Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2937
2588-2945
3
2
2019
12
01
Numerical Investigation of Step Depth Effects on Hydrodynamic Performance of Planing Hull Using Dynamic Mesh and Two Degree of Freedom Model
139
148
EN
Reza
Tork Chooran
Sea-Based Energy Research Group-Babol Noshirvani University of Technology-Babol-Iran
rtch22@chmail.ir
Rouzbeh
Shafaghat
Sea-Based Energy Research Group-Babol Noshirvani University of Technology-Babol-Iran
rshafaghat@nit.ac.ir
Reza
Yoosefi
Department of Mechanical Engineering, Babol Noshiravani University of Technology
reza_yousefi41@yahoo.com
10.22060/ajme.2019.14364.5723
At low speeds, planing hull performs like a displacement one and buoyancy force has the most influence on it, but, when it reaches to enough speed, hydrodynamic lift force equilibrates 50–90 percent of its weight. Planing hull researchers have introduced different methods in order to achieve the highest speed. A desirable planing hull has low weight-to-power ratio and good maneuverability. Several ways have been applied to reduce drag and one of the best strategies is to use step that leads to less wetted surface and more lift power. This work addresses the numerical study of step height effect on hydrodynamic performance of planing hull. A specified form of a monohull was changed to the step one while important geometric parameters such as Deadrise angle, width and length were equal in both of them. In order to simulate hull movements, a comprehensive series of viscous computational fluid dynamics simulations considering free-surface and two degree of freedom motion of the hull (heave and pitch) have been performed by application of dynamic mesh. Results have been presented as contours and plots. According to the results, deeper steps provide greater levels of ventilation but, there is a limit in step depth increment because porpoising happens after a specific height.
High speed planing hull,step,two degrees of freedom,trim angle,Volume of Fluid Method
https://ajme.aut.ac.ir/article_3239.html
https://ajme.aut.ac.ir/article_3239_41f140f72ababb9a8a8b91b56a9521bf.pdf
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2937
2588-2945
3
2
2019
12
01
Set Points Values of an Automatic Line Control Valve Installed on Natural Gas Pipeline
149
156
EN
Mehdi
Mahmoodi
Babol Noshirvani University of Technology
mehdymahmoody@gmail.com
Sobhan
Mosayebi-dorcheh
Babol Noshirvani University of Technology
sobhanmosayebi@yahoo.com
mofid
gorji bandpy
Babol University of Technology
gorji@nit.ac.ir
10.22060/ajme.2018.13735.5313
When a natural gas pipeline ruptures, the adjacent automatic line control valves should close quickly to prevent leakage or explosion. The differential pressure set point at each valve position has an essential role for value determining in automatic line control valves action. This study focused on the differential pressure set point values prediction for setting automatic line control valves installed on a gas pipeline. The effect of characteristic parameters such as pipeline operational pressure and pipeline pressure drop rate due to major leak or abrupt rupture was experimentally examined on differential pressure set point. 25 different conditions with double set of typical indicated characteristic factors were selected. The differential pressure for any unique condition was measured in 180s time duration by analyzing the experimental outcomes, statistically. The differential pressure set point increases by changing such as increase in pipeline pressure drop rate or decrease in pipeline operational pressure parameters. Due to applying nitrogen gas instead of natural gas on account of safety claiming, the differential pressure set point results practically can be implemented by adding a 15% safety coefficient. The diagram of differential pressure set point with respect to defined parameters was presented for different values of pipeline operational pressure.
Automatic Line Control Valve,Operating Pressure,Set Points,Drop Rate,Gas transmission pipeline
https://ajme.aut.ac.ir/article_2982.html
https://ajme.aut.ac.ir/article_2982_433e455fcd4e47b8245dc8401cac679e.pdf
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2937
2588-2945
3
2
2019
12
01
Laminar Viscous Flow of Micropolar Fluid through Non-Darcy Porous Medium Undergoing Uniform Suction or Injection
157
164
EN
AKINBOWALE
T.
AKINSHILO
DEPT. OF MECH. ENGR., UNIVERSITY OF LAGOS, NIGERIA.
ta.akinshilo@gmail.com
ADELEKE
ILLEGBUSI
DEPT. OF MECH. ENGR., YABA COLLEGE OF TECHNOLOGY, LAGOS
wilkyj4uall@yahoo.co.uk
10.22060/ajme.2018.14619.5736
In this study, the micropolar fluid flow conveyed through suction or injection in a non-Darcy porous medium with high mass transfer is considered. The micropolar fluid flow is described by coupled systems of higher order, ordinary, nonlinear differential equations. Therefore the variation of parameters method is utilized in generating analytical solutions to the mathematical models arising from flow and rotation of the micropolar fluid. As the variation of parameters method is a relatively easy, yet efficient approach of analyzing both strongly and weakly dependent nonlinear equations with a rapid convergence rate. Pertinent rheological fluid parameter effects such as non-Darcy parameter and Reynolds number on flow and rotation are examined using the obtained analytical solutions. Observations from graphical representation of result illustrate flow increase during injection and slight radial velocity decrease for suction flow. Reynolds parameter effect on fluid particles micro rotation also shows decrease in rotation profile during injection while during suction increased particle rotation is observed as a result of high mass transfer. Results obtained from study compared against existing works in literature prove to be in satisfactory agreement. Therefore this paper can be used to further study of micropolar fluids applications such as blood flow, lubricants and micro channel flows amongst others.
Micropolar fluid,non-Darcy porous channel, high mass transfer, Variation of parameters method
https://ajme.aut.ac.ir/article_3137.html
https://ajme.aut.ac.ir/article_3137_65306043d2d38be67bdd1ba372ec5f71.pdf
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2937
2588-2945
3
2
2019
12
01
Experimental and Image Processing Investigation on the Diffusion of Dust Particles in the Atmospheric Area
165
172
EN
mohammad
Alipour Shotlou
Department of Mechanical Engineering, University of Tabriz, Iran
m.alipoor92315@gmail.com
Mohammad Taghi
Shervani Tabar
Department of Mechanical engineering, University of Tabriz, Iran
msherv@tabrizu.ac.ir
Moharram
Jafari
Tabriz University*
mjafari@tabrizu.ac.ir
10.22060/ajme.2018.14359.5725
The diffusion and transfer of dust particles in the atmospheric area were investigated with experimental and image processing methods. In a flat field, the rising of dust particles into the air by plowing the field with a tractor and their spreading along the surrounding environment as a real model of dust diffusion in the atmospheric area. The experiments carried out for specifying the particle-size distribution of the bed dust and its density. The experimental photos of dust diffusion were analyzed by image processing. The intensity of the diffusion of dust particles in the atmospheric area at the different roughness of surfaces for the different speeds of the tractor movement was obtained. The roughness of the surface increases the impact threshold and reduce the number of splashing particles. As particles velocities increase, the particles height increases and the proportion slope decreases at the high velocities. A relative concentration parameter <em>C</em><em>α </em>was defined. The results of this study compared with previous works based on this relative concentration. The concentration of dust particles decreases exponentially by increasing up to a certain height and after this height, changes in concentration are minor. Also, the role of mid-air collisions is significant, especially at high speeds.
Diffusion,Dust particles,Saltation,Image processing,ENVIRONMENT
https://ajme.aut.ac.ir/article_3214.html
https://ajme.aut.ac.ir/article_3214_ec28a059b5970feebd692825e2a6ef29.pdf
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2937
2588-2945
3
2
2019
12
01
Reduced Order Model for Boundary Instigation of Burgers Equation of Turbulence Using Direct and Indirect Control Approaches
173
186
EN
Mohammad Kazem
Moayyedi
0000-0003-4016-1557
Department of Mechanical Engineering, University of Qom
moayyedi@qom.ac.ir
10.22060/ajme.2018.14240.5740
In this paper, a reduced order model is reconstructed for boundary control and excitation of the unsteady viscous Burgers equation. First, the standard reduced order proper orthogonal decomposition model, which has been extracted from the governing equations without control inputs, was evaluated and illustrated the satisfactory results in short time period. Two approaches are used to imply the effects of boundaries excitations and the related control routines. In the first, a source term was added to the governing equation of the reduced order dynamical system and was contributed as an expansion of the proper orthogonal decomposition modes without control input. For removing the inhomogeneities on the boundaries, the boundaries values are subtracted from all of the snapshots with an appropriate control input. The other approach is based on the rewriting of the diffusion term as an expanded form which contains the effect of boundaries values explicitly. In both approaches, the obtained reduced order models will contain two parts, the effect of system states and the influence of boundaries control functions. The results obtained from the reduced order model without the control inputs demonstrate a good agreement to the benchmark direct numerical simulations data and prove the high accuracy of the model.
Proper Orthogonal Decomposition,Galerkin projection,Reduced Order Model,Boundary control,Viscous Burger's equation
https://ajme.aut.ac.ir/article_3196.html
https://ajme.aut.ac.ir/article_3196_9353217a39a0df522ce1125b04929569.pdf
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2937
2588-2945
3
2
2019
12
01
On the Flow and Heat Transfer Analysis of Pipe Conveying Johnson-Segalman Fluid: Analytical Solution and Parametric Studies
187
196
EN
Gbeminiyi
Musibau
Sobamowo
Department of Mechanical Engineering, University of Lagos, Nigeria
mikegbeminiyi@gmail.com
10.22060/ajme.2018.14135.5706
In this study, Galerkin’s method of weighted residual is used to present simple approximate analytical solutions to flow and heat transfer characteristics in a pipe conveying Johnson-Segalman fluid. The developed approximate analytical solutions are verified with the results in literature. Thereafter, the solutions are used to investigate the effects of the pertinent parameters such as relaxation time parameter, viscosity parameter and Brinkman number on the fluid velocity and the temperature distributions of the pipe flow. From the results, it shows that the fluid velocity and temperature increase with the relaxation time parameter and Brinkman number. It is also established that relaxation time parameter increases with increase in the velocity of the fluid but decreases with increase in the fluid temperature. It is found that the relaxation parameter effect on the velocity distribution are not significant as the viscosity parameter approaches unity and when it is greater than unity. It is hope that the study will provide more physical insight into the flow phenomena.
heat transfer,Pipe flow,Johnson-Segalman fluid,Analytical solutions,Galerkin’s method of weighted residual
https://ajme.aut.ac.ir/article_2984.html
https://ajme.aut.ac.ir/article_2984_ee4104c978d0fd21b94504709ff580d0.pdf
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2937
2588-2945
3
2
2019
12
01
An Exact Solution for Fluid Flow and Heat Convection through Triangular Ducts Considering the Viscous Dissipation
197
204
EN
Mahmood
Norouzi
Faculty of Mechanical Engineering, Shahrood University of Technology, Shahrood, Iran
mnorouzi@shahroodut.ac.ir
Mohammad Mohsen
Sahhmardan
Faculty of Mechanical Engineering, Shahrood University of Technology, Shahrood, Iran
mmshahmardan@shahroodut.ac.ir
Mahdi
Davoodi
School of Engineering, University of Liverpool, Brownlow Hill, Liverpool, L69 3GH, UK.
m.davoodi@liverpool.ac.uk
Mostafa
Mahmoudi
Department of Mechanical Engineering, Northern Arizona University, Flagstaff, USA.
mm4238@nau.edu
10.22060/ajme.2018.14630.5737
Today, the study of flow and heat transfer in non-circular ducts are of increasing importance in various industries and applications such as microfluidics, where lithographic methods typically produce channels of square or triangular cross-section. Also, heat transfer in non-circular ducts is important in designing the compact heat exchangers to enhance the heat transfer. In the current study, an exact analytical solution for the convective heat transfer in conduits with equilateral triangle cross-section is presented for the first time. The effect of viscous dissipation on heat transfer and temperature distribution through the duct is investigated in detail. This effect is of great importance especially in flow of high viscous fluids in micro-channels. In order to study the effect of viscous dissipation in both cooling and heating cases, the Brinkman number is employed. The exact solution is found by calculating the particular solution which satisfies the thermal boundary conditions. Based on the finite expansion method, an exact analytical solution for temperature distribution and a correlation for dimensionless Nusselt number is obtained as functions of the Brinkman number. The maximum temperature and Nusselt number at the centroid of the conduit for the specific case of Brinkman number equal to zero is calculated equal to 5/9 and 28/9, respectively. The proposed method of solution could be used to find the exact solution for similar problems such as analysis the heat convection in non-circular geometries.
Forced Heat Convection,Triangular Duct,Brinkman number,Exact Solution,Internal Flow
https://ajme.aut.ac.ir/article_3197.html
https://ajme.aut.ac.ir/article_3197_3022907059051cc1b229313974f4a699.pdf
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2937
2588-2945
3
2
2019
12
01
Multi-objective optimization of the structure of triangular chevron channels
205
216
EN
Hossein
Dolatabadi
Department of mechanical engineering,Arak university of technology, Arak, Iran
dolat.hossein1@gmail.com
Abolfazl
Hajizadeh Aghdam
Department of mechanical engineering,Arak university of technology, Arak, Iran
abolfazl_hajizade@yahoo.com
10.22060/ajme.2019.14992.5755
Chevron channels are one of the popular techniques that are extensively used in different heat exchangers such as plate heat exchangers and solar air heaters. Numerical studies were carried out on turbulent heat transfer and friction factor loss through a triangular chevron channel for a uniform wall heat flux 3000 W/m<sup>2</sup> using air as a working fluid. The results of the average Nusselt number, friction factor and thermal enhancement factor in different phase shifts (<em>ϕ</em>) are presented. Reynolds number were varied from 10000 to 30000 and horizontal moving of the plates were horizontally moved with regards to each other (phase shift) at the range of 0° <em>≤ϕ≤</em>180° whereas, distance between chevron surfaces was constant (<em>D=</em>5 mm). The channels with phase shift angle of <em>ϕ = </em>18.28º, are the most attractive from the viewpoint of energy saving. The genetic algorithm optimization using non-dominated sorting genetic algorithm II showed that with increasing Reynolds number, Nusselt number increased and the thermal enhancement factor decreased. It also proved that <em>ϕ=</em>18.28º was the optimum phase shift. The results also indicated that the triangular chevron channels with (<em>Dv=</em>7.43mm) have maximum Nusselt number and thermal enhancement factor and minimum friction factor.
heat transfer,Pressure drop,Thermal Enhancement Factor,genetic algorithm
https://ajme.aut.ac.ir/article_3325.html
https://ajme.aut.ac.ir/article_3325_4da2e18fae18027f23c4301e7561cbe1.pdf
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2937
2588-2945
3
2
2019
12
01
The Effect of Compression Ratio and Alternative Fuels on Performance and Exhaust Emission in a Diesel Engine by Modelling Engine
217
228
EN
Saeed
Ahmadipour
Department of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
saeed.ahmadipour@mail.um.ac.ir
Mohammad Hossein
Aghkhani
Department of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
aghkhani@um.ac.ir
Javad
Zareei
Department of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
javadzareei@um.ac.ir
10.22060/ajme.2019.15162.5764
This study investigates the effect of compression ratio and different fuels on engine performance and exhaust emissions in a 6.8L turbocharged industrial diesel engine. For carried out this work, a 6 cylinder four stroke engine with gamma technologies power software is modelled and the effect of compression ratio (15:1 - 19:1) and alternative fuels (Diesel, Ethanol, Methanol, Decane, Soybean biodiesel, Diesel- Ethanol) at wide open throttle and various speeds from 800-2400 rpm are presented. The results indicate that the brake specific fuel consumptions of decane fuel at a compression ratio of 17:1 is lower than those of other fuels and also the maximum brake torque obtained with decane fuel at 1400 rpm. At this engine observed that decane fuel has higher brake power as compared to other fuels used due to higher heating value content. The emission results show that diesel fuel emitted more Carbon monoxide and Carbon dioxide emissions but soybean biodiesel (B100) has less Carbon monoxide, whereas highest oxides of nitrogen is founded with soybean biodiesel. Carbon monoxide and Carbon dioxide emissions are very close to each other when used decane and diesel fuel. In general decane fuel has higher performance and soybean biodiesel had fewer emissions at a compression ratio of 17:1.
Diesel Engine,Performance and Exhaust Emissions,Compression Ratio,Alternative Fuel
https://ajme.aut.ac.ir/article_3259.html
https://ajme.aut.ac.ir/article_3259_605b3c8cddc8014a3e57033924a48e3e.pdf
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2937
2588-2945
3
2
2019
12
01
Fatigue Life Evaluation of Single and Two Riveted Coach Peel Joints Using Strain- Life Criteria
229
234
EN
Hadi
Moslemi
Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
m.hmoslemi@yahoo.com
Khalil
Farhangdoost
000-0001-5463-6766
Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
farhang@um.ac.ir
Pedram
Zamani
Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
p.zamani@mail.um.ac.ir
10.22060/ajme.2019.14541.5731
In this paper, experimental investigation was performed to estimate fatigue life of single and double riveted coach peel joints of 2024 aluminum alloy. Load controlled fatigue tests were conducted with load ratio and frequency of 0.1 and 10 Hz, respectively. Failure of the specimens revealed three major modes of folded region fracture (A-type), fracture from edge of the rivet hole (B-type) and mixed mode fracture (A & B). Although all failure modes contributes equally in single riveted joint, mixed mode fracture was observed as dominant mode in two riveted ones. A numerical approach is applied to estimate fatigue life of riveted coach peel joints. Finite element analysis was implemented by ABAQUS as the first step of this approach to estimate stress distribution, stress concentration factor, stress and strain amplitude. Fatigue lives were then calculated using three fatigue life theories of Monson-Hirschberg, Smith-Watson-Topper and Morrow. Finally, good accordance between numerical and experimental results revealed that the finite element approach combined with fatigue life theories is capable for fatigue life prediction. It is concluded that adding a rivet in longitudinal direction to the single riveted coach peel joint decreases the life cycles by increasing the stress concentration factor. Moreover, results of finite element approach showed that Monson-Hirschberg and experimental data has the best agreement in compare with SWT and Morrow.
Coach peel joint,fatigue life estimation,Finite element analysis,riveted joint,strain-life method
https://ajme.aut.ac.ir/article_3288.html
https://ajme.aut.ac.ir/article_3288_a7372f4d8f6f4c2991a0cd29c1974a60.pdf
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2937
2588-2945
3
2
2019
12
01
Mixed-Mode Fracture Analysis of a Functionally Graded Layer with Clamped Longitudinal Edges
235
242
EN
Ali Mohammad
Baghestani
Babol Noshirvani University of Technology*
am_baghestany@yahoo.com
Shahriar
Fariborz
Amirkabir University of Technology(Tehran Polytechnic)*mechanical engineering
fariborz@aut.ac.ir
10.22060/ajme.2019.14844.5748
Properties of functionally graded materials as nonhomogeneous solids with gradually varied composition make them suitable for many applications, such as coating in interfacial zones. The present study investigates the plane elasticity problem for an isotropic functionally graded material layer containing multiple cracks using the distributed dislocation technique. The layer has a finite thickness and infinite length where it’s top and bottom surfaces are fixed. The elastic modulus of the medium is assumed to vary exponentially in the thickness direction. The Fourier integral transform method is used to obtain the stress fields caused by an edge dislocation in the layer. The stress components exhibit familiar Cauchy as well as logarithmic singularity at the dislocation position. In fact, the dislocation solution in this study is primarily employed to derive a set of integral equations to analyze cracks with arbitrary configuration. The numerical solution of these equations yields dislocation densities on a crack surface which is used to compute the crack stress intensity factors.Then after validating the formulation for homogenous case, several configurations of embedded cracks such as a rotating crack, a stationary horizontal and a rotating crack, two fixed vertical and a horizontal crack with variable location are investigated. Moreover, effects of important parameters on stress intensity factors such as crack geometries, material non-homogeneity and boundary condition are studied.
Functionally graded material layer,Mixed-mode,Fixed Boundary,Multiple Cracks
https://ajme.aut.ac.ir/article_3219.html
https://ajme.aut.ac.ir/article_3219_da3693203e8a793e65165d5709701060.pdf
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2937
2588-2945
3
2
2019
12
01
On the Low-Velocity Impact and Quasi-Static Indentation Studies of Nomex Honeycomb Composite Sandwich Panels
243
254
EN
Soroush
Sadeghnejad
0000-0001-8286-7756
Amirkabir University of Technology (Tehran Polytechnic)
s.sadeghnejad@aut.ac.ir
Yousef
Taraz Jamshidi
مهندسی مکانیک، دانشگاه تربیت دبیر شهید رجائی، تهران
y.jamshidi@aut.ac.ir
Mojtaba
Sadighi
Amirkabir University of Technology (Tehran Polytechnic), Mechanical Engineering
mojtaba@aut.ac.ir
10.22060/ajme.2018.15011.5758
An experimental–numerical methodology for investigation of quasi-static indentation and low velocity impact on sandwich panels with composite skins and Nomex™ honeycomb core is presented. Sandwich panels with glass/epoxy skins and a NomexTM honeycomb core were modeled by a three-dimensional finite element model implemented in ABAQUS/Explicit. The model was validated with experimental tests by comparing numerical and experimental results. The comparison has not only been based on a load–displacement and load time history curves, but has been further exemplified by detailed photographical images throughout the whole loading process and the local behavior of the cells crushing. Results show that fine micromechanical models based on shell elements give good correlation with honeycomb compression tests for Nomex™ honeycombs. Also the reference finite element numerical model demonstrates its capability to accurately reproduce the shape of the local damage of the panel. In other words, the calibrated micromechanical model is obtained to predict both quasi-static and low-velocity impact behavior. The mentioned model could be used for structural optimization with enhanced accuracy in contrast to conventional macro-mechanical models. The calibrated model is used to predict the cell size effect, friction and also geometric scale.
quasi-static,Low velocity impact,Sandwich panels,Nomex™ honeycomb,experimental–numerical methodology
https://ajme.aut.ac.ir/article_3160.html
https://ajme.aut.ac.ir/article_3160_d92399b747fe2766dda655d919dadec4.pdf