AerodynamicAerodynamic CharacteristicsCharacteristics ofof aa NACANACA 44124412 AirfoilAirfoil

Presented By: David Heffley Mentor: Dr. Van Treuren Scholar’s Day January 26, 2007 OverviewOverview

„ ObjectiveObjective „ TheoryTheory „ ApparatusApparatus „ ExperimentalExperimental ComparisonComparison „ ResultsResults „ SummarySummary „ RecommendationsRecommendations ObjectiveObjective

„ StudyStudy thethe liftlift andand dragdrag forcesforces onon aa NACANACA 44124412 airfoilairfoil „ ResolveResolve discrepancydiscrepancy inin windwind tunneltunnel datadata „ DevelopDevelop experimentalexperimental techniquestechniques forfor anan airfoilairfoil „ CompareCompare windwind tunneltunnel datadata „ ForceForce BalanceBalance toto PressurePressure DistributionDistribution „ BaylorBaylor datadata toto publishedpublished NACANACA datadata NACANACA 44124412 AirfoilAirfoil „ 4 digit code used to describe airfoil shapes „ 1st digit - maximum camber in percent chord „ 2nd digit - location of maximum camber along chord line (from leading edge) in tenths of chord „ 3rd and 4th digits - maximum thickness in percent chord „ NACA 4412 with a chord of 6” „ Max camber: 0.24” (4% x 6”) „ Location of max camber: 2.4” aft of leading edge (0.4 x 6”) z „ Max thickness: 0.72” (12% x 6”) Max thickness Mean camber line Max camber

Chord line Chord

x=0 x Leading edge

x=c Trailing edge TheoryTheory Lift,Lift, DragDrag andand AngleAngle ofof AttackAttack StallStall AngleAngle

Lift

V∞ α Drag Relative Wind

ρVc Momentum Reynolds Number = Re = = µ Viscous TheoryTheory

Direct Method (Force Balance) L D C = C = l 1 d 1 Relates lift and drag forces to the velocity ρV 2S ρV 2S 2 2

Pressure Distribution (Pressure Ported Airfoil) P − P C = Local Stat P Relates local pressure on an airfoil to the velocity PDyn y c y 1 x C = (C − C )d( ) C = (C − C )d( ) X ∫ PF PA Y ∫ PL PU y c 0 c − c

Cl = CY cosα − CX sinα Cd = CY sinα + C X cosα ExperimentalExperimental ApparatusApparatus BaylorBaylor UniversityUniversity WindWind TunnelTunnel

24” by 24” Test Section Test Range: 0 – 150 ft/s Open loop tunnel ExperimentalExperimental ApparatusApparatus

ForceForce BalanceBalance PressurePressure TappedTapped AirfoilAirfoil

Both NACA 4412 airfoils -8 to 20 Degrees 18 pressure ports are 24” wide with a 6” -18 to 20 Degrees chord length ExperimentalExperimental ComparisonComparison

NACA Baylor University

„ ReRe == 3,000,0003,000,000 „ ReRe == 150,000150,000 „ 5454 pressurepressure portsports „ 1818 pressurepressure portsports „ VariableVariable densitydensity windwind „ ConstantConstant densitydensity tunneltunnel windwind tunneltunnel „ 2424”” chordchord lengthlength „ 66”” chordchord lengthlength ResultsResults

„ StallStall angleangle „ 1111 degreesdegrees forfor 150,000150,000 ReRe (Baylor)(Baylor) „ 1515 degreesdegrees forfor 3,000,0003,000,000 ReRe (NACA)(NACA) „ LiftLift coefficientcoefficient agreesagrees withinwithin 2%2% ofof NACANACA publishedpublished datadata „ NoticeableNoticeable inaccuraciesinaccuracies inin dragdrag coefficientcoefficient datadata fromfrom thethe pressurepressure portedported airfoilairfoil „ DragDrag coefficientcoefficient isis ReRe dependentdependent AerodynamicAerodynamic CurvesCurves

LiftLift CurveCurve DragDrag CurveCurve

Cl Cd

Higher Re Curve

α Cl LiftLift CurveCurve

Cl v α

1.70 1.50 1.30 1.10 0.90 0.70 NACA Report 0.50 563 NACA Report 0.30 824 Force Balance 0.10 Coefficient Lift of Pressure -20 -16 -12 -8 -4-0.10 0 4 8 12 16 20 24 -0.30 -0.50 -0.70 -0.90 Angle of Attack (Degrees) LiftLift PressurePressure DistributionDistribution

10 degrees

CP vs. x/c

-4

-3

-2 Exp Lower Surface Exp Upper Surface P

C NACA 563 Lower Surface -1 NACA 563 Upper Surface

-0.1 0.1 0.3 0.5 0.7 0.9 1.1 0 x/c

1 DragDrag CurveCurve

CD v CL

0.045

0.04

0.035

0.03 NACA 563 0.025 NACA 824 0.02 Force Balance Pressure 0.015 Coefficient of Drag of Coefficient

0.01

0.005

0 -0.75 -0.25 0.25 0.75 1.25 Coefficient of Lift DragDrag PressurePressure DistributionDistribution

10 degrees

CP vs. y/c

-4

-3

-2 Exp Lower Surface Exp Upper Surface

P NACA 563 Lower Surface C NACA 563 Upper Surface -1

-0.04 -0.02 0 0.02 0.04 0.06 0.08 0.1 0.12 0 y/c

1 CCDD vs.vs. ReynoldsReynolds NumberNumber

Munson, B. R., Young, D. F., and Okiishi, T. H., 2006, Fundamentals of Fluid Mechanics SummarySummary

„ ObjectivesObjectives „ Study airflow over an airfoil „ Resolve discrepancy in previous wind tunnel data „ Compare wind tunnel data „ ResultsResults „ Stall angle is a function of the Reynolds number „ Lift coefficient relates closely to published data „ Insufficient pressure ports to accurately map the pressure distribution for drag coefficient „ Drag coefficient highly dependent on Reynolds number RecommendationsRecommendations

„ FurtherFurther experimentsexperiments „ NACANACA 00120012 (Double(Double thethe pressurepressure ports)ports) „ UtilizeUtilize BaylorBaylor’’ss 3D3D printerprinter „ DevelopDevelop liftlift andand dragdrag curvescurves forfor futurefuture experimentsexperiments toto referencereference QuestionsQuestions