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Helicopter Rotor Wake Geometry And Its Influence In Forward Flight
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Book Synopsis Helicopter Rotor Wake Geometry and Its Influence in Forward Flight. Volume 1: Generalized Wake Geometry and Wake Effect on Rotor Airloads and Performance by : T. A. Egolf
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.
Book Synopsis Helicopter Rotor Wake Geometry and Its Influence in Forward Flight by : T. Alan Egolf
Download or read book Helicopter Rotor Wake Geometry and Its Influence in Forward Flight written by T. Alan Egolf and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Helicopter Rotor Wake Geometry and Its Influence in Forward Flight: Generalized wake geometry and wake effect on rotor airloads and performance by : T. Alan Egolf
Download or read book Helicopter Rotor Wake Geometry and Its Influence in Forward Flight: Generalized wake geometry and wake effect on rotor airloads and performance written by T. Alan Egolf and published by . This book was released on 1983 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Helicopter Rotor Wake Geometry and Its Influence in Forward Flight. Volume 2: Wake Geometry Charts by : T. Alan Egolf
Download or read book Helicopter Rotor Wake Geometry and Its Influence in Forward Flight. Volume 2: Wake Geometry Charts written by T. Alan Egolf and published by . This book was released on 1983 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Helicopter Rotor Wake Geometry and Its Influence in Forward Flight by : T. Alan Egolf
Download or read book Helicopter Rotor Wake Geometry and Its Influence in Forward Flight written by T. Alan Egolf and published by . This book was released on 1983 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Experimental Evaluation of a Flat Wake Theory for Predicting Rotor Inflow-wake Velocities by : John C. Wilson
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 60 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Computation of Helicopter Rotor Wake Geometry and Its Influence on Rotor Harmonic Airloads by : Michael P. Scully
Download or read book Computation of Helicopter Rotor Wake Geometry and Its Influence on Rotor Harmonic Airloads written by Michael P. Scully and published by . This book was released on 1975* with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Helicopter Rotor Wake Geometry and Airloads and Helicopter Rotor Wakes by : M. P. Scully
Download or read book Helicopter Rotor Wake Geometry and Airloads and Helicopter Rotor Wakes written by M. P. Scully and published by . This book was released on 1972 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computer programs have been developed for the calculation of helicopter rotor tip vortex geometry in hover and forward flight and for the calculation of helicopter rotor harmonic airloads in forward flight. Calculated forward flight tip vortex geometries compare well in general with experimental smoke studies although there are differences in detail. The hovering tip vortex geometry agrees qualitatively with experiment but does not move downward fast enough. Airloads were computed using both the classical rigid wake assumption and the distorted tip vortex geometry obtained from the computer program. When compared with experimental airloads measurements the rigid wake airloads give better results than the distorted wake airloads. (Author).
Book Synopsis Wake Geometry Measurements and Analytical Calculations on a Small-Scale Rotor Model by : Terence A. Ghee
Download or read book Wake Geometry Measurements and Analytical Calculations on a Small-Scale Rotor Model written by Terence A. Ghee and published by . This book was released on 1996 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Rotorcraft Aeromechanics by : Wayne Johnson
Download or read book Rotorcraft Aeromechanics written by Wayne Johnson and published by Cambridge University Press. This book was released on 2013-04-29 with total page 949 pages. Available in PDF, EPUB and Kindle. Book excerpt: A rotorcraft is a class of aircraft that uses large-diameter rotating wings to accomplish efficient vertical take-off and landing. The class encompasses helicopters of numerous configurations (single main rotor and tail rotor, tandem rotors, coaxial rotors), tilting proprotor aircraft, compound helicopters, and many other innovative configuration concepts. Aeromechanics covers much of what the rotorcraft engineer needs: performance, loads, vibration, stability, flight dynamics, and noise. These topics include many of the key performance attributes and the often-encountered problems in rotorcraft designs. This comprehensive book presents, in depth, what engineers need to know about modelling rotorcraft aeromechanics. The focus is on analysis, and calculated results are presented to illustrate analysis characteristics and rotor behaviour. The first third of the book is an introduction to rotorcraft aerodynamics, blade motion, and performance. The remainder of the book covers advanced topics in rotary wing aerodynamics and dynamics.
Book Synopsis A Full Potential Flow Analysis with Realistic Wake Influence for Helicopter Rotor Airload Prediction by : T. Alan Egolf
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:
Book Synopsis Comparison of Calculated and Measured Model Rotor Loading and Wake Geometry by : Wayne Johnson
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:
Book Synopsis Preliminary Study of a Model Rotor in Descent by :
Download or read book Preliminary Study of a Model Rotor in Descent written by and published by . This book was released on 2000 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: Within a program designed to develop experimental techniques for measuring the trajectory and structure of vortices trailing from the tips of rotor blades, the present preliminary study focuses on a method for quantifying the trajectory of the trailing vortex during descent flight conditions. This study also presents rotor loads and blade surface pressures for a range of tip-path plane angles and Mach numbers. Blade pressures near the leading edge and along the outer radius are compared with data obtained on the same model rotor, but in open jet facilities. A triangulation procedure based on two directable laser-light sheets, each containing an embedded reference, proved effective in defining the spatial coordinates of the trailing vortex. When interrogating a cross section of the flow that contains several trailing vortices, the greatest clarity was found to result when the flow is uniformly seeded. Surface pressure responses during blade-vortex interactions appeared equally sensitive near the leading edge and along the outer portion of the blade, but diminished rapidly as the distance along the blade chord increased. The pressure response was virtually independent of whether the tip-path plane angle was obtained through shaft tilt or cyclic pitch. Although the shape and frequency of the pressure perturbations on the advancing blade during blade-vortex interaction are similar to those obtained in open-jet facilities, the angle of the tip-path plane may need to be lower than the range covered in this study.
Book Synopsis Experimental Investigation of Model Variable-geometry and Ogee Tip Rotors by : Anton J. Landgrebe
Download or read book Experimental Investigation of Model Variable-geometry and Ogee Tip Rotors written by Anton J. Landgrebe and published by . This book was released on 1974 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental investigation was conducted to systematically explore the effects of inter-blade spatial relationships and pitch variations on rotor performance and wake geometry. Variable-geometry rotors consisting of various combinations of blade length, axial spacing, azimuth spacing, and collective pitch were tested at model scale in hover and forward flight. In addition, a hover test of a model rotor with an ogee blade tip design was conducted to determine its performance and wake characteristics. The results of this investigation indicate that properly selected variable geometry rotor configurations can offer substantial improvements in hover performance without adversely affecting forward flight performance. Axial spacing of alternate blades was found to provide the greatest performance benefit, and further improvements were achieved by combining azimuth spacing with axial spacing. The performance benefit appears to be related to the relief of local adverse aerodynamic phenomena produced by vortex interference. The ogee tip design was found to substantially reduce the concentrated core intensity of the tip vortex, and could thus prove beneficial for the relief of blade-vortex interaction problems. However, the ogee tip was found to reduce hover performance at model scale.
Book Synopsis Main Rotor Free Wake Geometry Effects on Blade Air Loads and Response for Helicopters in Steady Maneuvers by : S. Gene Sadler
Download or read book Main Rotor Free Wake Geometry Effects on Blade Air Loads and Response for Helicopters in Steady Maneuvers written by S. Gene Sadler and published by . This book was released on 1972 with total page 116 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)
Book Synopsis Wake Geometry Measurements and Analytical Calculations on a Small-Scale Rotor Model by : National Aeronautics and Space Adm Nasa
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...
Book Synopsis A Method for Assessing the Impact of Wake Vortices of USAF Operations by : George Kurylowich
Download or read book A Method for Assessing the Impact of Wake Vortices of USAF Operations written by George Kurylowich and published by . This book was released on 1979 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experience as a consultant to the Safety Office at Norton AFB led to compiling the engineering tools presented so that this report can be used by engineering personnel to investigate future incidents/accidents and existing USAF operations that are impacted by the vortical wake hazard. The approach presented is amenable to easy hand computations. Mixed airplane/helicopter operations can be assessed, since the engineering tools to determine the location and strength of the rotor downwash field behind a helicopter are presented. Finally, a simplified mathematical model is given to represent this hazard for use in USAF simulators, to make pilots aware of the problems associated with operating in wake-contaminated airspace.
