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:
Download or read book Computation on helicoptor rotor wake geometry and its influence on rotor harmonic airloads written by Michael Patrick Scully and published by . This book was released on 1975 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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).
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.
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:
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:
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.
Download or read book Main Rotor Free Wake Geometry Effects on Blade Air Loads and Response for Helicopters in Steady Maneuvers Volume 2 Program Listings written by and published by . This book was released on 1972 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theoretical Determination of Rotor Blade Harmonic Airloads written by Rene H. Miller and published by . This book was released on 1964 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: A helicopter rotor in forward flight is subjected to a complex system of loads, both aerodynamic and inertial in origin. Of particular interest are the oscillatory airloads occurring at harmonics of the rotor speed. These loads are the primary source of the blade stresses which establish the fatigue life of the structure and of the oscillatory hub loads which determine the fuselage vibration level. Unlike a sing, the trailing- and shed-vortex system of the blade generates a spiral wake which returns close to the blade under most normal flight conditions. This returning wake critically influences the downwash distribution over the rotor disc and is the primary source of the higher harmonic airloading. The higher harmonic components of the airloading arise primarily from the downwash perpendicular to the plane of the rotor disc generated by this wake. Their analytical determination, therefore, requires some means of computing the downwash, which takes into account the spiral wake geometry, and of determining the unsteady aerodynamic effects associated with the blade passage through this variable velocity field. A better definition of the aerodynamics of a rotor in forward flight will also help in the design of hub and blades for minimum drag at the higher speeds envisaged for the next generation of helicopters.
Download or read book Interim Report on the Computation of Helicopter Rotor Wake Geometry written by Michael Scully and published by . This book was released on 1968 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Second Interim Report on the Computation of Helicopter Rotor Wake Geometry written by Michael Scully and published by . This book was released on 1968 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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:
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:
Download or read book On the Computation of Helicopter Rotor Wake Geometry written by M. P. Scully and published by . This book was released on 1968 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new technique is described whereby the rotor tip vortex geometry may be calculated.
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:
Download or read book Wake Model for Helicopter Rotors in High Speed Flight written by and published by . This book was released on 1988 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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:
