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Design and Optimization of a Subsonic Wind Tunnel Profile with Two Test Sections using CFD

Lotfi, Iman | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44561 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Darbandi, Masoud
  7. Abstract:
  8. In this project, we are willing to analyze and design a subsonic wind tunnel WT configuration for the Aerospace Engineering Department in Sharif University of Technology. This WT will be an open-circuit "suck down" type, whose entry is open to the atmosphere (laboratory) and three axial fans downstream of its test section. In addition to three parallel fans, we are expected to design two simultaneous small and large size test sections for it. The small and large sections would have an area about 1.4 and 4 m2and maintain a maximum air velocity of 100 and 50 m/s, respectively. So, our design is faced with two main complexities. In one hand, we are to manage the air flow through these two test sections with sufficient flow quality and flow uniformity. So, one main question in this project is to answer how these two test sections should be set; either serial or parallel. Additionally, in case of choosing a serial one, which test section would be placed first? In another hand, we are required to design a suitable diffuser, which converts the semi-triangle shape at the fan location to a rectangular one right at the test section. This complexity needs some additional considerations in diffuser design. For example, we need to consider some suitable flow guidance shapes inside the diffuser to avoid any flow separation there. To facilitate our analysis and design, we use commercial CFD software. We first place only one fan in the same WT and test different proposed test sections arrangements. This study helps to reduce the design time because a 3D CFD modeling is very time consuming. After finding the suitable arrangement, we extend our study to 3D simulations using 3 parallel fans right after the WT diffuser. In 3D study, we also design some suitable flow guidance shapes to avoid flow separation inside our different designed diffusers. We place them in a manner to avoid any recirculation and cavity zones in diffuser. A few important conclusions can be counted as follows. First, we show that the parallel arrangement of the two test sections is the best choice among many other different arrangements. Of course, this conclusion does not consider some other important factors such as the cost for constructing it and the difficulties to switch between them. On the other hand, to convert the semi-triangular shape right at fan locations to a rectangular shape at the test section outlet, we found that the best place for such flow guidance is at the middle of diffuser’s length. Among the three suggested configurations for the flow guidance shape, the one attached to the diffuser wall shows the best performance
  9. Keywords:
  10. Numerical Simulation ; Subsonic Wind Tunnel ; Subsonic Flow ; Test Sections ; Diffuser Shape ; Parallel Fans ; Computational Fluid Dynamics (CFD)

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