Supersonic Wind and Supersonic Wind and Imaging Flow Tunnel Imaging Flow Tunnel • Kendria Alt Kendria Alt • Joshua Clement Joshua Clement • Shannon Shannon Fortenberry Fortenberry • Katelynn Greer Katelynn Greer • David McNeill David McNeill • Charlie Murphy Charlie Murphy • Matthew Osborn Matthew Osborn • David Springer David Springer
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Supersonic Wind and Imaging Flow Tunnel Kendria AltKendria Alt Joshua ClementJoshua Clement Shannon FortenberryShannon Fortenberry Katelynn GreerKatelynn.
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Supersonic Wind and Supersonic Wind and Imaging Flow TunnelImaging Flow Tunnel
• Supersonic wind tunnel and flow Supersonic wind tunnel and flow visualization system visualization system
• Operable by engineering Operable by engineering undergraduatesundergraduates
• Mach 1.5 – 3 in 0.5 incrementsMach 1.5 – 3 in 0.5 increments• Mach ±0.05 accuracyMach ±0.05 accuracy
• Customer: Dr. Brian ArgrowCustomer: Dr. Brian Argrow
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BackgroundBackground
• Project attempted 6 years agoProject attempted 6 years ago– Failed due to choked flow before nozzleFailed due to choked flow before nozzle
• Commercially available supersonic wind Commercially available supersonic wind tunnelstunnels– Aerolab 1” x 1” with Schlieren and 4 modelsAerolab 1” x 1” with Schlieren and 4 models
• Commercially available Schlieren systemCommercially available Schlieren system– Focal length longer than cart topFocal length longer than cart top– Low qualityLow quality– Edmund OpticsEdmund Optics
•Steady State Run TimeSteady State Run Time– 5 sec5 sec
•Lab SessionLab Session– 12 runs at Mach 2 12 runs at Mach 2 without changing tankswithout changing tanks– 1 run in 30 min1 run in 30 min– Operable in Operable in temperatures of 20temperatures of 20oo - 80 - 80oo FF
•Size and WeightSize and Weight– Volume < 30” x 42” x Volume < 30” x 42” x 36”36”– Weight < 100 lbs/cart Weight < 100 lbs/cart toptop– 2 cart tops available2 cart tops available
•VisualizationVisualization– Used for Mach Used for Mach verificationverification– Must see aerodynamic Must see aerodynamic phenomena at front and phenomena at front and back of test objectback of test object
•Test SectionTest Section– Area ≥ 1” x 0.25”Area ≥ 1” x 0.25”– Test 3 objects at all Test 3 objects at all speedsspeeds
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Tunnel SystemTunnel System
Matt OsbornMatt OsbornDavid SpringerDavid Springer
• Too large of a compressor at Too large of a compressor at Mach 3Mach 3
• ComplicatedComplicated
Vacuum Reservoir
V
Nozzle
AtmosphereAtmosphere
Vacuum TunnelVacuum Tunnel (Appendix B)(Appendix B)
Not FeasibleNot Feasible
• Huge 21 ftHuge 21 ft33 required required• Need large vacuum pumpNeed large vacuum pump• Condensation and IcingCondensation and Icing
Pressure Reservoir
V
Nozzle
AtmosphereAtmosphere
Blowdown TunnelBlowdown Tunnel((Appendix B)Appendix B)
• Much smaller reservoir (high pressure)Much smaller reservoir (high pressure)• No condensation or icingNo condensation or icing• Commercial gas (no pumps)Commercial gas (no pumps)
• 48 Runs at Mach 248 Runs at Mach 2• Constant test section propertiesConstant test section properties
8 Tanks – 1 Regulator – Second Tank – 2 8 Tanks – 1 Regulator – Second Tank – 2 ValvesValves
• Second tankSecond tank– 4 cubic feet @ 1000 psi maximum4 cubic feet @ 1000 psi maximum– Can manufacture for ~ $700Can manufacture for ~ $700
• 12 Runs at Mach 212 Runs at Mach 2• Properties in test section changeProperties in test section change
Appendix C
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Tunnel Decisions
Steady State
Blowdown
Commercial Gas
Compressor
Oxygen
Air
Helium
Nitrogen
Gas Nitrogen
Liquid Nitrogen
Multiple Valves
1 ValveNo Flow Regulators
Flow Regulators
Direct
Second Tank
No Regulator
Regulator Between
Tanks
Vacuum
Gas Nitrogen
Liquid Nitrogen
Grade 705 Zirconium
InvarTitanium Beta
IIIK300 Nickle
Flange / Bolts Clamps
Slip Connector
Round Nozzle / Pipe
Threading
12 Nozzle / Test Sections
4 Nozzles and 3 Test Sections
Plexiglass Glass Polycarbonate
Liquid vs. Gaseous NitrogenLiquid vs. Gaseous Nitrogen
Pressure Reservoir
VR
ST
Conceptual Representation Only
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Liquid vs. Gaseous NitrogenLiquid vs. Gaseous Nitrogen
R
V
V
V
V
• Gaseous NitrogenGaseous Nitrogen– 8 Tanks – One Regulator – Two Gaseous Valves8 Tanks – One Regulator – Two Gaseous Valves– 8 Hoses and Manifold – Complicated ($$)8 Hoses and Manifold – Complicated ($$)
• Liquid NitrogenLiquid Nitrogen– 1 Tank –Cryogenic Valve – Heater Element – 1 Tank –Cryogenic Valve – Heater Element –
Gaseous ValveGaseous Valve– Hours of run timeHours of run time– 11,430.67 BTU/hr → $200 heater11,430.67 BTU/hr → $200 heater– Liquid Nitrogen available on campusLiquid Nitrogen available on campus– Thermal Fatigue on 2Thermal Fatigue on 2ndnd Tank Tank
• Currently not enough information to Currently not enough information to decidedecide– Parallel PathsParallel Paths– Drop Dead Date of Oct. 26Drop Dead Date of Oct. 26
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Tunnel Decisions
Steady State
Blowdown
Commercial Gas
Compressor
Oxygen
Air
Helium
Nitrogen
Gas Nitrogen
Liquid Nitrogen
Multiple Valves
1 ValveNo Flow Regulators
Flow Regulators
Direct
Second Tank
No Regulator
Regulator Between
Tanks
Plexiglass
Vacuum
Gas Nitrogen
Liquid Nitrogen
Glass Polycarbonate
Flange / Bolts Clamps
Slip Connector
Round Nozzle / Pipe
Threading
12 Nozzle / Test Sections
4 Nozzles and 3 Test Sections
Grade 705 Zirconium
InvarTitanium Beta III
K300 Nickle
Nozzle MaterialNozzle Material
Pressure Reservoir
VR
ST
Conceptual Representation Only
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Nozzle Material SelectionNozzle Material Selection
V∞
Not to Scale
•Temperature differences at throat and test section• Contraction differences modify Mach number
447.2°R
190.4°R
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Nozzle Material SelectionNozzle Material Selection
Ti-BetaIII
InvarK-300
NiGrade 705 Zr
Weight Score Score Score Score
CTE 60% 0.8 4.2 2.1 2.9
σ/ρ 20% 4.1 1.7 2.5 1.7
Cost 10% 2.1 1.3 3.7 2.9
Hard 10% 1.7 2.5 2.5 3.3
Total 100% 1.7 3.2 2.4 2.7
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
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Tunnel Decisions
Steady State
Blowdown
Commercial Gas
Compressor
Oxygen
Air
Helium
Nitrogen
Gas Nitrogen
Liquid Nitrogen
Multiple Valves
1 ValveNo Flow Regulators
Flow Regulators
Direct
Second Tank
No Regulator
Regulator Between
Tanks
Plexiglass
Vacuum
Gas Nitrogen
Liquid Nitrogen
Glass Polycarbonate
Flange / Bolts Clamps
Slip Connector
Round Nozzle / Pipe
Threading
12 Nozzle / Test Sections
4 Nozzles and 3 Test Sections
Grade 705 Zirconium
InvarTitanium Beta
IIIK300 Nickle
Test Section SidewallTest Section Sidewall
Pressure Reservoir
VR
ST
Conceptual Representation Only
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Test Section Material SelectionTest Section Material Selection
• Test section cross sectionTest section cross section
• Grey: Transparent windows Grey: Transparent windows
• Green: MetalGreen: Metal
• Materials contract at different Materials contract at different ratesrates
Not to Scale
190.4°R
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Test Section Material SelectionTest Section Material Selection
Glass Plexiglass Polycarbonate
Weight Score Score Score
k 20% 1.7 4.4 3.9
n 20% 5 2.2 2.8
CTE 15% 5.5 2.5 2
% Visible 15% 2.8 3.9 3.3
σ/ρ 15% 1.7 3.9 4.4
Cost 10% 3.1 3.9 3
Hard 5% 4.5 3.3 2.2
Total 100% 3.37 3.42 3.21
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
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Tunnel Decisions
Steady State
Blowdown
Commercial Gas
Compressor
Oxygen
Air
Helium
Nitrogen
Gas Nitrogen
Liquid Nitrogen
Multiple Valves
1 ValveNo Flow Regulators
Flow Regulators
Direct
Second Tank
No Regulator
Regulator Between
Tanks
Plexiglass
Vacuum
Gas Nitrogen
Liquid Nitrogen
Glass Polycarbonate
Flange / Bolts Clamps
Slip ConnectorRound Nozzle / Pipe Threading
12 Nozzle / Test Sections
4 Nozzles and 3 Test Sections
Grade 705 Zirconium
InvarTitanium Beta
IIIK300 Nickle
Test Section / Nozzle Test Section / Nozzle StructureStructure
Pressure Reservoir
VR
ST
Conceptual Representation Only
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Test Section / Nozzle Test Section / Nozzle StructureStructure
• Test Section/Nozzle configurationTest Section/Nozzle configuration– 4 Nozzles with 3 interchangeable test sections4 Nozzles with 3 interchangeable test sections– 12 Fixed nozzle / test section combos12 Fixed nozzle / test section combos
• Noise ConstraintsNoise Constraints– EH&S guidelinesEH&S guidelines– 85 dB85 dB
• Ability to TroubleshootAbility to Troubleshoot– In the event of initial failure to achieve supersonic In the event of initial failure to achieve supersonic
flowflow– Reservoir pressure and temperature Reservoir pressure and temperature
• Settling Tank Settling Tank ThermocoupleThermocouple– Easily integrated with LabViewEasily integrated with LabView– K typeK type– NPT fitting for pressure vesselsNPT fitting for pressure vessels
• Settling Tank Pressure Settling Tank Pressure TransducerTransducer– Commercially availableCommercially available– CompactCompact– Easily integrated with LabViewEasily integrated with LabView– 0 - 2000 psi0 - 2000 psi– NPT fittingNPT fitting
– Inadequate specificationsInadequate specifications– Thoroughly research heater optionsThoroughly research heater options
• Settling Tank Design and Thermal Fatigue (10/26)Settling Tank Design and Thermal Fatigue (10/26)– Inadequate specifications and costInadequate specifications and cost
• Custom or in-houseCustom or in-house– Contact vendors and Matt RhodeContact vendors and Matt Rhode
• Cryogenic Valve (10/26)Cryogenic Valve (10/26)– Inadequate specificationsInadequate specifications– Continue dialog with AirGas vendorContinue dialog with AirGas vendor
• Shadow GraphShadow Graph– 22ndnd derivative of density derivative of density– Simplest methodSimplest method– Lower contrastLower contrast
• SchlierenSchlieren– 11st st derivative of densityderivative of density– Small increase in complexitySmall increase in complexity– Increase in contrast Increase in contrast
• InterferometerInterferometer– DensityDensity– Sum of path differences < Sum of path differences < λλ
/10/10thth
– Least familiarityLeast familiarity
Example Pictures: Appendix F
Ref [1]Home
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Schlieren LayoutSchlieren Layout
VisualizationSystem
Interferometer
Shadowgraph
Achromatic Objective
Achromatic
Focusing
Fixed Lens
Mount
Double Pass
StraightSchlieren
Z
Horseshoe
Radial Color
Cart BaseStructure
AdjustableLens
Mount
Vertical Black and
White
Horizontal Black and
White
Linear Color
Metal Foundation
PlasticFoundation
CCD FILMCMOS
Commercial Mount
Manufactured Mount
2-Axis Adjustable
3-Axis Adjustable
Knife Edge / Filter
Interchange
Knife Edge Only
3-Axis Adjustable
2-Axis Adjustable
FireWire GPIB USB Ethernet
Plastic Encasing
Aluminum Encasing
Wooden Encasing
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Schlieren LayoutsSchlieren 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]
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Schlieren LayoutSchlieren Layout
Double Pass
ZHorsesho
eStraight
Weight ScoreScor
eScore Score
Clarity 35% 1 4 1 4
Size 20% 3 2 1 4
Setup 15% 3 1 2 4
Stability 10% 3 1.5 1.5 4
Cost 10% 4 2 2 2
Time to Build
5% 3 2 2 3
Ease of Design
5% 4 2 1 3
Total 100% 2.45 2.5 1.35 3.7
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
– Achromatic Objective LensAchromatic Objective Lens• Changes orientation of aberrationsChanges orientation of aberrations• Two lenses separated by air or oilTwo lenses separated by air or oil• Expensive ~$500 to $1000Expensive ~$500 to $1000
• SpecificationsSpecifications– Diameter: 3 inDiameter: 3 in– Focal Length: 0 to 6 inFocal Length: 0 to 6 in
– Clear black and white Clear black and white visualizationvisualization
– Vertical or horizontal Vertical or horizontal placement show different placement show different detailsdetails
• Radial Color FilterRadial Color Filter– Density variations stand Density variations stand
outout• Linear Color FilterLinear Color Filter
– Provides color and intensity Provides color and intensity differences for high and differences for high and low densitieslow densities
Ref [14 ]
Ref [15 ]
Ref [16 ]
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Refraction DetectionRefraction Detection
• Manual Three Axis SupportManual Three Axis Support– Easy calibration within 7.87 10Easy calibration within 7.87 10-5-5 in in– Calibration performed once per semesterCalibration performed once per semester– Cost ~ $500Cost ~ $500
• Motorized MountsMotorized Mounts– Expensive ~ $1000Expensive ~ $1000– Accurate to 3.94 10Accurate to 3.94 10-3-3 in in
• InterchangeInterchange– Provide 3 filters for the 4 visualization methodsProvide 3 filters for the 4 visualization methods– Filters mount on a 3-axis adjustable supportFilters mount on a 3-axis adjustable support
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Capture MethodCapture Method
VisualizationSystem
Interferometer
Shadowgraph
Achromatic Objective
Achromatic
Focusing
Fixed Lens
MountDouble Pass
StraightSchlieren
Z
Horseshoe
Radial Color
Cart BaseStructure
AdjustableLens
Mount
Vertical Black and
White
Horizontal Black and
White
Linear Color
Metal Foundation
PlasticFoundation
CCD FILMCMOS
Commercial Mount
Manufactured Mount
2-Axis Adjustable
3-Axis Adjustable
Knife Edge / Filter
Interchange
Knife Edge Only
3-Axis Adjustable
2-Axis Adjustable
FireWire GPIB USB Ethernet
Plastic Encasing
Aluminum Encasing
Wooden Encasing
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Capture MethodCapture Method
Film CMOS CCD
Weight Score Score Score
Frame/sec 30% 1 4.5 4.5
Remote Control 30% 0.5 4.75 4.75
Resolution 20% 5 2.5 2.5
Cost 20% 3.12 3.12 3.76
Total 100% 2.1 3.9 4.0
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]
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File Transfer MethodFile Transfer Method
USB GPIB FireWire Ethernet
Weight Score Score Score Score
LabStation Compatibility
30% 3.5 3.5 2 1
Cost 30% 3 2.5 3 1.5
LabView Compatibility
20% 2 2.5 5 0.5
Cable 10% 3 2.5 2 2.5
Speed 10% 2.5 1 5 1.5
Total 100% 3 2.55 3.2 1.25
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
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Camera AdjustabilityCamera Adjustability
• 2-Axis Adjustability2-Axis Adjustability – Ability to focus 3Ability to focus 3rdrd dimension with camera dimension with camera– Ease of useEase of use– LockingLocking
Schlieren Base and EncasingSchlieren Base and Encasing
VisualizationSystem
Interferometer
Shadowgraph
Achromatic Objective
Achromatic
Focusing
Fixed Lens
MountDouble Pass
StraightSchlieren
Z
Horseshoe
Radial Color
Cart BaseStructure
AdjustableLens
Mount
Vertical Black and
White
Horizontal Black and
White
Linear Color
Metal Foundation
PlasticFoundation
CCD FILMCMOS
Commercial Mount
Manufactured Mount
2-Axis Adjustable
3-Axis Adjustable
Knife Edge / Filter
Interchange
Knife Edge Only
3-Axis Adjustable
2-Axis Adjustable
FireWire GPIB USB Ethernet
Plastic Encasing
Aluminum Encasing
Wooden Encasing
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Schlieren Base and Schlieren Base and EncasingEncasing
• BaseBase– Use the cart topUse the cart top– Use a metal foundation to secure optical Use a metal foundation to secure optical
componentscomponents• EncasingEncasing
– Plastic is light and inexpensivePlastic is light and inexpensive• Metal and wood heavyMetal and wood heavy
– Protection of lenses and cameraProtection of lenses and camera • StudentsStudents• Dust, scratches, etc.Dust, scratches, etc.
– Light tight during testingLight tight during testing– Window for educational purposeWindow for educational purpose– Opening for T.A.s to access instrumentationOpening for T.A.s to access instrumentation
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Visualization RisksVisualization Risks
Consequence
5 Lenses
4 Internal Interference
Aberration
3 Optical Mounts Camera
2 External
Interference
1 Calibration Encasing
1 2 3 4 5
Likelihood
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Current ConfigurationCurrent Configuration
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Cost EstimatesCost EstimatesItem Qua Price Cost
Schlieren
Visualization System
CCD Camera PL-A781/2 1 1,583.00 1,583.00
Achromatic Objective Lenses 2 700.00 1,400.00
Optical Cell Mounts 3" 2 20.00 40.00
Knife Edge 1 10.00 10.00
Knife Edge Mount 1 295.00 295.00
Student Made Color Filter 2 10.00 20.00
Light source (straight filament) 1 4.99 4.99
Light mount with slit 1 10.00 10.00
Structure and Encasing
Aluminum Stock for machining mounts 1 9.19 9.19
Black Plexiglas sheet 12x12 (10 sheets) 1 46.90 46.90
Initial Total $7,534.87Contingency (25%) $1,883.72TOTALTOTAL$9,418.59$9,418.59Applying for UROP, EFF, Department and Dean’s Fund resources.
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Base DeliverablesBase Deliverables
Base: Base: $4000$4000
Consequence Consequence
2 Invar Nozzles / Test Sections2 Invar Nozzles / Test Sections Mach Accuracy not guaranteed at Mach Accuracy not guaranteed at all temperaturesall temperatures
Linkages for 1 tankLinkages for 1 tank Only 1 run tank, wastefulOnly 1 run tank, wasteful
1 Settling Tank1 Settling Tank
1 Manual Valve1 Manual Valve No one button start / stopNo one button start / stop
Tunnel Team Tunnel Team Responsibility BreakdownResponsibility Breakdown
Tunnel Team
Fluid
Structure
Aerodynamics
Nozzle / Test Section
Settling Tube
Dimensions
Object Placement
Velocity
Size
Straightening
Selection
Quantity
Phase
Transportation
Regulation
Heat Addition
Cost
Valves
Nozzle, TS, Settling Tube
AcousticEnclosure
Material
Thermal Contraction
Nozzle / Settling Tube Interface
Material
Support
Transfer Method
Transparency
Electronics
Storage Vessel
Tubing
Linkages
Massflow
Pressure / Temp.
Type
Acoustics
Diffuser
Pressure Capacity
Computer Interface
Fluid Heater
Settling TubeSensing
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Visualization Team Visualization Team Responsibility BreakdownResponsibility Breakdown
Visualization Team
Structures
Capture
Optics
Layout
Lens/Mirror
Filtration
Sensitivity
Size
Focal Length
Reflectivity
Size
Neccessity
Mirror Support
Protection
Purchase / Fabricate
Transparency
Pointing Accuracy
Camera / Knife Edge Support
Adjustment
Pointing Tolerance
Strength
Collapsibility
TS / Protection Interface
Purchase / Fabricate
Method
Electronics
Resolution
Frames / Sec
Cost
Transfer Rate
Camera Control
Light Source
Transfer Method
Sensitivity
Method
Aperture
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Semester ScheduleSemester Schedule
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Spring ScheduleSpring Schedule
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ReferencesReferences1.1. Merzkirch, Wolfgang. Merzkirch, Wolfgang. Flow VisualizationFlow Visualization. New York: . New York:
Academic P, 1974. 62-115. Academic P, 1974. 62-115. 2.2. Smits, A. J., and T. T. Lim. Smits, A. J., and T. T. Lim. Flow Visualization Techniques Flow Visualization Techniques
and Examplesand Examples. Covent Garden: Imperial College P, 2000. . Covent Garden: Imperial College P, 2000. 205-243205-243
3.3. Shevell, Richard S. Shevell, Richard S. Fundamentals of FlightFundamentals of Flight. 2nd ed. Upper . 2nd ed. Upper Saddle River: Prentice Hall, 1989Saddle River: Prentice Hall, 1989
5. RequirementsTunnel7. Tunnel Decision Flowdown9. Tunnel Configuration Alternatives10. Initial Analysis Conclusions12. Gas Selection15. Regulators vs. Second Tank17. Liquid vs. Gaseous Nitrogen19. Nozzle Material Selection (Diagram)20. Nozzle Material Selection (Trade Study)22. Test Section Material Selection (Diagram)23. Test Section Material Selection (Trade Study)25. Test Section/Nozzle Structure26. Additional Requirements & Risks27. Noise28. Troubleshooting Instrumentation29. Tunnel Risks (5x5)30. Tunnel Risk (Mitigations)
Visualization32. Visualization Decision Flowdown34. Schlieren, Shadowgraph, Interferometer36. Schlieren Layouts37. Schlieren Layout (Trade Study)39. Lenses41. Refraction Detection40. Refraction Detection44. Capture Method45. File Transfer Method46. Camera Adjustability48. Schlieren Base and Encasing49. Visualization Risks (5x5)50. Current Configuration
Budget51. Cost Estimates52. Base Deliverables53. Deliverable Upgrades
Team Management54. SWIFT Responsibility Breakdown55. Tunnel Team Responsibility Breakdown56. Visualization Team Responsibility Breakdown57. Semester Schedule58. Spring Schedule
Appendices62. Appendix A Trade Study Sensitivity Analysis63. Appendix B Assumptions and Key Equations64. Appendix B Steady State Tunnel67. Appendix B Vacuum Tunnel69. Appendix B Blowdown Tunnel74. Appendix C Gas Appendices77. Appendix D Material Selection 79. Appendix E Pitot Tube81. Appendix F Visualization Examples83. Appendix G Single Mirror Schlieren84. Appendix H Refraction Detection Focal Length Sensitivity86. Appendix I Measurement Feasibility87. Appendix J Future Consideration Nozzle
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Appendix AAppendix ATrade Study Sensitivity Trade Study Sensitivity
AnalysisAnalysis
Choice
1Choice
2Choice
3Choice
4
Weight Score Score Score Score
Criteria 1 60% 2 4 3 1
Criteria 2 20% 1 3 2 4
Criteria 3 10% 2 4 3 1
Criteria 4 10% 3 2 4 3
Total 100% 1.9 3.6 2.9 1.8
Analysis
• Sensitivity of weights, not scores
• Lower subjectivity in scores
• Varied weights and recalculated totals
• Investigated weight combinations that yielded different results
Conclusions
• Removed most subjectivity from trade studies
• Result often unchanged Home
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Appendix BAppendix BAssumptions and Key Assumptions and Key
EquationsEquations• AssumptionsAssumptions
(for the preliminary analysis only)(for the preliminary analysis only)
– Isentropic FlowIsentropic Flow– Ideal NozzleIdeal Nozzle– The Gas was Dry AirThe Gas was Dry Air
1120
2
11
ii
M 1
20
2
11
ii
Mp
p
20
2
11 i
iM
T
T
1/12
2
2
* 2
11
1
21
MMA
A
i
i
RTa
iii RTP
iii aMV
iiii AVm
Rslug
lbft 6006)(
Rslug
lbft 1718)(
-airc
-airR
p
condition streamX
condition stagnation
i
0
X
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Appendix B Appendix B Steady State TunnelSteady State Tunnel
• Axial CompressorAxial Compressor– Used in Jet EnginesUsed in Jet Engines– Expensive and ComplicatedExpensive and Complicated
• Centrifugal CompressorCentrifugal Compressor– TurbochargersTurbochargers– Common and Fairly CheepCommon and Fairly Cheep
Nozzle
AtmosphereAtmosphere
Compressor 1
20
2
11
ii
Mp
p
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Appendix B Appendix B Steady State Tunnel at Mach 2Steady State Tunnel at Mach 2
82.7100
atmatm T
T
p
pCPR
Observations
•Pressure Ratio
•7.82
•Test sec. temp. is room temperature
•518.7 ºR
•Energy required is relatively low
•31.1 kW
Need high compression ratio even at Mach 2. At Mach 3, would need a compression ratio of 36.73. Additionally, temperature in the test section is close to room temperature.
Appendix B Appendix B Steady State Tunnel at Mach 2Steady State Tunnel at Mach 2
Observations•Question:
Could stock parts from a turbocharger be used?
•Max Compression ~ 3•3 turbos at M=2•12 turbos at M=3
•Mass Flow much larger than needed.
•Cost•$300-1000 per unit
Conclusions
A steady state tunnel is not feasible to meet the requirements. Would need ideally 12 turbos, at Mach 3, in series to meet the mass flow, but the compression ratio probably decreases as p0 goes up.
Ref [4]Ref [5]
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Appendix B Appendix B Vacuum TunnelVacuum Tunnel
• Commonly used in Commonly used in SSWT applicationsSSWT applications
• Vacuum Reservoir must Vacuum Reservoir must be blow atm. pressure.be blow atm. pressure.
• Would to purchase Would to purchase vacuum tanks.vacuum tanks.– Not available from a Not available from a
vendor.vendor.Vacuum Reservoir
V
Nozzle
AtmosphereAtmosphere
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Appendix B Appendix B Vacuum Tunnel Mach 2Vacuum Tunnel Mach 2
Observations
•Tt = 288.2 ºR
•Condensation or ice in test section
•Need 21 cubic feet of tank volume for one 10 sec. run
•Need to buy and store
•Need vacuum pump to evacuate air
Conclusions
A vacuum tunnel is not feasible. A custom or multiple stock tanks would need to be purchased, none of which would meet storage requirements. Additional complexity in the vacuum pump, and condensation or icing in the flow tube.
A blowdown tunnel is feasible. Dried compressed gas eliminates icing in the tunnel. Renting tanks eliminates storage concerns and the need for a compressor.
*Not to Scale
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Appendix B Appendix B Blowdown Tunnel Static Blowdown Tunnel Static
PressurePressure
Observations
•Atm. pressure in test section
120
2
11
ii
Mp
p 20
2
11 i
iM
T
T
Observations
•Reservoir Temp. is Room Temp.
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Appendix B Appendix B Blowdown Tunnel Throat AreaBlowdown Tunnel Throat Area
1/12
2
2
* 2
11
1
21
MMA
A
i
i
Observations
This is a unit depth Area, since at any point the nozzle is 0.25 inches deep.
Observations
•Nozzle Tolerance if Mach tolerance is ±0.05
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Appendix B Appendix B Blowdown Tunnel Mass FlowBlowdown Tunnel Mass Flow
Observations
Mass flow increases with Test Section Area and Mach Number
QQaa Volume Flow Rate at Actual ConditionsVolume Flow Rate at Actual Conditions
QQss Volume Flow Rate at Standard ConditionsVolume Flow Rate at Standard Conditions
PPatm_satm_s Standard Absolute Atmospheric PressureStandard Absolute Atmospheric Pressure
PPatmatm Actual Absolute Atmospheric PressureActual Absolute Atmospheric Pressure
PPaa Actual Gage PressureActual Gage Pressure
TTaa Actual Absolute TemperatureActual Absolute Temperature
TTss Standard Absolute TemperatureStandard Absolute Temperature
Ref [11]
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Appendix CAppendix CNo Settling TankNo Settling Tank
•Assumptions•Adiabatic, Polytropic, Expansion
•Tank specs•8.5” diameter•50” height•2000 psi
•Venting straight from tank through nozzle and test section
2211 VPVP
•Conclusions•12 tanks for 12 runs of 6 sec at Mach 2 •Higher Pressure
•Increased structure•More expensive valves and linkages
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•Assumptions•Adiabatic, Polytropic, Expansion
•Tank Specs•8.5” diameter•50” height•2000 psi
Appendix CAppendix CSettling Tank OptimizationSettling Tank Optimization
2211 VPVP
•Conclusions•Settling tank: 4 ft3 at 450 psi for Mach 2 •8 tanks required for 12 runs at Mach 2•Pressure increases to 1000 psi (still 4 ft3) for Mach 3
Contours: Number of Tanks for 12 runs at Mach 2
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Appendix DAppendix DNozzle Material Selection Nozzle Material Selection
“Well, for example, suppose you place a 2-D wedge in the test section of your wind tunnel. With parallel light and good alignment you will see the wedge in silhouette and sharp lines representing the oblique shocks it generates, since the planar shocks will be aligned with the optical beam direction. Not so if you use non-parallel light: then the shocks (and all other flow features) will have an apparent ‘thickness’; although they are extremely thin in nature. This is so misleading that essentially no one ever does this in M>1 wind tunnel practice.”
• Thin boundary layerThin boundary layer• Worst case is ± .33 degreesWorst case is ± .33 degrees• High resolution camera is needed for High resolution camera is needed for