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Experimental Investigation of Acoustic Excitation on NACA 0012 Airfoil Wake Development
, M.Sc. Thesis Sharif University of Technology ; Soltani, Mohammad Reza (Supervisor) ; Masdari, Mehran (Supervisor)
Abstract
Acoustic excitation frequency effect on NACA 0012 airfoil boundary layer and on its wake development was investigated experimentally in two wind tunnels. Airfoils chord lentgh were 100 and 152 mm. Flow Reynolds numbers was 60000 and 160000 in the first wind tunnel and 100000 and 250000 in the second one. Excitation frequency range was chosen between 300 and 2400 Hz. Airfoil flow and sound characteristics was measured using a 1-D hot-wire sensor and two microphones, one mounted on the wind tunnel wall and the other flash mounted on the model at 10 percent of chord length, respectively. Airfoil angle of attack was set at zero degree in the first wind tunnel and at three angles of zero, five...
Flow-induced vibration of an elliptical cylinder and a wake-mounted flat plate
, Article Ocean Engineering ; Volume 279 , 2023 ; 00298018 (ISSN) ; Shariloo, K ; Masdari, M ; Sharif University of Technology
Elsevier Ltd
2023
Abstract
A numerical simulation is carried out to study flow-induced vibration of an elliptical cylinder equipped with a wake-mounted flat plate in a laminar flow regime at Re = 100. The objects are constrained to vibrate independently in the cross-flow direction. The Vortex-induced vibration of an upstream cylinder with four different aspect ratios (AR = 0.25, 0.5, 0.75, 1) is investigated in the presence of a plate mounted in different horizontal spacing of G = 0.5–3. Simulations are performed for a fixed mass ratio of 10 and negligible damping ratio across a range of reduced velocities (Ur = 2–12). The results demonstrate that the presence of the flat plate can amplify the vibration amplitude of...
Investigation of the pressure distribution and transition point over a swept wing
, Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1277-1286 ; 10263098 (ISSN) ; Ghorbanian, K ; Masdari, M ; Sharif University of Technology
2011
Abstract
A series of wind tunnel tests are performed to examine the flow field over a swept wing under various conditions. The wing has a laminar flow airfoil section, similar to those of the NACA 6-series. Static pressure distributions over the upper surface of the wing, in both chordwise and spanwise directions, are measured at different angles of attack. The data is employed to predict the transition point at each chordwise section. The skewness parameter of the pressure data shows that this factor drops to zero in the transition region. A comparison of the calculated transition point on the wing surface with that obtained from the 2D computational method shows reasonable agreement over a portion...
Effect of wind tunnel wall porosity on the flow around an oscillating airfoil at transonic speeds
, Article Scientia Iranica ; Volume 24, Issue 3 , 2017 , Pages 1069-1076 ; 10263098 (ISSN) ; Soltani, M. R ; Masdari, M ; Sharif University of Technology
Sharif University of Technology
2017
Abstract
The effect of porosity in oscillating situations (to the authors' knowledge, for the first time) on a supercritical airfoil (SC0410) has been experimentally investigated. Tests have been carried out in an open circuit suction-type wind tunnel at a free stream Mach number of M = 0:80. Both static and dynamic (pitching) tests have been carried out on the mentioned airfoil. The oscillation frequency for the unsteady tests has been set to 3 and 6 Hz. The amplitude of frequency is ±1 deg. The effect of porosity has been surveyed on the magnitude of pressure fluctuations, phase shift, and lift coefficient loop. The investigations show that increasing porosity in the test section of transonic...
Prediction of transition point on an oscillating airfoil using Neural network
, Article 2007 5th Joint ASME/JSME Fluids Engineering Summer Conference, FEDSM 2007, San Diego, CA, 30 July 2007 through 2 August 2007 ; Volume 2 FORA, Issue PART A , July , 2007 , Pages 33-39 ; 0791842886 (ISBN); 9780791842881 (ISBN) ; Seddighi, M ; Masdari, M ; Sharif University of Technology
2007
Abstract
Dynamic Neural network was used to minimize the amount of data required to predict the location of transition point on a 2-D oscillatory wing. For this purpose, various experimental tests were carried out on a section of a 660kw wind turbine blade. A multi layer non linear perceptrons network was trained using the output signals of four hot films attached on the upper surface of the model. Results show that using only 50% of the test data, the trained network was able to the transition point with an acceptable accuracy. Moreover, the method can predict the transition points at any position of the wing surface for different Reynolds numbers, amplitudes and initial angles of oscillation, and...
Experimental investigation of the leadingedge roughness on the boundary layer of a plunging airfoil
, Article 27th Congress of the International Council of the Aeronautical Sciences 2010, ICAS 2010, 19 September 2010 through 24 September 2010, Nice ; Volume 2 , 2010 , Pages 1582-1588 ; 9781617820496 (ISBN) ; Soltani, M. R ; Masdari, M ; Sharif University of Technology
2010
Abstract
Extensive experimental investigation was conducted to study the effect of leading-edge roughness on the state of the boundary layer of a wind turbine blade section. The application of surface grit roughness simulates surface irregularities that occur on the wind turbine blades. The measurements were done using multiple hot-film sensors and surface pressure transducers in both static and plunging oscillation of the airfoil. Frequency domain analysis was used to determine the state of the unsteady boundary layer
Effect of reduced frequency on the boundary layer of a plunging airfoil
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 1 , 2010 , Pages 185-190 ; 9780791849156 (ISBN) ; Soltani, M. R ; Masdari, M ; Sharif University of Technology
2010
Abstract
This investigation addresses the boundary layer study of a plunging airfoil. It specifically concerns the effect of reduced frequency on transition and separation/reattachment of the unsteady boundary layer. The wind tunnel measurements were conducted using multiple hot-film sensors, pressure transducers and a boundary-layer rake, at Reynolds numbers of 0.42 to 0.84 million, and over reduced frequencies from 0.05 to 0.11. It was observed the boundary layer transition occurs by a laminar separation bubble. The unsteady laminar separation is promoted (delayed) by the increase of the reduced frequency in upstroke (downstroke) portion of the equivalent angle of attack
An experimental investigation of transition point over a quasi-2D swept wing by using hot film
, Article Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering ; Volume 229, Issue 2 , February , 2015 , Pages 243-255 ; 09544100 (ISSN) ; Soltani, M. R ; Masdari, M ; Davari, A ; Sharif University of Technology
SAGE Publications Ltd
2015
Abstract
In this study, we performed experiments to investigate the effect of sweep angle on the transition location of laminar flow to turbulent flow. Three half wing models were used, each having a different sweep angle but with the same aspect ratio in various angles of attack. Two flat plates were used at the ends of the swept wing models to prevent the flow from rolling up over the wing. By simulating flow over infinity swept wing by eliminating tip vertices, the effect of sweep angle on flow transition phenomenon was investigated. The experiments included the study of transition flow via hot-film sensors, which were glued on the wing surface. We found that the small leading-edge radius and low...
Experimental investigation of shock-buffet criteria on a pitching airfoil
, Article Chinese Journal of Aeronautics ; Volume 35, Issue 7 , 2022 , Pages 179-191 ; 10009361 (ISSN) ; Zeinalzadeh, A ; Abdi, M. A ; Soltani, M. R ; Sharif University of Technology
Elsevier B.V
2022
Abstract
An experimental investigation of the shock-buffet phenomenon subject to unsteady pitching supercritical airfoil around its quarter chord has been conducted in a transonic wind tunnel. The model was equipped with pressure taps connected to the fast response pressure-transducers. Measurements were conducted at different free-stream Mach number from 0.61 to 0.76. The principle goal of this investigation was to experimentally discuss the shock-buffet criterion over a SC(2)-0410 supercritical pitching related to the hysteresis loops of total drag and trailing edge pressure, the behaviour of the shock wave foot location, the pressure distribution over the upper surface, and by implementing the...
Experimental Study of Boundary Layer Transition on a Swept Wing
, Ph.D. Dissertation Sharif University of Technology ; Soltani, Mohammad Reza (Supervisor) ; Ghorbanian, Kaveh (Supervisor)
Abstract
Swept wings are of great interest for achieving high speed as well as increasing the critical Mach number in aircrafts and unmanned flying vehicles. The governing fluid mechanical phenomenon on swept wings is strongly influenced by the chordwise and spanwise components of the cross-flow. Laminar airfoils are employed for drag reduction and postponing the boundary layer transition from laminar to turbulence. Hence, the knowledge about the boundary layer structure and instability modes is of great significance. A series of wind tunnel tests are performed to examine the flow field over a swept wing at various conditions. The wing has a laminar flow airfoil section similar to NACA 6-series ones....
Modeling Propagation of Cardiac Action Potential at Cellular Level
, M.Sc. Thesis Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
Heartbeat is the result of contractions of over 10 billion cardiac cells. These cells’ cytoplasms are connected to each other by gap junctions which are arrays of intercellular protein channels. Thus action potential can propagate from one cell to another and cause its contraction. In core-conductor model, one-dimensional microscopic representation of cardiac tissue, cells are attached to each other to form a ladder network. The parallel elements are connected to each other by series resistors which represent gap junctions. These resistors are nearly always considered as static elements. In this thesis I have investigated the effects of incorporating the dynamicity of gap junction resistors...
Distributed Cardiovascular System Modeling
, M.Sc. Thesis Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
Simulation of cardiovascular system functionality during various physiological conditions is essential at different diagnostic and clinical levels. A first step in studying the roots of cardiovascular diseases and abnormal activity is to study a practical yet complete model of the cardiovascular system. In this thesis we introduced a new approach for defining the distributed model of the cardiovascular system. Initially, we chose an appropriate subsystem, namely Arch of Aorta, and proposed a distributed model for it. The elements of the proposed model were nonlinear RLC elements that simulate resistance, blood viscosity and vessel elasticity respectively. To minimize the system complexity,...
Risk Breakdown Structure (RBS) Identification and Designing for projects
, M.Sc. Thesis Sharif University of Technology ; Sepehri, Mehran (Supervisor)
Abstract
To actualize and making the outputs of a project effectual, it is necessary to conduct an effective management during a project. This case may not be possible without accurately planning for activities, management and controlling all phases of a project ignoring the risk management of that project. If risks of a project cannot be detected before conducting a project, it is possible to challenge the performance and even effectiveness of the project. In current conditions, the most important problem of managers and executives of construction projects through the country is risk management of projects, not acknowledging with definitions of risk, models of risk management and lack of a model for...
Introducing a suitable Controller for Rowing Activity in Patients with Spinal CordInjuries using FES
, M.Sc. Thesis Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
Disconnections in neural paths from the central nervous system to the muscles or vice versa cause different neuropathies, thus paralysis in different limbs may occur. As a result of the lack of muscular activity and the decrease in blood perfusion in paralyzed limbs, problems like osteoporosis, increase in the risk of breaking, decline in muscle size, cardiovascular diseases, renal dysfunction, bedsores, etc may happen. In order to induce movement in paralyzed limbs, thus preventingmentioned problems, rowing exercise through Functional Electrical Stimulation (FES) may be utilized. In FES, electrical Stimulation using current stimulating pulses is applied to contracting and relaxing muscles,...
Performance Management of HSE Management System based on BSC Framework-the Case Study of Mapna Corporation
, M.Sc. Thesis Sharif University of Technology ; Sepehri, Mehran (Supervisor)
Abstract
A Balanced Scorecard (BSC) model is proposed to evaluate performance of Health, Safety and Environment (HSE) management systems. This model includes key performance indicators at three integrated levels. It has been tested and verified in a project-based organization in Iran, active in the area of power and energy. Results show that the company has done well in implementing HSE management processes, but no so well in growth and learning. This model may be used as a basis for comparing different companies and various proposed programs in the field of HSE management systems. The model includes indicators and sub-indicators in each category particularly related to stakeholders, processes, and...
Functional Modeling of Normal and CHF Heart and Control of Total Artificial Heart- An Optimizing Approach
, Ph.D. Dissertation Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
World-wide, Congestive Heart Failure (CHF) takes hundreds of thousands of lives each year. This chronic heart disease causes poor performance of the heart and insufficient blood pumping to the organs. A significant percentage of patients with CHF require heart transplants for their survival. The high cost of heart transplant, shortage of donor hearts and possibility of its rejection by recipients are serious problems of this type of treatment. Therefore a large number of heart patients are potential beneficiaries of artificial blood pumps such as Ventricular Assist Device (VAD) and Total Artificial Heart (TAH). Performance of these systems must be compliant and complementary to the existing...
Identifying Affecting HR Factors on Unsuccessful Reengineering Projects
, M.Sc. Thesis Sharif University of Technology ; Sepehri, Mehran (Supervisor)
Abstract
In this study, factors which lead in failures in reengineering processes in project based companies have been investigated. The research used qualitative methods, and finally using theme analysis to identify the main factors.Consequently, the main causes of failure of re-engineering projects have been identified and classified in six basic categories including: organizational leadership, planning, human resources management, mental models causing resistance, culture and organizational climate and communication. That each of these themes includes some subset of the agents it represents. In this study, a suitable pattern for organizations which intend to perform reengineering has been...
Applying Tandem CONWIP Policy to Assembly Supply Chain
, M.Sc. Thesis Sharif University of Technology ; Sepehri, Mehran (Supervisor)
Abstract
Supply chain management has been developed extensively in second half of last century and the development has been continued up to present century. Nowadays Development and conformity of production and inventory control methods with JIT philosophy in production line level is one of the topics that received much attention from researchers. An increasing interest in the scope of JIT philosophy is on the extension and adaptation of Pull policies such as Kanban and CONWIP for materials and production control. In a real-life environment, companies are subjected to various types of uncertainties such as stochastic processing times and variable demand. This uncertain environment could cause lots...
Joint Segmentation and Motion Estimation of Cardiac Cine MR Image Sequences
, Ph.D. Dissertation Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
In this study a variational framework for joint segmentation and motion estimation is provided for inspecting heart in Cine MRI sequences. In the first work, a functional including Mumford-Shah segmentation and optical flow based dense motion estimation is proposed. However, the motion estimation technique is replaced with warping estimation in the second work to reach in more regular and smooth motion field based on tracking of cardiac boundaries. Both of these functionals are then approximated by using the phase-field method to make them suitable for extracting Euler-Lagrange equations. Numerical solution to the optimization problem, when the time and image spaces are discretized by finite...
Dynamics and Control of Needle Movement in Percutaneous Interaction with Prostate Tissue
, Ph.D. Dissertation Sharif University of Technology ; Jahed, Mehran (Supervisor)
Abstract
In many modern medical procedures, needle insertion is an inevitable part of the diagnosis or treatment protocols. The accuracy of the needle insertion is adversely affected by a number of factors. A needle, frequently assumed to be flexible, is inserted into a soft tissue and induces complex mechanical interactions that may result in considerable uncertainties. Tissue intrinsic characteristics as well as its deformation and rotation may cause dramatic complexities. This work considers the needle movement inside the tissue from the dynamics and control point of view. The proposed approach can be regarded as an initial step towards automation of needle insertion procedures; it can also be...