Download or read book In flight Receptivity Experiments on a 30 degree Swept wing Using Micron sized Discrete Roughness Elements written by Andrew L. Carpenter and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: One of the last remaining challenges preventing the laminarization of sweptwings is the control of unstable crossflow vortices. In low-disturbance environments the transition from laminar to turbulent flow on the swept-wing initially takes the path of receptivity, where surface roughness or disturbances in the environment introduce shortwavelength disturbances into the boundary layer. This is followed by development and linear growth of stationary crossflow vortices that modify the mean flow, changing the stability characteristics of the boundary layer. Finally, breakdown to turbulence occurs over a short length scale due to the high-frequency secondary instability. The receptivity mechanism is the least understood, yet holds the most promise for providing a laminar flow control strategy. Results of a 3-year flight test program focused on receptivity measurements and laminar flow control on a 30-degree swept-wing are presented. A swept-wing test article was mounted on the port wing of a Cessna O-2A aircraft and operated at a chord Reynolds number of 6.5 to 7.5 million. Spanwise-periodic, micronsized discrete roughness elements were applied at the leading edge of the swept-wing in order to excite the most unstable crossflow wavelength and promote early boundary layer transition. An infrared camera was used to detect boundary-layer transition due to changes in leading-edge roughness. Combined with the IR camera, a new technique of calibrating surface-mounted hotfilms was developed for making disturbance-amplitude measurements downstream of modulated roughness heights. This technique proved to be effective at measuring disturbance amplitudes and can be applied in future tests where instrumentation is limited. Furthermore, laminar flow control was performed with subcritically-spaced roughness. A 100% increase in the region of laminar flow was achieved for some of the conditions tested here.
Download or read book Seventh IUTAM Symposium on Laminar Turbulent Transition written by Philipp Schlatter and published by Springer Science & Business Media. This book was released on 2010-03-11 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt: The origins of turbulent ?ow and the transition from laminar to turbulent ?ow are the most important unsolved problems of ?uid mechanics and aerodynamics. - sides being a fundamental question of ?uid mechanics, there are numerous app- cations relying on information regarding transition location and the details of the subsequent turbulent ?ow. For example, the control of transition to turbulence is - pecially important in (1) skin-friction reduction of energy ef?cient aircraft, (2) the performance of heat exchangers and diffusers, (3) propulsion requirements for - personic aircraft, and (4) separation control. While considerable progress has been made in the science of laminar to turbulent transition over the last 30 years, the c- tinuing increase in computer power as well as new theoretical developments are now revolutionizing the area. It is now starting to be possible to move from simple 1D eigenvalue problems in canonical ?ows to global modes in complex ?ows, all - companied by accurate large-scale direct numerical simulations (DNS). Here, novel experimental techniques such as modern particle image velocimetry (PIV) also have an important role. Theoretically the in?uence of non-normality on the stability and transition is gaining importance, in particular for complex ?ows. At the same time the enigma of transition in the oldest ?ow investigated, Reynolds pipe ?ow tran- tion experiment, is regaining attention. Ideas from dynamical systems together with DNS and experiments are here giving us new insights.
Download or read book Issues in Aerospace and Defense Research and Application 2011 Edition written by and published by ScholarlyEditions. This book was released on 2012-01-09 with total page 385 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Aerospace and Defense Research and Application: 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Aerospace and Defense Research and Application. The editors have built Issues in Aerospace and Defense Research and Application: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Aerospace and Defense Research and Application in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Aerospace and Defense Research and Application: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
Download or read book Receptivity Studies on a Swept wing Model written by Matthew Jeffery Woodruff and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A series of flight tests was performed using a swept-wing model mounted on a Cessna O-2 aircraft. The crossflow waves on the airfoil were excited by pneumatic spanwise-periodic distributed roughness elements (DREs). The objective of the experiment was to determine the roughness receptivity i.e. the relationship between roughness height and the amplitude of the unstable crossflow wave. The local skin-friction variation was measured using an array of calibrated and temperature-compensated hotfilm sensors. The amplitudes of the disturbance shear stress were compared to the amplitudes of the DREs. It was found that there is a relationship between the shear stress and DRE amplitude that needs to be studied more before any definitely conclusions can be made. It was also found that the sensitivity of the crossflow to DREs is highly dependent on the freestream turbulence levels.
Download or read book Variable Sweep Transition Flight Experiment VSTFE parametric Pressure Distribution Boundary Layer Stability Study and Wing Glove Design Task written by and published by . This book was released on 1986 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Variable Sweep Transition Flight Experiment (VSTFE) was initiated to establish a boundary-layer transition data base for laminar flow wing design. For this experiment, full-span upper-surface gloves will be fitted to a variable sweep F-14 aircraft. The results of two initial tasks are documented: a parametric pressure distribution/boundary-layer stability study and the design of an upper-surface glove for Mach 0.8. The first task was conducted to provide a data base from which wing-glove pressure distributions could be selected for glove designs. Boundary-layer stability analyses were conducted on a set of pressure distributions for various wing sweep angles, Mach numbers, and Reynolds number in the range of those anticipated for the flight-test program. The design procedure for the Mach 0.8 glove is described, and boundary-layer stability calculations and pressure distributions are presented both at design and off-design conditions. Also included is the analysis of the clean-up glove (smoothed basic wing) that will be flight-tested initially and the analysis of a Mach 0.7 glove designed at the NASA Langley Research Center.
Download or read book Transition Flight Experiments on a Swept Wing with Suction written by D.V. Maddalon and published by . This book was released on 1989 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Laminar Flow Experiment in Flight on a Swept Wing A W 52 written by W.E. Gray and published by . This book was released on 1953 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Research Related to Variable Sweep Aircraft Development written by and published by . This book was released on 1981 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flight Testing of a Variable Sweep Wing Aircraft written by C. H. Meyer and published by . This book was released on 1963 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the late 1940's, it appeared that the capabilities of the catapult and arresting gear on existing carriers were becoming inadequate for the higher airplane weights and speeds which accompanied the introduction of turbojet-powered, swept-wing carrier-based aircraft. The U.S. Navy's approach to the problem encompassed two developments, the angled carrier deck in combination with the steam catapult and the Grumman XF10F-1 fighter with variable geometry wings for reduction of take-off and landing speeds. Although the XF10F-1 did not go into production because of certain other unsatisfactory design innovations, the wing, which could be swept in the air from 13 1/2 to 42 1/2 degrees, was shown to be operationally feasible and structurally practical. It also gave the expected reduction in aircraft take-off and landing speeds which could have offset carrier modifications. As aircraft size and performance continued to increase during the last decade, the problem of catapult capability versus carrier aircraft weight and speed again became apparent. This time, the TFX variable geometry wing aircraft was considered a more practical solution than further increasing the carrier catapult and arresting capabilities. (Author).
Download or read book Free flight Tests of 45 Degree Swept Wings of Aspect Ratio 3 15 and Taper Ratio 0 54 to Measure Wing Damping of the First Bending Mode and to Investigate the Possibility of Flutter at Transonic Speeds written by Burke R. O'Kelly and published by . This book was released on 1954 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Loadings on a 35 Degree Swept Wing Body Tested in an R A E Transonic Tunnel and Comparisions with Theoretical Results written by De Havilland Aircraft Company Ltd and published by . This book was released on 1963 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Swept Wing Tests at Supersonic Speeds written by P. R. Owen and published by . This book was released on 1950 with total page 2 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Flight Measurements of the Lift and Drag of a 40 Degree Swept Wing Aircraft modified Hunter Mk 1 with Blowing Over Plain Trailing Edge Flaps written by K.J. Staples and published by . This book was released on 1963 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Natural Laminar Flow and Laminar Flow Control written by R.W. Barnwell and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 415 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book The Aerodynamic Design of Aircraft written by Dietrich Küchemann and published by AIAA Education. This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dietrich Kuchemann's The Aerodynamic Design of Aircraft is as relevant and as forward looking today as it was when it was first published in 1978. It comprises the philosophy and life's work of a unique and visionary intellect. Based upon material taught in a course at Imperial College London, the insight and intuition conveyed by this text are timeless. With its republication, Kuchemann's influence will extend to the next generation of aerospace industry students and practitioners and the vehicles they will produce. Kuchemann establishes three classes of aircraft based on the character of flow involved. Each class is suitable for a distinct cruise speed regime: classical and swept aircraft for subsonic and transonic cruise, slender-wing aircraft for supersonic cruise, and wave-rider aircraft for hypersonic cruise. Unlike most engineering texts, which focus on a set of tools, Kuchemann's approach is to focus on the problem and its solution - what kind of flow is best for a given class of aircraft and how to achieve it.With this approach, Kuchemann fully embraces the true inverse nature of design; rather than answer what flow given the shape, he strives to answer what flow given the purpose and then what shape given the flow.
Download or read book Responding to Oil Spills in the U S Arctic Marine Environment written by National Research Council and published by National Academies Press. This book was released on 2014-08-01 with total page 343 pages. Available in PDF, EPUB and Kindle. Book excerpt: U.S. Arctic waters north of the Bering Strait and west of the Canadian border encompass a vast area that is usually ice covered for much of the year, but is increasingly experiencing longer periods and larger areas of open water due to climate change. Sparsely inhabited with a wide variety of ecosystems found nowhere else, this region is vulnerable to damage from human activities. As oil and gas, shipping, and tourism activities increase, the possibilities of an oil spill also increase. How can we best prepare to respond to such an event in this challenging environment? Responding to Oil Spills in the U.S. Arctic Marine Environment reviews the current state of the science regarding oil spill response and environmental assessment in the Arctic region north of the Bering Strait, with emphasis on the potential impacts in U.S. waters. This report describes the unique ecosystems and environment of the Arctic and makes recommendations to provide an effective response effort in these challenging conditions. According to Responding to Oil Spills in the U.S. Arctic Marine Environment, a full range of proven oil spill response technologies is needed in order to minimize the impacts on people and sensitive ecosystems. This report identifies key oil spill research priorities, critical data and monitoring needs, mitigation strategies, and important operational and logistical issues. The Arctic acts as an integrating, regulating, and mediating component of the physical, atmospheric and cryospheric systems that govern life on Earth. Not only does the Arctic serve as regulator of many of the Earth's large-scale systems and processes, but it is also an area where choices made have substantial impact on life and choices everywhere on planet Earth. This report's recommendations will assist environmentalists, industry, state and local policymakers, and anyone interested in the future of this special region to preserve and protect it from damaging oil spills.
Download or read book Boundary Layer Flows written by Vallampati Ramachandra Prasad and published by BoD – Books on Demand. This book was released on 2020-01-22 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: Written by experts in the field, this book, "Boundary Layer Flows - Theory, Applications, and Numerical Methods" provides readers with the opportunity to explore its theoretical and experimental studies and their importance to the nonlinear theory of boundary layer flows, the theory of heat and mass transfer, and the dynamics of fluid. With the theory's importance for a wide variety of applications, applied mathematicians, scientists, and engineers - especially those in fluid dynamics - along with engineers of aeronautics, will undoubtedly welcome this authoritative, up-to-date book.
