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Supersonic Wind and Imaging Flow Tunnel

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  1. Supersonic Wind and Imaging Flow Tunnel Kendria Alt Joshua Clement Shannon Fortenberry Katelynn Greer • David McNeill • Charlie Murphy • Matthew Osborn • David Springer

  2. Content • Background • Objective • Tunnel Design • Visualization Design • Current Configuration • Project Management

  3. Objective • Supersonic wind tunnel and flow visualization system • Operable by engineering undergraduates • Mach 1.5 – 3 in 0.5 increments • Mach ±0.05 accuracy • Customer: Dr. Brian Argrow Home

  4. Background • Project attempted 6 years ago • Failed due to choked flow before nozzle • Commercially available supersonic wind tunnels • Aerolab 1” x 1” with Schlieren and 4 models • $127,213.00 • Footprint ≈ 30 ft2 • Noise ≈ 120 dB • Commercially available Schlieren system • Focal length longer than cart top • Low quality • Edmund Optics Home

  5. Requirements Home

  6. Tunnel System Valve Regulator Matt Osborn David Springer Nozzle and Test Section Settling Tank Pressure Reservoir **Conceptual Representation Only Home

  7. V R Pressure Reservoir ST Conceptual Representation Only Tunnel Decision Flowdown Home

  8. V R Pressure Reservoir ST Conceptual Representation Only Tunnel Configuration Alternatives Home

  9. Pressure Reservoir Steady State(Appendix B) Not Feasible Vacuum Tunnel(Appendix B) Not Feasible Blowdown Tunnel (Appendix B) Compressor Atmosphere V Nozzle Nozzle Nozzle V Atmosphere Atmosphere Vacuum Reservoir • Too large of a compressor at Mach 3 • Complicated • Huge 21 ft3 required • Need large vacuum pump • Condensation and Icing • Much smaller reservoir (high pressure) • No condensation or icing • Commercial gas (no pumps) Tunnel Configuration Alternatives Home

  10. Initial Analysis Conclusions Full Mach Range Home

  11. V R Pressure Reservoir ST Conceptual Representation Only Gas Selection Home

  12. Gas Selection • Specifics • Oxygen eliminated on safety • Nitrogen selected over air based on cost • 2200 psi: $6.45 • 3500 psi: $138 • 6000 psi: $198 Conclusions Nitrogen available in both liquid and gaseous forms. Purchase through AirGas or on campus. Home

  13. V R Pressure Reservoir ST Conceptual Representation Only Liquid vs. Gas Nitrogen Home

  14. V R Pressure Reservoir ST Conceptual Representation Only Regulators vs. Second Tank Home

  15. R R R R R R R V R V R V Regulators vs. Second Tank 8 Tanks – 8 Regulators • Requirement • 0.0183 slugs/s → 29,000 scfh • Tanks: 4000 scfh • Minimum 8 tanks • Regulators: 6000 scfh • Minimum 6 regulators • Each regulator > $300 • 48 Runs at Mach 2 • Constant test section properties 8 Tanks – 1 Regulator – Second Tank – 2 Valves • Second tank • 4 cubic feet @ 1000 psi maximum • Can manufacture for ~ $700 • 12 Runs at Mach 2 • Properties in test section change Conceptual Representations Only Appendix C Home

  16. V R Pressure Reservoir ST Conceptual Representation Only Liquid vs. Gaseous Nitrogen Home

  17. V R V V V Liquid vs. Gaseous Nitrogen • Gaseous Nitrogen • 8 Tanks – One Regulator – Two Gaseous Valves • 8 Hoses and Manifold – Complicated ($$) • Liquid Nitrogen • 1 Tank –Cryogenic Valve – Heater Element – Gaseous Valve • Hours of run time • 11,430.67 BTU/hr → $200 heater • Liquid Nitrogen available on campus • Thermal Fatigue on 2nd Tank • Currently not enough information to decide • Parallel Paths • Drop Dead Date of Oct. 26 Home

  18. V R Pressure Reservoir ST Conceptual Representation Only Nozzle Material Home

  19. Nozzle Material Selection V∞ 447.2°R 190.4°R Not to Scale • Temperature differences at throat and test section • Contraction differences modify Mach number Home

  20. Nozzle Material Selection • Specifics • CTE: Coefficient of Thermal Expansion • Specific Strength: lightweight under pressure • Hardness affects machinability • Assumed 120 sec of continuous Mach 2 flow • Conclusions • Sensitivity analysis supports Invar for CTE > 43% Material Specs:Appendix D Home

  21. V R Pressure Reservoir ST Conceptual Representation Only Test Section Sidewall Home

  22. Test Section Material Selection • Test section cross section • Grey: Transparent windows • Green: Metal • Materials contract at different rates 190.4°R Not to Scale Home

  23. Test Section Material Selection • Specifics • k: Conductivity affects condensation • n: Refractive Index - visualization • % Visible - transparency • Hardness - scratch resistance • Assumed 120 sec of continuous Mach 2 flow • Conclusions • Sensitivity analysis shows Plexiglass and Glass ~50/50 Material Specs :Appendix D Home

  24. V R Pressure Reservoir ST Conceptual Representation Only Test Section / Nozzle Structure Home

  25. Test Section / Nozzle Structure • Requirement: 3 objects, 4 Mach numbers each • Test Section/Nozzle configuration • 4 Nozzles with 3 interchangeable test sections • 12 Fixed nozzle / test section combos • Less complex • Nozzle / Settling Tank Connection • Round nozzle w/ pipe threads • Slip connector • Flanges w/ clamps • Easy to use • Quick change out of nozzle Home

  26. Additional Requirements & Risks • Noise Constraints • EH&S guidelines • 85 dB • Ability to Troubleshoot • In the event of initial failure to achieve supersonic flow • Reservoir pressure and temperature measurements • Risks • Budget • Manufacturing • Safety Home

  27. Noise Ref [7] Ref [7] Home

  28. Troubleshooting Instrumentation • Settling Tank Thermocouple • Easily integrated with LabView • K type • NPT fitting for pressure vessels • Settling Tank Pressure Transducer • Commercially available • Compact • Easily integrated with LabView • 0 - 2000 psi • NPT fitting • Pitot TubeAppendix E Ref [8] Ref [9] Home

  29. Tunnel Risks Home

  30. Tunnel Risk • Liquid Nitrogen Heater (11/01) • Inadequate specifications • Thoroughly research heater options • Settling Tank Design and Thermal Fatigue (10/26) • Inadequate specifications and cost • Custom or in-house • Contact vendors and Matt Rhode • Cryogenic Valve (10/26) • Inadequate specifications • Continue dialog with AirGas vendor Home

  31. Visualization System Kendria Alt Josh Clement Home

  32. Visualization Decision Flowdown Home

  33. Schlieren, Shadowgraph, Interferometer Home

  34. Schlieren, Shadowgraph, Interferometer • Shadow Graph • 2nd derivative of density • Simplest method • Lower contrast • Schlieren • 1st derivative of density • Small increase in complexity • Increase in contrast • Interferometer • Density • Sum of path differences < λ/10th • Least familiarity Example Pictures: Appendix F Home Ref [1]

  35. Schlieren Layout Home

  36. Schlieren Layouts • Z • Precise angles prevent coma aberration • Large footprint • Double Pass • Nonparallel light in test section • Advantage of size • Straight Schlieren • Smaller focal length • Ease of integration Ref [2] Home

  37. Schlieren Layout • Specifics • Clarity: most important, verification • Size: must be able to fit on cart top • Stability: must be able to withstand movement without quality loss • Time to build: number of parts, complexity, and tolerances • Ease of design: depth of calculations • Conclusions • Straight setup has high accuracy and small footprint • Straight setup is easy to use and calibrate Home

  38. Visualization Decision Flowdown Home

  39. Lenses • Types • Focusing Lens • Different wavelengths have different focal lengths • Achromatic Lens • Reduces chromatic aberration • Dual lenses • Achromatic Objective Lens • Changes orientation of aberrations • Two lenses separated by air or oil • Expensive ~$500 to $1000 • Specifications • Diameter: 3 in • Focal Length: 0 to 6 in Home

  40. Refraction Detection Method Home

  41. Refraction Detection • Knife Edge • Clear black and white visualization • Vertical or horizontal placement show different details • Radial Color Filter • Density variations stand out • Linear Color Filter • Provides color and intensity differences for high and low densities Ref [14 ] Ref [15 ] Ref [16 ] Home

  42. Refraction Detection • Manual Three Axis Support • Easy calibration within 7.87 10-5 in • Calibration performed once per semester • Cost ~ $500 • Motorized Mounts • Expensive ~ $1000 • Accurate to 3.94 10-3 in • Interchange • Provide 3 filters for the 4 visualization methods • Filters mount on a 3-axis adjustable support Home

  43. Capture Method Home

  44. Capture Method • Specifics • Requirement: 2 fps • Resolution normalized to 3 Mega pixels • Frames per second normalized to 20 fps • Prices normalized to a $1500 camera • Conclusions • CMOS and CCD comparable • Final decision based on individual specifications Ref [18] Home

  45. File Transfer Method • Specifics • Speed normalized to 10 Mbytes/s • Cable cost includes max length and durability • Only USB and GPIB are immediately compatible with LS • FireWire cards $50 • Ethernet activation- $350 • Conclusions • The ideal file transfer method will be FireWire • Other constraints may require a less desirable method Home

  46. Camera Adjustability • 2-Axis Adjustability • Ability to focus 3rd dimension with camera • Ease of use • Locking • Commercial Mount • Expensive ~ $350 • Custom Mount • Complicated design • Intricate Fabrication Ref [12] Home

  47. Schlieren Base and Encasing Home

  48. Schlieren Base and Encasing • Base • Use the cart top • Use a metal foundation to secure optical components • Encasing • Plastic is light and inexpensive • Metal and wood heavy • Protection of lenses and camera • Students • Dust, scratches, etc. • Light tight during testing • Window for educational purpose • Opening for T.A.s to access instrumentation Home

  49. Visualization Risks Home

  50. Current Configuration Home