uav research international “providing integrated consultation to mav project engineers at eglin...
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UAV Research InternationalUAV Research International““Providing integrated consultation to MAV project Providing integrated consultation to MAV project
engineers at Eglin AFB”engineers at Eglin AFB”
Chris McGrathChris McGrathNeil GrahamNeil Graham
Alex von OetingerAlex von OetingerJohn DascombJohn Dascomb
Sponsor :Sponsor :Dr. Gregg AbateDr. Gregg Abate
April 6, 2006April 6, 2006
OverviewOverview
Problem StatementProblem Statement Design SpecificationsDesign Specifications Design SolutionDesign Solution Scale Model Design/FabricationScale Model Design/Fabrication TestingTesting
Problem StatementProblem Statement
To design a means of characterizing MAV To design a means of characterizing MAV handling during flighthandling during flight
Test must be repeatableTest must be repeatable
Data must be collected to characterize the Data must be collected to characterize the MAVMAV
Project SpecificationsProject Specifications
Weight Weight 100 – 200 grams (g) 100 – 200 grams (g) Flight Speed Flight Speed 0 – 25 meters per second 0 – 25 meters per second
(m/s)(m/s) Exterior Material Exterior Material Carbon Fiber Composite Carbon Fiber Composite Wing Tip Length Wing Tip Length 15 – 30 centimeters 15 – 30 centimeters
(cm)(cm) MAV Flight Control MAV Flight Control Both 2 and 3 axis Both 2 and 3 axis Type of Thrust Type of Thrust Pusher, Puller, None Pusher, Puller, None
Design Selection:Design Selection:Free Flight Wind TunnelFree Flight Wind Tunnel
The free flight wind tunnel The free flight wind tunnel has been successfully has been successfully created before created before
Design is a conventional Design is a conventional wind tunnel with wind tunnel with unobstructed test sectionunobstructed test section
Relative velocity of MAV to Relative velocity of MAV to
the ground is zerothe ground is zero
MAV Handling:MAV Handling: Initial Set-up Initial Set-up
MAV Handling:MAV Handling:Reel and Restraint Set-upReel and Restraint Set-up
Wind Tunnel DesignWind Tunnel Design
In wind tunnel design In wind tunnel design Three properties are Three properties are most important to most important to consider:consider:
– Tunnel geometryTunnel geometry
– Flow qualityFlow quality
– Fan SelectionFan Selection
Wind Tunnel DesignWind Tunnel Design
Wind Tunnel Geometry:Wind Tunnel Geometry:Test section DimensionsTest section Dimensions
For the minimum analysis For the minimum analysis of the flight, the MAV of the flight, the MAV needs to move laterally or needs to move laterally or vertically twice its vertically twice its wingspan wingspan
Minimum cross section for Minimum cross section for 12” wingspan is 4.5 ft x 4.5 12” wingspan is 4.5 ft x 4.5 ftft
Allow ten feet for Allow ten feet for longitudinal motionlongitudinal motion
Wind Tunnel GeometryWind Tunnel Geometry
Wind Tunnel Geometry:Wind Tunnel Geometry:11stst Diffuser Diffuser
Expands the ducting from area of test Expands the ducting from area of test section to the area of the fansection to the area of the fan
Diffuser angle < 5Diffuser angle < 5° for laminar flow° for laminar flow
Wind Tunnel GeometryWind Tunnel Geometry
Wind Tunnel Design:Wind Tunnel Design:Turns 1 and 2Turns 1 and 2
Corner Vanes assist flow Corner Vanes assist flow around the 4 90 degree turnsaround the 4 90 degree turns
Corner Vanes improve Corner Vanes improve efficiency by decreasing efficiency by decreasing pressure losspressure loss
Even with vanes 61% of all Even with vanes 61% of all pressure loss occurs at the 1pressure loss occurs at the 1stst two turnstwo turns
Wind Tunnel GeometryWind Tunnel Geometry
Wind Tunnel Design:Wind Tunnel Design: Fan SelectionFan Selection
Fan selection based on volume flow rate Fan selection based on volume flow rate and static pressure loss in tunneland static pressure loss in tunnel
Volume flow rate at maximum of 25 m/s is Volume flow rate at maximum of 25 m/s is 100000 CFM100000 CFM
Total pressure loss in tunnel = 600 PaTotal pressure loss in tunnel = 600 Pa
Wind Tunnel Design:Wind Tunnel Design: Fan SelectionFan Selection
Howden Buffalo 54-26 series fan Howden Buffalo 54-26 series fan Fan has a 54 in diameter, and a 125 HP motor Fan has a 54 in diameter, and a 125 HP motor
Wind Tunnel Design:Wind Tunnel Design: Flow Quality Flow Quality
Motor housing Motor housing
Anti-swirl vanesAnti-swirl vanes
Wind Tunnel GeometryWind Tunnel Geometry
Wind Tunnel Geometry:Wind Tunnel Geometry: 22ndnd Diffuser, Turns 3 and 4 Diffuser, Turns 3 and 4
Diffuser increases area final area ratio of 6Diffuser increases area final area ratio of 6
Final area ratio is most important factor in tunnelFinal area ratio is most important factor in tunnel
Turning vanes keep flow as laminar as possibleTurning vanes keep flow as laminar as possible
Wind Tunnel GeometryWind Tunnel Geometry
Wind Tunnel Design:Wind Tunnel Design: Flow QualityFlow Quality
Honeycombs - remove Honeycombs - remove lateral components of lateral components of turbulenceturbulence
3 Screens – remove 3 Screens – remove axial components of axial components of turbulenceturbulence
Wind Tunnel Geometry:Wind Tunnel Geometry: Contraction ConeContraction Cone
Contraction cone Contraction cone quickly increases flow quickly increases flow velocityvelocity
When condensing, When condensing, flow will not separate flow will not separate like diffuserlike diffuser
Wind Tunnel Geometry :Wind Tunnel Geometry : Tunnel Geometry – Constrained tunnelTunnel Geometry – Constrained tunnel
Total tunnel length is 36.6 ftTotal tunnel length is 36.6 ft
InstrumentationInstrumentation
On-Board MeasurementOn-Board Measurement
Flow Quality MeasurementFlow Quality Measurement
Traversing SystemTraversing System
Data Collection SoftwareData Collection Software
Data Acquisition SystemData Acquisition System
On-Board Measurement On-Board Measurement
Kestrel AutopilotKestrel Autopilot– 16.65 grams (2” x 1.37” 16.65 grams (2” x 1.37”
x .47”)x .47”)– Three-axis rate gyrosThree-axis rate gyros– AccelerometersAccelerometers– Air pressure sensorsAir pressure sensors
Data Collection SoftwareData Collection Software
Virtual CockpitVirtual Cockpit
LabviewLabview
Cost AnalysisCost Analysis
Scale ModelScale Model
Too expensive to build the designed tunnelToo expensive to build the designed tunnel
Built a 1/12 scale model Built a 1/12 scale model
Physically test flow quality of full scale Physically test flow quality of full scale design to determine if free flight is feasibledesign to determine if free flight is feasible
Scale EffectsScale Effects
Scale model Reynolds number 1/12 that of full Scale model Reynolds number 1/12 that of full scale modelscale model
Use hot-wire Anemometer to measure velocity Use hot-wire Anemometer to measure velocity fluctuation though test sectionfluctuation though test section
Velocity is not dependent on Reynolds number, Velocity is not dependent on Reynolds number, scaling effects can be ignored for our testsscaling effects can be ignored for our tests
Scale ModelScale Model
Contraction ConeContraction Cone
Contraction ConeContraction Cone
Total Elapsed Time:Total Elapsed Time:
2 Hours2 Hours 20 Hours20 Hours
Contraction ConeContraction Cone
Total Elapsed Time: 41 HoursTotal Elapsed Time: 41 Hours
Contraction ConeContraction Cone
Joining MethodJoining Method
Turning VanesTurning Vanes
DiffusersDiffusers
Settling ChamberSettling Chamber
Fan Fan
Model ResultsModel Results
Manufacturing CompleteManufacturing Complete
TestingTesting– Initial correction of flow through turning vanesInitial correction of flow through turning vanes– Inconclusive analysis of tunnel due to lack of testing Inconclusive analysis of tunnel due to lack of testing
Potential TestingPotential Testing– Fine tune internal geometry Fine tune internal geometry – Correction of all Turning vanesCorrection of all Turning vanes– Measuring Pressure fluctuations through test sectionMeasuring Pressure fluctuations through test section
Problems Encountered Problems Encountered
Wait time on ordered partsWait time on ordered parts MSC acrylic sheetsMSC acrylic sheets McMaster-Carr fan orderMcMaster-Carr fan order
Fabrication of contraction coneFabrication of contraction cone
Testing Time Constraints Testing Time Constraints
Questions?Questions?