. The two-dimensional stepped basin single slope solar still was investigated and contrasted with the traditional single slope still in terms of heat transfer and fluid dynamics. To optimize the configuration for better performance in various types of climatic and operational circumstances that imitate the scenario of daily life, design elements such as the number of steps and the different heights of the basin are also taken into account. Each step was added with far more success than the one before it, up until the length was reduced to 1.16% of the entire shorter length. This numerical study enables us to draw the conclusion that the rise in natural heat transfer rate with the addition of steps is mostly caused by the increased surface area and the inherently restrictive nature within the domain. Additionally, with an increase in Rayleigh number, Ra, the gradient variations of the traditional single slope solar still overheat transfer features have been greatly regulated and successfully raised for the modified stepped basin Solar still.
{"title":"Convection heat transfer of stepped basin single slope solar still: A numerical investigation","authors":"M. Varun, S. Subhani, R. Senthil Kumar","doi":"10.15282/jmes.17.2.2023.2.0746","DOIUrl":"https://doi.org/10.15282/jmes.17.2.2023.2.0746","url":null,"abstract":"Solar-powered desalination is a quick and easy way to make drinking water. Numerous solar distillation systems have been investigated for various parameter modifications based on local resource availability. In this work, a solar still with a modified stepped basin is investigated to raise the rate of internal evaporation and, therefore the output yield of the solar still. Stepped basin solar stills are taken into consideration for the study since they are very effective because the water's surface exposure to radiation is greater. Thus, increasing the rate of internal water evaporation enhances the rate of convective heat transfer between the evaporating and condensing surfaces, leading to improved and consistent output. The two-dimensional stepped basin single slope solar still was investigated and contrasted with the traditional single slope still in terms of heat transfer and fluid dynamics. To optimize the configuration for better performance in various types of climatic and operational circumstances that imitate the scenario of daily life, design elements such as the number of steps and the different heights of the basin are also taken into account. Each step was added with far more success than the one before it, up until the length was reduced to 1.16% of the entire shorter length. This numerical study enables us to draw the conclusion that the rise in natural heat transfer rate with the addition of steps is mostly caused by the increased surface area and the inherently restrictive nature within the domain. Additionally, with an increase in Rayleigh number, Ra, the gradient variations of the traditional single slope solar still overheat transfer features have been greatly regulated and successfully raised for the modified stepped basin Solar still.","PeriodicalId":16166,"journal":{"name":"Journal of Mechanical Engineering and Sciences","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41769045","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}
Pub Date : 2023-06-28DOI: 10.15282/jmes.17.2.2023.1.0745
M. A. Fitriady, N. A. Rahmat, A. F. Mohammad, S.A. Zaki
For decades wind tunnel has been utilized to generate a quasi-atmospheric boundary layer to observe the wake flow around objects submerged within the Atmospheric Boundary Layer. The quarter elliptic-wedge spire is the most commonly used as a vortex generator among other passive devices. However, despite numerous past studies that utilize rows of spires to generate deep quasi-ABL, only a few researchers targeted spires as the main subject of their investigation. Hence, the present work originally aims to investigate the wake flow structure behind a single quarter elliptic-wedge spire and its aerodynamic interaction with a smooth wall boundary layer. A computational fluid dynamics simulation predicting the wake flow structure behind a single quarter elliptic-wedge spire was conducted using the OpenFOAM® software. The computational domain consists a smooth flat plate, and a single quarter elliptic-wedge spire. A comparison of two Reynolds-Averaged Navier–Stokes turbulence models, namely the k-ɛ model and the SST k-ω model, was conducted. A SIMPLE algorithm was used as the solver in the simulation iteration and ParaFOAM® was used as the post-processing software. The development of the boundary layer height from streamwise x0=0.5S to downwind x0=20S was observed. The mean vertical velocity profiles predicted by both turbulence models are in good agreement with the previous wind tunnel experimental results. However, the results obtained with the k-ɛ model were overpredicted compared to the results of the SST k-ω model causing deviation of the boundary layer height from the wind tunnel experimental data. This anomaly might be caused by the velocity deficit recovery above the boundary layer height region where the turbulence is low.
{"title":"Numerical simulation of the boundary layer development behind a single quarter elliptic-wedge spire","authors":"M. A. Fitriady, N. A. Rahmat, A. F. Mohammad, S.A. Zaki","doi":"10.15282/jmes.17.2.2023.1.0745","DOIUrl":"https://doi.org/10.15282/jmes.17.2.2023.1.0745","url":null,"abstract":"For decades wind tunnel has been utilized to generate a quasi-atmospheric boundary layer to observe the wake flow around objects submerged within the Atmospheric Boundary Layer. The quarter elliptic-wedge spire is the most commonly used as a vortex generator among other passive devices. However, despite numerous past studies that utilize rows of spires to generate deep quasi-ABL, only a few researchers targeted spires as the main subject of their investigation. Hence, the present work originally aims to investigate the wake flow structure behind a single quarter elliptic-wedge spire and its aerodynamic interaction with a smooth wall boundary layer. A computational fluid dynamics simulation predicting the wake flow structure behind a single quarter elliptic-wedge spire was conducted using the OpenFOAM® software. The computational domain consists a smooth flat plate, and a single quarter elliptic-wedge spire. A comparison of two Reynolds-Averaged Navier–Stokes turbulence models, namely the k-ɛ model and the SST k-ω model, was conducted. A SIMPLE algorithm was used as the solver in the simulation iteration and ParaFOAM® was used as the post-processing software. The development of the boundary layer height from streamwise x0=0.5S to downwind x0=20S was observed. The mean vertical velocity profiles predicted by both turbulence models are in good agreement with the previous wind tunnel experimental results. However, the results obtained with the k-ɛ model were overpredicted compared to the results of the SST k-ω model causing deviation of the boundary layer height from the wind tunnel experimental data. This anomaly might be caused by the velocity deficit recovery above the boundary layer height region where the turbulence is low.","PeriodicalId":16166,"journal":{"name":"Journal of Mechanical Engineering and Sciences","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44006119","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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