INTRODUCTION TO NEW THEORY OF FLIGHT REVEALING THE SECRET OF FLIGHT - PowerPoint PPT Presentation

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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

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  1. INTRODUCTION TONEW THEORY OF FLIGHTREVEALINGTHE SECRET OF FLIGHT UNDERSTANDING WHY IT IS POSSIBLE TO FLY JOHAN HOFFMAN JOHAN JANSSON CLAES JOHNSON

  2. WEB SITE: THE SECRET OF FLIGHT http://secretofflight.wordpress.com/ • MATHEMATICS • FLUID MECHANICS • COMPUTATION • MEASUREMENT • APPLICATIONS • HISTORY

  3. 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

  4. OLD THEORY • KUTTA-ZHUKOVSKY 1904 • FATHERS OF MODERN AERONAUTICS • PRANDTL 1904 • FATHER OF MODERN FLUID MECHANICS • KZP THEORY

  5. SCIENTIFIC MATHEMATICAL THEORIES FOR UNEDUCATED: 1. TRIVIAL AND CORRECT 2. TRIVIAL AND INCORRECT FOR EDUCATED: 3. NON-TRIVIAL AND INCORRECT: OLD 4. NON-TRIVIAL AND CORRECT: NEW

  6. NEW THEORY • PHYSICAL • MATHEMATICAL • CORRECT • DOES REVEAL THE SECRET • USEFUL

  7. OLD THEORY • UNPHYSICAL • UNMATHEMATICAL • INCORRECT • DOES NOT REVEAL THE SECRET • DANGEROUS

  8. WHAT TO EXPLAIN: LIFT / DRAG =L/D = 10 - 70AIRBUS L/D=20 GLIDER L/D=70

  9. THE SECRET: L/D = 10 - 70 • SURPRISING • INGENIOUS • ELEGANT • INCOMPRESSIBLE FLOW • SLIGHTLY VISCOUS FLOW

  10. 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!!

  11. DA VINCI FLYING MACHINE 1500

  12. GOSSAMER CONDOR 1978FIRST HUMAN POWERED FLIGHT

  13. CONFESSIONS ABOUT OLD THEORY

  14. 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?

  15. 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!!

  16. LONGER PATH THEORY INCORRECT

  17. SKIPPING STONE THEORY: NEWTON

  18. VENTURI THEORY: BERNOULLI

  19. HOFFREN 2001 AIAA • A SATISFACTORY THEORY OF LIFT IS STILL LACKING • THERE IS A GENUINE NEED FOR ONE

  20. WHAT KEEPS PLANES IN THE AIR? • INCORRECT THEORY OK AS LONG AS YOU DON’T USE IT • NOT USEFUL • NEW THEORY: CORRECT: USEFUL

  21. WHYCORRECT 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

  22. DRAG CAR COMPUTABLE

  23. LIFT DRAG WING COMPUTABLE VELOCITY PRESSURE

  24. PRESSURE DISTRIBUTION C_PUPPERLOWER SURFACE

  25. LIFT DRAG OF WING COMPUTABLE MAX L = 1.5 L/D = 50 AOA = 16

  26. 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

  27. OPPOSING FLOW INSTABILITY

  28. STABLE ATTACHMENTUNSTABLE SEPARATION: OPPOSING FLOW

  29. FROM CYLINDER TO AIRFOIL: ROUNDED LEADING + TRAILING EDGEUNDERST CYL = UNDERSTAND AIRFOIL

  30. 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

  31. 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

  32. 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

  33. AIRFOIL – AIRPLANE WING

  34. OBSERVATION WIND TUNNEL

  35. OBSERVATION: 2D SECTION OF 3D

  36. OBSERVATION LIFT • UPPER LEADING EDGE SUCTION • LOWER LEADING EDGE PUSH DRAG • LEADING EDGE PUSH/SUCTION • SEPARATION WITHOUT PRESSURE RISE/DROP • DOWNWASH

  37. RECALL C_P UPPERLOWER

  38. NAVIER-STOKES

  39. PRESSURE AOA = 5

  40. VELOCITY AOA = 10

  41. VELOCITY AOA = 10

  42. VELOCITY AOA = 15

  43. UNDERSTANDING: THEORY • MATHEMATICAL MODEL OF PHYSICS • ASSUMPTIONS MATHEMATICAL MODEL = EQUATION: • NAVIER-STOKES + BC: GENERAL • LAPLACE + BC: SPECIAL • MATHEMATICAL THEORY: SOLVE EQUATION

  44. LAPLACE EQN: POTENTIAL FLOW • INCOMPRESSIBLE: CORRECT FOR SUBSONIC FLIGHT • INVISCID - SMALL VISCOSITY: CORRECT • SLIP BOUNDARY CONDITION: SMALL SKIN FRICTION: CORRECT • IRROTATIONAL?? NO VORTICES • STATIONARY?? • 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??

  45. 1- 4 : LAPLACE’S EQN: POTENTIAL: HARMONIC FUNCTION + SLIP

  46. LAPLACE VS NAVIER-STOKES LAPLACE SIMPLIFIED VERSION OF NAVIER-STOKES POTENTIAL SOLUTION: • 2D • STATIONARY • IRROTATIONAL • LAPLACE SOLUTIONS NOT TURBULENT • NAVIER-STOKES SOLUTIONS TURBULENT

  47. CIRC CYLINDER: POTENTIAL FLOW:P = 0 P = 1 P = - 3 V = 1 V = 0 V = 2

  48. POTENTIAL FLOW: BERNOULLI’S LAW ½ V2 + P = CONSTANT • HIGH PRESSURE P – LOW VELOCITY V • LOW PRESSURE P – HIGH VELOCITY V

  49. CIRC CYLINDER: POTENTIAL FLOW:ZERO LIFT + ZERO DRAG(L/D = 3)

  50. LIFT OF HALF CYLINDER