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 15 of 15 for “"rotor noise"”.
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High Fidelity Open Rotor Noise Prediction
… the next generation of jet engines. An ``open rotor'' replaces the fan of the turbofan with a set of external rotors. This has the potential to offer a significant improvement in propulsive efficiency, but the design for low noise is a key challenge. Hence, high fidelity noise prediction …
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Prediction & Active Control of Multi-Rotor Noise
… More chiefly, they operate with multiples of rotors, which may pose some issues aerodynamically, as well as acoustically. The aim of this research is to first investigate the various noise sources in multi-rotor systems. High-fidelity simulations of two in-line counter-rotating propellers in …
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Aerodynamic and Acoustic Modeling for eVTOL Rotor Noise Prediction
… electric vertical takeoff and landing (eVTOL) rotor in both hover and edgewise flight conditions. The approach couples sectional two-dimensional Reynolds-Averaged Navier-Stokes (2D-RANS) airfoil simulations with rotor loading predictions from the Comprehensive Hierarchical Aeromechanics …
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An experimental and theoretical study of helicopter rotor noise.
Thesis. 1975. Ph.D.--Massachusetts Institute of Technology. Dept. of Aeronautics and Astronautics.
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ANC of UAS Rotor Noise using Virtual Error Sensors
Traditional active noise control (ANC) systems rely on a physical sensor to measure the error signal at the desired location of attenuation. The error signal is then used to update an adaptive controller, which ultimately attenuates the measured response. However, it is not always practical to use …
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Measurement and Prediction of Rotor Noise Sources for sUAS in Outdoor and Laboratory Environments
… comparison of aerodynamic performance and noise of eVTOL rotors operating in multiple facilities, and analysis of the noise associated with an outrunner brushless DC motor. Empirical and low-order models are used to predict aerodynamic performance, tonal noise, and broadband noise for …
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Aeroacoustics Applications to Jets and Rotors
… This dissertation investigates two key topics: noise suppression in supersonic rectangular jets and rotor noise characterization in hover and ground effect. Using high-fidelity numerical simulations and theoretical analyses, this research aims to develop effective noise mitigation strategies and …
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Numerical investigation of air vehicle noise propagation effects
… part of this environmental impact is the noise emitted by air vehicles, which is considered rather significant for community annoyance. The generation and propagation of air vehicle noise are two different areas of interest, which require accurate prediction in order to control the emitted …
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Rotor Inflow Noise Caused by a Boundary Layer: Inflow Measurements and Noise Predictions
A rotor immersed in a thick turbulent boundary layer produces unsteady loading on the blades which generates unwanted noise and vibration. Two point velocity fluctuations were measured in detail to determine the full four-dimensional correlation function of a boundary layer generated over a smooth …
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The Impact of Three Dimensional Flow Anisotropy and Transients on Turbulence Ingestion Noise in Open Rotors
… structure and radiated turbulence ingestion noise of a rotor in two experimental configurations is studied. The first consists of a non-axisymmetric boundary layer wake ingested by a rotor mounted at the aft of a body of revolution inclined at 5 degree angle of attack. In the second …
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The Interaction of a Transient Forward Axial Disturbance Flow With a Rotor
… characteristics of a scaled-down Joby Aviation rotor, focusing on its performance under realistic conditions for urban air mobility (UAM). Utilizing a high-fidelity numerical simulation approach that combines Large-Eddy Simulation (LES) and Unsteady Reynolds-Averaged Navier-Stokes (URANS) …
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Noise And Propulsive Efficiency Interactions For Rotors And Propellers At Constant Thrust
… travel. These vehicles must have low noise and particulate emissions while also having enough propulsive efficiency to complete the mission. This thesis aims to study the relationship between noise and propulsive efficiency as related to any aircraft equipped with an electric motor and …