Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 197 for “"rotors"”.
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Aeroelastic modelling of gyroplane rotors
… of the helicopter during the 1940s. Gyroplane rotors are not powered in flight and work in autorotative regime and hence the characteristics of a helicopter rotor during powered flight and a rotor in autorotation differ significantly. Gyroplanes in the UK have been involved in number of fatal …
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Aeroacoustics Applications to Jets and Rotors
<p>Aeroacoustics plays a critical role in the advancement of propulsion technologies for both conventional and emerging aerial systems. This dissertation investigates two key topics: noise suppression in supersonic rectangular jets and rotor noise characterization in hover and ground effect. Using …
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Developments on Electrodynamic Levitation of Rotors
… bearings are systems capable of supporting rotors in absence of mechanical contact. Among many advantages with respect to ball and roller bearings are the possibilities of operating at extremely high rotational speeds and free of maintenance. Nevertheless, classical active magnetic bearings …
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Turbulence ingestion noise of open rotors
… Noise (UDN), is likely to be higher for open rotors than for conventional turbofan engines since the rotors are fully exposed to oncoming turbulence and lack ducting to attenuate the radiated sound. However, UDN has received less attention to date, particularly in wind-tunnel and flight …
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Dynamic performance of magnetically levitated rotors
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1995.
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Dynamics of rotors incorporating squeeze film dampers
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1988.
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Aerodynamic broadband noise from contra-rotating open rotors
… been growing interest in contra-rotating open rotors (CRORs) for use as the power plants on aircraft, since they are estimated to burn 20% to 30% less fuel than equivalent turbofan engines for short-haul flights. However, one of the main challenges for their introduction is their very high …
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Studies on the Motion of Continuous Viscoelastic Rotors
This analytical investigation of continuous viscoelastic rotor motion is based upon undeformed rotor geometry being that of a right circular cylindrical shaft. The derivation of the motion equations for this Euler beam rotating shaft utilizes the work-energy approach. It is assumed that constant …
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Flow randomness and tip losses in transonic rotors
… are used in conjunction with data from the three rotors. Also, randomness calculations are performed for each rotor. The flowfield randomness of the two fans is shown to correlate well with their respective high tip losses. The core compressor is shown to have a very random flowfield, with no …
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A new appreciation of inflow modelling for autorotative rotors
… to applying this model to analyse autorotative rotors (i.e. rotors in the windmill-brake state), which differ from powered helicopter rotors (i.e. rotors in the normal working state) in that the geometric relation between the inflow and the rotor disc. The principal aim of this research is to …
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An Improved Prescribed Wake Analysis for Wind Turbine Rotors
… are examined (2, 5 and 10). Finally, data for rotors with one, two and three blades are presented. The pitch of the ensuing helical wake is found to be modeled well by the reciprocal of the rotor tip speed ratio. The radial locations of the tip vortices stay relatively constant at 97% radius. …
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Modeling, Design and Testing Techniques for New Generation Industrial Rotors
L'abstract è presente nell'allegato / the abstract is in the attachment
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An extension to Hanson’s theory of harmonic noise of rotors
Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-05-01
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Excitation of gyroscopic precession in overhung rotors at critical speeds
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1953.
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Internal Torques and Forces in Gyrostats with Magnetically Suspended Rotors
Active magnetic bearings have several potential applications in spacecraft design. Based on the gyrostat model, we develop equations that describe the internal torques and forces that occur between the body and one of the attached wheels. We evaluate the transverse torques for the torque--free …
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Development of a Magnetic Levitation System for High Gyroscopic Moment Rotors
L'abstract è presente nell'allegato / the abstract is in the attachment
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Quantum Resonant Beats and Revivals in the Morse Oscillators and Rotors
… systems. Interesting physical effects in quantum rotors between half-integer spin and integer spin systems were observed to show effects of symmetry. Essentially, the quantum revivals in these quantum systems exhibited number-information aspects of surprisingly simple Farey-sum and Ford circles …
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Noise And Propulsive Efficiency Interactions For Rotors And Propellers At Constant Thrust
… and build of a rotor test stand used to test rotors to validate the simulation results and provide hardware-based solutions for the power required by a rotor in hover. Based on the experimental and simulation results, a closed form equation is also proposed that shows the power required for a …
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Homopolar bearingless slice motors with magnet-free rotors for extracorporeal life support
… that levitate and rotate disk-shaped solid iron rotors. Our first bearingless motor uses a ring-shaped D2 steel rotor which generates a driving torque via hysteresis coupling. Our second bearingless motor uses a low-carbon steel rotor with surface saliencies which, in conjunction with a homopolar …
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