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Author : Peter Crimi
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (686 download)
Download or read book Theoretical Prediction of the Flow in the Wake of a Helicopter Rotor written by Peter Crimi and published by . This book was released on 1965 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Peter Crimi
Publisher :
ISBN 13 :
Total Pages : 93 pages
Book Rating : 4.:/5 (227 download)
Download or read book Theoretical Prediction of the Flow in the Wake of a Helicopter Rotor. Part I. Development of Theory and Results of Computations written by Peter Crimi and published by . This book was released on 1965 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was performed with the objective of predicting the time-varying flow in the vicinity of a helicopter in hovering or forward flight. An analytical model was formulated which represents the rotor, its wake and the fuselage of the aircraft. The model for the wake has been simplified in a manner consistent with flow visualization studies by representing the wake as tip vortices emanating from each blade. The wake vortices are assumed to be free to convect under the influence of the blades, the fuselage and the wake itself. The fuselage has been replaced by a surface distribution of sources, the strength per unit area being determined by assuming that the fuselage is subjected to a uniform, steady free stream. A digital computer program was written which implements the model developed. Flow calculations were performed which agree well with measurements of the time average of the flow in the wake of a two-bladed rotor. Extensive calculations were then carried out which define the flow in the vicinity of a UH-1B helicopter for a range of flight conditions from hover to high-speed cruise. Upon analysis of the results, it was concluded that the model developed provides a valid representation of the unsteady flow in the vicinity of a helicopter. It was pointed out that the formulation is somewhat restrictive, in that the flow in the rotor plane and immediately adjacent to the fuselage cannot be accurately predicted. However, the suitable refinements incorporated, these regions could be investigated as well. (Author).
Author : Peter Crimi
Publisher :
ISBN 13 :
Total Pages : 60 pages
Book Rating : 4.E/5 ( download)
Download or read book Theoretical Prediction of the Flow in the Wake of a Helicopter Rotor written by Peter Crimi and published by . This book was released on 1966 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: The addendum reports the results of an extension to the study to determine the time varying flow in the vicinity of a helicopter rotor in hovering and forward flight and having a fuselage immersed in the rotor wake. The purpose of the extension was to compare two models representing the fuselage. The first fuselage model (AD-629 782 and AD-629 783), was based upon the assumption that the fuselage was immersed in a constant and uniform flow; the second model was based upon the assumption that the fuselage was immersed in a constant but nonuniform flow. Comparisons between the two models are presented. Program listings and operational information related to the programs are given. (Author).
Author : Peter Crimi
Publisher :
ISBN 13 :
Total Pages : 82 pages
Book Rating : 4.:/5 (227 download)
Download or read book Theoretical Prediction of the Flow in the Wake of a Helicopter Rotor. Part 2. Formulation and Application of the Rotor-wake-flow Computer Program written by Peter Crimi and published by . This book was released on 1965 with total page 82 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two digital computer programs were prepared which direct the calculation of the time-varying flow in the vicinity of a helicopter rotor in forward or hovering flight. Fuselage interference effects are taken into account. The applicability of these programs to specific problems and procedures for their use are discussed. First, the assumptions made in constructing the mathematical model and the relationship of the model to the physical flow are outlined. In this connection, the assumptions necessary for numerical analysis and the functional structure of the programs are also given. Then, the formulations which were coded are presented. Included in the formulations are the coordinate identifications used and the definitions of program variables. Finally, the procedures for implementation of the programs are given. The relationship of input quantities to aircraft flight parameters, program accuracy and computer running time are specified. A sample calculation, including both inputs and outputs, is presented. Program listings and operational information related to the programs are given. (Author).
Author : John C. Wilson
Publisher :
ISBN 13 :
Total Pages : 62 pages
Book Rating : 4.:/5 (317 download)
Download or read book Experimental Evaluation of a Flat Wake Theory for Predicting Rotor Inflow-wake Velocities written by John C. Wilson and published by . This book was released on 1992 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 776 pages
Book Rating : 4.E/5 ( download)
Download or read book Technical Abstract Bulletin written by and published by . This book was released on with total page 776 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 : T. A. Egolf
Publisher :
ISBN 13 :
Total Pages : 228 pages
Book Rating : 4.:/5 (317 download)
Download or read book Helicopter Rotor Wake Geometry and Its Influence in Forward Flight. Volume 1: Generalized Wake Geometry and Wake Effect on Rotor Airloads and Performance written by T. A. Egolf and published by . This book was released on 1983 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analytic investigation to generalize wake geometry of a helicopter rotor in steady level forward flight and to demonstrate the influence of wake deformation in the prediction of rotor airloads and performance is described. Volume 1 presents a first level generalized wake model based on theoretically predicted tip vortex geometries for a selected representative blade design. The tip vortex distortions are generalized in equation form as displacements from the classical undistorted tip vortex geometry in terms of vortex age, blade azimuth, rotor advance ratio, thrust coefficient, and number of blades. These equations were programmed to provide distorted wake coordinates at very low cost for use in rotor airflow and airloads prediction analyses. The sensitivity of predicted rotor airloads, performance, and blade bending moments to the modeling of the tip vortex distortion are demonstrated for low to moderately high advance ratios for a representative rotor and the H-34 rotor. Comparisons with H-34 rotor test data demonstrate the effects of the classical, predicted distorted, and the newly developed generalized wake models on airloads and blade bending moments. Use of distorted wake models results in the occurrence of numerous blade-vortex interactions on the forward and lateral sides of the rotor disk. The significance of these interactions is related to the number and degree of proximity to the blades of the tip vortices. The correlation obtained with the distorted wake models (generalized and predicted) is encouraging.
Author :
Publisher :
ISBN 13 :
Total Pages : 726 pages
Book Rating : 4.3/5 (91 download)
Download or read book Government-wide Index to Federal Research & Development Reports written by and published by . This book was released on 1966-06 with total page 726 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : R.J. Adrian
Publisher : Springer Science & Business Media
ISBN 13 : 3642569633
Total Pages : 624 pages
Book Rating : 4.6/5 (425 download)
Download or read book Laser Techniques Applied to Fluid Mechanics written by R.J. Adrian and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 624 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the tradition of its predecessors, this volume comprises a selection of the best papers presented at the Ninth International Symposium on Applications of Laser Techniques to Fluid Mechanics, held in Lisbon in July 2000. The papers reflect the state-of-the-art in laser applications of laser techniques in fluid mechanics describing novel ideas for instrumentation, instrumentation developments, results of measurements of wall-bounded flows, free flows and flames and flow and combustion in engines. The papers demonstrate the continuing interest in the development of an understanding of new methodologies and implementation in terms of new instrumentation.
Author : Paul Soohoo
Publisher :
ISBN 13 :
Total Pages : 120 pages
Book Rating : 4.:/5 (227 download)
Download or read book Rotor Wake Effects on Hub/Pylon Flow. Volume I. Theoretical Formulation written by Paul Soohoo and published by . This book was released on 1978 with total page 120 pages. Available in PDF, EPUB and Kindle. Book excerpt: An investigation has been conducted to demonstrate the use of the Green's function method to study rotor wake effects on helicopter hub/pylon flow. This report consists of two volumes which document the theoretical formulation and the use of the digital computer program SHAPES (Subsonic Helicopter Aerodynamics Program with Effects of Separaton). Volume I presents the theoretical formulation and corresponding numerical procedure for the study of incompressible potential aerodynamics with separated flow. While the formulation is valid for fully unsteady aerodynamics, this report is mainly concerned with rotor aerodynamics. A potential flow aerodynamic program, SHAPES, with suitable rotor wake representation was developed to predict the separation characteristics of arbitrary three-dimensional helicopter configurations. In particular, the effect of the rotor blade wake, blade shank wake, and hub wake in the separation of the flow over a lifting helicopter in forward flight is analyzed. The present method has potential application in the design of helicopters because it provides an analytical capability which can be used to develop low-drag profile as well as to explore problem areas. Extensive numerical results obtained from Program SHAPES demonstrated the flexibility and accuracy of the method. These results are in excellent agreement with existing data. (Author).
Author : F. A. DuWaldt
Publisher :
ISBN 13 :
Total Pages : 110 pages
Book Rating : 4.E/5 ( download)
Download or read book Wakes of Lifting Propellers (rotors) in Ground Effect written by F. A. DuWaldt and published by . This book was released on 1966 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report presents the development of a wake model for a lifting propeller (rotor) in ground effect and the computational procedure used to determine the spacial distribution of wake vorticity and the induced velocity field accompanying that vorticity distribution. Sample calculations for a two-bladed rotor were carried out on an IBM 7044 computer. Locations of wake vortical elements and the associated induced velocities at selected field points are presented for advance ratios of 0, 0.02, 0.05, and 0.10 for an H/R (ratio of rotor height above ground to rotor radius) of 1.0. Also, a few results for a hovering case with H/R = 0.5 are presented. A calculated root-mean-square velocity map is compared with measured hovering data (time averaged) and good agreement is obtained in the outer half of the slipstream. The implications of computed results with respect to the flow field at a horizontal stabilizer or tail rotor are noted as examples of the use of the model. The wake vortex model used for these calculations is a distorted continuous helix emanating from each blade tip. (Author).
Author :
Publisher :
ISBN 13 :
Total Pages : 46 pages
Book Rating : 4.:/5 (317 download)
Download or read book Flow Field Around a Hovering Rotor written by and published by . This book was released on 1997 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 :
Publisher : DIANE Publishing
ISBN 13 : 1428916822
Total Pages : 32 pages
Book Rating : 4.4/5 (289 download)
Download or read book Correlation of Puma Airloads--Lifting-Line and Wake Calculation written by and published by DIANE Publishing. This book was released on with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 892 pages
Book Rating : 4.:/5 (31 download)
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 840 pages
Book Rating : 4.:/5 (334 download)
Download or read book U.S. Government Research & Development Reports written by and published by . This book was released on 1968 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt:
