Download or read book Laminar Flow Analysis of a Rotor in Hover written by R. Ganesh Rajagopalan and published by . This book was released on 1989 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Boundary layer Studies on Helicopter Rotors in Forward Flight written by W. J. McCroskey and published by . This book was released on 1968 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the analysis of boundary layers on rotors in forward flight, the essential features of the flow were demonstrated by means of relatively simple analytical solutions. Within the framework of the small crossflow and quasi-steady approximations, which are valid over most of the rotor, the laminar flow is now well understood. An important exception is the detailed structure of the flow near the separation lines, where recourse to numerical analysis of the full three-dimensional, unsteady Navier-Stokes equations are required if to predict accurately the maximum lift that can be produced by a rotor. (Author).

Download or read book Analysis of Small scale Rotor Hover Performance Data written by and published by . This book was released on 1990 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A Closed Form Analysis of Rotor Blade Flap Lag Stability in Hover and Low Speed Forward Flight in Turbulent Flow written by J. E. Prussing and published by . This book was released on 1983 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Transonic Flow Analysis for Rotors Part 3 Three dimensional Quasi steady Euler Calculation written by I-Chung Chang and published by . This book was released on 1990 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Free Wake Analysis of Hover Performance Using a New Influence Coefficient Method written by Todd R. Quackenbush and published by . This book was released on 1990 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Aeronautical Engineering written by and published by . This book was released on 1991 with total page 538 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Flow Field Analysis of Highly twisted Rotors in Hover written by Gloria Kazuko Yamauchi and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1970 with total page 772 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Free Wake Analysis of Helicopter Rotor Flow Fields Using a Coupled Vorticity Embedding Fractional Step Method written by and published by . This book was released on 2000 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: A hybrid CFD (Computational Fluid Dynamics) method combining a potential-based Vorticity Embedding method with an Euler solver is presented and validated for isolated rotor flows. First, a formulation of Vorticity Embedding is developed and validated for Cartesian grids. This formulation is utilized together with simple lifting lines to represent an isolated rotor in hover. The results for an isolated rotor are then compared with experiment. The method is then hybridized by coupling the Vorticity Embedding grid containing the rotor to a region containing a ground plane where a standard finite difference Euler solver is utilized. initial results from this hybrid scheme are presented including a demonstration of the code's potential to calculate the ground vortex roll-up generated by a rotor in ground effect in the presence of a cross-wind.

Download or read book A User s Manual for ROTTILT Solver Tiltrotor Fountain Flow Field Prediction written by and published by . This book was released on 1999 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Free Wake Analysis of a Rotor in Hover written by C. S. Chen and published by . This book was released on 1987 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: A numerical method based on the axisymmetric, incompressible Navier-Stokes equations is combined with a lifting surface code to predict the vortex wake of hovering rotors. The lifting surface code, AMI Hover, is used to obtain the circulation distribution on the blade. This circulation distribution is fed into the Navier-Stokes code to compute the vortex wake under this specified circulation distribution. An iteration approach is used between these two codes to converge the circulation distribution and the shape of the vortex wake. A relaxation scheme is developed to resolve the instability encountered among the tip vortices. A reconcentration scheme is used to solve the diffusion problem due to the strong artificial viscosity. The results from the present method are compared with experimental data obtained by smoke-flow visualization and hot-wire measurements for several rotor blade configurations. The comparisons show that the present method is able to predict the complex wake system shed by a hovering rotor.

Download or read book Free Wake Analysis of Helicopter Rotor Blades in Hover Using a Finite Volume Technique written by Krishnamurthi Ramachandran and published by . This book was released on 1987 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the computation of helicopter rotor flow fields, wake effects can be very important since each blade passes close to the wake produced by the preceding ones, causing a large local effect. Also, the vortical flow from the wake of a number of blade passages causes a large global effect. Extensive work has been done on helicopter rotor flows using integral methods to follow the vortex wake. These generally cannot treat compressibility effects. Also, they have difficulty attaining stable solutions, particularly in hover, where a large number of interacting vortex sheets must be treated. A new method has been developed which like integral methods does not constrain or spread the wake. Also, like finite difference methods, it can treat compressibility effects. This method has been developed into a computer program for the computation of rotor flow fields in hover with free wakes. The method utilizes a finite volume potential flow technique. The basic approach involves modifying the potential flow wake treatment so that, within the numerical approximation, the momentum is conserved there as in the rest of the flow field. The internal structure of the vortex is not solved for, but is modeled and spread over several grid points. The wake position and vorticity strength are computed so that the momentum over the wake is balanced in an integral sense. Results computed by this approach for the circulation and wake geometry are compared with experimentally measured data. Cases treated include subsonic and transonic flows, high and low aspect ratios, and two and four-bladed rotor configurations. (SDW).

Download or read book An Evaluation of Linearized Vortex Theory as Applied to Single and Multiple Rotors Hovering in and Out of Ground Effect written by Harry H. Heyson and published by . This book was released on 1959 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Transonic Flow Analysis for Rotors written by I-Chung Chang and published by . This book was released on 1990 with total page 28 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Large Eddy Simulation of the Tip Flow of a Rotor in Hover written by and published by . This book was released on 2005 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: The blade-tip vortex is one of the most important aerodynamic feature of a helicopter rotor wake, The strength, size, location and orientation of the tip vortices affect the blade loads and rotor performance. The overall goal of the current project was to develop a large-eddy simulation (LES) capability to simulate the rotor-tip vortex and use these simulations to perform a detailed analysis of the dynamics of this flow, The specific objectives of this research project are (1) Develop a LES based computational approach for simulating the tip flow of a rotor in hover. (2) Validate the computational approach against PIV measurements of a hovering rotor (3) Use the solver to gain insight into the formation, structure and downstream evolution of the tip-vortex and the dynamics of the turbulence associated with the tip vortex.

Download or read book Aeromechanical Stability of a Hingeless Rotor in Hover and Forward Flight Analysis and Wind Tunnel Tests written by and published by . This book was released on 1983 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt: A research effort of analysis and testing has been conducted in the NASA-Langley Transonic Dynamics Tunnel to investigate the ground resonance phenomenon of a soft in-plane hingeless rotor. Experimental data were obtained using a 9 ft. (2.74 m) diameter model rotor in hover and forward flight. Eight model rotor configurations were investigated. Configuration parameters included pitch-flap coupling, blade sweep and droop, and precone of the blade feathering axis. An analysis based on a comprehensive analytical model of rotorcraft aerodynamics and dynamics was used for this study. The moving-block method was used to experimentally determine the regressing lead-lag mode damping. Good agreement has been obtained between the analysis and test. Both analysis and experiment indicated ground resonance instability in hover. The paper presents an outline of the analysis, a description of the experimental model and procedures, and comparison of the analytical and experimental data. (Author).