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 19 of 19 for “"Rotor model"”.
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Development of a Rotordynamic Signal Processing MATLAB Interface and a Two-Disk Rotor Model
… program meant to monitor the behavior of rotordynamic systems in real-time was developed and tested. By using traditional analysis methods in this field of engineering, commonly desired data representations such as bode, polar, orbit, full spectrum plots were able to be produced to a very …
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Development of a rotor model for the numerical simulation of helicopter exterior flow-fields
A numerical methodology is developed to model the effect of a rotor on the surrounding flow-field. The model calculates the time-averaged aerodynamic forces exerted on the air by the fan blades within the blade-swept region, and permits the user to specify blade properties such as cross-sectional …
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Implementation of a trim routine in a rotor model for the numerical simulation of helicopter flow-fields
… and implement a trim routine for a numerical rotor model, developed for the use in simulations of a helicopter exterior flow-field. In this investigation a ROBIN fuselage geometry was utilised. Simulations of the fuselage without the rotor were carried out initially so that investigations into …
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An investigation of the three-dimensional vibration characteristics of a rotor-bearing system using the finite element method
A vibration analysis of a high-speed rotor-bearing system using the finite element is presented. Models were developed to study the effect of rotor mass and stiffness, support bearing stiffness, and bearing pedestal stiffness on rotor critical speeds. Bearing stiffnesses were obtained from a …
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Two-dimensional terahertz rotational spectroscopy in the gas phase
… freedom. Based on the quantum mechanical rigid rotor model, we have developed simulation and calculation approaches to disentangling spectroscopic signals from molecular rotations.
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Study of Contra-Rotating Coaxial Rotors in Hover: A Performance Model Based on Blade Element Theory Including Swirl Velocity
… purpose of this study is to create a simple model to evaluate the performance of a counter-rotating coaxial rotor system. As it is based on the blade element theory, it could be used as a design tool where the engineer can modify all parameters - rotor radius, blade pitch distribution, tip …
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The Quantum Kicked Rotor
The quantum kicked rotor has served as a model for testing the ideas of quantum chaos since the field's inception. In this thesis we present an overview of the kicked rotor, both from a semiclassical standpoint as well as from a purely quantum standpoint. At the heart of our kicked rotor model is a …
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A parabolized Navier-Stokes method for wind farm applications
… and incorporates more physics. A wind turbine model is developed and coupled with the PNS method for simulating wind turbines and entire wind farms. The wind turbine model is adapted for spatial marching and is based on the Actuator Line rotor model and Blade Element Momentum theory. The …
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Design of an Experimental Rig to Characterize the Gust Response of Small Wind Turbines and Autorotating Seeds
… behavior of abstracted small-wind-turbine rotors exposed to a sudden increase in oncoming flow velocity, i.e. a gust. These rotors consisted of blades with aspect ratios characteristic of samara seeds, which are known for their ability to maintain autorotation in unsteady wind. The models …
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Mixed-domain performance model of the piezoelectric traveling-wave motor and the development of a two-sided device
… parallel objectives: (1) to develop an advanced modeling approach for the accurate prediction of steady-state performance of piezoelectric traveling-wave motors, and (2) to improve upon the typical piezoelectric traveling-wave motor configuration by investigating the novel implementation of …
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Transient response technique applied to active magnetic bearing machinery during rotor drop
… indispensable to protect the magnetic bearing rotor and stator, and other stationary seals along the rotor shaft. In this paper, a theoretical formulation is proposed and solved numerically to examine the transient response of the flexible rotor, from the time just previous to the AMB shuts …
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Critical speeds and unbalance response of cantilever-sleeve rotors using finite elements with efficient higher order basis functions
Design of industrial rotor-bearing systems requires an understanding of their dynamic behavior, which involves the determination of their critical speeds and unbalance response. Dynamic behavior of simple rotor systems can be studied using analytical techniques. However, for complex rotor systems …
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Advanced Modelling of Helicopter Nonlinear Dynamics and Aerodynamics
… comprehensive dynamic and aerodynamic helicopter model. The possible applications of this work are wide including, control systems applications, reference and trajectory tracking methods implementation amongst others. The model configuration corresponds to a Sikorsky helicopter; a main rotor in …
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Chaos and Localisation
… and kicked atoms which mimic the delta-kicked rotor model. Both of these systems show a complex dynamical evolution arising from the interaction with an external time-periodic driving force. In particular two quantum phenomena, which have no counterpart on the classical level, are studied: the …
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Helicopter rotor smoothing with a continuous trailing - edge flap
… source of helicopter vibration is the main rotor. Since rotor hub loads are the summation of loads on each blade, the vibratory loads, for a rotor with identical blades, consist of harmonics of integer multiples of the rotational speed. A conventional vibration reduction process (only …
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Helicopter Flight Dynamics Simulation with a Time-Accurate Free-Vortex Wake Model
… the implementation and validation of a coupled rotor-fuselage simulation model with a time-accurate free-vortex wake model capable of capturing the response to maneuvers of arbitrary amplitude. The resulting model has been used to analyze different flight conditions, including both steady and …
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Aerothermal Sentencing for Manufacturing Variations on Turbine Blade Shrouds
… RANS simulations are run on a three passage HPT rotor model with engine-representative shroud platform manufacturing variations applied to the middle blade passage. Engine representative shroud platform manufacturing variations, consisting of platform steps and inter-platform gap width …
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An investigation of a scalable flight control system for a variable pitch, fuel powered, quad-rotor craft
Submitted in the fulfillment of requirements of the degree of Master of Mechanical Engineering, Durban University of Technology, Durban, South Africa, 2023.
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Autonomous Autorotation of a Tilt-Rotor Aircraft Using Model Predictive Control
<p>Tilt rotor vehicles are governed by FAA laws also used for conventional helicopters, which require autorotational maneuvering and landing given a total power failure. With low inertia rotors and high disk loading of tilt rotor vehicles, this already difficult task becomes significantly more …