Sharif University of TechnologyScientia Iranica1026309824520171001Piezoelectric energy harvesting from vertical piezoelectric beams in the horizontal fluid flows23962405424010.24200/sci.2017.4240ENYasserAminiIran

Boushehr

PG
university

school of
Mechanical EngineeringHomayoonEmdadDepartment of Mechanical Engineering School, Shiraz University, Shiraz, IranM.FaridIran Shiraz Shiraz University school of Mechanical EngineeringJournal Article20151024Piezoelectric Energy harvesting (PEH) from fluid flow energy has attracted significant attention throughout the last decade. In the previous PEH from fluid flow, a piezoelectric beam placed behind a bluff body such as circular cylinders. Hence, the piezoelectric beam oscillated due to the vortex shedding behind of the bluff body. Subsequently, this vibration generates voltage in the beam. In many engineering vehicles such as airplanes the strong vortex shedding caused by bluff body is destructive and reduces the efficiency of devices, therefore; it is not proper to attach a bluff body to these devises.<br /> In this paper PEH from vertical beams in low speeds and high speed flows are investigated. Current work shows that in contrast to the low speed flows the extracted power from vertical beam in the high speed flows are considerable. Moreover, for a practical example of vertical beam in high speed flows the energy harvesting from piezoelectric Gurney flap attached to a NACA2412 airfoil is investigated. Finally, this study proposes a piezoelectric vertical beam with attached end cylinder as an energy harvester in the low speed flows. It is indicated that this device has strong vibration and therefore produces a remarkable electrical powerhttp://scientiairanica.sharif.edu/article_4240_8a588a004e5ef31e0edf5a407e8fc3ee.pdfSharif University of TechnologyScientia Iranica1026309824520171001Topological and nontopological soliton solution of the 1 + 3 dimensional GrossPitaevskii equation with quadratic potential term24292435424110.24200/sci.2017.4241ENHitenderKumarDepartment of Humanities and Sciences, Dr. B. R. Ambedkar Institute of Technology, Port Blair744103, IndiaP.SaravananDepartment of Applied Sciences, G. B. Pant Engineering College,New Delhi110020, IndiaJournal Article20160107This paper carries out the integration of the 1 + 3 dimensional GrossPitaevskii equation (GPE) in presence of quadratic potential term to ob tain the 1soliton solutions. The solitary wave ansatz method is employed to integrate the considered equation. Parametric conditions for the existence of the soliton solutions are determined. Both nontopological (bright) and topological (dark) solitonsolutions are reported and we observed that the existence condition for bright and dark soliton solutions are opposite to each other. Finally, the two integrals of motion of the governing model equation have been extractedhttp://scientiairanica.sharif.edu/article_4241_6c0c7caeb709367ce9ceb16fbb48ca4e.pdfSharif University of TechnologyScientia Iranica1026309824520171001Generalized Heat Transfer and Entropy Generation of Stratified AirWater Flow in Entrance of a Minichannel24072417424210.24200/sci.2017.4242ENNavidZehtabiyan  RezaieMechanical Engineerin
g Department, Amirkabir University of Technology, Tehran, IranSaeede Rahimi DAmirchi  DarasiIndustrial Engineering Department, Amirkabir University of Technology, Tehran, IranMohammad HosseinFazel ZarandiKnowledge Intelligent System Laboratory, University of Toronto, Toronto, CanadaMajidSaffar  AvvalMechanical Engineerin
g Department, Amirkabir University of Technology, Tehran, IranJournal Article20151031In the present study a rulebased fuzzy inference system is used to predict heat transfer and entropy generation of stratified airwater flow in horizontal minichannel as a function of a wide range of important parameters. Numerical data of our recent study are used to develop and test the system. The GK clustering algorithm is used to cluster the data. Fuzzy rules are generated based on the SugenoYasukawa algorithm by using trapezoidal membership functions. The FATI and FITA approaches are implemented in the inference engine and finally the combination of the two approaches is defuzzified. The Mamdani and logical methods with the Yager operators are used and unified in both approaches. The parametric form of the system is a feature of the present study which can be used as an effective tool to improve the accuracy of the results. The novelty of the present study is the presentation of the generalized diagrams for the developing region of the channel which seems to be useful for engineering applications. In addition, generalized diagrams of average Nusselt numbers as well as total entropy generation can identify the appropriate range of volumetric flow rate ratio and the Reynolds number.http://scientiairanica.sharif.edu/article_4242_2fc91089acdf985fbbbaf70c881dff81.pdfSharif University of TechnologyScientia Iranica1026309824520171001COMPARATIVE STUDY OF THE EFFECT OF TWO TYPE OF RIBS ON THERMAL PERFORMANCE OF SOLAR AIR HEATERS24182428424310.24200/sci.2017.4243ENAmelBoulemtafes  BoukadoumCentre de Développement des Energies Renouvelables, CDER, Algiers,16340, AlgeriaAhmedBenzaouiLTSE, Faculté de Physique, USTHB, Algiers, 16000, AlgeriaHafidaDaaou NedjariCentre de Développement des Energies Renouvelables, CDER, Algiers,16340, AlgeriaJournal Article20151201This paper aims to analyze fluid flow characteristics and heat transfer augmentation in the air duct of a solar air heater using CFD techniques. The air duct has a rectangular section, the top wall is the glazing and the bottom one is the absorber provided with transverse rectangular or squared ribs. The simulations are performed in the turbulent regime and RANS formulation is used to modelize the flow and resolve mass, momentum and energy equations using Finite Volumes method. The air flow analysis shows that the velocity profile was not disturbed by the ribs outside the laminar sublayer. Heat transfer analysis based on the calculation of Nusselt Number, friction factor and thermohydraulic performance has highlighted the heat transfer enhancement, and no big friction losses were recorded. A comparative study between two ribs shape (square and rectangular) was achieved and showed a better thermohydraulic performance for rectangular ribs.http://scientiairanica.sharif.edu/article_4243_a406947ac71328fa9259f50165f5ce2e.pdfSharif University of TechnologyScientia Iranica1026309824520171001An investigation into the accelerometer mounting effects on signal transmissibility in modal measurements24362444424410.24200/sci.2017.4244ENSaeedShokrollahiMalek
Ashtar University of Technology, Space Research Institute, Modal Testing
laboratory,
Lavizan,
Tehran 14665/143, IranFarhadAdelMalek
Ashtar University of Technology, Space Research Institute, Modal Testing
laboratory,
Lavizan,
Tehran 14665/143, IranHamidAhmadianIran University of Science and Technology, School of Mechanical Engineering,
Narmak, Tehran 16844, IranJournal Article20160210The purpose of this study is to define a simple model and discuss the main effects due to the use of the sensors with imperfect mounting in experimental measurements. This paper presents a theoretical and experimental investigation for the effects of different mounting methods of accelerometers on signal transmissibility in modal testing. In the theoretical part, a two degreeoffreedom (2DOF) model is used, where the first DOF accounts for the accelerometer seismic mass and Piezocrystal and the second DOF represents the mounting interface dynamics. An experimental modal analysis is conducted on a simple steel freefree beam using impact hammer excitation. The time domain signals and frequency response functions (FRFs) are measured in the case of magnetic, wax and stud mounting. It is found that the method of mounting has a significant effect on damping rates of measured responses. Although natural frequencies have no important changes, but the quality of measured FRFs is degraded considerably.http://scientiairanica.sharif.edu/article_4244_314a69ed1325d3405b76d8dfa3463ca9.pdfSharif University of TechnologyScientia Iranica1026309824520171001Light Oil – Gas TwoPhase Flow Pattern Identification in Different Pipe Orientations: An Experimental Approach24452456430310.24200/sci.2017.4303ENP.HanafizadehCenter of Excellence in Design and Optimization of Energy Systems
School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, IranJ.EshraghiCenter of Excellence in Design and Optimization of Energy Systems
School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, IranY.NazariCenter of Excellence in Design and Optimization of Energy Systems
School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, IranK.YousefpourCenter of Excellence in Design and Optimization of Energy Systems
School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, IranM.A.Akhavan BehabadiCenter of Excellence in Design and Optimization of Energy Systems
School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran, IranJournal Article20160222In this paper, an experimental study on the flow patterns of twophase airlight oil flow is performed in a 20 mm diameter pipe with a length of 6 m in different orientations with pipe angles in the range of 45 to +45. The flow regimes are captured by a high speed camera. In the experiments, the air with the viscosity of 0.019 mPa.s and the density of 1.2 Kg/m<sup>3</sup> and a light oil with the viscosity of 2.6 mPa.s and the density of 840 Kg/m<sup>3</sup> are used. During the experiments, different flow patterns are observed such as bubbly, slug, smooth stratified, wavy stratified, and annular flows. Flow regimes in different pipe inclination angles are inspected in twophase airlight oil flow and flow pattern maps are proposed for every pipe inclination angle. In addition, a comprehensive study on major forces acted on dispersed phase are presented theoretically to perform a thorough discussion on effects of pipe inclination angle on transition boundaries between flow patterns in twophase airlight oil flow. It is inferred that nonstratified flows are dominant flow patterns in the upward flows and stratified flows are dominant flow patterns in the downward flows.http://scientiairanica.sharif.edu/article_4303_0cff1721257000f938a4afe95b7f7622.pdfSharif University of TechnologyScientia Iranica1026309824520171001Airflow patterns in a 3D model of the human acinus23792386430410.24200/sci.2017.4304ENMohammad AliEslami SarayDepartment of Mechanical Engineering, Sharif University of Technology, Tehran, IranMohammad SaidSaidiDepartment of Mechanical Engineering, Sharif University of Technology, Tehran, IranGoodarzAhmadiDepartment of Mechanical and Aeronautical Engineering, Clarkson University, New York, USAJournal Article20141022Based on the recent photographs of microstructures of anacinus a novel 3D computational model for airflow and particle transport and deposition was developed. To model the entireacinar region simultaneously, an approach was proposed to reduce the computational space. The airflow was solved using numerical simulations for the cases of expanding and contracting the asinus wall. The volume change of the lung was imposed based on the normal breathing condition with 15% volumetric expansion ratio. Since the entire acinar region was modeled, realistic pressure type boundary conditions were used and the use of earlier unrealistic boundary conditions was avoided. The simulation results showed that the flow patterns in an acinus with moving walls were significantly different from those for the rigid wall case. Furthermore, due to the asymmetric configuration, the flow patterns were not quite symmetric. It was shown that the ratio of alveolar flow to ductal flow rate controlled the dominant flow regime in each generation. Ratios below 0.005led to recirculation regime where flow separation occurred, while values above this threshold led to flows with radial streamlines. In summary, while the flow in the primary generations was characterized by the formation of recirculation regions in the alveoli, the terminal generations were characterized by radial streamlines which move towards the alveolar wall. Both flow regimes had substantial effects on particle deposition in the acinus.http://scientiairanica.sharif.edu/article_4304_59b1b029b145c5145a824a92a8cf5a41.pdfSharif University of TechnologyScientia Iranica1026309824520171001Magnetohydrodynamic flow of linear viscoelastic fluid model above a shrinking/stretching sheet: A series solution24662472430510.24200/sci.2017.4305ENYasirKhanDepartment of Mathematics, Zhejiang University, Hangzhou 310027, ChinaJournal Article20140617In this paper, a series solution is obtained for MHD flow of linear viscoelastic fluid over a shrinking/stretching sheet by using homotopy perturbation method (HPM). The governing NavierStokes equations of the flow are transformed to an ordinary differential equation by a suitable similarity transformation and stream function. The influence of various parameters such as Hartman number and Deborah number on the velocity field is analyzed by appropriate graphs. Finally, the validity of results is verified by comparing with numerical results. Results are presented graphically and in tabulated forms to study the efficiency and accuracy of the homotopy perturbation method.http://scientiairanica.sharif.edu/article_4305_bc06c8b7059a30959653fd955ff76a31.pdfSharif University of TechnologyScientia Iranica1026309824520171001Integrated Optimization of Guidance and Control Parameters in a Dual Spin Flying Vehicle24732489430610.24200/sci.2017.4306ENHadiNobahariDepartment of Aerospace Engineering, Sharif University of Technology, Zip Code 1458889694, Tehran, IranMojtabaArab KermaniDepartment of Aerospace Engineering, Sharif University of Technology, Zip Code 1458889694, Tehran, IranJournal Article20150528In this paper, integrated optimization of the guidance and control parameters of a dual spin flying vehicle is presented. The vehicle is composed of two parts: a free rolling aft body including the engine and the stabilizing fins and a roll isolated front body including all necessary guidance and control equipments such as onboard computer, control fins and an inertial navigation system. After developing the governing equations of motion, control loops and the guidance algorithm are constructed. Controllers are designed for two operating points and the guidance algorithm consists of a midcourse and a terminal phase. In midcourse phase, a virtual target, located on the nominal trajectory, is followed using proportional navigation law; while in the terminal phase, the vehicle is guided toward the real target. A new nonlinear saturation function is defined in order to saturate the maximum lateral acceleration command, as a function of dynamic pressure. Finally, the integrated tuning of 23 guidance and control parameters is formulated as an optimization problem. The optimization problem is solved using a metaheuristic algorithm, called <em>tabu continuous ant colony system</em>. The performance of the optimized guidance and control system is evaluated using Monte Carlo simulations, based on the complete nonlinear model.http://scientiairanica.sharif.edu/article_4306_84f8464288f41a8bcc8eecfd7105606c.pdfSharif University of TechnologyScientia Iranica1026309824520171001Conditioning of vitrified and resin bond CBN grinding wheels using a picosecond laser23692378430710.24200/sci.2017.4307ENAliZahediInstitute for Precision Machining (KSF), Furtwangen University, 78054 Schwenningen, BadenWürttemberg, GermanyBahmanAzarhoushangInstitute for Precision Machining (KSF), Furtwangen University, 78054 Schwenningen, BadenWürttemberg, GermanyJavadAkbariCenter of Excellence in Design, Robotics and Automation, School of Mechanical Engineering, Sharif University of Technology, Tehran, IranJournal Article20140515Laser ablation is a novel nonmechanical wheel preparation method for optimizing the<br />treatment costs of superabrasive tools. In this study, the thermal effects of picosecond laser radiation<br />on vitrified and resin bond CBN superabrasive grinding wheel surfaces was analytically and<br />experimentally investigated. The analytical approach is intended to find threshold process parameters<br />for selective ablation of cutting grains and bond material. A picosecond Yb:YAG laser device was<br />integrated with a cylindrical grinding machine which facilitates the treatment of grinding wheel as it<br />is mounted on the grinding spindle. It has been shown that, the extent of material ablation is defined<br />by the maximum surface temperature induced by the laser radiation which is in turn defined by the<br />laser pulse energy. It is also suggested that, the depth of laser thermal effects is governed by the<br />relative speed of the laser scanner with respect to the wheel surfacehttp://scientiairanica.sharif.edu/article_4307_0b9252a731319dd3cfaafd27ce4c6069.pdfSharif University of TechnologyScientia Iranica1026309824520171001An Optimum Neural Network for Evolutionary Aerodynamic Shape Design24902500430810.24200/sci.2017.4308ENN.TimnakAerospace Engineering Department, Amirkabir University of Technology, Tehran, IranA.JahangirianAerospace Engineering Department, Amirkabir University of Technology, Tehran, IranS. A.SeyyedsalehiBioEngineering Department, Amirkabir University of Technology, Tehran, IranJournal Article20151024Two new techniques are proposed to enhance the estimation abilities of the conventional neural network (NN) method for its application to the fitness function estimation of aerodynamic shape optimization with the genetic algorithm (GA). The first technique is preprocessing the training data in order to increase the training accuracy of the multilayer perceptron (MLP) approach. The second technique is a new structure for the network to improve its quality through a modified growing and pruning method. Using the proposed techniques, one can obtain the best estimations from the NN with less computational time. The new methods are applied for optimum design of a transonic airfoil and the results are compared with those obtained from the accurate Computational Fluid Dynamics (CFD) fitness evaluator and also with the conventional MLP NN approach. The numerical experiments show that using the new method can reduce the computational time significantly while achieving the improved accuracy.http://scientiairanica.sharif.edu/article_4308_e583adfadd7dd433ffa95aa8a2f86f7c.pdfSharif University of TechnologyScientia Iranica1026309824520171001Experimental Investigation of Shock Waves Formation and Development Process in Transonic Flow24572465430910.24200/sci.2017.4309ENM.FarahaniDepartment of Aerospace Engineering, Sharif University of Technology, Azadi Street, Tehran, IranA.JaberiDepartment of Aerospace Engineering, Sharif University of Technology, Tehran, IranJournal Article20160511An extensive experimental investigation was performed to explore the shock waves formation and development process in transonic flow. Shadowgraph visualization technique was employed to provide visual description of the flowfield features. Based on the visualization, the formation process was categorized into two intrinsically different phases, subsonic and supersonic. The characteristics of subsonic phase are well known; however, those of the supersonic ones are far less studied. The supersonic phase itself is made up of two consecutive phases, namely approaching and sweeping. The effects of each phase on the flowfield characteristics and on shaping the supersonic regime have been studied in details. In order to generalize the results, three different models were tested. Moreover, a special terminology is suggested by authors to ease the process description and to pave a way for future studies. Above all, as the transition from transonic regime to supersonic one is a vague concept in terms of physical reasoning, a new explanation was proposed that could be used as a criterion for distinguishing between transonic and supersonic regimes.http://scientiairanica.sharif.edu/article_4309_c43461d2f23fc775c28b148da53b7971.pdfSharif University of TechnologyScientia Iranica1026309824520171001Theoretical and computational investigation of optimal wall shear stress in bifurcations: a generalization of Murray’s law23872395450610.24200/sci.2017.4506ENMatinGolozarDepartment of Mechanical Engineering, Isfahan University of Technology, Isfahan 8415683111, IranMohammadSayed RazaviDepartment of Mechanical Engineering, Isfahan University of Technology, Isfahan 8415683111, IranEbrahimShiraniDepartment of Engineering, Foolad Institute of Technology, Fooladshahr 8491663763, Isfahan, IranJournal Article20150912In this study, the optimal distribution of Wall Shear Stress (WSS) in a bifurcation and its effect on the morphology of blood vessels were investigated. The optimal WSS was obtained through minimization of energy loss due to friction and metabolic consumption. It was shown that the optimal WSS is a function of metabolic rate, fluid properties, diameter, and flow regime. For fully developed laminar and turbulent flows different patterns of WSS were observed. For laminar flows WSS is constant but for turbulent flows WSS is a function of diameter such that the exponent of diameter varies by tube relative roughness. Based on the optimal WSS and conservation of mass, the optimal relationship between diameters of mother and daughters’ vessels was obtained for different flow regimes. Also, it was theoretically shown that the optimal distribution of WSS in a bifurcation minimizes flow resistance as well as energy loss. In addition, it was demonstrated that the specific relationship between the length and diameters of a blood vessel and optimal relationship between diameters lead to optimal WSS distribution. Finally, the numerical simulation was used to investigate the effect of Reynolds number on the optimal WSS and flow resistance, and to verify the theoretical formula predictions, obtained in this work.<strong></strong>http://scientiairanica.sharif.edu/article_4506_90dd94c0d4b230cf55aab49792903b20.pdf