Sharif Digital Repository

Focusing on unsteady flow field over delta wings due to vacuity of researches in this branch on one hand and requiring of modern aircrafts designers to this science on the other hand, expresses necessity of accomplishing present investigation. Scrutiny of pressure distribution of low aspect ratio wings in unsteady state and determination of aerodynamic characteristics of these wings in variant conditions, can be beneficial to plan aircrafts need to fly with high maneuverability in high speeds. This issue becomes important when in supersonic regime, with respect to emerged shock waves and vortices, develop complicated pressure distributions on the wing surface in unsteady state that affect... 

In this experimental study, a series of wind tunnel tests were performed to examine the wake flow profile over three swept wings with sweep angles of 23, 33 and 40 degrees with similar aspect ratio at various conditions. The airfoil of wing was a NACA 6-series airfoil designed to provide a laminar flow on the front half of the airfoil. The tests, made at a mid aerodynamic chord Reynolds number of 8×〖10〗^5, covered an angle of attack range of -2 to 10 degree. The wing tip vortex effects are eliminated by placing an End-plate on the wing tip.The tests were carried out at two main section of wing and two various position from behind of wing. A total pressure rake and transducers was used to... 

Application of canard next to the wing have been widely used in military industry for decades. Although it’s most application is in supersonic flying objects, It has to do it’s duty in lower air speeds too. The aim of this study was to investigate the influence on the wing due to the presence of canard in supersonic flow regime. But because of the importance of the issue, significant attempts has been conducted in subsonic flow regime. High research volume, Absence of a comprehensive theory in this branch and the local defense industry demand as a developing country on the other hand, delivers the importance and applicability of the subject. Another issue of importance is that the... 

Flow characteristics analysis over a wing, is one of the pioneer challenges in super and sub-sonic flow near flying objects. Taking into account of growing rate of low aspect ratio utilization, usually called Delta wings, investigation of vortex behavior over this wings is highly noticeable. In addition, the lack of research in this branch of Aerodynamics inside the country, considering it’s critical application, has doubled the importance of doing research in this filled. Experimental researches on super-sonic flow over a Delta wing is limited and there are not much accurate researches about vortexes in this category of wings. In this work, the main effort is to investigate the phenomena in... 

In recent years, renewable energy equipments such as wind turbines has become more common for electric power generation. Due to the complexity of the aerodynamics of wind turbines,experimental studies in this field are very important. The purpose of this study is to investigate the aerodynamic performance of a new wind turbine airfoil in static mode and pitching motion.The airfoil is a section of 2 MW wind turbine blade, pitching around its quarter-chord axis .All experiments are carried out in a subsonic wind tunnel. In these experiments, the reynolds number is 140,000 and the reduced frequency varies from 0.034 to 0.126. Pressure transducers have been used to determine the pressure... 

Liquefaction is an important phenomenon in geotechnical engineering which can cause severe damages to structures. Liquefaction-induced lateral spreading is defined as the lateral displacement in mild slopes or level grounds ending in free faces (such as quay walls) triggered by liquefaction in subsurface soil layers. During recent years, extensive studies have been conducted around the world documenting liquefaction induced lateral spreading and its effects on deep foundations. In the present study, a series of shaking table experiments which were previously conducted at Sharif University of Technology are numerically simulated using the three dimensional finite difference based program,... 

In the last few decades, the consumption of fossil fuels and its increasing worldwide price on one hand, and the severity of global warming on the other hand have led researchers and engineers to invent and expand new cooling technologies. Cooling has the largest portion of energy consumption of households during the hot season of a year. In addition to high energy consumption, the common cooling systems utilize gases which are harmful for environment. Thermoacoustics is a new and recent technology which has arised from combination of acoustics and thermodynamics. In Iran, research in this new field was pioneered by Ghorbanian in Department of Aerospace Engineering at Sharif University of... 

Twin intake is a new version of intakes for supersonic fighters with high performance. Investigations on these types of intakes show that with some modifications in design procedure and modifying the desired parameters, one could result in an intake compatible with the body and nose of the fighter with high efficiency. In this investigation the results of experiments on a supersonic air intake which is designed for 1.7 Mach number at angles of attack ranging from -4 to +6 degrees are presented. The main goal of this investigation is to analyze the effect of angle of attack on the performance of the intake in design and off-design conditions. In order to reduce the boundary layer thickness... 

The design of an indicator for "quality rate measurement" has been done in many countries around the world, and the quality rate, like other economic indicators, is subject to public judgment. Prerequisite for the formation of this index is the existence of a "comprehensive system" for quality management in the country, in which the duties and powers of various institutions in the issue of quality are specified and responsible for each process. With this excellent system, quality management is done in an integrated manner and quality can be managed efficiently by providing indicators.Quality assessment, in addition to hearing the customer's voice, requires other aspects, including examining... 

In this study, by performing a series of experiments, the effect of the presence of cylinders on the formation of vortices and the interaction of cylinders on each other and, finally, transverse propagation in a steady flow are investigated. The cylinder cylinders that are in the direction of the motion of the water, have a significant effect on the hydrodynamic aspects and propagation in these streams. In the pattern of flow around cylindrical cylinders, with increasing Reynolds number, the vortex behind the stem begins to oscillate and when they reach, vortices flow into the stream. The flow velocity field, the formation and vortex fluctuation, affects the process of particle propagation... 

Supersonic inlets, as one of the most important components of fighter aircraft, are designed to provide the required airflow with an acceptable level of energy and quality and with a minimum drag. From the inlet design point of view, there exist various configurations that are based on different criterion such as supersonic flow compression region, flow dimensions, and installation position, to name a few. The flight Mach number, M∞, could further complicate the design and structure of these types of inlets. One of the requirements for minimum drag is that at supersonic speed the shock wave that forms in front of the inlet must impinge on the cowl lip, called shock on lip condition (SOL). ...