Kanat kesitleri teorisi

The Theory of wing sections

Tez No: 66611
Yazar: İSMAİL SAMİ ÖZDEMİR
Danışmanlar: PROF. DR. AHMET NURİ YÜKSEL
Tez Türü: Yüksek Lisans
Konular: Uçak Mühendisliği, Aircraft Engineering
Anahtar Kelimeler: Belirtilmemiş.
Yıl: 1997
Dil: Türkçe
Üniversite: İstanbul Teknik Üniversitesi
Enstitü: Fen Bilimleri Enstitüsü
Ana Bilim Dalı: Uçak ve Uzay Mühendisliği Ana Bilim Dalı
Bilim Dalı: Uçak Mühendisligi Bilim Dalı
Sayfa Sayısı: 389

Özet

The gradual development of wing theory tended to isolate the wing section problem found from the effects of plan form and led to a more systematic experimental approach. The tests made at Göttingen during the furs World War contributed much to the development of modern types of wing sections. Up you about second World War, most wing sections in common use were derived from more or less direct extensions of the work at Göttingen. During this period many families of wing sections were tests in the laboratories of various countries but the work of NACA was outstanding. The NACA investigations were further systematised by separation of the effects of camber and thickness distributions and the experimental work was performed at higher Reynolds numbers than were generally obtained elsewhere. The wing sections now in common use either NACA sections or have been strongly influenced by the NACA investigation. For this reason, and because the NACA sections from the consistent families, detailed attention will be given only the modern NACA wing sections. The theories permit reasonably accurate calculations to be made of certain characteristics of wing sections but the simplifying assumptions made in the development of these theories limit their over-all applicability. For instance, the perfect fluid theories permit the pressure distribution to be calculated, provided that the effects of boundary-layer flow on the pressure distributions are small. Similarly the viscous theories permit the calculation of some of the boundary-layer conditions, provided that the pressure distribution is known. Obvious interaction between the viscous and potential flows are the relatively small affective changes of body shaped caused by the displacement thickness of the unseparated boundary layer and the seriously large changes caused by separations. None of the wing characteristics can be calculated with confidence if the flow is separated over an appreciable part of the surface. Under these circumstances, wing section characteristics used for design are obtained experimentally. Wind-tunnel investigations of wing characteristics were made before airplanes were successfully flown and still constitute an important phase of aerodynamic testing. Until recently wing characteristics were usually obtained from tests of models of finite aspect ratio. The development of wing theory led to idea of wing sections' characteristics that were derived from data obtained from tests of finite-aspect-ratio wings. These derived data were than used to predict the characteristic of wing of different plan forms. The systematic investigations in the NACA variable-density wind tunnel were examples of this type of investigations. This method of testing is hampered by the difficulties of obtaining full-scale values of Reynolds number and sufficiently low air stream turbulence to duplicate flight conditions properly without excessive cost with equipment and models. Other difficulties were experienced in properly correcting the data for the support tares and interference effects and in deriving the section characteristics from tests of models necessarily having varied span- load distributions and tip effects. To avoid some of these difficulties and to permit testing of models that are large relative to the size of the wind tunnel, two-dimensional testing equipment was built by the NACA. The NACA two-dimensional low-turbulence pressure tunnel provides facilities for testing wing sections in two dimensional flow at large Reynolds numbers in an air stream of very low turbulence approaching that of the atmosphere. The wing sections' data presented here were obtained from tests in this tunnel. There are some high lift devices on the wings. This auxiliary devices are essentially movable elements that permit the pilot to change the geometry and xxm

Özet (Çeviri)

aerodynamic characteristics of the wing sections to control the motion of airline or to improve the performance in some desired manner. The desire improve performance by increasing the wing loading while maintaining acceptable landing and take-off speeds led to the development of retractable devices to improve the maximum lift coefficient of wings without changing the characteristics for the cruising and high speed flight conditions. Some typical high-lift devices are plain flap, split flap, external airfoil flap, slotted flap, double-slotted flap and leading edge slat. In this study, some NACA airfoils that was given as an example are so appropriate for design problems and studies. XXIVThe gradual development of wing theory tended to isolate the wing section problem found from the effects of plan form and led to a more systematic experimental approach. The tests made at Göttingen during the furs World War contributed much to the development of modern types of wing sections. Up you about second World War, most wing sections in common use were derived from more or less direct extensions of the work at Göttingen. During this period many families of wing sections were tests in the laboratories of various countries but the work of NACA was outstanding. The NACA investigations were further systematised by separation of the effects of camber and thickness distributions and the experimental work was performed at higher Reynolds numbers than were generally obtained elsewhere. The wing sections now in common use either NACA sections or have been strongly influenced by the NACA investigation. For this reason, and because the NACA sections from the consistent families, detailed attention will be given only the modern NACA wing sections. The theories permit reasonably accurate calculations to be made of certain characteristics of wing sections but the simplifying assumptions made in the development of these theories limit their over-all applicability. For instance, the perfect fluid theories permit the pressure distribution to be calculated, provided that the effects of boundary-layer flow on the pressure distributions are small. Similarly the viscous theories permit the calculation of some of the boundary-layer conditions, provided that the pressure distribution is known. Obvious interaction between the viscous and potential flows are the relatively small affective changes of body shaped caused by the displacement thickness of the unseparated boundary layer and the seriously large changes caused by separations. None of the wing characteristics can be calculated with confidence if the flow is separated over an appreciable part of the surface. Under these circumstances, wing section characteristics used for design are obtained experimentally. Wind-tunnel investigations of wing characteristics were made before airplanes were successfully flown and still constitute an important phase of aerodynamic testing. Until recently wing characteristics were usually obtained from tests of models of finite aspect ratio. The development of wing theory led to idea of wing sections' characteristics that were derived from data obtained from tests of finite-aspect-ratio wings. These derived data were than used to predict the characteristic of wing of different plan forms. The systematic investigations in the NACA variable-density wind tunnel were examples of this type of investigations. This method of testing is hampered by the difficulties of obtaining full-scale values of Reynolds number and sufficiently low air stream turbulence to duplicate flight conditions properly without excessive cost with equipment and models. Other difficulties were experienced in properly correcting the data for the support tares and interference effects and in deriving the section characteristics from tests of models necessarily having varied span- load distributions and tip effects. To avoid some of these difficulties and to permit testing of models that are large relative to the size of the wind tunnel, two-dimensional testing equipment was built by the NACA. The NACA two-dimensional low-turbulence pressure tunnel provides facilities for testing wing sections in two dimensional flow at large Reynolds numbers in an air stream of very low turbulence approaching that of the atmosphere. The wing sections' data presented here were obtained from tests in this tunnel. There are some high lift devices on the wings. This auxiliary devices are essentially movable elements that permit the pilot to change the geometry and xxmaerodynamic characteristics of the wing sections to control the motion of airline or to improve the performance in some desired manner. The desire improve performance by increasing the wing loading while maintaining acceptable landing and take-off speeds led to the development of retractable devices to improve the maximum lift coefficient of wings without changing the characteristics for the cruising and high speed flight conditions. Some typical high-lift devices are plain flap, split flap, external airfoil flap, slotted flap, double-slotted flap and leading edge slat. In this study, some NACA airfoils that was given as an example are so appropriate for design problems and studies. XXIVThe gradual development of wing theory tended to isolate the wing section problem found from the effects of plan form and led to a more systematic experimental approach. The tests made at Göttingen during the furs World War contributed much to the development of modern types of wing sections. Up you about second World War, most wing sections in common use were derived from more or less direct extensions of the work at Göttingen. During this period many families of wing sections were tests in the laboratories of various countries but the work of NACA was outstanding. The NACA investigations were further systematised by separation of the effects of camber and thickness distributions and the experimental work was performed at higher Reynolds numbers than were generally obtained elsewhere. The wing sections now in common use either NACA sections or have been strongly influenced by the NACA investigation. For this reason, and because the NACA sections from the consistent families, detailed attention will be given only the modern NACA wing sections. The theories permit reasonably accurate calculations to be made of certain characteristics of wing sections but the simplifying assumptions made in the development of these theories limit their over-all applicability. For instance, the perfect fluid theories permit the pressure distribution to be calculated, provided that the effects of boundary-layer flow on the pressure distributions are small. Similarly the viscous theories permit the calculation of some of the boundary-layer conditions, provided that the pressure distribution is known. Obvious interaction between the viscous and potential flows are the relatively small affective changes of body shaped caused by the displacement thickness of the unseparated boundary layer and the seriously large changes caused by separations. None of the wing characteristics can be calculated with confidence if the flow is separated over an appreciable part of the surface. Under these circumstances, wing section characteristics used for design are obtained experimentally. Wind-tunnel investigations of wing characteristics were made before airplanes were successfully flown and still constitute an important phase of aerodynamic testing. Until recently wing characteristics were usually obtained from tests of models of finite aspect ratio. The development of wing theory led to idea of wing sections' characteristics that were derived from data obtained from tests of finite-aspect-ratio wings. These derived data were than used to predict the characteristic of wing of different plan forms. The systematic investigations in the NACA variable-density wind tunnel were examples of this type of investigations. This method of testing is hampered by the difficulties of obtaining full-scale values of Reynolds number and sufficiently low air stream turbulence to duplicate flight conditions properly without excessive cost with equipment and models. Other difficulties were experienced in properly correcting the data for the support tares and interference effects and in deriving the section characteristics from tests of models necessarily having varied span- load distributions and tip effects. To avoid some of these difficulties and to permit testing of models that are large relative to the size of the wind tunnel, two-dimensional testing equipment was built by the NACA. The NACA two-dimensional low-turbulence pressure tunnel provides facilities for testing wing sections in two dimensional flow at large Reynolds numbers in an air stream of very low turbulence approaching that of the atmosphere. The wing sections' data presented here were obtained from tests in this tunnel. There are some high lift devices on the wings. This auxiliary devices are essentially movable elements that permit the pilot to change the geometry and xxmaerodynamic characteristics of the wing sections to control the motion of airline or to improve the performance in some desired manner. The desire improve performance by increasing the wing loading while maintaining acceptable landing and take-off speeds led to the development of retractable devices to improve the maximum lift coefficient of wings without changing the characteristics for the cruising and high speed flight conditions. Some typical high-lift devices are plain flap, split flap, external airfoil flap, slotted flap, double-slotted flap and leading edge slat. In this study, some NACA airfoils that was given as an example are so appropriate for design problems and studies. XXIV

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