introduction to new theory of flight revealing the secret of flight
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INTRODUCTION TO NEW THEORY OF FLIGHT REVEALING THE SECRET OF FLIGHT. UNDERSTANDING WHY IT IS POSSIBLE TO FLY JOHAN HOFFMAN JOHAN JANSSON CLAES JOHNSON. WEB SITE: THE SECRET OF FLIGHT. http://secretofflight.wordpress.com/ MATHEMATICS FLUID MECHANICS COMPUTATION MEASUREMENT APPLICATIONS - PowerPoint PPT PresentationTRANSCRIPT
INTRODUCTION TO NEW THEORY OF FLIGHT
REVEALING
THE SECRET OF FLIGHT
UNDERSTANDING WHY IT IS POSSIBLE TO FLY
JOHAN HOFFMAN JOHAN JANSSON CLAES JOHNSON
WEB SITE: THE SECRET OF FLIGHT
http://secretofflight.wordpress.com/
• MATHEMATICS• FLUID MECHANICS• COMPUTATION• MEASUREMENT• APPLICATIONS• HISTORY
NEW THEORY SUBMITTED TO AIAA
• MAIN JOURNAL OF AERONAUTICS• NOW UNDER SCRUTINY OF EXPERTS• FOLLOW THE REVIEW PROCESS ON WEB SITE
• FIRST VERSION PRESENTED IN NORMAT 2009
OLD THEORY
• KUTTA-ZHUKOVSKY 1904• FATHERS OF MODERN AERONAUTICS
• PRANDTL 1904• FATHER OF MODERN FLUID MECHANICS
• KZP THEORY
SCIENTIFIC MATHEMATICAL THEORIES
FOR UNEDUCATED: 1. TRIVIAL AND CORRECT 2. TRIVIAL AND INCORRECT
FOR EDUCATED: 3. NON-TRIVIAL AND INCORRECT: OLD4. NON-TRIVIAL AND CORRECT: NEW
NEW THEORY
• PHYSICAL • MATHEMATICAL• CORRECT• DOES REVEAL THE SECRET• USEFUL
OLD THEORY
• UNPHYSICAL • UNMATHEMATICAL• INCORRECT• DOES NOT REVEAL THE SECRET• DANGEROUS
WHAT TO EXPLAIN: LIFT / DRAG =L/D = 10 - 70
AIRBUS L/D=20 GLIDER L/D=70
THE SECRET: L/D = 10 - 70
• SURPRISING• INGENIOUS • ELEGANT
• INCOMPRESSIBLE FLOW• SLIGHTLY VISCOUS FLOW
IS THEORY NEEDED?• BIRDS HAVE LEARNED TO FLY WITHOUT• THEORY OF FLIGHT• BUT IT TOOK 100 MILLION YEARS• FROM DINOSAUR TO ARCHAEOPETRYX
• HUMANS HAVE LEARNED TO FLY WITHOUT• THEORY OF FLIGHT• BUT IT TOOK 500 YEARS • FROM DA VINCI TO SUCCESS: GOSSAMER CONDOR 1978
• BECAUSE OF LACK OF THEORY!!
DA VINCI FLYING MACHINE 1500
GOSSAMER CONDOR 1978FIRST HUMAN POWERED FLIGHT
CONFESSIONS ABOUT OLD THEORY
NEW YORK TIMES 2003 (CHANG)
To those who fear flying, it is probably disconcerting that physicists and aeronautical engineers still passionately debate the fundamental issue underlying this endeavor: WHAT KEEPS PLANES IN THE AIR?
NASA LISTS INCORRECT THEORIES
• LONGER DISTANCE• SKIPPING STONE• VENTURI
• BUT NO THEORY CLAIMED TO BE CORRECT!!
• NASA DOES NOT SEEM TO KNOW WHAT KEEPS PLANES IN THE AIR!!
LONGER PATH THEORY INCORRECT
SKIPPING STONE THEORY: NEWTON
VENTURI THEORY: BERNOULLI
HOFFREN 2001 AIAA
• A SATISFACTORY THEORY OF LIFT IS STILL LACKING
• THERE IS A GENUINE NEED FOR ONE
WHAT KEEPS PLANES IN THE AIR?
• INCORRECT THEORY OK AS LONG AS YOU DON’T USE IT • NOT USEFUL
• NEW THEORY: CORRECT: USEFUL
WHY CORRECT THEORY ONLY 2009?
• COMPUTE TURBULENT SOLUTIONS OF • NAVIER-STOKES EQUATIONS + SLIP BC
• DIRECT SIMULATION WITHOUT TURBULENCE MODELING
• POSSIBLE WITH ~ 1 MILLION MESH POINTS
• COMPUTATION TELLS THE TRUTH • STUDY REVEALS THE SECRET
DRAG CAR COMPUTABLE
LIFT DRAG WING COMPUTABLE VELOCITY PRESSURE
PRESSURE DISTRIBUTION C_PUPPER LOWER SURFACE
LIFT DRAG OF WING COMPUTABLE MAX L = 1.5 L/D = 50 AOA = 16
TO UNDERSTAND: STABILITY
• STABILITY - INSTABILITY OF FLUID MOTION
• STABLE COMPUTABLE ASPECTS OF TURBULENT FLOW
• LIFT DRAG MOMENTS..: COMPUTABLE• ALL YOU MAY WANT TO KNOW: COMPUTABLE
OPPOSING FLOW INSTABILITY
STABLE ATTACHMENTUNSTABLE SEPARATION:
OPPOSING FLOW
FROM CYLINDER TO AIRFOIL: ROUNDED LEADING + TRAILING EDGE
UNDERST CYL = UNDERSTAND AIRFOIL
SHORT STORY: THEORIES OF FLIGHT
• NEWTON 17H MATH: IMPOSSIBLE: WRONG• D’ALEMBERT 18TH MATH: IMPOSSIBLE: WRONG
• WRIGHT BROTHERS 1903 REAL EXP : POSSIBLE• KUTTA-ZHUKOVSKY 1904 MATH: POSSIBLE:
WRONG: OLD THEORY OF FLIGHT
• HOFFMAN-JOHNSON 2009 MATH: POSSIBLE: RIGHT: NEW THEORY OF FLIGHT
NEW VS OLD THEORY
• NEW THEORY REVEALS THE SECRET OF FLIGHT• OLD THEORY HIDES THE SECRET OF FLIGHT
• OLD: RULING PARADIGM• OLD: NOT FUNCTIONAL• NEW INCOMPATIBLE WITH OLD• SCIENTIFIC REVOLUTION A LA KUHN
LIFT AND DRAG OF LONG WING
• SUCTION ON UPPER LEADING EDGE/SURFACE:• LIFT + NEGATIVE DRAG
• PUSH ON LOWER LEADING EDGE/SURFACE:• LIFT + POSITIVE DRAG
• FLOW SEPARATES AT TRAILING EDGE WITHOUT PRESSURE RISE/DROP: ELEGANT SEPARATION
AIRFOIL – AIRPLANE WING
OBSERVATION WIND TUNNEL
OBSERVATION: 2D SECTION OF 3D
OBSERVATION
LIFT • UPPER LEADING EDGE SUCTION• LOWER LEADING EDGE PUSH
DRAG• LEADING EDGE PUSH/SUCTION
• SEPARATION WITHOUT PRESSURE RISE/DROP• DOWNWASH
RECALL C_P UPPER LOWER
NAVIER-STOKES
PRESSURE AOA = 5
VELOCITY AOA = 10
VELOCITY AOA = 10
VELOCITY AOA = 15
UNDERSTANDING: THEORY
• MATHEMATICAL MODEL OF PHYSICS• ASSUMPTIONS
MATHEMATICAL MODEL = EQUATION:
1. NAVIER-STOKES + BC: GENERAL2. LAPLACE + BC: SPECIAL
• MATHEMATICAL THEORY: SOLVE EQUATION
LAPLACE EQN: POTENTIAL FLOW1. INCOMPRESSIBLE: CORRECT FOR SUBSONIC FLIGHT2. INVISCID - SMALL VISCOSITY: CORRECT3. SLIP BOUNDARY CONDITION: SMALL SKIN FRICTION: CORRECT
4. IRROTATIONAL?? NO VORTICES5. STATIONARY?? 6. 2D??
• V = GRADIENT OF HARMONIC FUNCTION• 2D FOR CYLINDER LONG WING
• 1 + 2 + 3 VALID!! EVERYWHERE!! NAVIER-STOKES• 4 + 5 +6 VALID?? SOMEWHERE BUT NOT EVERYWHERE!! LAPLACE??
1- 4 : LAPLACE’S EQN: POTENTIAL: HARMONIC FUNCTION + SLIP
LAPLACE VS NAVIER-STOKES
LAPLACE SIMPLIFIED VERSION OF NAVIER-STOKES
POTENTIAL SOLUTION:
• 2D• STATIONARY• IRROTATIONAL
• LAPLACE SOLUTIONS NOT TURBULENT• NAVIER-STOKES SOLUTIONS TURBULENT
CIRC CYLINDER: POTENTIAL FLOW:P = 0 P = 1 P = - 3
V = 1 V = 0 V = 2
POTENTIAL FLOW: BERNOULLI’S LAW
½ V2 + P = CONSTANT
• HIGH PRESSURE P – LOW VELOCITY V• LOW PRESSURE P – HIGH VELOCITY V
CIRC CYLINDER: POTENTIAL FLOW:ZERO LIFT + ZERO DRAG
(L/D = 3)
LIFT OF HALF CYLINDER
THEORY: POTENTIAL FLOW: D’ALEMBERT’S PARADOX 1752:
ZERO LIFT AND DRAG
POTENTIAL FLOW VS OBSERVATION
POTENTIAL FLOW• SEPARATION BEFORE TRAILING EDGE
• HIGH PRESSURE AT SEPARATION REQUIRED TO BRING FLOW TO STAGNATION
• NO DOWNWASH
• MATHEMATICAL SOLUTION• BUT NOT OBSERVED IN REALITY• UNPHYSICAL!! WHY??
WHAT’S WRONG WITH POTENTIAL FLOW??
D’ALEMBERT COULD NOT UNDERSTAND 1752
D’ALEMBERT’S PARADOX 1752
It seems to me that the theory (potential flow), developed in all possible rigor, gives, at least in several cases, a strictly vanishing resistance, a singular paradox which I leave to future Geometers to elucidate”.
WHAT’S WRONG WITH POTENTIAL FLOW??
EULER COULD NOT UNDERSTAND???? 18TH
POTENTIAL FLOW SOLVES EULER’S EQNS
WHAT’S WRONG WITH POTENTIAL FLOW??
LAPLACE COULD NOT UNDERSTAND???? 19TH
POTENTIAL FLOW SOLVES LAPLACE’S EQN
WHAT’S WRONG WITH POTENTIAL FLOW??
CAUCHY COULD NOT UNDERSTAND???? 19TH
MASTER OF HARMONIC FCNS
WHAT’S WRONG WITH POTENTIAL FLOW??
POISSON COULD NOT UNDERSTAND??? 19TH
NOBODY COULDUNDERSTAND
WILBUR + ORWILLE WRIGHT: FLYER DEC 17 1903
KUTTA-ZHUKOVSKY 1904
• SEPARATION AT TRAILING EDGE BY ADDING CIRCULATION
• LIFT BUT NO DRAG
FATHERS OF MODERN AERODYNAMICS
CIRCULATION: LIFT BUT NO DRAG
FATHER OF MODERN FLUID MECHANICS
LUDWIG PRANDTL 1904
• SLIP BOUNDARY CONDITION IS WRONG
• NO-SLIP IS RIGHT:• THIN BOUNDARY LAYER
• DRAG BUT NO LIFT
TURBULENT WAKE: DRAG BUT NO LIFT
INCORRECT + INCORRECT = CORRECT?
• (-1) x (-1) = 1• NO!!
• PRANDTL INCORRECT• KUTTA-ZHUKOVSKY INCORRECT
• WHAT IS THEN CORRECT?
RESOLUTION OF D’ALEMBERT’S PARADOX
• JOHAN HOFFMAN AND CLAES JOHNSON• J MATHEMATICAL FLUID MECHANICS 2008
• FINALLY AFTER 256 YEARS• SPIN-OFF: SECRET OF FLIGHT 2012
POTENTIAL FLOW: STABLE ATTACHMENT
UNSTABLE SEPARATION: OPPOSING FLOW
POTENTIAL FLOW SEPARATION INSTABILITY
TROUBLE: TRAILING EDGE• POTENTIAL FLOW SEPARATION: • UNPHYSICAL UNSTABLE: OPPOSING FLOW
• POTENTIAL FLOW ATTACHMENT: • PHYSICAL STABLE
• NON-POTENTIAL FLOW SEPARATION??
• 3D ROTATIONAL SEPARATION: PHYSICAL STABLE: AVOIDS OPPOSING FLOW
CIRC CYLINDER: POTENTIAL FLOW:P = 0 P = 1 P = - 3
V = 1 V = 0 V = 2 ZERO LIFT DRAG
CIRCULAR CYLINDER: 3D ROTATIONAL SEPARATION: LOW MEAN PRESSURE
3D ROTATIONAL SEPARATION
KUTTA-ZHUKOVSKY CIRCULATION THEORY VS NEW THEORY
STREAMWISE VORTICITY
3D SEPARATION AT TRAILING EDGE
• 3D ROTATIONAL SEPARATION: • WITHOUT PRESSURE RISE• WITHOUT PRESSURE DROP: WAKE
• ELEGANT SEPARATION
• PRESSURE RISE: • 2D IRROTATIONAL POTEN. FLOW SEPARATION• PRESSURE DROP: WAKE SEPARATION
THE SECRET
• POTENTIAL FLOW: • BEFORE SEPARATION
• NON-POTENTIAL AT SEPARATION:• 3D ROTATIONAL SLIP SEPARATION WITH POINT
STAGNATION
• 256 YEARS: 1752 - 2008 TO UNDERSTAND
FROM CYLINDER TO AIRFOIL: ROUNDED LEADING + TRAILING EDGE
UNDERST CYL = UNDERSTAND AIRFOIL
THE SECRET: L/D = 10
THE SECRET
• INCOMPRESSIBLE• SLIGHTLY VISCOUS FLOW
• POTENTIAL FLOW BEFORE SEPARATION• 3D TRAILING EDGE SEPARATION WITHOUT
PRESSURE RISE/DROP
SECRET OF FLIGHT
• HOW TO SEPARATE IN AN ELEGANT WAY:• WITHOUT PRESSURE RISE/DROP
• ENGAGEMENT: EASY• DIVORCE: DIFFICULT
• THE TRICK: ELEGANT DIVORCE
NEW THEORY: NEW WING DESIGNHUMPBACK WHALE LEADING EDGE
NEW THEORY: NEW DESIGNROUNDED TRAILING EDGE WIND TURBIN BLADE
THE SECRET OF FLIGHT WEB SITE
• FULL STORY• MATHEMATICS• PHYSICS• COMPUTATION• APPLICATIONS: SAILING, SWIMMING,….• BACKGROUND• HISTORY INCORRECT THEORY…