2020
4
1
0
148
Stall margin improvement and increase pressure ratio in transonic axial compressor using circumferential groove casing treatment
2
2
AbstractMaximum pressure ratio and aerodynamic blades loading are the most important factors in designing axial compressor restricted by minimum airflow. The present work aims to stall margin and total pressure ratio in transonic axial compressor using circumferential groove casing treatment (CGCT). In the first step, untreated compressor was simulated, compared, and agreed well with the experimental data. Then the treated rotor was simulated and results indicated that using CGCT improves the stall margin and increases the rotor pressure ratio. Stall margin was improved by 8% and the pressure ratio before stall condition and at the design point increased by 2.6% and 2.8 %, respectively. Additionally, it replaces normal shock with oblique shock near instability, causing less total pressure drop, moreover, the oblique shocks occurrence restricts separation zones and assists the rotor to perform far from instability. Furthermore, axial speed passing through rotor in a certain mass flow increases by 15 m/s, and then kinetic energy and stability increased. However, total efficiency of rotor reduces near 1%. In the last step, engine was analyzed with the aid of cycle analysis and leads to 62kW increase in shaft power as well as 1.87 g/kNs less fuel consumption due to 2.8% increase in the rotor pressure ratio.
1

3
16


Alireza
Jafar Gholi Beik
Energy exchange, Mech. Eng. Dept., Jundi Shapor University of Technology, Dezful, Iran
Energy exchange, Mech. Eng. Dept., Jundi
Iran
jafargholibeik@jsu.ac.ir


Seyed Hosein
Torabi
Aerospace. Eng. Dept., Khaje Nasir Toosi University of Technology, Tehran, Iran
Aerospace. Eng. Dept., Khaje Nasir Toosi
Iran
htorabi@mail.kntu.ac.ir


Hassan
Basirat Tabrizi
Amirkabir University of Technology(Tehran Polytechnic)*mechanical engineering
Amirkabir University of Technology(Tehran
Iran
hbasirat@aut.ac.ir
Transonic axial compressor
Circumferential groove casing treatment
Stall margin
EFFICIENCY
Air Bubble Collapse in NonNewtonian Medium with an Application in Biology
2
2
An unsteady compressible multiphase flow solver is developed and used to simulate shockbubble interaction in a nonNewtonian fluid. A fiveequation multiphase model that accounts for capillary and viscous effects is employed and discretized by finite volume methodology. HartenLaxvan LeerContact (HLLC) Riemann solver is invoked to compute the convective fluxes and Tangent of Hyperbola for Interface Capturing (THINC) interface sharpening scheme is applied to reduce the excessive diffusion at the interface. Multiple benchmark problems such as AirHelium Shock Tube, shock cavity interaction, RayleighTaylor instability and underwater explosion are probed to evaluate the performance and accuracy of this method. The results obtained compare well with the available experimental and numerical data. The developed solver is then used to study shockinterface interaction in both Newtonian and nonNewtonian mediums. NonNewtonian liquid is resembling the blood modeled by CarreauYasuda constitutive equation. The obtained results show an expedition of bubblecollapse with a higher jet tip velocity in nonNewtonian medium compared to that in the Newtonian surrounding liquid. Moreover, a third phase adjacent to the bubble collapse is considered and the penetration depth of the reentrant jet in the neighboring phase is studied as a measure of tissue injury. Our results show that by increasing post shock pressure, the reentrant jet velocity and thus the penetration depth increases. Furthermore, increasing the adjacent phase viscosity results into less penetration depth in the tissue.
1

17
30


Shahrokh
Boland
University of Tehran
University of Tehran
Iran
shahrokhboland@ut.ac.ir


Sahand
Majidi
Shahid Beheshti University
Shahid Beheshti University
Iran
s_majidi@sbu.ac.ir


Asghar
Afshari
University of Tehran*
University of Tehran*
Iran
afsharia@ut.ac.ir
Compressible multiphase flow
Shockwave lithotripsy
CarreauYasuda model
Shock bubble interaction
Modeling of an UpperConvectedMaxwell fluid hammer phenomenon in the pipe system
2
2
In this paper, the occurrence of water hammer phenomenon is examined in a situation that instead of water, an upperconvectedMaxwell fluid flows in a pipe system. This phenomenon is called an “upperconvectedMaxwell fluid hammer”. This expression relates to the transients of Maxwell fluid caused by the sudden alteration in the conditions of flow. UpperconvectedMaxwell fluids are a kind of nonNewtonian viscoelastic fluids. The properties of this group of fluids lead to their different behaviour during fluid hammer phenomenon compared to Newtonian fluids. The system studied is a valve horizontal pipe and reservoir. The equations representing the conservation of mass and momentum govern the transitional flow in the pipe system. The numerical method used is a twostep variant of the LaxFriedrichs (LxF) method. Firstly, the nondimensional form of governing equations is defined, then, the effect of Deborah and Reynolds numbers on pressure historic is investigated. The results revealed that increasing Deborah number, indicating the elasticity of the polymer, increases the oscillation height and consequently attenuation time of the transient flow becomes longer. It was also found that in low Reynolds, in a Newtonian fluid, ‘‘line packing phenomenon’’effect is observed only at the first time period but in UCM fluid the effect of this phenomenon continues to more time periods and damping time becomes longer.
1

31
40


Banafsheh
Norouzi
Civil Engineering, Shahrood University of Technology, Shahrood, Iran
Civil Engineering, Shahrood University of
Iran
hatami1355@yahoo.com


ahmad
Ahmadi
Civil Engineering, Shahrood University of Technology, Shahrood, Iran
Civil Engineering, Shahrood University of
Iran
a.ahmadi@shahroodut.ac.ir


Mahmood
Norouzi
Mechanic Engineering, Shahrood University of Technology, Shahrood, Iran
Mechanic Engineering, Shahrood University
Iran
m.norouzi@shahroodut.ac.ir


Mohsen
LashkarBolook
Civil Engineering, Golestan University, Gorgan, Iran
Civil Engineering, Golestan University, Gorgan,
Iran
mlbolok@iust.ac.ir
Upper Convected Maxwell Model
LaxFriedrichs (LxF) method
non Newtonian fluid Hammer
Geometry Shape Effects of Nanoparticles on Fluid Heat Transfer Through Porous Channel
2
2
In this paper the geometry effects of different nanoparticles such as cylindrical, spherical and lamina on heat transfer of fluid transported through contracting or expanding microchannel are considered. The nanofluid flow and heat transfer through the porous channel are described using mathematical models. Since the mathematical models are nonlinear in nature the homotopy perturbation method (HPM), an approximate analytical method is adopted to provide analytical solution to the mathematical model. The fast convergence rate coupled with analytical procedural stability motivates the use of the HPM as the favored method in providing solutions to the system of coupled, higher order differentials.The obtained analytical solution is used to investigate the influence of particle shape of the nano sized materials on heat transfer of fluid flowing through a porous medium considering a uniform magnetic field. It is illustrated from results that lamina nanoparticle shape shows higher dimensionless temperature and thermal conductivity when compared with nano shaped particles of cylinder and sphere respectively due to variations in thermal boundary layers. Results obtained from this study prove useful in the advancement of science and technology including micro mixing, nanofluidics and energy conservation. Comparing obtained analytical solution with fourth order numerical solution, good agreement was established.
1

41
50


AKINBOWALE
AKINSHILO
DEPT. OF MECH. ENGR., UNIVERSITY OF LAGOS, NIGERIA.
DEPT. OF MECH. ENGR., UNIVERSITY OF LAGOS,
Nigeria
ta.akinshilo@gmail.com
heat transfer
Nanofluid
Porous channel
magnetic field
Homotopy Perturbation Method
MHD effect on Nanofluid Flow and Heat transfer in BackwardFacing Step using twophase Model
2
2
Magneto hydrodynamics (MHD) effects on nanofluid flow in backwardfacing step is studied using twofluid model of Buongiorno. The results of the current finite element simulations are compared with previous experimental and numerical analysis. Due to the utilization of twophase model, variable nanoparticle concentration and nanofluid properties are considered. Thermophoresis and Brownian diffusivities are calculated in particle dispersion. Effects of Reynolds number, particle volume fraction, magnetic field and Hartmann numbers are studied on heat transfer and fluid flow characteristics. It is shown that introduction of nanoparticles as a second phase, pushes reattachment point further into the downstream, while magnetic field has opposite effect and pushes it backward into the upstream. Particles are shown to be migrating from hot to cold regions due to the dispersion mechanisms considered. In comparison to single phase models, there is 3.7% decrease in maximum Nusselt number and more than 40% difference in the reattachment point location. Accuracy of the reattachment point is shown through previous pure fluid studies, the comparison to which show less than 0.8% tolerance with most recent studies. Relative effect of diffusion mechanisms is compared in different flow conditions, which show up to 12.5% difference. Application of magnetic field results in average Nusselt number increase of more than 10% by Hartmann number of 12.
1

51
66


Farrokh
Mobadersani
Department of Mechanical Engineering, Urmia University of Technology
Department of Mechanical Engineering, Urmia
Iran
f.mobadersani@mee.uut.ac.ir


Araz
Rezavand Hesari
Mechanical Engineering Department, Universite Laval, Quebec, Canada
Mechanical Engineering Department, Universite
Canada
araz.rezavandhesari.1@ulaval.ca
Nanofluid
Buongiorno Model
Brownian motion
Thermophoresis effect
MHD
The effects of subcooled temperatures on transient pool boiling of deionized water under atmospheric pressure
2
2
Pool boiling heat transfer and critical heat flux (CHF) were experimentally studied in subcooled temperatures ranging 0 to 20 under transient power conditions. The heating rate in the test section was increased linearly depending on time by applying voltage control for 1 to 1000s. The increase in heat flux starts from the free convection regime to the filmboiling regime. The transient boiling heat transfer coefficient (TBHTC), transient wire superheat temperature, transient heat flux and transient CHF were also obtained. The results showed that in the case of all subcooled temperatures and periods, the TBHTC increased in the nucleate boiling region because of the growth, separation, motion and turbulence of the bubbles. The TBHTC also decreased in the transition from nucleate boiling to film boiling because some part of the wire covered by temporary thin vapor film. The wire isolated from the body of working fluid and the bubble separations decreased. The TBHTC again increased in film boiling due to the increment of radiation heat transfer. The TBHTC decreased in the second part of the film boiling due to the heat flux and the vapor film thickness around the wire had increased. Relative to the saturation condition, the timely average of the wire superheat temperature for subcooled temperatures of 10 and 20, respectively, decreased by 9.23 and 9.29% in the nucleate boiling region and in a time period of 1000s. A highspeed camera was used to show bubble and vapor film behavior around the heating wire for the subcooled temperatures.
1

67
78


ahmadreza
ayoobi
department of mechanical engineering, yazd university
department of mechanical engineering, yazd
Iran
ar.ayoobi@stu.yazd.ac.ir


Ahmadreza
Faghih Khorasani
Department of Mechanical Engineering, Yazd University
Department of Mechanical Engineering, Yazd
Iran
faghih@yazd.ac.ir


Mohammad Reza
Tavakoli
Department of Mechanical Engineering, Isfahan University of Technology
Department of Mechanical Engineering, Isfahan
Iran
mrtavak@cc.iut.ac.ir
transient pool boiling
CHF
heating rate
subcooled temperature
TBHTC
An experimental study on submerged flame in a twolayer porous burner
2
2
Combustion in porous media is an effective method to minimize dissipations and save energy. It enhances the efficiency of the system while reducing environmental pollution. The conditions for the formation of a steadystate submerged flame in a ceramic (SiC) porous medium were investigated at four firing rates. The results were obtained on a ceramic foam with a cross section area of 63.6 cm2 and pore density of either 10 or 30 ppi. The reactants were air and natural gas with various equivalence ratios. In this experimental study, eight thermocouples were mounted on the burner walls along its axis in order to track the flame position, and the results were presented as temperature profiles of the porous wall. It was observed that the formation of submerged flame depends on firing rate and equivalence ratio. The stability limit of submerged flame (the range between surface flame and flash back limits) is reduced by increasing the firing rate. Results show that the maximum temperature takes place near the interface of the two layers. Also, it was observed that when the mixture velocity is low, the stability limit extends. Finally, the ranges of equivalence ratio and mixture velocity for the formation of submerged flame are presented at various firing rates.
1

79
88


Seyed abdolmehdi
Hashemi
Department of Mechanical Engineering, University of Kashan, Kashan, Iran
Department of Mechanical Engineering, University
Iran
hashemi@kashanu.ac.ir


Mohammad Reza
Faridzadeh
Department of Mechanical Engineering, University of Kashan, Kashan, Iran
Department of Mechanical Engineering, University
Iran
mr.faridzadeh@gmail.com
Experimental study
Flame Formation
Porous burner
Premixed MethaneAir Combustion
Thermodynamic analysis of a novel heat pipe based regenerative combined system
2
2
A comprehensive thermodynamic analysis is presented of a new solar system for heating and power generation. Energy and exergy analyses are used to characterize the exergy destruction rate in any component and investigate solar system performance. The system composed of a solar heat pipe evaporator (SHPE), an auxiliary pump, a condenser, a turbine, an electrical generator, a domestic water heater, a regenerator, a water preheater and a pump. The solar system provides heating and electricity during the summer and spring in Tabriz, Iran. The analysis involves the specification of effects of varying SHPE condenser pinch point temperature, varying solar radiation intensity and varying SHPE heat removal factor on the energetic and exergetic performance of the system. The performance parameters calculated are energy flow, exergy destruction rate, energetic and exergetic efficiencies. The results also showed that the main source of the exergy destruction rate is the SHPE. In the SHPE, 291.1 kW of the input exergy was destroyed. Other main sources of exergy destruction rate are the SHPE condenser, at 6.655kW; then the turbine, at 6.228 kW; and the water preheater, at 0.907 kW. The overall energetic and exergetic efficiencies of the combined solar system was approximately 69.57% and 12.41%, respectively.
1

89
102


Vahid
Beygzadeh
Faculty of Mechanical Engineering, Urmia University of Technology, Urmia, Iran
Faculty of Mechanical Engineering, Urmia
Iran
vbeygzadeh@gmail.com


Shahram
Khalilarya
Mechanical Engineering Department, Faculty of Engineering, Urmia University, Urmia, Iran
Mechanical Engineering Department, Faculty
Iran
sh.khalilarya@urmia.ac.ir


Iraj
Mirzaee
Mechanical Engineering Department, Faculty of Engineering, Urmia University, Urmia, Iran
Mechanical Engineering Department, Faculty
Iran
i.mirzaee@urmia.ac.ir


Vahid
Zare
Faculty of Mechanical Engineering, Urmia University of Technology, Urmia, Iran
Faculty of Mechanical Engineering, Urmia
Iran
v.zare@uut.ac.ir


Gholamreza
Miri
Department of Business Management, National Iranian Oil Refining & Distribution Company, Tehran, Iran
Department of Business Management, National
Iran
gholamreza.miri@gmail.com
Energy Efficiency
Exergy efficiency
solar heat pipe system
regenerative organic Rankine cycle
TimeDependent Creep Response of MagnetoElectroElastic Rotating Disc in Thermal and Humid Environmental Condition
2
2
The aim of this paper is to analyze the timedependent stress redistribution of a rotating magnetoelectroelastic (MEE) disc. The disc is supposed to be placed in an axisymmetric temperature and moisture fields. Besides, the disc is under a centrifugal body force, an induced electric potential in addition to magnetic potential. Using equilibrium, electrostatic and magnetostatic equations, straindisplacement and stressstrain relations together with hygrothermal equations, a differential equation is obtained in which there are creep strains. Primarily, disregarding the creep strain, an analytical solution for the initial stresses, electromagnetic potentials and displacement is developed. Then, using PrandtlReuss relations, creep stress rates and electromagnetic potentials rates are obtained. Finally, the history of stresses, electric and magnetic potentials is obtained iteratively. In the numerical section, the influence of creep evolution, hygrothermal environmental condition, angular velocity and temperature and moisturedependency of elastic coefficients on the behavior of MEE disc is analyzed comprehensively. The results show that the effect of hygrothermal loading and angular velocity becomes less significant after creep evolution. Also, the results imply that analysis of the effect of temperature and moisture dependence after creep evolution must be considered in the design progress. Besides, to avoid cracking, increasing in the tensile hoop stress at the internal surface with increasing in hygrothermal loading must be considered in design progress.
1

103
118


Mahdi
Saadatfar
Department of Mechanical Engineering, University of Qom
Department of Mechanical Engineering, University
Iran
m.saadatfar@gmail.com
Rotating disc
magnetoelectroelastic
Timedependent creep
Hygrothermal loading
Effects of Functionalized MultiWalled Carbon Nanotubes on the LowVelocity Impact Response of Sandwich Plates
2
2
One method to reduce the damage caused by lowvelocity impact in sandwich composites is using nanoparticles as the reinforcement material in the face sheets. The aim of this study is to investigate the effects of different weights of functionalized multiwalled carbon nanotubes on mechanical properties of face sheets and response of sandwich plates that undergo lowvelocity impact through experimental investigations. The face sheets are made of nanomodified EPIKOTE 828 with triethylenetetramine as the curing agent, and a core of polyurethane foam. The functionalized multiwalled carbon nanotubes are dispersed into the epoxy system in 0.1%, 0.3% and 0.5% weighttomatrix. The lowvelocity impact test was performed using a drop tower impact machine, at two different energy levels. The stressstrain, history of contact force, velocitytime, absorbed energytime and forcedeflection are plotted and some parameters such as elastic modulus, tensile strength, bounce time, upward velocity, peak load and maximum deflection are reported. The tensile test results show that with the slight increase in the volume fraction of carbon nanotubes, the elastic modulus and ultimate tensile strength are improved. Also, the minor amount of carbon nanotubes reduce bounce time, residual deformation, and maximum deflection and increase peak load in the sandwich plate. In addition, carbon nanotubes reduce the damaged area.
1

119
126


Ehsan
Rashidi
Department of Mechanical Engineering, Razi University, Kermanshah, Iran
Department of Mechanical Engineering, Razi
Iran
e.rashidii@gmail.com


Saeid
Feli
Department of Mechanical Engineering, Razi University, Kermanshah, Iran
Department of Mechanical Engineering, Razi
Iran
felisaeid@razi.ac.ir
Nanocomposite
Sandwich composite
Lowvelocity impact
Functionalized multiwalled carbon nanotubes
Damage
Effect of Stator dynamics on the Chaotic Behavior of RotorDiskBearing System under RubImpact between Disk and Stator
2
2
In the present study, the effect of stator dynamics on the chaotic behavior of a rotordiskbearing system with rubimpact between disk and stator is investigated. The governing equations of motion are derived using Jeffcott model and Newton's second law and then are made dimensionless. Governing Equations are also achieved utilizing the Short Bearing Theory and considering nonlinear forces acting on the oil film. Furthermore, unbalance force and bow shaft force which cause rubimpact between disk and stator are considered in the equations of motion. In the beginning, the system is modeled regardless of stator dynamics, and then the stator dynamics is also considered in the modeling of the system. In both cases, the system behavior is studied by bifurcation diagrams, time series diagrams, phase plane diagrams, power spectrum diagrams, Poincaré maps, and maximum Lyapunov exponent, respectively. The obtained results show that the type of stator dynamics modeling has a significant effect on the prediction of the response of a diskbearing system with rubimpact between disk and stator. In other words, the results show the system has a chaotic behavior without considering the dynamics of the stator in mathematical modeling, while in the case of considering the stator dynamics and using the suitable values for the stator stiffness, the motion behavior of the system can be changed from the chaotic to the regular and periodic motion. Keywords: Rotordiskbearing, stator dynamics, rubimpact, chaotic behavior.
1

127
148


Abbas
Rahi
Faculty of Mechanical & Energy Engineering, Shahid Beheshti University
Faculty of Mechanical & Energy Engineering
Iran
a_rahi@sbu.ac.ir


Ahmad
Haghani
Faculty of Mechanical & Energy Engineering, Shahid Beheshti University
Faculty of Mechanical & Energy Engineering
Iran
ahaghani70@gmail.com


Pedram
Safarpour
Faculty of Mechanical & Energy Engineering, Shahid Beheshti University
Faculty of Mechanical & Energy Engineering
Iran
p_safarpour@sbu.ac.ir
Rotordiskbearing
stator dynamics
rubimpact
chaotic behavior