eng
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2945
2588-2937
2019-12-01
3
2
139
148
10.22060/ajme.2019.14364.5723
3239
Numerical investigation of step depth effects on hydrodynamic performance of planing hull using dynamic mesh and 2-DOF model
Reza Tork Chooran
rtch22@chmail.ir
1
Rouzbeh Shafaghat
rshafaghat@nit.ac.ir
2
Reza Yoosefi
reza_yousefi41@yahoo.com
3
Sea-Based Energy Research Group-Babol Noshirvani University of Technology-Babol-Iran
Sea-Based Energy Research Group-Babol Noshirvani University of Technology-Babol-Iran
Department of Mechanical Engineering, Babol Noshiravani University of Technology
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 CFD simulations considering free-surface and 2-DOF 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.
https://ajme.aut.ac.ir/article_3239_41f140f72ababb9a8a8b91b56a9521bf.pdf
High speed planing hull
step
two degrees of freedom
trim angle
Volume of Fluid Method
eng
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2945
2588-2937
2019-12-01
3
2
149
156
10.22060/ajme.2018.13735.5313
2982
Set Points Values of an Automatic Line Control Valve Installed on Natural Gas Pipeline
Mehdi Mahmoodi
mehdymahmoody@gmail.com
1
Sobhan Mosayebi-dorcheh
sobhanmosayebi@yahoo.com
2
mofid gorji bandpy
gorji@nit.ac.ir
3
Babol Noshirvani University of Technology
Babol Noshirvani University of Technology
Babol University of Technology
When a natural gas pipeline ruptures, the adjacent automatic line control valves (ALCVs) should close quickly to prevent leakage or explosion. The differential pressure set point (DPS) at each valve location is the main criteria for value setting in ALCV action. If the DPS is not properly adjusted, the ALCV may mistakenly close or it may not take any action at proper time. This study focused on the DPS values prediction for setting ALCV installed on a gas pipeline. The effect of characteristic parameters such as pipeline operational pressure (POP) and pipeline pressure drop rate (ROD) due to rupture or major leak was experimentally investigated on DPS. 25 different conditions with double set of typical mentioned characteristic parameters were chosen. For each condition, the differential pressure (DP) was measured over 180s by statistically analyzing the experimental results. Therefore, 25 maximum DP values (DPSs) were obtained. The DPS increases by increase in ROD or decreasing POP parameters. Because of using nitrogen gas instead of natural gas due to safety reasons, the DPS results can be practically applied by adding a safety factor of 15%. The diagram of DPS with respect to ROD and DOP versus RTP were provided for different POPs.
https://ajme.aut.ac.ir/article_2982_433e455fcd4e47b8245dc8401cac679e.pdf
Automatic Line Control Valve
Operating Pressure
Set Points
Pressure Drop Rate
Gas Pipeline
eng
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2945
2588-2937
2019-12-01
3
2
157
164
10.22060/ajme.2018.14619.5736
3137
Laminar Viscous Flow of Micropolar Fluid through Non-Darcy Porous Medium Undergoing Uniform Suction or Injection
AKINBOWALE AKINSHILO
ta.akinshilo@gmail.com
1
ADELEKE ILLEGBUSI
wilkyj4uall@yahoo.co.uk
2
DEPT. OF MECH. ENGR., UNIVERSITY OF LAGOS, NIGERIA.
DEPT. OF MECH. ENGR., YABA COLLEGE OF TECHNOLOGY, LAGOS
In this study, the flow of micropolar fluid, driven by suction or injection through a non-Darcy porous medium with high mass transfer is considered. The micropolar fluid flow is described by coupled systems of higher order, nonlinear, ordinary differential equations. Therefore the variation of parameters method (VPM) is utilized in generating analytical solutions to the mathematical models arising from flow and rotation of the micropolar fluid. As the VPM 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.
https://ajme.aut.ac.ir/article_3137_65306043d2d38be67bdd1ba372ec5f71.pdf
Micropolar fluid
non-Darcy porous channel, high mass transfer, Variation of parameters method
eng
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2945
2588-2937
2019-12-01
3
2
165
172
10.22060/ajme.2018.14359.5725
3214
Experimental and Image Processing Investigation on the Diffusion of Dust Particles in the Atmospheric Area
mohammad Alipour Shotlou
m.alipoor92315@gmail.com
1
Mohammad Taghi Shervani Tabar
msherv@tabrizu.ac.ir
2
Moharram Jafari
mjafari@tabrizu.ac.ir
3
Department of Mechanical Engineering, University of Tabriz, Iran
Department of Mechanical engineering, University of Tabriz, Iran
Tabriz University*
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 C_α 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.
https://ajme.aut.ac.ir/article_3214_ec28a059b5970feebd692825e2a6ef29.pdf
Diffusion
Dust particles
Saltation
Image processing
ENVIRONMENT
eng
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2945
2588-2937
2019-12-01
3
2
173
186
10.22060/ajme.2018.14240.5740
3196
Reduced Order Model for Boundary Instigation of Burgers’ Equation of Turbulence Using Direct and Indirect Control Approaches
Mohammad Kazem Moayyedi
moayyedi@qom.ac.ir
1
Department of Mechanical Engineering, University of Qom
In this paper, a reduced order model is reconstructed for boundary control and excitation of the unsteady viscous Burger's equation. First, the standard reduced order POD 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 POD 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 DNS data and prove the high accuracy of the model. The results obtained from the reduced order model without the control inputs demonstrate a good agreement to the benchmark DNS data and prove the high accuracy of the model.
https://ajme.aut.ac.ir/article_3196_9353217a39a0df522ce1125b04929569.pdf
Proper Orthogonal Decomposition
Galerkin projection
Reduced Order Model
Boundary control
Viscous Burger's equation
eng
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2945
2588-2937
2019-12-01
3
2
187
196
10.22060/ajme.2018.14135.5706
2984
On Heat transfer analysis in pipe flow of Johnson-Segalman Fluid: Analytical Solution and Parametric Studies
Gbeminiyi Sobamowo
mikegbeminiyi@gmail.com
1
Department of Mechanical Engineering, University of Lagos, Nigeria
In this study, Galerkin’s method of weighted residual has been applied to present simple approximate analytical solutions to flow and heat transfer in a pipe conveying Johnson-Segalman fluid. The developed approximate analytical solutions are verified with the results in literature and then 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 effects of relaxation parameters on the velocity distribution are not significant as the viscosity parameter approaches unity and when it is greater than unity. On the use of Galerkin’ method of weighted residual in providing approximate analytical solutions to nonlinear problems, it is demonstrated in this study that the second degree's trial function converges to result with a good accuracy. This fact had been pointed out earlier studies that additional terms should not be necessary in most instances and further refinement should not be necessary. It is hope that the study will provide more physical insight into the flow phenomena.
https://ajme.aut.ac.ir/article_2984_ee4104c978d0fd21b94504709ff580d0.pdf
heat transfer
Pipe flow
Johnson-Segalman fluid
Analytical solutions
Galerkin’s method of weighted residual
eng
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2945
2588-2937
2019-12-01
3
2
197
204
10.22060/ajme.2018.14630.5737
3197
An Exact Solution for Fluid Flow and Heat Convection through Triangular Ducts Considering the Viscous Dissipation
Mahmood Norouzi
mnorouzi@shahroodut.ac.ir
1
Mohammad Mohsen Sahhmardan
mmshahmardan@shahroodut.ac.ir
2
Mahdi Davoodi
m.davoodi@liverpool.ac.uk
3
Mostafa Mahmoudi
mm4238@nau.edu
4
Faculty of Mechanical Engineering, Shahrood University of Technology, Shahrood, Iran
Faculty of Mechanical Engineering, Shahrood University of Technology, Shahrood, Iran
School of Engineering, University of Liverpool, Brownlow Hill, Liverpool, L69 3GH, UK.
Department of Mechanical Engineering, Northern Arizona University, Flagstaff, USA.
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.
https://ajme.aut.ac.ir/article_3197_3022907059051cc1b229313974f4a699.pdf
Forced Heat Convection
Triangular Duct
Brinkman number
Exact Solution
Internal Flow
eng
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2945
2588-2937
2019-12-01
3
2
205
216
10.22060/ajme.2019.14992.5755
3325
Multi-objective optimization of the structure of triangular chevron channels
Hossein Dolatabadi
dolat.hossein1@gmail.com
1
Abolfazl Hajizadeh Aghdam
abolfazl_hajizade@yahoo.com
2
Department of mechanical engineering,Arak university of technology, Arak, Iran
Department of mechanical engineering,Arak university of technology, Arak, Iran
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 to improve heat transfer potential. 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/m2) using air as a working fluid. The results of the average Nusselt number, friction factor and thermal enhancement factor (TEF) in different phase shifts (ϕ) 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° ≤ϕ≤180° whereas, distance between chevron surfaces was constant (D=5 mm). The channels with phase shift angle of ϕ = 18.28º, are the most attractive from the viewpoint of energy saving. The Genetic Algorithm optimization using NSGA II algorithm showed that with increasing Reynolds number, Nusselt number (Nu) increased and the Thermal Enhancement Factor (TEF) decreased. It also proved that ϕ=18.28º was the optimum phase shift. The results also indicated that the triangular chevron channels with special geometry (Dv=7.43mm) have maximum Nu and TEF and the minimum friction factor.
https://ajme.aut.ac.ir/article_3325_4da2e18fae18027f23c4301e7561cbe1.pdf
Chevron channel
heat transfer
Pressure drop
Thermal Enhancement Factor
genetic algorithm
eng
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2945
2588-2937
2019-12-01
3
2
217
228
10.22060/ajme.2019.15162.5764
3259
The effect of compression ratio and alternative fuels on performance and exhaust emission in a diesel engine by modelling engine
Saeed Ahmadipour
saeed.ahmadipour@mail.um.ac.ir
1
Mohammad Hossein Aghkhani
aghkhani@um.ac.ir
2
Javad Zareei
javadzareei@um.ac.ir
3
Department of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
Department of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
Department of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, Mashhad, Iran
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 GT 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 WOT 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 NOx 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.
https://ajme.aut.ac.ir/article_3259_605b3c8cddc8014a3e57033924a48e3e.pdf
Diesel Engine
Performance and Exhaust Emissions
Compression Ratio
Alternative Fuel
eng
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2945
2588-2937
2019-12-01
3
2
229
234
10.22060/ajme.2019.14541.5731
3288
Fatigue Life Evaluation of Single and Two Riveted Coach Peel Joints Using Strain-Life Criteria
Hadi Moslemi
m.hmoslemi@yahoo.com
1
Khalil Farhangdoost
farhang@um.ac.ir
2
Pedram Zamani
p.zamani@mail.um.ac.ir
3
Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
Department of Mechanical Engineering, Ferdowsi University of Mashhad, Mashhad, Iran
In the present paper, an experimental investigation was carried out 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. Observations on failure of coach peel specimens revealed three major failure modes of folded region fracture (A-type), fracture from edge of the rivet hole (B-type) and mixed mode fracture (both of 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 single and two riveted coach peel joints. Finite element analysis was performed by ABAQUS commercial software as the first step of this numerical approach in order to estimate stress distribution, stress concentration factor, stress and strain amplitude. Fatigue lives of the coach peel joints were then calculated using three fatigue life theories of Monson-Hirschberg (MH), Smith-Watson-Topper (SWT) 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 of coach peel joints. It is also 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.
https://ajme.aut.ac.ir/article_3288_a7372f4d8f6f4c2991a0cd29c1974a60.pdf
Coach peel joint
fatigue life estimation
Finite element analysis
riveted joint
strain-life method
eng
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2945
2588-2937
2019-12-01
3
2
235
242
10.22060/ajme.2019.14844.5748
3219
Mixed-mode fracture analysis of a FGM layer with clamped longitudinal edges
Ali Mohammad Baghestani
am_baghestany@yahoo.com
1
Shahriar Fariborz
fariborz@aut.ac.ir
2
Babol Noshirvani University of Technology*
Amirkabir University of Technology(Tehran Polytechnic)*mechanical engineering
Properties of functionally graded materials (FGMs) 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 FGM layer containing multiple cracks using the distributed dislocation technique. The layer has a finite thickness and infinite length where its 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 (SIFs). 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 SIFs such as crack geometries, material non-homogeneity and boundary condition are studied.
https://ajme.aut.ac.ir/article_3219_da3693203e8a793e65165d5709701060.pdf
FGM Layer
Mixed-mode
Fixed Boundary
Multiple Cracks
eng
Amirkabir University of Technology
AUT Journal of Mechanical Engineering
2588-2945
2588-2937
2019-12-01
3
2
243
254
10.22060/ajme.2018.15011.5758
3160
On the Low-Velocity Impact and Quasi-Static Indentation Studies of Nomex™ Honeycomb Composite Sandwich Panels
Soroush Sadeghnejad
s.sadeghnejad@aut.ac.ir
1
Yousef Taraz Jamshidi
y.jamshidi@aut.ac.ir
2
Mojtaba Sadighi
mojtaba@aut.ac.ir
3
Amirkabir University of Technology (Tehran Polytechnic)
مهندسی مکانیک، دانشگاه تربیت دبیر شهید رجائی، تهران
Amirkabir University of Technology (Tehran Polytechnic), Mechanical Engineering
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. A dedicated focus on numerical models of this research is presented. Particular attention has been paid to verify the modeling of core behavior during the last part of low-velocity impact loading. 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. The influence of various parameters has been also evaluated from a numerical point of view. 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 of briefly FE 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.
https://ajme.aut.ac.ir/article_3160_d92399b747fe2766dda655d919dadec4.pdf
quasi-static
Low-velocity impact
Sandwich panels
Nomex™ honeycomb
experimental–numerical methodology