Experimental Investigation of the Effects of Suction and Wall Porosity on the Surface Pressure and Aerodynamic Forces in Transonic Wind Tunnel

, M.Sc. Thesis Sharif University of Technology Amiri, Kaveh (Author) ; Soltani, Mohammad Reza (Supervisor)

Abstract

Transonic speed is one of the most important flight regimes. There are two main significances related to it. First, all of the supersonic air vehicles should pass through this regime to reach to their final speed. Second, nowadays most of the commercial airplanes fly in nearsonic speeds. According to nonlinear nature of the flow through the speeds, the related researchers haven’t been successful in development of a comprehensive theory as well as subsonic and supersonic ones. So, transonic flow is one of the most critical regimes in wind tunnel testing. In order to eliminate the shock-boundary layer interaction and wave cancellation, perforated walls and side suction are used in test section...

A New Testing Approach to Evaluate the Role of Unsaturated Stress State Variables and Degree of Saturation of Infill Materials on the Behavior of Infilled Rock Fractures

, M.Sc. Thesis Sharif University of Technology Dadashi Serej, Ali (Author) ; Khosravi, Ali (Supervisor)

Abstract

Theoretical and experimental studies have shown that natural fractures may exhibit capillary behavior because of either their wall-roughed nature or presence of partially saturated fine materials within the fractures. Different factors are expected to affect the capillary behavior and consequently the hydraulic and mechanical properties of fractures including topology of void spaces in fractures, and state of stress of infill materials and their initial innate conditions (e.g., void ratio, water content, degree of saturation and dry density). Therefore, comprehensive characterization of their hydro-mechanical behavior requires knowledge of morphological details of fracture surface, as well...

Aerodynamic Optimization of Transonic Airfoils and Wings by Using Shock Control Bump, Suction and Blowing with Adjoint Method

, Ph.D. Dissertation Sharif University of Technology Nejati, Ashkan (Author) ; Mazaheri, Karim (Supervisor)

Abstract

Shock control bump (SCB) and suction and blowing are flow control methods used to control the shock wave/boundary layer interaction (SWBLI) in order to reduce the resulting wave drag in transonic flows. A SCB uses a small local surface deformation to reduce the shock-wave strength, while suction decreases the boundary-layer thickness and blowing delays the flow separation. Here, a single-point, a multi-point, and a robust optimization method are used to find the optimum design of SCB and suction and blowing. The flow control methods are used separately or together on two transonic airfoils i.e.; RAE-2822 and NACA-64A010 for a wide range of off-design transonic Mach numbers. The RANS flow...

Evaluation Of The Effects Of Degree Of Saturation And Suction On Dynamic Properties Of Sand: Experimental Study On Babolsar Sand

, Ph.D. Dissertation Sharif University of Technology Ahmadinezhad, Adel (Author) ; Jafarzadeh, Fardin (Supervisor)

Abstract

The ground experiences various hydraulic conditions under climate and groundwater level changes, and it becomes dry or wet frequently. The states of pore-water within the geomaterial, being signified in terms of suction and saturation degree, change during these variations, and consequently affect the soil behavior. In the course of isotropic or anisotropic dynamic loading on soil deposits, the altered hydraulic conditions can lead to different responses. Systematic investigation of these effects with element laboratory tests on a poorly graded sand is the main objective of the current study. Therefore, the dynamic response of sand in terms of dynamic properties (i.e. shear modulus, damping...