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An Experimental And Computational Investigation Of Oscillating Airfoil Unsteady Aerodynamics At Large Mean Incidence Nasa Cr 2003 212199
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Book Synopsis An Experimental and Computational Investigation of Oscillating Airfoil Unsteady Aerodynamics at Large Mean Incidence by :
Download or read book An Experimental and Computational Investigation of Oscillating Airfoil Unsteady Aerodynamics at Large Mean Incidence written by and published by DIANE Publishing. This book was released on 2003 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781726203241 Total Pages :42 pages Book Rating :4.2/5 (32 download)
Book Synopsis An Experimental and Computational Investigation of Oscillating Airfoil Unsteady Aerodynamics at Large Mean Incidence by : National Aeronautics and Space Administration (NASA)
Download or read book An Experimental and Computational Investigation of Oscillating Airfoil Unsteady Aerodynamics at Large Mean Incidence written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-27 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: A major challenge in the design and development of turbomachine airfoils for gas turbine engines is high cycle fatigue failures due to flutter and aerodynamically induced forced vibrations. In order to predict the aeroelastic response of gas turbine airfoils early in the design phase, accurate unsteady aerodynamic models are required. However, accurate predictions of flutter and forced vibration stress at all operating conditions have remained elusive. The overall objectives of this research program are to develop a transition model suitable for unsteady separated flow and quantify the effects of transition on airfoil steady and unsteady aerodynamics for attached and separated flow using this model. Furthermore, the capability of current state-of-the-art unsteady aerodynamic models to predict the oscillating airfoil response of compressor airfoils over a range of realistic reduced frequencies, Mach numbers, and loading levels will be evaluated through correlation with benchmark data. This comprehensive evaluation will assess the assumptions used in unsteady aerodynamic models. The results of this evaluation can be used to direct improvement of current models and the development of future models. The transition modeling effort will also make strides in improving predictions of steady flow performance of fan and compressor blades at off-design conditions. This report summarizes the progress and results obtained in the first year of this program. These include: installation and verification of the operation of the parallel version of TURBO; the grid generation and initiation of steady flow simulations of the NASA/Pratt&Whitney airfoil at a Mach number of 0.5 and chordal incidence angles of 0 and 10 deg.; and the investigation of the prediction of laminar separation bubbles on a NACA 0012 airfoil.Capece, Vincent R. and Platzer, Max F.Glenn Research CenterUNSTEADY AERODYNAMICS; TURBOMACHINERY; AIRFOILS; AEROELASTICITY; GAS TURBINE ENGINES; INCIDENCE; FORCED VIBRATION...
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781723047541 Total Pages :158 pages Book Rating :4.0/5 (475 download)
Book Synopsis Experimental and Computational Investigation of Lift-Enhancing Tabs on a Multi-Element Airfoil by : National Aeronautics and Space Administration (NASA)
Download or read book Experimental and Computational Investigation of Lift-Enhancing Tabs on a Multi-Element Airfoil written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-17 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental and computational investigation of the effect of lift-enhancing tabs on a two-element airfoil has been conducted. The objective of the study was to develop an understanding of the flow physics associated with lift-enhancing tabs on a multi-element airfoil. An NACA 63(2)-215 ModB airfoil with a 30% chord fowler flap was tested in the NASA Ames 7- by 10-Foot Wind Tunnel. Lift-enhancing tabs of various heights were tested on both the main element and the flap for a variety of flap riggings. A combination of tabs located at the main element and flap trailing edges increased the airfoil lift coefficient by 11% relative to the highest lift coefficient achieved by any baseline configuration at an angle of attack of 0 deg, and C(sub 1max) was increased by 3%. Computations of the flow over the two-element airfoil were performed using the two-dimensional incompressible Navier-Stokes code INS2D-UP. The computed results predicted all of the trends observed in the experimental data quite well. In addition, a simple analytic model based on potential flow was developed to provide a more detailed understanding of how lift-enhancing tabs work. The tabs were modeled by a point vortex at the air-foil or flap trailing edge. Sensitivity relationships were derived which provide a mathematical basis for explaining the effects of lift-enhancing tabs on a multi-element airfoil. Results of the modeling effort indicate that the dominant effects of the tabs on the pressure distribution of each element of the airfoil can be captured with a potential flow model for cases with no flow separation. Ashby, Dale L. Ames Research Center LIFT; AIRFOILS; TABS (CONTROL SURFACES); WIND TUNNEL TESTS; ANGLE OF ATTACK; NAVIER-STOKES EQUATION; COMPUTATIONAL FLUID DYNAMICS; GRID GENERATION (MATHEMATICS); AIRFOIL PROFILES; FLAPS (CONTROL SURFACES); TRAILING EDGES; INCOMPRESSIBLE FLOW; DATA CORRELATION; PREDICTION ANALYSIS TECHNIQUES; VORTICES; POTENTIAL FLOW; PRESSURE DISTRIBUTION; AERODYNAMIC C...
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781720448167 Total Pages :64 pages Book Rating :4.4/5 (481 download)
Book Synopsis Comparison of Theoretical and Experimental Unsteady Aerodynamics of Linear Oscillating Cascade with Supersonic Leading-Edge Locus by : National Aeronautics and Space Administration (NASA)
Download or read book Comparison of Theoretical and Experimental Unsteady Aerodynamics of Linear Oscillating Cascade with Supersonic Leading-Edge Locus written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-29 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental influence coefficient technique was used to obtain unsteady aerodynamic influence coefficients and, consequently, unsteady pressures for a cascade of symmetric airfoils oscillating in pitch about mid-chord. Stagger angles of 0 deg and 10 deg were investigated for a cascade with a gap-to-chord ratio of 0.417 operating at an axial Mach number of 1.9, resulting in a supersonic leading-edge locus. Reduced frequencies ranged from 0.056 to 0.2. The influence coefficients obtained determine the unsteady pressures for any interblade phase angle. The unsteady pressures were compared with those predicted by several algorithms for interblade phase angles of 0 deg and 180 deg.Ramsey, John K. and Erwin, DanGlenn Research CenterUNSTEADY AERODYNAMICS; INFLUENCE COEFFICIENT; PRESSURE MEASUREMENT; PRESSURE OSCILLATIONS; WIND TUNNEL TESTS; CASCADE FLOW; MACH NUMBER; SUPERSONIC FLUTTER; AIRFOIL OSCILLATIONS; PRESSURE DISTRIBUTION; SUPERSONIC WIND TUNNELS
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781721940967 Total Pages :228 pages Book Rating :4.9/5 (49 download)
Book Synopsis An Experimental Investigation of Unsteady Surface Pressure on an Airfoil in Turbulence by : National Aeronautics and Space Administration (NASA)
Download or read book An Experimental Investigation of Unsteady Surface Pressure on an Airfoil in Turbulence written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-27 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurements of fluctuating surface pressure were made on a NACA 0015 airfoil immersed in grid generated turbulence. The airfoil model has a 2 ft chord and spans the 6 ft Virginia Tech Stability Wind Tunnel test section. Two grids were used to investigate the effects of turbulence length scale on the surface pressure response. A large grid which produced turbulence with an integral scale 13% of the chord and a smaller grid which produced turbulence with an integral scale 1.3% of the chord. Measurements were performed at angles of attack, alpha from 0 to 20 . An array of microphones mounted subsurface was used to measure the unsteady surface pressure. The goal of this measurement was to characterize the effects of angle of attack on the inviscid response. Lift spectra calculated from pressure measurements at each angle of attack revealed two distinct interaction regions; for omega(sub r) = omega b / U(sub infinity) is less than 10 a reduction in unsteady lift of up to 7 decibels (dB) occurs while an increase occurs for omega(sub r) is greater than 10 as the angle of attack is increased. The reduction in unsteady lift at low omega(sub r) with increasing angle of attack is a result that has never before been shown either experimentally or theoretically. The source of the reduction in lift spectral level appears to be closely related to the distortion of inflow turbulence based on analysis of surface pressure spanwise correlation length scales. Furthermore, while the distortion of the inflow appears to be critical in this experiment, this effect does not seem to be significant in larger integral scale (relative to the chord) flows based on the previous experimental work of McKeough suggesting the airfoils size relative to the inflow integral scale is critical in defining how the airfoil will respond under variation of angle of attack. A prediction scheme is developed that correctly accounts for the effects of distortion when the inflow integral scale is small relative t
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722107598 Total Pages :34 pages Book Rating :4.1/5 (75 download)
Book Synopsis Comparison of Computational and Experimental Results for a Supercritical Airfoil by : National Aeronautics and Space Administration (NASA)
Download or read book Comparison of Computational and Experimental Results for a Supercritical Airfoil written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-08-20 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: A computational investigation was performed to study the flow over a supercritical airfoil model. Solutions were obtained for steady-state transonic flow conditions using a thin-layer Navier-Stokes flow solver. The results from this computational study were compared with time-averaged experimental data obtained over a wide Reynolds number range at transonic speeds in the Langley 0.3-Meter Transonic Cryogenic Tunnel. Comparisons were made at a nominal Mach number of 0.72 and at Reynolds numbers ranging from 6 x 10(exp 6) to 35 x 10(exp 6). Rivers, Melissa B. and Wahls, Richard A. Langley Research Center RTOP 505-59-10-31...
Book Synopsis Analysis of Low-Speed Unsteady Airfoil Flows by : Tuncer Cebeci
Download or read book Analysis of Low-Speed Unsteady Airfoil Flows written by Tuncer Cebeci and published by Springer. This book was released on 2009-09-02 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: The standard textbooks on aerodynamics usually omit any discussion of un steady aerodynamics or, at most, consider it only in a single chapter, based on two justifications. The first is that unsteady aerodynamics should be regarded as a specialized subject required "only" in connection with understanding and an alyzing aeroelastic phenomena such as flutter and gust response, and therefore should be dealt with in related specialist books. The second reason appears to be reluctance to discuss aerodynamics with the inclusion of the time-dependent terms in the conservation equations and the boundary conditions for fear that added complications may discourage the reader. We take the opposite view in this book and argue that a full understanding of the physics of lift generation is possible only by considering the unsteady aerody namics of the starting vortex generation process. Furthermore, certain "steady" flows are inherently unsteady in the presence of flow separation, as for example the unsteady flow caused by the Karman vortex shedding downstream of a cylin der and "static" airfoil stall which is an inherently unsteady flow phenomenon. Therefore, it stands to reason that a unified treatment of aerodynamics that yields steady-state aerodynamics as a special case offers advantages. This rea soning is strengthened by the developments in computational fluid dynamics over the past forty years, which showed that accurate steady-state solutions can be obtained efficiently by solving the unsteady flow equations.
Book Synopsis Analysis of Low-speed Unsteady Airfoil Flows by :
Download or read book Analysis of Low-speed Unsteady Airfoil Flows written by and published by Springer. This book was released on 2005 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an introduction to unsteady aerodynamics with emphasis on the analysis and computation of inviscid and viscous two-dimensional flows over airfoils at low speeds. It begins with a discussion of the physics of unsteady flows and an explanation of lift and thrust generation, airfoil flutter, gust response and dynamic stall. This is followed by an exposition of the four major calculation methods in currents use, namely inviscid-panel, boundary-layer, viscous-inviscid interaction and Navier-Stokes methods. Examples are provided to demonstrate the use of each method and panel and interactive boundary layer codes are included on the CD-ROM. Undergraduate and graduate students, teachers, scientists and engineers concerned with aeronautical, hydronautical and mechanical engineering problems will gain understanding of the physics of unsteady low-speed flows and an ability to analyze these flows with modern computational methods.
Book Synopsis The NASA Langley Laminar-flow-control Experiment on a Swept Supercritical Airfoil: Basic Results for Slotted Configuration by :
Download or read book The NASA Langley Laminar-flow-control Experiment on a Swept Supercritical Airfoil: Basic Results for Slotted Configuration written by and published by . This book was released on 1989 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781721147588 Total Pages :108 pages Book Rating :4.1/5 (475 download)
Book Synopsis Unsteady Aerodynamic Response of a Linear Cascade of Airfoils in Separated Flow by : National Aeronautics and Space Administration (NASA)
Download or read book Unsteady Aerodynamic Response of a Linear Cascade of Airfoils in Separated Flow written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-15 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: The overall objective of this research program was to investigate methods to modify the leading edge separation region, which could lead to an improvement in aeroelastic stability of advanced airfoil designs. The airfoil section used is representative of current low aspect ratio fan blade tip sections. The experimental potion of this study investigated separated zone boundary layer from removal through suction slots. Suction applied to a cavity in the vicinity of the separation onset point was found to be the most effective location. The computational study looked into the influence of front camber on flutter stability. To assess the influence of the change in airfoil shape on stability the work-per-cycle was evaluated for torsion mode oscillations. It was shown that the front camberline shape can be an important factor for stabilizing the predicted work-per-cycle and reducing the predicted extent of the separation zone. In addition, data analysis procedures are discussed for reducing data acquired in experiments that involve periodic unsteady data. This work was conducted in support of experiments being conducted in the NASA Glenn Research Center Transonic Flutter Cascade. The spectral block averaging method is presented. This method is shown to be able to account for variations in airfoil oscillation frequency that can occur in experiments that force oscillate the airfoils to simulate flutter. Capece, Vincent R. and Ford, Christopher and Bone, Christopher and Li, Rui Glenn Research Center NAG3-2695
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781724254054 Total Pages :30 pages Book Rating :4.2/5 (54 download)
Book Synopsis Calculation of Boundary Layers of Oscillating Airfoils by : National Aeronautics and Space Administration (NASA)
Download or read book Calculation of Boundary Layers of Oscillating Airfoils written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-25 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: A two-point finite difference unsteady laminar and turbulent boundary layer computational method was used to investigate the properties of the flow around an airfoil (NACA 0012) oscillating through angles of attack up to 18 degrees, for reduced frequencies of 0.01 and 0.20. The unsteady potential flow was determined using the unsteady potential flow method of Geissler. The influence of transition location on stal behavior was investigated, using both experimentally determined transition information, and transition located at the pressure peak; the results show the need for viscous-inviscid interaction in future computation of such flows. Cebeci, T. and Carr, L. W. Ames Research Center NASA-TM-85943, A-9599, NAS 1.15:85943, USAAVSCOM-TR-84-A-1 RTOP 505-31-32
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781723516009 Total Pages :412 pages Book Rating :4.5/5 (16 download)
Book Synopsis An Experimental Study of the Aerodynamics of a Naca0012 Airfoil with a Simulated Glaze Ice Accretion, Volume 2 by : National Aeronautics and Space Administration (NASA)
Download or read book An Experimental Study of the Aerodynamics of a Naca0012 Airfoil with a Simulated Glaze Ice Accretion, Volume 2 written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-23 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is the second volume of a report documenting the effect of simulated ice accretion on the aerodynamic performance of a NACA 0012 airfoil. Both an experimentally measured and a computer generated ice shape are studied. The purpose of this report is to present the results of the measurements, not an analysis of the data. Surface pressure, integrated lift and pitching moment data are presented as well as drag from a wake survey. A split hot film probe was used to document the flow-field about the airfoil with simulated ice. Data in the separation bubbles, reattached boundary layer and wake are presented. Both tabulated and graphical data are presented in the paper. The data are also available on computer disk for easy access. Bragg, Michael B. Unspecified Center NASA-CR-191007, E-7690, NAS 1.26:191007 NAS3-28; RTOP 505-68-10...
Book Synopsis Transonic Unsteady Aerodynamics and Aeroelasticity, 1987 by :
Download or read book Transonic Unsteady Aerodynamics and Aeroelasticity, 1987 written by and published by . This book was released on 1989 with total page 684 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722365943 Total Pages :70 pages Book Rating :4.3/5 (659 download)
Book Synopsis Effect of an Extendable Slat on the Stall Behavior of a Vr-12 Airfoil by : National Aeronautics and Space Administration (NASA)
Download or read book Effect of an Extendable Slat on the Stall Behavior of a Vr-12 Airfoil written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-06 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experimental and computational tests were performed on a VR-12 airfoil to determine if the dynamic-stall behavior that normally accompanies high-angle pitch oscillations could be modified by segmenting the forward portion of the airfoil and extending it ahead of the main element. In the extended position the configuration would appear as an airfoil with a leading-edge slat, and in the retracted position it would appear as a conventional VR-12 airfoil. The calculations were obtained from a numerical code that models the vorticity transport equation for an incompressible fluid. These results were compared with test data from the water tunnel facility of the Aeroflightdynamics Directorate at Ames Research Center. Steady and unsteady flows around both airfoils were examined at angles of attack between 0 and 30 deg. The Reynolds number was fixed at 200,000 and the unsteady pitch oscillations followed a sinusoidal motion described by alpha = alpha(sub m) + 10 deg sin(omega t). The mean angle (alpha(sub m)) was varied from 10 to 20 deg and the reduced frequency from 0.05 to 0.20. The results from the experiment and the calculations show that the extended-slat VR-12 airfoil experiences a delay in both static and dynamic stall not experienced by the basic VR-12 airfoil. Dehugues, P. Plantin and Mcalister, K. W. and Tung, C. Ames Research Center...
Book Synopsis Effect of Ground Proximity on the Aerodynamic Characteristics of Aspect-ratio-1 Airfoils with and Without End Plates by : Arthur W. Carter
Download or read book Effect of Ground Proximity on the Aerodynamic Characteristics of Aspect-ratio-1 Airfoils with and Without End Plates written by Arthur W. Carter and published by . This book was released on 1961 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation has been made to determine the effect of ground proximity on the aerodynamic characteristics of aspect-ratio-1 airfoils. The investigation was made with the model moving over the water in a towing tank in order to eliminate the effects of wind-tunnel walls and of boundary layer on ground boards at small ground clearances. The results indicated that, as the ground was approached, the airfoils experienced an increase in lift-curve slope and a reduction in induced drag thus, lift-drag ratio was increased. As the ground was approached, the profile drag remained essentially constant for each airfoil. Near the ground, the addition of end plates to the airfoil resulted in a large increase in lift-drag ratio. The lift characteristics of the airfoils indicated stability of height at positive angles of attack and instability of height at negative angles; therefore, the operating range of angles of attack would be limited to positive values. At positive angles of attack, the static longitudinal stability was increased as the height above the ground was reduced. Comparison of the experimental data with Wieselsberger's ground-effect theory (NACA Technical Memorandum 77) indicated generally good agreement between experiment and theory for the airfoils without end plates.
Book Synopsis Low Reynolds Number Aerodynamics by : Thomas J. Mueller
Download or read book Low Reynolds Number Aerodynamics written by Thomas J. Mueller and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt: Current interest in a variety of low Reynolds number applications has focused attention on the design and evaluation of efficient airfoil sections at chord Reynolds numbers from about 100,000 to about 1,000,000. These applications include remotely piloted vehicles (RPVs) at high altitudes, sailplanes, ultra-light man-carrying/man powered aircraft, mini-RPVs at low altitudes and wind turbines/propellers. The purpose of this conference was to bring together those researchers who have been active in areas closely related to this subject. All of the papers presented are research type papers. Main topics are: Airfoil Design and Analysis, Computational Studies, Stability and Transition, Laminar Separation Bubble, Steady and Unsteady Wind Tunnel Experiments and Flight Experiments.
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722873516 Total Pages :42 pages Book Rating :4.8/5 (735 download)
Book Synopsis The NASA Langley Laminar-Flow-Control Experiment on a Swept, Supercritical Airfoil - Drag Equations by : National Aeronautics and Space Administration (NASA)
Download or read book The NASA Langley Laminar-Flow-Control Experiment on a Swept, Supercritical Airfoil - Drag Equations written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-13 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Langley Research Center has designed a swept, supercritical airfoil incorporating Laminar Flow Control for testing at transonic speeds. Analytical expressions have been developed and an evaluation made of the experimental section drag, composed of suction drag and wake drag, using theoretical design information and experimental data. The analysis shows that, although the sweep-induced boundary-layer crossflow influence on the wake drag is too large to be ignored and there is not a practical method for evaluating these crossflow effects on the experimental wake data, the conventional unswept 2-D wake-drag computation used in the reduction of the experimental data is at worst 10 percent too high. Brooks, Cuyler W., Jr. and Harris, Charles D. and Harvey, William D. Langley Research Center RTOP 505-60-31-03...
