Pub Date : 2016-12-01DOI: 10.5923/J.JMEA.20160606.01
R. Felix, Thales Prini Franchi
The proposed project corresponds to a sealing system designed to perform simulations of air leaks in several industrial segments and gain control using low-cost controller. Its main objective is to evaluate the quality of the final product and can be applied to various industrial segments. The pneumatic system used in the prototype is fed with pressurized dry air, after filling the test piece with air, it waits to stabilize and measure the remaining flow through a mass flow sensor, directly indicating the volumetric leakage of the part under test. The leakage is simulated by opening and closing a flow regulator installed prior to the mass flow measurement system. This leakage is then compared to the adjusted parameters and obtains a possible approval of the part if it is within the conformities, depending on the acceptable flow rate provided by the final product manufacturer. The entire process of prototype automation has been developed an algorithm implementation on Open-Source platform using low-cost controller. The interest in further study of the chosen theme emerged for several reasons, including: to contribute to improving the performance and productivity of the processes in the industrial area; predict and prevent possible failures that cause environmental impact in the future; show that it is possible to achieve automation and sealing control system inexpensively, opting for a more cost-effective, since this market is becoming increasingly attractive to businesses.
{"title":"Automation and Leak Control System with Use of Clean Energy Supply (Compressed Air)","authors":"R. Felix, Thales Prini Franchi","doi":"10.5923/J.JMEA.20160606.01","DOIUrl":"https://doi.org/10.5923/J.JMEA.20160606.01","url":null,"abstract":"The proposed project corresponds to a sealing system designed to perform simulations of air leaks in several industrial segments and gain control using low-cost controller. Its main objective is to evaluate the quality of the final product and can be applied to various industrial segments. The pneumatic system used in the prototype is fed with pressurized dry air, after filling the test piece with air, it waits to stabilize and measure the remaining flow through a mass flow sensor, directly indicating the volumetric leakage of the part under test. The leakage is simulated by opening and closing a flow regulator installed prior to the mass flow measurement system. This leakage is then compared to the adjusted parameters and obtains a possible approval of the part if it is within the conformities, depending on the acceptable flow rate provided by the final product manufacturer. The entire process of prototype automation has been developed an algorithm implementation on Open-Source platform using low-cost controller. The interest in further study of the chosen theme emerged for several reasons, including: to contribute to improving the performance and productivity of the processes in the industrial area; predict and prevent possible failures that cause environmental impact in the future; show that it is possible to achieve automation and sealing control system inexpensively, opting for a more cost-effective, since this market is becoming increasingly attractive to businesses.","PeriodicalId":383435,"journal":{"name":"Journal of Mechanical Engineering and Automation","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122480961","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 : 2016-07-01DOI: 10.5923/J.JMEA.20160605.02
T. Hirai, F. Kuratani, T. Yoshida
In this paper, we consider a joined structure in which a long plate is sandwiched between two short plates, and we investigate the effect of the size of an overlapping region, i.e., the short plate length, on damping characteristics. For this, we calculate energy dissipation due to friction at the contact interface, which produces damping, using static contact analysis. In the contact analysis, a surface load is applied at the contact interface and then a distributed forced displacement is applied. For the distributed displacement, mode shape is used to estimate the modal damping ratio for each mode. The results show that the dissipated energy increases with short plate length for all modes, though this increase differs between them. This indicates that the modal damping ratio depends on both the short plate length and the mode. This is explained by changes in the slip displacement and contact force with the short plate length for each mode.
{"title":"Effect of an Overlapping Region on Damping due to Friction in Joined Plate Structures","authors":"T. Hirai, F. Kuratani, T. Yoshida","doi":"10.5923/J.JMEA.20160605.02","DOIUrl":"https://doi.org/10.5923/J.JMEA.20160605.02","url":null,"abstract":"In this paper, we consider a joined structure in which a long plate is sandwiched between two short plates, and we investigate the effect of the size of an overlapping region, i.e., the short plate length, on damping characteristics. For this, we calculate energy dissipation due to friction at the contact interface, which produces damping, using static contact analysis. In the contact analysis, a surface load is applied at the contact interface and then a distributed forced displacement is applied. For the distributed displacement, mode shape is used to estimate the modal damping ratio for each mode. The results show that the dissipated energy increases with short plate length for all modes, though this increase differs between them. This indicates that the modal damping ratio depends on both the short plate length and the mode. This is explained by changes in the slip displacement and contact force with the short plate length for each mode.","PeriodicalId":383435,"journal":{"name":"Journal of Mechanical Engineering and Automation","volume":"105 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121773597","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 : 2015-02-21DOI: 10.5923/J.JMEA.20150501.05
Jibrin Sule, S. Ganguly, H. Coules, T. Pirling
Complex thermal stresses generated in welded structures are undesirable but inevitable in fusion welding. The presence of residual stresses can be detrimental to the integrity of a welded joint. In this research, redistribution of residual stress magnitude and profile was studied and compared in two multi-pass welded structural alloys (API X100 and 304L stainless steel) after cold rolling and laser processing. The residual stress field was studied by neutron diffraction using the SALSA strain scanner at their reactor neutron source at ILL, Grenoble. In addition to a complex distribution of residual stress state, multi-pass welds also forms dendritic grain structure, which are repeatedly heated, resulting in segregation of alloying elements. Dendritic grain structure is weaker and segregation of alloying elements may result in formation of corrosion microcells as well as reduction in overall corrosion prevention due to depletion of alloying elements in certain areas. The modification of as-welded residual stress state was done by cold rolling which was followed by laser processing to create a recrystallized microstructure to minimise segregation. The main objective of this study is to understand the suitability of this novel manufacturing technique to create a stress free weldment with recrystallised grain structure. Hardness evolution in the welded structures was scanned following welding, post weld cold rolling and cold rolling followed by laser processing. Hardness distribution in both the structural alloys showed a significant evidence of plastic deformation near the cap pass of the weld metal. Residual stress redistribution was observed up to 4 mm from the capping pass for ferritic steel, while in austenitic steel weld, post weld cold rolling was effective in modifying the residual stress redistribution throughout the entire thickness. Laser processing in both cases reinstated the as-welded residual stress distribution and resulted in softening of the strained area.
{"title":"Comparative study of evolution of residual stress state by local mechanical tensioning and laser processing of ferritic and austenitic structural steel welds.","authors":"Jibrin Sule, S. Ganguly, H. Coules, T. Pirling","doi":"10.5923/J.JMEA.20150501.05","DOIUrl":"https://doi.org/10.5923/J.JMEA.20150501.05","url":null,"abstract":"Complex thermal stresses generated in welded structures are undesirable but inevitable in fusion welding. The presence of residual stresses can be detrimental to the integrity of a welded joint. In this research, redistribution of residual stress magnitude and profile was studied and compared in two multi-pass welded structural alloys (API X100 and 304L stainless steel) after cold rolling and laser processing. The residual stress field was studied by neutron diffraction using the SALSA strain scanner at their reactor neutron source at ILL, Grenoble. In addition to a complex distribution of residual stress state, multi-pass welds also forms dendritic grain structure, which are repeatedly heated, resulting in segregation of alloying elements. Dendritic grain structure is weaker and segregation of alloying elements may result in formation of corrosion microcells as well as reduction in overall corrosion prevention due to depletion of alloying elements in certain areas. The modification of as-welded residual stress state was done by cold rolling which was followed by laser processing to create a recrystallized microstructure to minimise segregation. The main objective of this study is to understand the suitability of this novel manufacturing technique to create a stress free weldment with recrystallised grain structure. Hardness evolution in the welded structures was scanned following welding, post weld cold rolling and cold rolling followed by laser processing. Hardness distribution in both the structural alloys showed a significant evidence of plastic deformation near the cap pass of the weld metal. Residual stress redistribution was observed up to 4 mm from the capping pass for ferritic steel, while in austenitic steel weld, post weld cold rolling was effective in modifying the residual stress redistribution throughout the entire thickness. Laser processing in both cases reinstated the as-welded residual stress distribution and resulted in softening of the strained area.","PeriodicalId":383435,"journal":{"name":"Journal of Mechanical Engineering and Automation","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122373258","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 : 2012-12-01DOI: 10.5923/J.JMEA.20120206.03
Hani Aziz Ameen, K. S. Hassan, Muwafaq Mahdi Salah
Th is investigation explain the effects of annealing on the torsion aspects of carbon steel St.35. ANSYS12 software was used in investigation. Test specimens were prepared according to ASTM and heated with different temperature namely 850, 650, 450 and 150 ° C for one hour and followed by cooling process via furnace. M icrostructure and torsion test after heating were examined. It was found that increasing annealing temperature, the hardness decreased and torsion properties and consequently increasing the plastic depth and the optimu m heat treatment conditions is annealing at 450° C which produce angle twist 680 deg co mpared with metal as received.
{"title":"Experimental and Finite Element Investigation of Annealing on the Torsional Aspects of Carbon Steel St35","authors":"Hani Aziz Ameen, K. S. Hassan, Muwafaq Mahdi Salah","doi":"10.5923/J.JMEA.20120206.03","DOIUrl":"https://doi.org/10.5923/J.JMEA.20120206.03","url":null,"abstract":"Th is investigation explain the effects of annealing on the torsion aspects of carbon steel St.35. ANSYS12 software was used in investigation. Test specimens were prepared according to ASTM and heated with different temperature namely 850, 650, 450 and 150 ° C for one hour and followed by cooling process via furnace. M icrostructure and torsion test after heating were examined. It was found that increasing annealing temperature, the hardness decreased and torsion properties and consequently increasing the plastic depth and the optimu m heat treatment conditions is annealing at 450° C which produce angle twist 680 deg co mpared with metal as received.","PeriodicalId":383435,"journal":{"name":"Journal of Mechanical Engineering and Automation","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131708325","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 : 2012-12-01DOI: 10.5923/J.JMEA.20120205.01
Y. Shin, Ho Ju Lee, Kyung-Soo Kim, Soohyun Kim
In this paper, we newly develop a finger-type manipulator driven by the slidingactuation with min iaturized brushless DC(BLDC) motors. The mechanism allows the usage of the maximalcapacity of actuators by employing the distributed actuation principle while maintaining thesmall size. Thanks to the high thrust force of the BLDC motors, the maximu m fingertipforce of the developed robot finger is remarkab ly enhanced. Through experimentation, thefingertip force of the proposed robot finger is assessed and compared with the former versionwith the ultrasonic motors.
{"title":"Output Force Enhancement of Finger-type Manipulator by Adopting Brushless DC Motors for Sliding Actuation","authors":"Y. Shin, Ho Ju Lee, Kyung-Soo Kim, Soohyun Kim","doi":"10.5923/J.JMEA.20120205.01","DOIUrl":"https://doi.org/10.5923/J.JMEA.20120205.01","url":null,"abstract":"In this paper, we newly develop a finger-type manipulator driven by the slidingactuation with min iaturized brushless DC(BLDC) motors. The mechanism allows the usage of the maximalcapacity of actuators by employing the distributed actuation principle while maintaining thesmall size. Thanks to the high thrust force of the BLDC motors, the maximu m fingertipforce of the developed robot finger is remarkab ly enhanced. Through experimentation, thefingertip force of the proposed robot finger is assessed and compared with the former versionwith the ultrasonic motors.","PeriodicalId":383435,"journal":{"name":"Journal of Mechanical Engineering and Automation","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127426378","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 : 2012-12-01DOI: 10.5923/J.JMEA.20120206.07
Z. Zidane, M. A. Lafkih, M. Ramzi
Small hydro power is one of the most important renewable energy in the world. It does not encounter the problem of population displacement and is not as expensive as solar or wind energy. However, small hydro electrical generating units are usually isolated fro m the grid network; thus, they require control to maintain of constant the power for any working conditions. This paper presents a flow control approach for the speed control of hydro turbines. Power can be controlled by controlling the amount volume of water running into turbine. In this study, the adaptive predictive control is designed to control a flow for the automatic control of s mall hydro power plants. The standard Generalized Predictive Control (GPC) algorith m is presented. The Adaptive Generalized Predictive Control is then applied to achieve set point tracking of the output of the plant. A Single Input Single Output (SISO) model is used for control purposes. The model parameters are estimated on-line using an identification algorith m based on Recursive Least Squares (RLS) method. The performance of the proposed controller is illustrated by a simulation examp le of Small hydro power plant. Obtained results have shown better characteristics concerning both set point tracking and disturbance robustness for adaptive predictive control.
{"title":"Simulation Studies of Adaptive Predictive Control for Small Hydro Power Plant","authors":"Z. Zidane, M. A. Lafkih, M. Ramzi","doi":"10.5923/J.JMEA.20120206.07","DOIUrl":"https://doi.org/10.5923/J.JMEA.20120206.07","url":null,"abstract":"Small hydro power is one of the most important renewable energy in the world. It does not encounter the problem of population displacement and is not as expensive as solar or wind energy. However, small hydro electrical generating units are usually isolated fro m the grid network; thus, they require control to maintain of constant the power for any working conditions. This paper presents a flow control approach for the speed control of hydro turbines. Power can be controlled by controlling the amount volume of water running into turbine. In this study, the adaptive predictive control is designed to control a flow for the automatic control of s mall hydro power plants. The standard Generalized Predictive Control (GPC) algorith m is presented. The Adaptive Generalized Predictive Control is then applied to achieve set point tracking of the output of the plant. A Single Input Single Output (SISO) model is used for control purposes. The model parameters are estimated on-line using an identification algorith m based on Recursive Least Squares (RLS) method. The performance of the proposed controller is illustrated by a simulation examp le of Small hydro power plant. Obtained results have shown better characteristics concerning both set point tracking and disturbance robustness for adaptive predictive control.","PeriodicalId":383435,"journal":{"name":"Journal of Mechanical Engineering and Automation","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129391745","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 : 2012-12-01DOI: 10.5923/J.JMEA.20120206.02
Salih N. Akour
Nonlinear beam resting on linear elastic foundation and subjected to harmonic excitation is investigated. The beam is simp ly supported at both ends. Both linear and nonlinear analyses are carried out. Hamilton's principle is utilized in deriv ing the governing equations. Well known forced duffing oscillator equation is obtained. The equation is analyzed numerically using Runk-Kutta technique. Three main parameters are investigated: the damp ing coefficient, the natural frequency, and the coefficient of the nonlinearity. Stability reg ions for first mode analyses are unveiled. Co mparison between the linear and the nonlinear model is presented. It is shown that first mode shape the natural frequency could be approximated as square root of the sum of squares of both natural frequency of the beam and the foundation. The stretching potential energy is proved to be responsible for generating the cubic nonlinearity in the system.
{"title":"Parametric Study of Nonlinear Beam Vibration Resting on Linear Elastic Foundation","authors":"Salih N. Akour","doi":"10.5923/J.JMEA.20120206.02","DOIUrl":"https://doi.org/10.5923/J.JMEA.20120206.02","url":null,"abstract":"Nonlinear beam resting on linear elastic foundation and subjected to harmonic excitation is investigated. The beam is simp ly supported at both ends. Both linear and nonlinear analyses are carried out. Hamilton's principle is utilized in deriv ing the governing equations. Well known forced duffing oscillator equation is obtained. The equation is analyzed numerically using Runk-Kutta technique. Three main parameters are investigated: the damp ing coefficient, the natural frequency, and the coefficient of the nonlinearity. Stability reg ions for first mode analyses are unveiled. Co mparison between the linear and the nonlinear model is presented. It is shown that first mode shape the natural frequency could be approximated as square root of the sum of squares of both natural frequency of the beam and the foundation. The stretching potential energy is proved to be responsible for generating the cubic nonlinearity in the system.","PeriodicalId":383435,"journal":{"name":"Journal of Mechanical Engineering and Automation","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116402449","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 : 2012-12-01DOI: 10.5923/J.JMEA.20120206.06
Chigbogu Ozoegwu, S. Omenyi, C. Achebe, C. F. Uzoh
The model fo r regenerative vibration of linear orthogonal turning process is a second order time -invariant delay differential equation. Stability analysis resulted in lobes that combine to give transition curve that separates the paramete r space of spindle speed and depth of cut into stable and unstable subspaces. It is found that there is a subspace of the stable subspace in which the turning process is delay-independent stable. The size of this subspace is found to be a function of modal parameters and increases with damping ratio of the tool. Non -linear analysis of turning by some investigators suggests that subcritical bifurcations always occur thus the need to design a portion of the subspace of delay -independent stability for global stability. The subspace of global stability is also theoretically and quantitatively demonstrated to increase faster than the driving increase in damp ing ratio.
{"title":"Effect of Modal Parameters on Both Delay-Independent and Global Stability of Turning Process","authors":"Chigbogu Ozoegwu, S. Omenyi, C. Achebe, C. F. Uzoh","doi":"10.5923/J.JMEA.20120206.06","DOIUrl":"https://doi.org/10.5923/J.JMEA.20120206.06","url":null,"abstract":"The model fo r regenerative vibration of linear orthogonal turning process is a second order time -invariant delay differential equation. Stability analysis resulted in lobes that combine to give transition curve that separates the paramete r space of spindle speed and depth of cut into stable and unstable subspaces. It is found that there is a subspace of the stable subspace in which the turning process is delay-independent stable. The size of this subspace is found to be a function of modal parameters and increases with damping ratio of the tool. Non -linear analysis of turning by some investigators suggests that subcritical bifurcations always occur thus the need to design a portion of the subspace of delay -independent stability for global stability. The subspace of global stability is also theoretically and quantitatively demonstrated to increase faster than the driving increase in damp ing ratio.","PeriodicalId":383435,"journal":{"name":"Journal of Mechanical Engineering and Automation","volume":"175 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129502174","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 : 2012-12-01DOI: 10.5923/J.JMEA.20120206.09
Yaozhong Xu, E. Bideaux, S. Sesmat, J. Simon
The intermediate block is a basic element in an hydraulic control system, and is usually used to install all hydraulic components and guides the fluid flows. However, the effect of this block is usually neglected, but it has to be taken into consideration when high performance applications, especially at high frequencies, have to be achieved. This paper focuses on this component and shows how it can influence the hydraulic system dynamics. The main contributions of this work are the implementation of a Bond Graph model of this component, which can easily be integrated in the whole system model, and a complete analysis of the effects (pressure drop, compressibility, inertia) induced by the intermediate block on the whole system performances. The relationship between flow rates and pressure drops along with the energy losses in the block are obtained according to a method based on the decomposition of the circuit in parts for which the local losses can be obtained from abacuses. The Computational Fluid Dynamics (CFD) is used for the validation of the results. Besides, the compressibility and inertial effects are carefully studied since they have a great influence on the hydraulic frequency. Finally, simulations and experiments are implemented for demonstrating the importance of the effect of the intermediate block in the hydraulic system modeling. By introducing compressibility and inertial effects of the intermediate block, the simulation result shows better agreement with experimental results at high frequencies. This comparison demonstrates that the control design can reach better performance when considering the dynamic model of the intermediate block.
{"title":"Dynamic Effect of the Intermediate Block in a Hydraulic Control System","authors":"Yaozhong Xu, E. Bideaux, S. Sesmat, J. Simon","doi":"10.5923/J.JMEA.20120206.09","DOIUrl":"https://doi.org/10.5923/J.JMEA.20120206.09","url":null,"abstract":"The intermediate block is a basic element in an hydraulic control system, and is usually used to install all hydraulic components and guides the fluid flows. However, the effect of this block is usually neglected, but it has to be taken into consideration when high performance applications, especially at high frequencies, have to be achieved. This paper focuses on this component and shows how it can influence the hydraulic system dynamics. The main contributions of this work are the implementation of a Bond Graph model of this component, which can easily be integrated in the whole system model, and a complete analysis of the effects (pressure drop, compressibility, inertia) induced by the intermediate block on the whole system performances. The relationship between flow rates and pressure drops along with the energy losses in the block are obtained according to a method based on the decomposition of the circuit in parts for which the local losses can be obtained from abacuses. The Computational Fluid Dynamics (CFD) is used for the validation of the results. Besides, the compressibility and inertial effects are carefully studied since they have a great influence on the hydraulic frequency. Finally, simulations and experiments are implemented for demonstrating the importance of the effect of the intermediate block in the hydraulic system modeling. By introducing compressibility and inertial effects of the intermediate block, the simulation result shows better agreement with experimental results at high frequencies. This comparison demonstrates that the control design can reach better performance when considering the dynamic model of the intermediate block.","PeriodicalId":383435,"journal":{"name":"Journal of Mechanical Engineering and Automation","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130612265","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 : 2012-12-01DOI: 10.5923/J.JMEA.20120206.08
H. khozeymehnezhad, S. Mirbozorgi
Nu merical calcu lations are carried out for natural convection induced by a temperature difference between a cold outer square enclosure and a hot inner cy linder with two different geo metries (i.e. circular and square). A two-dimensional solution for natural convection is obtained, using the finite volu me method for different Rayleigh nu mbers varying over the range of (10 3 -10 5 ). The study goes further to investigate the effect of vertical position of the inner cylinder on the heat transfer and flow field. The location of the inner cylinder is vertically changed along the center-line of the square enclosure. The number, size and form of the vortices strongly depend on the Rayleigh nu mber and the position of the inner cylinder. The results show that for both cylinders, at low Rayleigh numbers of 10 3 and 10 4 , the bifurcation fro m the bicellular vortices to an uni-cellular vortex occurs when an inner cylinder is placed at a certain distance from the center of the enclosure. When Ra = 10 5 , only a uni-cellu lar vortex is formed in the enclosure irrespective of the position of the inner cylinder. A lso as the obtained total surfaces-averaged Nusselt numbers of the enclosure show, in all cases, at the same Rayleigh number, the rate of heat transfer fro m the enclosure which the circular cylinder is located inside is better.
{"title":"Comparison of Natural Convection around a Circular Cylinder with a Square Cylinder Inside a Square Enclosure","authors":"H. khozeymehnezhad, S. Mirbozorgi","doi":"10.5923/J.JMEA.20120206.08","DOIUrl":"https://doi.org/10.5923/J.JMEA.20120206.08","url":null,"abstract":"Nu merical calcu lations are carried out for natural convection induced by a temperature difference between a cold outer square enclosure and a hot inner cy linder with two different geo metries (i.e. circular and square). A two-dimensional solution for natural convection is obtained, using the finite volu me method for different Rayleigh nu mbers varying over the range of (10 3 -10 5 ). The study goes further to investigate the effect of vertical position of the inner cylinder on the heat transfer and flow field. The location of the inner cylinder is vertically changed along the center-line of the square enclosure. The number, size and form of the vortices strongly depend on the Rayleigh nu mber and the position of the inner cylinder. The results show that for both cylinders, at low Rayleigh numbers of 10 3 and 10 4 , the bifurcation fro m the bicellular vortices to an uni-cellular vortex occurs when an inner cylinder is placed at a certain distance from the center of the enclosure. When Ra = 10 5 , only a uni-cellu lar vortex is formed in the enclosure irrespective of the position of the inner cylinder. A lso as the obtained total surfaces-averaged Nusselt numbers of the enclosure show, in all cases, at the same Rayleigh number, the rate of heat transfer fro m the enclosure which the circular cylinder is located inside is better.","PeriodicalId":383435,"journal":{"name":"Journal of Mechanical Engineering and Automation","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2012-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124992878","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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