Development of a Rotor/body Coupled Analysis for an Active-mount, Aeroelastic Rotor Testbed PDF Download
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Author: Matthew Lee Wilbur
Publisher:
ISBN:
Category :
Languages : en
Pages : 300
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Book Description
Author: Matthew Lee Wilbur
Publisher:
ISBN:
Category :
Languages : en
Pages : 300
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Book Description
Author: Matthew L. Wilbur
Publisher:
ISBN:
Category : Rotors (Helicopters)
Languages : en
Pages : 112
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Author:
Publisher: DIANE Publishing
ISBN: 1428995803
Category :
Languages : en
Pages : 115
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 118
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 166
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Author: Michael J. McNulty
Publisher:
ISBN:
Category :
Languages : en
Pages : 396
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Author:
Publisher:
ISBN:
Category : Government publications
Languages : en
Pages : 658
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Author: Nicolas Reveles
Publisher:
ISBN:
Category : Aeroelasticity
Languages : en
Pages :
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Book Description
Simulations play an integral role in the understanding and development of rotor- craft aeromechanics. Computational Fluid Dynamics coupled with Computational Structural Dynamics (CFD/CSD) offers an excellent approach to analyzing rotors. These methods have been traditionally "loosely-coupled" where data are exchanged periodically, motion is prescribed for CFD, and the updated loads have a static component for CSD. Loosely-coupled CFD/CSD assumes the solution to be periodic, which may not be true for some simulations. "Tightly-coupled" CFD/CSD, where loads and motion are exchanged at each time step, does not make this periodic assumption and opens up new avenues of simulation to research. A major drawback to tightly-coupled CFD/CSD is an increase in computational cost. Different approaches are explored to reduce this cost as well as examine numerical implications in solutions from tightly and loosely-coupled CFD/CSD. A trim methodology optimized for tightly-coupled simulations is developed and found to bring trim costs within parity of loosely-coupled CFD/CSD simulations. Aerodynamic loading is found to be nearly similar for fixed controls. However, the lead-lag blade motion is determined to contain a harmonic in the tightly-coupled analysis that is not an integer multiple of the rotor speed. A hybrid CFD/CSD methodology employing the use of a free-wake code to model the far-field effects of the rotor wake is developed to aid in computational cost reduction. Investigation of this approach reveals that computational costs may be reduced while preserving solution accuracy. This work's contributions to the community include the development of a trim algorithm appropriate for use in tightly-coupled CFD/CSD simulations along with a detailed examination of the physics predicted by loose and tight coupling for quasi-steady level flight conditions. The influence of the wake in such cases is directly examined using a modular hybrid coupling to a free-wake code that is capable of reduced cost computations.
Author:
Publisher:
ISBN:
Category : Airframes
Languages : en
Pages : 224
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 323
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Book Description
The blade loads analysis calculates rotor blade flapwise, chordwise, and torsional deflections and loads, together with rotor performance, control system forces, and vibratory hub loads. Articulated and hingeless rotors with 2 to 9 blades and large twist may be analyzed. The analysis considers coupled flapwise-chordwise-torsion deflections of the rotor blades. Boundary conditions for either articulated or hingeless rotors are applied and the solution is obtained by expanding the variables in a 10-harmonic Fourier series. Airload calculations include the effects of airfoil section geometry, compressibility, stall, 3-dimensional flow, unsteady aerodynamics, and nonuniform inflow. In the area of rotor loads, correlation of prop/rotor and helicopter rotor loads test data has been made with the fully coupled rotor loads and steady in-plane hub moments for prop/rotors and for alternating blade loads, pitch link loads, and airloads for helicopters. An unexpected discovery of this study was the sensitivity of the rotor derivatives to blade lead-lag motion when the frequency of this mode is near 1 per rev. This result was subsequently confirmed by test. The impact of the new prediction capabilities and possible refinement or development of design criteria through use of the analysis are discussed. The methods contained in this report are intended to be used by designers to calculate with improved accuracy, the dynamic and aeroelastic response characteristics of rotor powered V/STOL aircraft. The essential new feature of these methods is that the coupled flap-pitch-lag blade deflections are taken into account. These calculations are essential if a high level of confidence is to be had in the results.
