Dynamic Stall Measurements And Computations For A Vr 12 Airfoil With A Variable Droop Leading Edge PDF Download
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Author | : P. B. Martin |
Publisher | : BiblioGov |
Total Pages | : 22 |
Release | : 2013-08 |
Genre | : |
ISBN | : 9781289292850 |
Download Dynamic Stall Measurements and Computations for a Vr-12 Airfoil with a Variable Droop Leading Edge Book in PDF, ePub and Kindle
High density-altitude operations of helicopters with advanced performance and maneuver capabilities have lead to fundamental research on active high-lift system concepts for rotor blades. The requirement for this type of system was to improve the sectional lift-to-drag ratio by alleviating dynamic stall on the retreating blade while simultaneously reducing the transonic drag rise of the advancing blade. Both measured and computational results showed that a Variable Droop Leading Edge (VDLE) airfoil is a viable concept for application to a rotor high-lift system. Results are presented for a series of 2D compressible dynamic stall wind tunnel tests with supporting CFD results for selected test cases. These measurements and computations show a dramatic decrease in the drag and pitching moment associated with severe dynamic stall when the VDLE concept is applied to the Boeing VR-12 airfoil. Test results also show an elimination of the negative pitch damping observed in the baseline moment hysteresis curves.
Author | : Robert J Flemming |
Publisher | : SAE International |
Total Pages | : 122 |
Release | : 2015-04-16 |
Genre | : Technology & Engineering |
ISBN | : 0768081203 |
Download Ice Accretion and Icing Technology Book in PDF, ePub and Kindle
The effects of inflight atmospheric icing can be devastating to aircraft. Universities and industry have been hard at work to respond to the challenge of maintaining flight safety in all weather conditions. Proposed changes in the regulations for operation in icing conditions are sure to keep this type of research and development at its highest level. This is especially true for the effects of ice crystals in the atmosphere, and for the threat associated with supercooled large drop (SLD) icing. This collection of ten SAE International technical papers brings together vital contributions to the subject. Icing on aircraft surfaces would not be a problem if a material were discovered that prevented the freezing and accretion of supercooled drops. Many options that appeared to have promising icephobic properties have had serious shortfalls in durability. This title addresses, among other topics, the measurement techniques and the drop physics that apply to icing, certification for flight through ice crystal clouds and in supercooled large drops, improvements in predictive techniques, scaling methods, test facilities and techniques, and rotorcraft icing.
Author | : K. W. McAlister |
Publisher | : |
Total Pages | : 80 |
Release | : 1993 |
Genre | : Aerofoils |
ISBN | : |
Download Suppression of Dynamic Stall with a Leading-edge Slat on a VR-7 Airfoil Book in PDF, ePub and Kindle
Author | : National Aeronautics and Space Administration (NASA) |
Publisher | : Createspace Independent Publishing Platform |
Total Pages | : 70 |
Release | : 2018-07-06 |
Genre | : |
ISBN | : 9781722365943 |
Download Effect of an Extendable Slat on the Stall Behavior of a Vr-12 Airfoil Book in PDF, ePub and Kindle
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...
Author | : Gordon J. Leishman |
Publisher | : Cambridge University Press |
Total Pages | : 860 |
Release | : 2006-04-24 |
Genre | : Science |
ISBN | : 9780521858601 |
Download Principles of Helicopter Aerodynamics with CD Extra Book in PDF, ePub and Kindle
Written by an internationally recognized teacher and researcher, this book provides a thorough, modern treatment of the aerodynamic principles of helicopters and other rotating-wing vertical lift aircraft such as tilt rotors and autogiros. The text begins with a unique technical history of helicopter flight, and then covers basic methods of rotor aerodynamic analysis, and related issues associated with the performance of the helicopter and its aerodynamic design. It goes on to cover more advanced topics in helicopter aerodynamics, including airfoil flows, unsteady aerodynamics, dynamic stall, and rotor wakes, and rotor-airframe aerodynamic interactions, with final chapters on autogiros and advanced methods of helicopter aerodynamic analysis. Extensively illustrated throughout, each chapter includes a set of homework problems. Advanced undergraduate and graduate students, practising engineers, and researchers will welcome this thoroughly revised and updated text on rotating-wing aerodynamics.
Author | : P. Plantin De Hughes |
Publisher | : |
Total Pages | : 66 |
Release | : 1993 |
Genre | : Aerofoils |
ISBN | : |
Download Effect of an Extendable Slat on the Stall Behavior of a VR-12 Airfoil Book in PDF, ePub and Kindle
Experimental and computational tests were performed on a VR- 1 2 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 Aeroflight-dynamics Directorate at Ames Research Center. Steady and unsteady flows around both airfoils were examined at angles of attack between 0 deg and 30 deg. The Reynolds number was fixed at 200,000 and the unsteady pitch oscillations followed a sinusoidal motion described by alpha = alpha (m) + 10 deg sin(wt). The mean angle (alpha m)was varied from 10 deg 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-1 2 airfoil experiences a delay in both static and dynamic stall not experienced by the basic VR- 12 airfoil. Airfoil stall, Dynamic stall, Leading-edge slat, High-lift device.
Author | : Giovanni Berselli |
Publisher | : BoD – Books on Demand |
Total Pages | : 732 |
Release | : 2012-10-17 |
Genre | : Technology & Engineering |
ISBN | : 9535107984 |
Download Smart Actuation and Sensing Systems Book in PDF, ePub and Kindle
The objective of the present book, which tries to summarize in an edited format and in a fairly comprehensive manner, many of the recent technical research accomplishments in the area of Smart Actuators and Smart Sensors, is to combine researchers and scientists from different fields into a single virtual room. The book hence reflects the multicultural nature of the field and will allow the reader to taste and appreciate different points of view, different engineering methods and different tools that must be jointly considered when designing and realizing smart actuation and sensing systems.
Author | : |
Publisher | : |
Total Pages | : 630 |
Release | : 2005 |
Genre | : Aeronautics |
ISBN | : |
Download 43rd AIAA Aerospace Sciences Meeting & Exhibit Book in PDF, ePub and Kindle
Author | : National Aeronautics and Space Administration (NASA) |
Publisher | : Createspace Independent Publishing Platform |
Total Pages | : 76 |
Release | : 2018-07-16 |
Genre | : |
ISBN | : 9781722792268 |
Download Suppression of Dynamic Stall with a Leading-Edge Slat on a Vr-7 Airfoil Book in PDF, ePub and Kindle
The VR-7 airfoil was experimentally studied with and without a leading-edge slat at fixed angles of attack from 0 deg to 30 deg at Re = 200,000 and for unsteady pitching motions described by alpha equals alpha(sub m) + 10 deg(sin(wt)). The models were two dimensional, and the test was performed in a water tunnel at Ames Research Center. The unsteady conditions ranged over Re equals 100,000 to 250,000, k equals 0.001 to 0.2, and alpha(sub m) = 10 deg to 20 deg. Unsteady lift, drag, and pitching-moment measurements were obtained along with fluorescent-dye flow visualizations. The addition of the slat was found to delay the static-drag and static-moment stall by about 5 degrees and to eliminate completely the development of a dynamic-stall vortex during unsteady motions that reached angles as high as 25 degrees. In all of the unsteady cases studied, the slat caused a significant reduction in the force and moment hysteresis amplitudes. The reduced frequency was found to have the greatest effect on the results, whereas the Reynolds number had little effect on the behavior of either the basic or the slatted airfoil. The slat caused a slight drag penalty at low angles of attack, but generally increased the lift/drag ratio when averaged over the full cycle of oscillation. Mcalister, K. W. and Tung, C. Ames Research Center...
Author | : American Institute of Aeronautics and Astronautics |
Publisher | : |
Total Pages | : 958 |
Release | : 2006 |
Genre | : Aeronautics |
ISBN | : |
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