Amirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29374420201201Prediction of Flow Behavior and Level of Hemolysis in a Pulsatile Left Ventricular Assist Device427434375710.22060/ajme.2020.16951.5843ENAmir HosseinVakilzadehUniversity of GuilanKouroshJavaherdehUniversity of GuilanJournal Article20190822Heart failure claims the lives of thousands of people annually. Left ventricular assist device is a valid treatment option for patients with an advanced stage of heart failure. The left ventricular assist device is a blood pump increasing the pumping ability of the bottom left chamber of the patient's heart. In this study, we investigate the hemolytic characteristics of a left ventricular assist device. The main objective of this paper is to explore the effects of amplitude and frequency on levels of hemolysis via computational fluid dynamic in an implantable reciprocating pump. Thus, the dynamic mesh technique is utilized to simulate piston motion and valves closure. Moreover, a system of time-dependent nonlinear partial differential equations is coupled with each other to predict blood flow and hemolysis index. Fluid dynamic characteristics are obtained by employing continuity and momentum equations and the levels of hemolysis are also calculated by applying two additional scalar transport equations based on an Eulerian transport approach. The results depicted the favorable reduction in hemolysis index by increasing frequency and decreasing amplitude simultaneously at specific Reynolds number, they also showed that the average hemolysis at the right side of the piston is slightly higher than the left side and it obtains its maximum value at valves and clearance domains.https://ajme.aut.ac.ir/article_3757_b4affa4f6b27df047d63d66fe4ac5600.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29374420201201Variable Population Models in a Neural Network- Augmented Genetic Algorithm for Shape Optimization435448375810.22060/ajme.2020.16445.5819ENAli R.DavariDepartment of MEchanical and Aerospace Eng., Schience and Research Branch, Azad University0000-0003-0101-7069S. M.PourkiaeiDepartment of Engineering, Science and Research Branch, Islamic Azad UniversityJournal Article20190528The optimization process for an airfoil using genetic algorithm has been an increasingly popular problem in recent years. In recent years, the role of the population model in genetic algorithm has been underlined. In many of the recently proposed models, the convergence time was adversely increased or the elitism or mutation operators failed to work properly due to the inherent oscillations in the oncoming generations. In this paper, the idea of continuous variable population size has been introduced to optimize the airfoil shape. This scheme has been shown to converge to higher performance airfoils and can decrease the convergence time, without any oscillatory behavior. Furthermore, to reduce the run time to evaluate the fitness value, a generalized regression neural network has been developed and trained by the numerical data to evaluate the lift to drag ratio for a vast range of NACA four digits airfoils. The values predicted by this neural network have been proved to be in good agreement with the other experimental and numerical data and were then used to calculate the lift-to-drag ratios as the fitness value for various airfoils generated during the optimization process. The idea can ever be more effective in similar problems with a huge amount of computational time to calculate the fitness values and converge to the most efficient airfoil in a reasonable time.https://ajme.aut.ac.ir/article_3758_3df07fdae1ab273a967aaa1d355b8bb6.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29374420201201Computational fluid dynamics modeling and multi-objective optimization of flat tubes partially filled with a porous layer using ANFIS, GMDH, and NSGA II approaches449464419310.22060/ajme.2020.16836.5836ENEhsanRezaeiMechanical Engineering, Amirkabir university of Technology, Tehran, IranAbbasAbbassiMechanical Engineering, Amirkabir university of Technology, Tehran, IranJournal Article20190727In this work, the fluid flow in flat tubes armed with a porous layer is modeled and multi-objectively optimized utilizing computational fluid dynamics methods, Adaptive-network-based fuzzy inference system, grouped technique of data handling type artificial neural network, and non-dominated sorting genetic algorithm II. The variables design includes the tubes’ two geometrical parameters, porous layer thickness ratio, tube flattening, porosity, entrance flow rate, and wall heat flux. The purposes are to minimize the pressure drop and to maximize the convection heat transfer coefficient. Initially, utilizing computational fluid dynamics methods the problem is solved numerically in different flat tubes to calculate two objective parameters in tubes. Using numerical results of the preceding step, and are modeled through adaptive-network-based fuzzy inference system and grouped technique for handling the data. Then, Pareto-based multi-objective optimizing will be performed employing grouped technique of data handling model and non-dominated sorting genetic algorithm II. The results revealed that a better predicting is obtained by the adaptive-network-based fuzzy inference system model compared to the other approaches and the significant design information is included in the attained Pareto solution on flow parameters in flat tubes partly with porous insert. Based on the findings, the best configuring for the highest heat transfer and the least pressure loss is <em>H<sub>p</sub>= </em>0.75<em> and H=</em>4mm<em>.</em>https://ajme.aut.ac.ir/article_4193_3770282ae7c0e576d1017a97a9260a3f.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29374420201201Effect of Thermophoresis, Brownian and Turbulent Mass Fluxes in the Simulation of Two-Phase Turbulent Free Convection of Nanofluid Inside the Enclosure using v2-f Model365480402510.22060/ajme.2020.16761.5832ENSaberYekani Motlaghdepartment of renewable energy, faculty of mechanical engineering, urmia university of technologyJournal Article20190714In this article, two-phase alumina-water turbulent natural convection with Reynolds-averaged Navier-Stokes based <em>v<sup>2</sup>-f</em> model in a square cavity has been investigated. Buongiorno’s two-phase model is modified for considering the nanoparticles diffusion via turbulent flow eddies. Using the finite volume method and the semi-implicit method for pressure-linked equations algorithm, the governing equations along with boundary conditions have been discretized. The left and right vertical walls of the cavity are kept at constant temperatures, while the other walls are thermally insulated. Calculations are performed for high Rayleigh numbers (10<sup>7</sup>–10<sup>9</sup>) and average volume fractions of nanoparticles (0 - 0.04). The results are analyzed through the thermal and dynamical fields with a particular interest in the turbulent intensity, turbulent kinetic energy, thermophoresis, Brownian and turbulent mass flux distribution inside the cavity, and Nusselt number variations. It is shown that nanoparticles had no significant effects on turbulent kinetic energy and intensity, and the thermophoresis effect is dominant at the near-wall regions. Furthermore, there are optimal average volume fractions with the maximum heat transfer rate depending on the Rayleigh number. Moreover, the magnitude of the turbulent Schmidt number had a negligible effect on the estimation of heat transfer rate. Against, low turbulent Prandtl numbers predicted higher values for the Nusselt number.https://ajme.aut.ac.ir/article_4025_1625abb8e458a79765c62009235e9d5b.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29374420201201Improving Thermo-hydraulic Performance of Parallel-plate Flow with a Particular Counter-current Flow Division481492340210.22060/ajme.2019.15507.5776ENMohsenGoodarziFaculty of Engineering, Bu_Ali Sina University, Hamedan, Iran0000-0002-0321-2135NimaEshghabadiFaculty of Engineering, Bu_Ali Sina University, Hamedan, IranRahimehSadeghiFaculty of Engineering, Bu_Ali Sina University, Hamedan, IranJournal Article20181224A particular counter-current flow division has been introduced to improve the thermal and hydraulic performances of flow through two isotherm parallel plates. It has been constructed by inserting two zero thickness and impermeable flat plates within the parallel-plate channel to establish a central and two external sub-channels. The total flow rate has been subdivided into two streams for supplying into the central and two external sub-channels in counter-current directions. The effect of the cross-section ratio on the thermal and hydraulic performances has been investigated for two flow division regimes. The obtained results showed that better thermal performance could be enhanced when the cross-section of the central sub-channel was greater than the external ones. Regarding the overall performance, it has been concluded that the best performance could be enhanced when the flow and cross-section were equally subdivided. In this particular case, the percent of the heat transfer enhancement compared to the single-pass channel was 50%. Meanwhile, the power consumption increment of the proposed flow arrangement significantly decreased compared to the two previously proposed double-pass arrangements. It seems that the proposed flow arrangement is a better alternative for double-pass arrangement.https://ajme.aut.ac.ir/article_3402_91d0dbfd38d950cb716c4dd26c5da08a.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29374420201201Experimental Investigation on Effects of Trapezoidal Ribs on Heat Transfer Enhancement with Electrohydrodynamics Active Method into Duct493504382510.22060/ajme.2020.16725.5840ENAminAlami Niaدانشگاه شهیدمدنی آذربایجان-تبریزJournal Article20190814In this work, the heat transfer enhancement of trapezoidal ribs is investigated. Cooling of the three trapezoidal ribs has been achieved with electrohydrodynamicsactive method by experimental apparatus. The hydrodynamic and heat transfer behavior of air flow was studied by electrohydrodynamics active method. The aim of the present work is heat transfer enhancement with low pressure loss. In active method, two arrangements of wire electrodes have been applied. The results show that in the same Reynolds numbers and voltages of wire electrodes, the heat transfer was increased in arrangement 1 than arrangement 2. Density of electric charge around wire electrodes in arrangement 1 is higher than in arrangement 2. Therefore, arrangement 1 is better than arrangement 2. Arrangements 1 and 2 are different with the position of wire electrodes. With attention to results the power of corona wind in low Reynolds flows is higher than in high Reynolds flows, signifying that the corona wind in low Reynolds numbers is better than in high Reynolds numbers. In the same Reynolds numbers and voltages of wires, the average performance evaluation criteria were increased in arrangement 2 than arrangement 1.<br /> https://ajme.aut.ac.ir/article_3825_c24fe9f765a44048868b5a620f05678e.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29374420201201Extending Inverse Heat Conduction Method to Estimate Flight Trajectory of a Reentry Capsule505522375910.22060/ajme.2020.17000.5845ENVahidTahmasbiDepartment of Aerospace Engineering, Amirkabir University of Technology, Tehran, IranSaharNooriDepartment of Aerospace Engineering, Amirkabir University of Technology, Tehran, IranJournal Article20190904This study is dedicated to the solution of the inverse heat conduction problem for estimation of the time-varying velocity and altitude profiles regarding the flight trajectory of an earth-entry capsule. Four tungsten-rhenium sensors are supposed to be embedded inside the ablative heat shield of the probe, three of which cannot tolerate high-temperature conditions and burn out during entry and the other one remained intact until the end of the simulation. The conventional Levenberg-Marquardt method is reinforced by a relaxation scheme to prevent unfavorable severe oscillations encountered in the inverse iterations. To keep the generality of the method, no prior knowledge on the thermal condition and surface recession of ablative insulator is utilized in the current estimation. Therefore, in the associated direct problem, velocity and altitude profiles are given and the temperature field inside the heat shield is determined. Accordingly, a solution of the direct problem consists of (i) bow shock calculations in dissociated air (ii) boundary layer solver to compute stagnation heating rate (iii) identification of the thermal response of charring ablative heat shield. It is shown that if the standard deviation of the temperature measurement error is 5 K, estimation of altitude and velocity are associated with approximately 10 and 5 percent normalized error, respectively.https://ajme.aut.ac.ir/article_3759_cbf22ab286e2ad4900bdf5d6a2e47009.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29374420201201Kinematic Reliability Analysis of 3-PSS manipulator based on the explicit solution and design of experiment method523534364010.22060/ajme.2019.16240.5813ENAmirhosseinValiDepartment of Mechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez Ave, Tehran, IranAfshinTaghvaeipourDepartment of Mechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez Ave, Tehran, IranAliKamaliDepartment of Mechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez Ave, Tehran, IranMohsenRezaeian AkbarzadehDepartment of Mechanical Engineering, Amirkabir University of Technology (Tehran Polytechnic), Hafez Ave, Tehran, IranJournal Article20190430This paper aims at the kinematic reliability analysis of the 3-PSS parallel robot. Parallel manipulators bear many advantages like higher stiffness, more accuracy, and speed compared to the serial counterparts. Because of several uncertainty factors such as actuators error, links flexibility, etc. a robot moving platform cannot follow the desired trajectory without an error. In this study, at first, eight, and next twelve uncertainties that seem to affect the kinematics of robot are selected. Next, the probability distribution of the moving platform position is conducted using the closed-form kinematic relation of a robot and the Monte Carlo Simulation, then, the kinematic reliability is calculated for different levels of accuracy. As the closed-form kinematic relation between the actuators rate and the moving platform position cannot be obtained, a polynomial algebraic equation is fitted via the design of experiments method. Using fitted polynomial kinematic equation at hand, the reliability analysis is conducted and evaluated for different levels of accuracy. Also, an experimental reliability analysis is performed to evaluate the results which are obtained numerically. The results show that the difference between the reliability values obtained by the design of experiments and the Monte Carlo Simulation methods is %4.7, and between the design of experiments method and experimental data is %7.7. In the end, a sensitivity analysis is conducted to determine the influence of each uncertainty on the accuracy. https://ajme.aut.ac.ir/article_3640_4f11b55f57612f06fe9638b99f6c66e6.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29374420201201Analysis and Optimization of Fibre-Metal Laminate Cylindrical Shells Subjected to Transverse Impact Loads535552378210.22060/ajme.2020.16490.5820ENRezaAzarafzaدانشگاه صنعتی مالک اشتر- مجتمع دانشگاهی مواد و فناوریهای ساخت- گروه مکانیکAliDavarدانشگاه صنعتی مالک اشتر- مجتمع دانشگاهی مواد و فناوریهای ساخت- گروه کامپوزیتJournal Article20190604The main aim of the present paper is multi-objective optimization of circular cylindrical shells composed of fibre metal laminate. For this purpose, the genetic algorithms method is applied for optimization of combination of the objective functions including weight and transverse impact response and two constraints including critical buckling loads and principle strains. The initial compressive stress is taken to be equal to half of the axial critical buckling load of the shell. Nine design variables including material properties (fibre and matrix), volume fraction of fibre, fibre orientation, and volume fraction of metal layers are considered. In analytical solution, transient dynamic response due to low-velocity transverse impact of a large mass on the mid-span of composite circular cylindrical shells is investigated based on the first-order shear deformation shell theory and mode superposition method. The impact force of an isotropic sphere impactor is calculated using a Two-Degree-Of-Freedom (TDOF) spring-mass model. Different fibre metal laminate layups are considered for optimization and the results are compared. Results show that fibre metal laminate layup with 2/1 configuration has the smallest weight and impact response as compared to the other layups.https://ajme.aut.ac.ir/article_3782_f87e955fd6b89f8963b6934beb077d6e.pdfAmirkabir University of TechnologyAUT Journal of Mechanical Engineering2588-29374420201201Theoretical and Numerical Analysis of Jamming Phenomenon in Positioning of Circular Workpiece on Horizontal Surface553564380910.22060/ajme.2020.16132.5806ENHadiParvazFaculty of Mechanical and Mechatronics Engineering, Shahrood University of Technology, Shahrood, Iran0000-0003-4806-7311Journal Article20190414Grasping or positioning workpiece with circular geometry is a common process in fixture design and robotic manipulation systems. The typical two-contact mechanisms that are usually used for gripping or positioning of these kinds of workpieces are prone to jam. Determination of the conditions in which jamming occurs in such systems seems to be necessary for research purposes as well as industrial applications. In the present study, jamming of the workpiece with the circular cross-section is investigated during its positioning on the horizontal surface. The theoretical foundation is established based on two models as far as the force equilibrium equations and the minimum norm principle. Validation of the theoretical predictions is conducted through the numerical analysis in the Adams software. The distance that the workpiece should travel to jam is obtained from the numerical analysis and compared to the theoretical predictions. By assuming the coefficient of friction equal to 0.4 and the radius of the workpiece equal to 10mm, jamming-in travel of the workpiece was obtained as 24.38mm and 25.58mm from the theoretical models and numerical analysis, respectively. A relative error of 4.9% is obtained between the theoretical predictions and numerical results. This value indicates the accuracy of predictions of the suggested theoretical models and the credibility of their results.https://ajme.aut.ac.ir/article_3809_38ef4b66cb25e92abe4d594acb841471.pdf