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cylinder
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Low-speed wind energy harvesting from a vibrating cylinder and an obstacle cylinder by flow-induced vibration effect
, Article International Journal of Environmental Science and Technology ; 2021 ; 17351472 (ISSN) ; Shariatzadeh, M. J ; Bijarchi, M. A ; Pournasiri Masouleh, E ; Shafii, M. B ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2021
Abstract
An experimental setup has been developed to analyse the impact of cylinder transverse vibration caused by flow-induced vibration, and to improve wind energy harvesting from these vibrations. The setup consists of a cylinder mounted on four springs and is subjected to a uniform and steady flow of wind. In the first part, the effect of mounting a fixed cylinder as an obstacle with different diameters and distances from the downstream vibrating cylinder is investigated. It has been observed that the vibration amplitude on the wake of an unequal-sized obstacle is greatly amplified compared to the case of a single cylinder or an equal-sized cylinder. Numerical simulations has been conducted to...
Optimum arrangement of layers in multi-layer compound cylinders
, Article International Journal of Applied Mechanics ; Vol. 6, issue. 5 , 2014 ; Arghavani, J ; Hematiyan, M. R ; Sharif University of Technology
Abstract
In this paper, using an analytical optimization method, optimum design of multi-layer compound cylinders with different materials in layers is investigated. For this purpose, considering Tresca criterion, maximum shear stress in each layer is minimized. At the optimum condition, the maximum shear stress at all layers occurs simultaneously. The general analytical relations for optimum dimension of layers, residual pressures and radial interferences are derived. The existence condition of the optimum solution is also investigated and the constraints for materials selection are derived too. It is shown that the allowable shear stress ratio of materials must be close to their geometric mean...
An analytical solution for optimum design of shrink-fit multi-layer compound cylinders
, Article International Journal of Applied Mechanics ; Volume 4, Issue 4 , December , 2012 ; 17588251 (ISSN) ; Arghavani, J ; Hematiyan, M. R ; Sharif University of Technology
2012
Abstract
In this paper, employing an analytical method, optimum design of multi-layer compound cylinders is investigated. To this end, considering Tresca criterion, maximum shear stress in each layer is minimized. Analytical relations for optimum values of a layer dimension, residual pressures and radial interferences are derived. A technique for shrink-fitting of layers is also proposed and relationships for radial interferences, residual pressures and required temperature differences during the shrink-fitting process are derived. Three different examples are presented to show the effectiveness of the proposed method. It is shown that increasing the number of layers makes shear stress distribution...
Effect of centrifugal force on frequency characteristic of rotating hollow cylinders using a newly designed cylindrical super element
, Article 2006 ASME International Mechanical Engineering Congress and Exposition, IMECE2006, Chicago, IL, 5 November 2006 through 10 November 2006 ; 2006 ; 10716947 (ISSN); 0791837904 (ISBN); 9780791837900 (ISBN) ; Ahmadian, M. T ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2006
Abstract
A sixteen node cylindrical super element is presented for evaluating the free vibration characteristics of a rotating laminated cylinder with conventional boundary conditions. It is shown that the natural frequencies are affected considerably when the centrifugal force is also taken into account. The vibration frequencies of rotating finite cylinder, obtained by conventional finite element are used to evaluate the accuracy of this approach. The special case of a stationary cylinder with zero spinning velocity is also considered as a check on this method. Results indicate only few number of cylindrical super elements are capable of predicting the natural frequency of the rotating cylinder...
Feasibility And Study(CNG Cylinder Production Plant)
, M.Sc. Thesis Sharif University of Technology ; Haji, Alireza (Supervisor)
Abstract
Nowadays best using of fossil fuels sources of the country (and) importance of comparison against lack of capacity in petrol production make determined the programmers and the directors to foresee and design expanded programs of the goals, to use natural gas for car fuels. To reach fulfillment of these programs, the confirmed needs of the natural gas cylinders are improved and make it essential to invest on producing compressive natural gas cylinders. In this way economical and technical change researches has been done in order to construct on department to produce 200,000 compressive natural gas cylinders in a year during two sets.(shifts) According to the results of technical researches...
Effect of Melt Quality & Melt Flow on Defects in Gravity Casting of AS5U3G Aluminum Alloy
, M.Sc. Thesis Sharif University of Technology ; Varahram, Naser (Supervisor)
Abstract
AS5U3G and AS7U3G are two prevalent types of alloy which are used in producing cylinder head. In this research AS5U3G alloy is studied. Gravity casting is one of the method of producing this part. Produced porosities in cylinder head casting process, cause leakage in this part. In order to solve this problem, some actions have been taken that we can divide them into quality operations improvement of melt and making changes in casts. The sampling is done in four levels to evaluate the gas porosity and shrinkage. In these levels, pressure and degassing duration and strontium's modifying in a fixed temperature have been evaluated. Based on reports by comparing density of relative samples, it...
Thermo-mechanical behaviours of light alloys in comparison to high temperature isothermal behaviours
, Article Materials at High Temperatures ; Vol. 31, issue. 1 , 2014 , pp. 12-17 ; ISSN: 09603409 ; Farrahi, G. H ; Winter, G ; Eichlseder, W ; Sharif University of Technology
Abstract
In this article, out-of-phase thermo-mechanical fatigue (TMF) behaviours of light alloys were investigated in comparison to their high temperature low cycle fatigue (LCF) behaviours. For this objective, strain based fatigue tests were performed on the A356 aluminium alloy and on the AZ91 magnesium alloy. Besides, TMF tests were carried out, where both strain and temperature changed. The fatigue lifetime comparison demonstrated that the TMF lifetime was less than that one under LCF loadings at elevated temperatures for both light alloys. The reason was due to severe conditions in TMF tests in comparison to LCF tests. The temperature varied in TMF test but it was constant under LCF loadings....
3D numerical modeling of wave forces on tandem fixed cylinders using the BEM
, Article Journal of Marine Science and Application ; Volume 12, Issue 3 , September , 2013 , Pages 279-285 ; 16719433 (ISSN) ; Abaiee, M. M ; Ahmadi, A ; Sharif University of Technology
2013
Abstract
In this paper a 3D numerical model was developed to study the complicated interaction between waves and a set of tandem fixed cylinders. The fluid was considered to be inviscid and irrotational. Therefore, the Helmholtz equation was used as a governing equation. The boundary element method (BEM) was adopted to discretize the relevant equations. Open boundaries were used in far fields of the study domain. Linear waves were generated and propagated towards tandem fixed cylinders to estimate the forces applied on them. Special attention was paid to consideration of the effect on varying non-dimensional cylinder radius and distance between cylinders, ka and kd on forces and trapped modes. The...
Investigation of flow around a confined elliptical cylinder using the Lattice Boltzmann method
, Article Middle East Journal of Scientific Research ; Volume 15, Issue 1 , 2013 , Pages 8-13 ; 19909233 (ISSN) ; Esfahanian, V ; Salari, M ; Sharif University of Technology
2013
Abstract
This paper deals with the investigation of the laminar flow past an elliptical cylinder confined in a channel. In this paper, the Lattice Boltzmann (LB) method is used to simulate flow in two dimensions. The present LB method with the used boundary conditions is validated in simulations of the incompressible flow past a circular cylinder. The simulations are carried out in a range of condition, 0≤θ≤90 (angle of incidence), 5≤Re≤100, (Reynolds number) for AR=0.25,0.5 (aspect ratio). The effects of those parameters on the drag and lift coefficients and other flow characteristics of the cylinder are examined in detail. The results demonstrate that the drag and lift coefficients increase with...
Investigation of flow around a confined elliptical cylinder using the Lattice Boltzmann method
, Article World Applied Sciences Journal ; Volume 22, Issue 7 , 2013 , Pages 1013-1018 ; 18184952 (ISSN) ; Salari, M ; Esfahanian, V ; Sharif University of Technology
2013
Abstract
This paper deals with the investigation of the laminar flow past an elliptical cylinder confined in a channel. In this paper, the Lattice Boltzmann (LB) method is used to simulate flow in two dimensions. The present LB method with the used boundary conditions is validated in simulations of the incompressible flow past a circular cylinder. The simulations are carried out in a range of condition, 0 90 (angle of incidence), 5 Re 100, (Reynolds number) for AR=0.25,0.5 (aspect ratio). The effects of those parameters on the drag and lift coefficients and other flow characteristics of the cylinder are examined in detail. The results demonstrate that the drag and lift coefficients increase with the...
Assessment of the LES-WALE and Zonal-DES turbulence models in simulation of the flow structures around the finite circular cylinder
, Article Journal of Applied Fluid Mechanics ; Volume 9, Issue 2 , 2016 , Pages 909-923 ; 17353572 (ISSN) ; Javadi, K ; Kiani, F ; Sharif University of Technology
Isfahan University of Technology
Abstract
Three-dimensional unsteady flow field around a finite circular cylinder standing in a flat-plate boundary layer is studied. For this purpose, two different numerical turbulence approaches as wall adapted local eddyviscosity LES (LES-WALE) and the zonal hybrid RANS-LES approach of Detached-Eddy Simulation (Zonal-DES) are used. Analysis is carried out for a finite circular cylinder with diameter of D = 3 mm and length-to-diameter ratio of L/D=6 which leads to the Reynolds number 2×104. Numerical simulation has been performed based on the LES-WALE and Zonal-DES turbulence models using coarse and fine grids. Ability and accuracy of two models in capturing the complex physics of present...
Calculation of stress intensity factor for functionally graded cylinders with two radial cracks using the weight function method
, Article Theoretical and Applied Fracture Mechanics ; Volume 85 , 2016 , Pages 447-456 ; 01678442 (ISSN) ; Azimi, M ; Mirjavadi, S. S ; Sharif University of Technology
Elsevier B.V
2016
Abstract
In this study, obtaining stress intensity factors (SIFs) for functionally graded cylinders with two internal radial cracks using the weight function method has been discussed. For this purpose, reference SIFs are calculated from the results of finite element analysis, using a modified domain of the J integral. Subsequently, SIFs have been calculated for different combinations of cylinder geometry, crack depth, and material gradation by implementing the weight function method and it is shown that the results are consistent with corresponding results obtained from finite element analysis. Moreover, the effects of variation in the elastic modulus ratio on SIFs have been investigated. © 2016...
Flow past confined nano cylinder in microscale channels
, Article Proceedings of the 7th International Conference on Nanochannels, Microchannels, and Minichannels 2009, ICNMM2009, 22 June 2009 through 24 June 2009, Pohang ; Issue PART A , 2009 , Pages 433-440 ; 9780791843499 (ISBN) ; Setayeshgar, A ; Sharif University of Technology
Abstract
Simulations of flow through microchannels over nano particles are widely encountered in solid particle transportation. In these simulations, the rarefaction phenomenon will affect the microflow behavior and subsequently the aerodynamics coefficients such as the drag coefficient derived for the suspended particles in the flow stream. This is why we use the Lattice Boltzmann method LBM to study the flow past a confined cylinder placed in a microchannel. The LBM is a mesoscopic method capable of solving flow in macro and micro scales. Applying the Maxwellian scattering kernel, the slip velocity is modeled on the channel and cylinder walls appropriately. To validate our formulations, we firstly...
Towards an understanding of marine fouling effects on VIV of circular cylinders: Aggregation effects
, Article Ocean Engineering ; Volume 147 , 2018 , Pages 227-242 ; 00298018 (ISSN) ; Zeinoddini, M ; Soltanpour, M ; Zandi, A. P ; Seif, M. S ; Sharif University of Technology
Abstract
The current study is aimed at getting a further insight into the changes the fouling brings to the Vortex Induced Vibration (VIV) of circular cylinders. Instead of regular patterns considered in previous studies, using the Poisson Cluster Process, an aggregated spatial distribution was considered for the artificial marine fouling. This is believed to better simulate the natural settlement of the marine biofouling. Different coverage ratios and fouling shapes plus regular and aggregated distributions were considered. The towing tank VIV tests were conducted on elastically mounted rigid cylinders. The Reynolds number ranged from around 7.8 × 103 to 4.9 × 104. On the whole, the maximum...
Flow control around a circular cylinder with swinging thin plates
, Article Journal of Fluids and Structures ; Volume 81 , 2018 , Pages 738-760 ; 08899746 (ISSN) ; Javadi, K ; Sharif University of Technology
Academic Press
2018
Abstract
Flow around a 2D circular cylinder with attached swinging thin splitter plates is numerically investigated. The ratio of the plates’ length to the cylinder diameter is 1 ([Formula presented]=1) where L is the Plates’ length and D is the cylinder diameter. The plates are attached at ±55 degrees (trigonometric angle) downstream and are forced to oscillate at different ratios of the natural vortex shedding frequencies with magnitudes of FR=0.75,1,1.25,1.5 and 2. The oscillation amplitude “α” as the other main variable ranges from 10 to 18 degrees. Two-dimensional simulations are carried out at the Reynolds number 100, and then extended to higher Reynolds number of 200. The results show that in...
Utilising flags to reduce drag around a short finite circular cylinder
, Article Journal of Turbulence ; Volume 19, Issue 3 , 2018 , Pages 229-251 ; 14685248 (ISSN) ; Kiani, F ; Tahaye Abadi, M ; Sharif University of Technology
Taylor and Francis Ltd
2018
Abstract
This paper utilises flags to decrease the drag around a short finite circular cylinder. Wall-adapted large eddy simulation and two-way fluid–structure interaction methods were applied to resolve unsteady turbulent flow structure. The far-field Reynolds number of the current configuration based on the cylinder diameter was chosen to be 20,000. In addition, the length-to-diameter ratio of the cylinder was assumed to be L/D = 2 whereas the flexible flag had a width-to-diameter ratio of W/D = 1.5. The results were compared with the regular short finite circular cylinder and the rigid flagged cylinder in our previous work. The results indicate that utilising flags inside the near-wake region of...
Steady-state thermal and mechanical stresses in two-dimensional functionally graded piezoelectric materials (2D-FGPMs) for a hollow infinite cylinder
, Article Scientia Iranica ; Volume 26, Issue 1B , 2019 , Pages 428-444 ; 10263098 (ISSN) ; Selk Ghafari, A ; Firoozbakhsh, K ; Jabbari, M ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
In this paper, the general analysis of two-dimensional steady-state thermal and mechanical stresses for a hollow thick infinite cylinder made of Functionally Graded Piezoelectric Materials (2D-FGPMs) is performed and developed. The general form of thermal, mechanical, and electrical boundary conditions is considered on the inside and outside surfaces. A direct method is used to solve the heat conduction equation and the non-homogenous system of partial differential Navier equations, using the complex Fourier series and the power law functions method. The material properties are assumed dependent on the radial and circumferential variables and are expressed as power law functions along the...
Steady-state thermal and mechanical stresses in two-dimensional functionally graded piezoelectric materials (2D-FGPMs) for a hollow infinite cylinder
, Article Scientia Iranica ; Volume 26, Issue 1B , 2019 , Pages 428-444 ; 10263098 (ISSN) ; Selk Ghafari, A ; Firoozbakhsh, K ; Jabbari, M ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
In this paper, the general analysis of two-dimensional steady-state thermal and mechanical stresses for a hollow thick infinite cylinder made of Functionally Graded Piezoelectric Materials (2D-FGPMs) is performed and developed. The general form of thermal, mechanical, and electrical boundary conditions is considered on the inside and outside surfaces. A direct method is used to solve the heat conduction equation and the non-homogenous system of partial differential Navier equations, using the complex Fourier series and the power law functions method. The material properties are assumed dependent on the radial and circumferential variables and are expressed as power law functions along the...
Experimental and finite element prediction of bursting pressure in compound cylinders
, Article International Journal of Pressure Vessels and Piping ; Volume 81, Issue 12 , 2004 , Pages 889-896 ; 03080161 (ISSN) ; Farrahi, G. H ; Pipelzadeh, M. K ; Akbari, A ; Sharif University of Technology
Elsevier BV
2004
Abstract
Aluminium cylinders with a constant ratio of outer to inner radii, k=2.2, with different diametral interferences and various shrinkage radii were subjected to bursting and autofrettage pressures. Numerical simulations of the compound cylinders were also performed using the finite element code, NISA. The results can predict the optimum shrinkage radius to a reasonable accuracy with the use of finite element analysis. This radius corresponds to the situation when the maximum von-Mises stress at the internal radii of both the inner and outer cylinders become equal. It was shown that the maximum von-Mises stress across the wall of the cylinder is at the minimum at this shrinkage radius. The...
Flow and Heat Transfer between Two Cylinders with Internal Rotation
, M.Sc. Thesis Sharif University of Technology ; Noori Boroujerdi, Ali (Supervisor)
Abstract
The objective of this project is numerical simulation of air flow and heat transfer between two horizontal concentric cylinders with rotation of inner cylinder and inertia of outer cylinder grooves on the inner cylinder. In this study, the air, meanwhile rotational motion by the inner cylinder will enter into the annular space between two cylinders with certain flow rate. It can be mentioned to cooling of power plant generators, Electric motors and rotating machines among usages of air flow between two cylinders. In this article the objective is calculation of pressure drop and Nusselt number, temperature distribution on the inner cylinder under conditions of constant temperature of...