Design of a Diffuser for a Subsonic Wind Tunnel Equipped with Three Axial Fans Using CFD

, M.Sc. Thesis Sharif University of Technology Saboohi, Zoheir (Author) ; Darbandi, Masoud (Supervisor)

Abstract

Nowadays, a wind tunnel is a tool used in aerodynamic research to study the effects of air moving past solid objects. By employing a wind tunnel, we can compeletely control the conditions of aerodynamic testing on specific models. In this research, the design of a diffuser for the subsonic wind tunnel has been taken into account by CFD. The wind tunnel is of suction type and is powered by three axial fans which are manufactured by LTG Inc. The tunnel test section has a 140 cm height and 195cm width which can provide a necessary Mach number. Considering the setting of the three axial fans, located at the end of the diffuser and parallel to each other, it’s necessary to take into consideration...

Analysis of Degradation for Laminated Notched Plate in Micromechanics by “Strain Energy Release Rate” Method and Illustrations the Results in Ansys

, M.Sc. Thesis Sharif University of Technology Gholi Mesgarha, Payam (Author) ; Hosseini Kordkheili, Ali (Supervisor)

Abstract

By developing composites, difficulties of modeling of degradation of properties as stiffness is most considered. The recent advances in the modeling of degradations in stratified composites have led to improved models on all scales. Macro scales methods are good to estimate fracture but not to estimate the failure in micro scale (as microcrack) and moreover, they need many experimental data. Therefore by considering a stratified structure which contains fiber, matrix and intermediate area, mesoscale modeling method is most suitable. In this research Micromechanical Progressive Algorithm (MPA) is used. The method employed is Micromechanic Method of Fracture (MMF). In this work by developing a...

Numerical Investigation of Flow Oscillation in the Diffuser Inlet & Test Chamber of High-Altitude Simulator

, M.Sc. Thesis Sharif University of Technology Zahedifar, Fatemeh (Author) ; Farahani, Mohammad (Supervisor) ; Fouladi, Nematollah (Supervisor)

Abstract

The present research was conducted to numerical simulation and phenomenology of the pressure fluctuations and instability of the diffuser with the ratio of the diffuser inlet to the nozzle outlet of 1.91. The numerical simulation has been done with k-ω-SST and k-ω-GEKO turbulence models with both steady and unsteady methods for the nozzle with an expansion ratio of 30. Validation of the numerical solution has been done with the help of the experimental test data of the high-altitude test simulator available in the Research Institute of Space Transportation Systems. Tests were conducted by cold gas. Investigations indicate that two types of start occur in the system, stable and unstable...