Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
Download Comparison Of Calculated And Measured Model Rotor Loading And Wake Geometry full books in PDF, epub, and Kindle. Read online Comparison Of Calculated And Measured Model Rotor Loading And Wake Geometry ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Author : Wayne Johnson
Publisher :
ISBN 13 :
Total Pages : 38 pages
Book Rating : 4.:/5 (317 download)
Download or read book Comparison of Calculated and Measured Model Rotor Loading and Wake Geometry written by Wayne Johnson and published by . This book was released on 1980 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : National Aeronautics and Space Adm Nasa
Publisher : Independently Published
ISBN 13 : 9781730900822
Total Pages : 70 pages
Book Rating : 4.9/5 (8 download)
Download or read book Wake Geometry Measurements and Analytical Calculations on a Small-Scale Rotor Model written by National Aeronautics and Space Adm Nasa and published by Independently Published. This book was released on 2018-11-05 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation was conducted in the Langley 14- by 22-Foot Subsonic Tunnel to quantify the rotor wake behind a scale model helicopter rotor in forward level flight at one thrust level. The rotor system in this test consisted of a four-bladed fully articulated hub with blades of rectangular planform and an NACA 0012 airfoil section. A laser light sheet, seeded with propylene glycol smoke, was used to visualize the vortex geometry in the flow in planes parallel and perpendicular to the free-stream flow. Quantitative measurements of wake geometric proper- ties, such as vortex location, vertical skew angle, and vortex particle void radius, were obtained as well as convective velocities for blade tip vortices. Comparisons were made between experimental data and four computational method predictions of experimental tip vortex locations, vortex vertical skew angles, and wake geometries. The results of these comparisons highlight difficulties of accurate wake geometry predictions. Ghee, Terence A. and Berry, John D. and Zori, Laith A. J. and Elliott, Joe W. Unspecified Center...
Author : S. Gene Sadler
Publisher :
ISBN 13 :
Total Pages : 132 pages
Book Rating : 4.:/5 (31 download)
Download or read book Development and Application of a Method for Predicting Rotor Free Wake Positions and Resulting Rotor Blade Air Loads written by S. Gene Sadler and published by . This book was released on 1971 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rotor wake geometries are predicted by a process similar to the startup of a rotor in a free stream. An array of discrete trailing and shed vortices is generated with vortex strengths corresponding to stepwise radial and azimuthal blade circulations. The array of shed and trailing vortices is limited to an arbitrary number of azimuthal steps behind each blade. The remainder of the wake model of each blade is an arbitrary number of trailing vortices. Vortex element end points were allowed to be transported by the resultant velocity of the free stream and vortex-induced velocities. Wake geometry, wake flow, and wake-induced velocity influence coefficients are generated by this program for use in the blade loads portion of the calculations. Blade loads computations include the effects of nonuniform inflow due to a free wake, nonlinear airfoil characteristics, and response of flexible blades to the applied loads. Computed wake flows and blade loads are compared with experimentally measured data. Predicted blade loads, response and shears and moments are obtained for a model rotor system having two independent rotors. The effects of advance ratio, vertical separation of rotors, different blade radius ratios, and different azimuthal spacing of the blades of one rotor with respect to the other are investigated.
Author :
Publisher :
ISBN 13 :
Total Pages : 38 pages
Book Rating : 4.:/5 (317 download)
Download or read book Finite Difference Modeling of Rotor Flows Including Wake Effects written by and published by . This book was released on 1982 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper gives a brief consideration of rotary wing finite difference methods. The main concern is the specification of boundary conditions to properly account for the effect of the wake on the blade. Examples are given of an approach where wake effects are introduced by specifying an equivalent angle of attack. An alternate approach is also given where discrete vortices are introduced into the finite difference grid. The resulting computations of hovering and high advance-ratio cases compare well with experiment. Some consideration is also given to the modeling of low-to-moderate advance-ratio flows. (Author).
Author :
Publisher :
ISBN 13 :
Total Pages : 44 pages
Book Rating : 4.:/5 (317 download)
Download or read book Comparison of Calculated and Measured Pressures on Straight and Swept-tip Model Rotor Blades written by and published by . This book was released on 1983 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 62 pages
Book Rating : 4.:/5 (317 download)
Download or read book Comparison of Calculated and Measured Helicopter Rotor Lateral Flapping Angles written by and published by . This book was released on 1980 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 13 pages
Book Rating : 4.:/5 (318 download)
Download or read book Airloads and Wake Geometry Calculations for an Isolated Tiltrotor Model in a Wind Tunnel written by and published by . This book was released on 2001 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comparisons of measured and calculated aerodynamic behavior of a tiltrotor model are presented. The test of the Tilt Rotor Aeroacoustic Model (TRAM) with a single, 0.25-scale V-22 rotor in the German-Dutch Wind Tunnel (DNW) provides an extensive set of aeroacoustic, performance, and structural loads data. The calculations were performed using the rotorcraft comprehensive analysis CAMRAD II. Presented are comparisons of measured and calculated performance for hover and helicopter mode operation, and airloads for helicopter mode. Calculated induced power, profile power, and wake geometry provide additional information about the aerodynamic behavior. An aerodynamic and wake model and calculation procedure that reflects the unique geometry and phenomena of tiltrotors has been developed. There are major differences between this model and the corresponding aerodynamic and wake model that has been established for helicopter rotors. In general, good correlation between measured and calculated performance and airloads behavior has been shown. Two aspects of the analysis that clearly need improvement are the stall delay model and the trailed vortex formation model.
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781722815387
Total Pages : 36 pages
Book Rating : 4.8/5 (153 download)
Download or read book Studies of a Flat Wake Rotor Theory written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-11 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: A computer code was developed at Princeton University to calculate the velocity components in the flow field near a lifting rotor. The induced velocity components in the rotor flow field predicted by this theory are compared with experiment. It appears that on balance, this relatively simple theory gives a reasonable prediction of the average induced velocities in a rotor flow and is quite suitable for such applications as estimating the influence of the rotor wake on the tail surfaces of rotorcraft. The theory predicts that significant induced velocity components are present in all three flow directions in the wake at a lifting rotor. It should be noted , however, that there are a few experimental measurements of the longitudinal and lateral induced velocity components in the rotor wake. This theory, known as the flat wake theory, is essentially the rotary wing analog of Prandtl's lifting line theory. The theory is described in this report. Calculations based on the theory are presented and compared with a modern free wake theory. Curtiss, H. C., Jr. and Mckillip, R. M., Jr. Unspecified Center NAG1-1038...
Author : S. Gene Sadler
Publisher :
ISBN 13 :
Total Pages : 788 pages
Book Rating : 4.F/5 ( download)
Download or read book Development and Application of a Method for Predicting Rotor Free Wake Positions and Resulting Rotor Blade Air Loads written by S. Gene Sadler and published by . This book was released on 1971 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rotor wake geometries are predicted by a process similar to the startup of a rotor in a free stream. An array of discrete trailing and shed vortices is generated with vortex strengths corresponding to stepwise radial and azimuthal blade circulations. The array of shed and trailing vortices is limited to an arbitrary number of azimuthal steps behind each blade. The remainder of the wake model of each blade is an arbitrary number of trailing vortices. Vortex element end points were allowed to be transported by the resultant velocity of the free stream and vortex-induced velocities. Wake geometry, wake flow, and wake-induced velocity influence coefficients are generated by this program for use in the blade loads portion of the calculations. Blade loads computations include the effects of nonuniform inflow due to a free wake, nonlinear airfoil characteristics, and response of flexible blades to the applied loads. Computed wake flows and blade loads are compared with experimentally measured data. Predicted blade loads, response and shears and moments are obtained for a model rotor system having two independent rotors. The effects of advance ratio, vertical separation of rotors, different blade radius ratios, and different azimuthal spacing of the blades of one rotor with respect to the other are investigated.
Author : T. Alan Egolf
Publisher :
ISBN 13 :
Total Pages : 104 pages
Book Rating : 4.F/5 ( download)
Download or read book A Full Potential Flow Analysis with Realistic Wake Influence for Helicopter Rotor Airload Prediction written by T. Alan Egolf and published by . This book was released on 1987 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : George E. Sweet
Publisher :
ISBN 13 :
Total Pages : 28 pages
Book Rating : 4.:/5 (31 download)
Download or read book Hovering Measurements for Twin-rotor Configurations with and Without Overlap written by George E. Sweet and published by . This book was released on 1960 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Wayne Johnson
Publisher :
ISBN 13 :
Total Pages : 34 pages
Book Rating : 4.:/5 (317 download)
Download or read book Comparison of Calculated and Measured Blade Loads on a Full-scale Tilting Proprotor in a Wind Tunnel written by Wayne Johnson and published by . This book was released on 1980 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 19 pages
Book Rating : 4.:/5 (61 download)
Download or read book Comparison of Rotor Structural Loads Calculated Using Comprehensive Analysis written by and published by . This book was released on 2005 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: Blade flap and chord bending and torsion moments are investigated for six rotors operating at transition and high speed: H-34 in flight and wind tunnel, SA 330 (research Puma), SA 349/2, UH-60A full-scale, and BO-105 model (HART-I). The measured data from flight and wind tunnel tests are compared with calculations obtained using the comprehensive analysis CAMRAD II. The calculations were made using two free wake models: rolled-up and multiple-trailer with consolidation models. At transition speed, there is fair to good agreement for the flap and chord bending moments between the test data and analysis for the H-34, research Puma, and SA 349/2. Torsion moment correlation, in general, is fair to good for all the rotors investigated. Better flap bending and torsion moment correlation is obtained for the UH-60A and BO-105 rotors by using the multiple-trailer with consolidation wake model. In the high speed condition, the analysis shows generally better correlation in magnitude than in phase for the flap bending and torsion moments. However, a significant underprediction of chord bending moment is observed for the research Puma and UH-60A. The poor chord bending moment correlation appears to be caused by the airloads model, not the structural dynamics.
Author :
Publisher :
ISBN 13 :
Total Pages : 26 pages
Book Rating : 4.:/5 (317 download)
Download or read book Results of the Integration of a Transonic Full-potential Analysis Program with a Free-wake Lifting-line Program for Hovering Rotors written by and published by . This book was released on 1987 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Danny R. Hoad
Publisher :
ISBN 13 :
Total Pages : 36 pages
Book Rating : 4.:/5 (31 download)
Download or read book Rotor Induced-inflow-ratio Measurements and CAMRAD Calculations written by Danny R. Hoad and published by . This book was released on 1990 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Thomas Alan Egolf
Publisher :
ISBN 13 :
Total Pages : 75 pages
Book Rating : 4.:/5 (227 download)
Download or read book An Analytical and Experimental Study of Farfield Rotor Wake Geometry and Velocity written by Thomas Alan Egolf and published by . This book was released on 1973 with total page 75 pages. Available in PDF, EPUB and Kindle. Book excerpt: All fixed wing aircraft generate trailing vortex wakes whose circulatory strength is dependent on flight conditions and aircraft geometry. A rotor also generates a vortex wake. A vortex sheet is shed from each blade. Each sheet rolls up rapidly outboard to form a tip vortex. The purpose of the study reported here is to estimate the rotor wake geometry and velocity field downstream of the rotor for the particular case where the rotor wake exhibits strong similarities to the fixed wing wake. A method is developed by which the helicopter far field wake can be readily compared to the far field wake generated by an equivalent wing. (Author).
Author :
Publisher :
ISBN 13 :
Total Pages : 16 pages
Book Rating : 4.:/5 (318 download)
Download or read book Calculation of Rotor Performance and Loads Under Stalled Conditions written by and published by . This book was released on 2003 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rotor behavior in stalled conditions is investigated using wind tunnel test data of a 1/10-scale CH-47B/C type rotor, which provides a set of test conditions extending from unstalled to light stall to some deep stall conditions over a wide range of advance ratios. The rotor performance measured in the wind tunnel is similar to the main rotor performance measured during the NASA/Army UH-60A Airloads Program, although the two rotors are quite different. The analysis CAMRAD II has been used to predict the rotor performance and loads. Full-scale airfoil test data are corrected for Reynolds number effects for comparison with the model-scale rotor test. The calculated power coefficient shows good correlation with the measurements below stall with the Reynolds number-corrected airfoil table. Various dynamic stall models are used in the calculations. The Boeing model shows the lift augmentation at low advance ratios and the Leishman-Beddoes model shows better correlation of torsion moment than the other models at mu = 0.2. However, the dynamic stall models, in general, show only a small influence on the rotor power and torsion moment predictions especially at higher advance ratios.
