Search results for: natural-laminar-flow-and-laminar-flow-control

Natural Laminar Flow and Laminar Flow Control

Author : R.W. Barnwell
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Research on laminar flow and its transition to turbulent flow has been an important part of fluid dynamics research during the last sixty years. Since transition impacts, in some way, every aspect of aircraft performance, this emphasis is not only understandable but should continue well into the future. The delay of transition through the use of a favorable pressure gradient by proper body shaping (natural laminar flow) or the use of a small amount of suction (laminar flow control) was recognized even in the early 1930s and rapidly became the foundation of much of the laminar flow research in the U.S. and abroad. As one would expect, there have been many approaches, both theoretical and experimental, employed to achieve the substantial progress made to date. Boundary layer stability theories have been formu lated and calibrated by a good deal of wind tunnel and flight experiments. New laminar now airfoils and wings have been designed and many have been employed in aircraft designs. While the early research was, of necessity, concerned with the design of subsonic aircraft interest has steadily moved to higher speeds including those appropriate to planetary entry. Clearly, there have been substantial advances in our understanding of transition physics and in the development and application of transition prediction methodolo gies to the design of aircraft.

Overview of Laminar Flow Control

Author : Ronald D. Joslin
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Research in Natural Laminar Flow and Laminar Flow Control Part 3

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Natural Laminar Flow and Laminar Flow Control

Author : R.W. Barnwell
File Size : 27.55 MB
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Research on laminar flow and its transition to turbulent flow has been an important part of fluid dynamics research during the last sixty years. Since transition impacts, in some way, every aspect of aircraft performance, this emphasis is not only understandable but should continue well into the future. The delay of transition through the use of a favorable pressure gradient by proper body shaping (natural laminar flow) or the use of a small amount of suction (laminar flow control) was recognized even in the early 1930s and rapidly became the foundation of much of the laminar flow research in the U.S. and abroad. As one would expect, there have been many approaches, both theoretical and experimental, employed to achieve the substantial progress made to date. Boundary layer stability theories have been formu lated and calibrated by a good deal of wind tunnel and flight experiments. New laminar now airfoils and wings have been designed and many have been employed in aircraft designs. While the early research was, of necessity, concerned with the design of subsonic aircraft interest has steadily moved to higher speeds including those appropriate to planetary entry. Clearly, there have been substantial advances in our understanding of transition physics and in the development and application of transition prediction methodolo gies to the design of aircraft.

Research in Natural Laminar Flow and Laminar Flow Control Part 2

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Research in Natural Laminar Flow and Laminar Flow Control Part 1

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Research in Natural Laminar Flow and Laminar flow Control

Author : United States. National Aeronautics and Space Administration
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Research in natural laminar flow and laminar flow control

Author : Jerry N. Hefner
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Application of Laminar Flow Control to Supersonic Transport Configurations

Author : National Aeronautics and Space Administration (NASA)
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The feasibility and impact of implementing a laminar flow control system on a supersonic transport configuration were investigated. A hybrid laminar flow control scheme consisting of suction controlled and natural laminar flow was developed for a double-delta type wing planform. The required suction flow rates were determined from boundary layer stability analyses using representative wing pressure distributions. A preliminary design of structural modifications needed to accommodate suction through a perforated titanium skin was carried out together with the ducting and systems needed to collect, compress and discharge the suction air. The benefits of reduced aerodynamic drag were weighed against the weight, volume and power requirement penalties of suction system installation in a mission performance and sizing program to assess the net benefits. The study showed a feasibility of achieving significant laminarization of the wing surface by use of a hybrid scheme, leading to an 8.2 percent reduction in the cruise drag. This resulted in an 8.5 percent reduction in the maximum takeoff weight and a 12 percent reduction in the fuel burn after the inclusion of the LFC system installation penalties. Several research needs were identified for a resolution of aerodynamics, structural and systems issues before these potential benefits could be realized in a practical system. Parikh, P. G. and Nagel, A. L. Unspecified Center AERODYNAMIC DRAG; BOUNDARY LAYER CONTROL; BOUNDARY LAYER STABILITY; LAMINAR BOUNDARY LAYER; PRESSURE DISTRIBUTION; SUPERSONIC TRANSPORTS; WING PLANFORMS; WINGS; AERODYNAMICS; DRAG REDUCTION; FLOW VELOCITY; LAMINAR FLOW; SUCTION; TAKEOFF; TITANIUM...

A Flight Test of Laminar Flow Control Leading edge Systems

Author : M. C. Fischer
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Fatigue Response of Perforated Titanium for Application in Laminar Flow Control

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NASA Technical Paper

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Government Reports Announcements Index

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Survey and Bibliography on Attainment of Laminar Flow Control in Air Using Pressure Gradient and Suction Volume 1

Author : Dennis M. Bushnell
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Recent Results in Laminar Turbulent Transition

Author : Siegfried Wagner
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The 24 papers presented at the international concluding colloquium of the German priority programme (DFG-Verbundschwerpunktprogramm) "Transition", held in April 2002 in Stuttgart. The unique and successful programme ran six years, starting April 1996, and was sponsored mainly by the Deutsche Forschungsgemeinschaft, DFG, but also by the Deutsches Zentrum für Luft-und Raumfahrt, DLR, the Physikalisch-Technische Bundesanstalt Braunschweig, PTB, and Airbus Deutschland. The papers summarise the results of the programme and cover transition mechanisms, transition prediction, transition control, natural transition and measurement techniques, transition - turbulence - separation, and visualisation issues. Three invited papers are devoted to mechanisms of turbulence production, to a general framework of stability, receptivity and control, and a forcing model for receptivity analysis. Almost every transition topic arising in subsonic and transonic flow is covered.

Optimal Design of Natural and Hybrid Laminar Flow Control on Wings

Author : Jan Oscar Pralits
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Scientific and Technical Aerospace Reports

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Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.

Pressure Distributions from Subsonic Tests of an Advanced Laminar flow control Wing with Leading and Trailing edge Flaps

Author : Zachary T. Applin
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The NASA Langley Laminar flow control Experiment on a Swept Supercritical Airfoil Evaluation of Initial Perforated Configuration

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Boundary Layer and Flow Control

Author : G. V. Lachmann
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Boundary Layer and Flow Control: Its Principles and Application, Volume 2 focuses on the layer of fluid in the immediate area of a bounding surface where the effects of viscosity are substantial. This book is organized into two main topics—boundary layer control for low drag, and shock-induced separation and its prevention by design and boundary layer control. It specifically discusses the nature of transition, effect of two-dimensional and isolated roughness on laminar flow, and progress in the design of low drag aerofoils. The onset of separation effects for aerofoils and wings, shock-induced separation for laminar boundary layers, and shock-induced separation for laminar boundary layers are also deliberated. This volume is recommended to physicists and specialists interested in boundary layer and flow control.