Wind tunnel design

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subsonic wind tunnel design methodology

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  • If the test chamber length is more than 3 times of hyddia, then the boundary layer thickness increases. If the test chamber length is less than 0.5 times of hyddia, boundary layer thickness is too short
  • Wind tunnel design

    1. 1. Subsonic wind tunneldesign methodology By ANIRUDH B 11MN01
    2. 2. What is a wind tunnel?Wind tunnels are measurement tools to study gas flows around a body and the forces generated by the gas-body interactionMostly air is used in wind tunnelsUsing such tool it is possible to measure global and local flow velocities, as well as pressure and temperature around the body
    3. 3. Components of a wind tunnel Bell mouth section/Nozzle Fine screen mesh
    4. 4. Components of a wind tunnel Diffuser section with a Test chamber Suction fan located at The left of the diffuser
    5. 5. Wind tunnel Design Closed circuit wind tunnel
    6. 6. Wind tunnel DesignTest Chamber: Dimensions, shape and air velocity
    7. 7. Wind tunnel DesignTest Chamber: Dimensions, shape and air velocity*
    8. 8. Wind tunnel DesignNozzle: Area ratio
    9. 9. Wind tunnel Design Nozzle: Area ratio*
    10. 10. Wind tunnel Design Nozzle: Area ratio*
    11. 11. Wind tunnel DesignNozzle: Area ratio
    12. 12. Wind tunnel DesignSecond Diffuser
    13. 13. Wind tunnel DesignSecond Diffuser: Inlet cross sectional area*
    14. 14. Wind tunnel DesignSecond Diffuser: Inlet cross sectional area*
    15. 15. Wind tunnel DesignSecond Diffuser: Inlet cross sectional area*
    16. 16. Wind tunnel Design Shape adapter: LengthShape adapter is also designed and its total Length equals 0.3m
    17. 17. Wind tunnel DesignFirst Diffuser: side l of the outlet CS area*
    18. 18. Wind tunnel DesignFirst Diffuser: side l of the outlet CS area
    19. 19. Wind tunnel DesignFirst Diffuser: side l of the outlet CS area*
    20. 20. Wind tunnel Design Corners: small corners and large corners*
    21. 21. Wind tunnel DesignCorners: small corners and large corners*
    22. 22. Wind tunnel Design Settling chamberSettling chamber consists of honeycombs and mesh screen to reduce the flow turbulence before it enters the nozzle.
    23. 23. Wind tunnel DesignSettling chamber: honeycomb Key design factors are: 1) Length 2) Hydraulic diameter 3) porosity
    24. 24. Wind tunnel DesignSettling chamber: honeycomb
    25. 25. Wind tunnel DesignSettling chamber: honeycomb
    26. 26. Wind tunnel DesignSettling chamber: honeycomb
    27. 27. Wind tunnel DesignSettling chamber: screens To have effective reducing in turbulence the porosity must lie between 0.58 to 0.8 Different mesh qualities (coarse, medium, f ine) are efficient than single fine mesh
    28. 28. Wind tunnel Design Pressure losses1) Pressure loss in constant cross section area sections (friction)2) Pressure loss in diffusers (friction and expansion)3) Pressure loss in corners (friction and expansion)4)Pressure loss in screens(porosity or its complement solidity, the Reynolds numberCalculated with wire diameter, and mesh factor)5) Pressure loss in honeycombs (length to cell hydraulic diameter ratio, porosity and Reynolds number)6) Pressure loss in nozzles (skin friction)
    29. 29. Wind tunnel DesignFan selection
    30. 30. SummaryThe design procedure consists of the following main steps:1. Defining the test section dimensions and desired flow velocity by test type;2. Wind tunnel component design by test section criteria;3. Wind tunnel component pressure loss calculation;4. Determining pressure loss throughout the wind tunnel circuit as a functionof the possible flow velocity in the testing section in both open and closedconfigurations;5. Matching wind tunnel components to commercial fans, and energyconsiderations.
    31. 31. References:1)Justin D Periera, “Wind tunnels-Aerodynamics, models and experiments”,Nova science publishers2) Metha R. D., Bradshaw P. “Design Rules for Small Low Speed Wind Tunnels”Journal of Royal Aeronautical Society 1979, Vol. 73.3)Wind tunnel design and wind tunnel parts-NASA

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