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 22 for “"unsteady loading"”.
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Characterization of unsteady loading due to impeller-diffuser interaction in centrifugal compressors
… simulations are used to characterize the unsteady impeller blade loading due to imipeller-diffuser interaction in centrifugal compressor stages. The capability of simulations are assessed by comparing results against unsteady pressure and velocity measurements in the vaneless space. …
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Correlation between Unsteady Loading and Tip Gap Flow Occurring in a Linear Cascade with Simulated Stator-Rotor Interaction
… Measurements of the midspan and the tip blade loading were made using static pressure taps. The tip loading shows that the minimum suction surface pressure coefficient increases in magnitude linearly up to a tip clearance of 7.9% chord. Unsteady pressure was measured on the pressure and suction …
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Characterization of unsteady flow processes in a centrifugal compressor stage
… have been implemented to characterize the unsteady loading on the rotating impeller blades in a modem centrifugal compressor. These consist of unsteady Reynolds-averaged Navier Stokes simulations of three-dimensional and quasi-two dimensional approximate models. The interaction between the …
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Stator loading measurements behind a fan with trailing edge blowing
The effects of trailing edge blowing on stator unsteady loading were investigated through a set of experiments on a trailing edge blowing fan. Flow field measurements and stator unsteady loading measurements were taken at five radial locations. Reductions in the relative wake harmonics were seen at …
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Characterization of the flow field response to vaneless space reduction in centrifugal compressors
The unsteady three-dimensional flow field for two centrifugal compressors of nearly identical design (one with a marginally smaller impeller-diffuser gap) is interrogated to assess the difference in the time averaged performance and unsteady loading characteristics of the impeller blades. …
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Granular Activated Carbon Sorption as a Load Equalization Mechanism in Operation of Air Pollution Control Devices
Transient periods of unsteady loading pose a challenge in design and operation of bioreactors for air pollution control. As a potential means of overcoming some of these challenges, a systematic study of granular activated carbon (GAC) sorption was conducted to further evaluate its potential as a …
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Predicting Interference Patterns Between Offshore Wind Farms through Wake Analysis
… in some cases, threatens structural integrity. Unsteady loading and fluxes in wind turbine power generation are born out of turbulence and can further lead to a reduction in the overall energy production of a wind farm. As the offshore wind industry exhibits rapid growth, an immediate need for …
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Rotor Inflow Noise Caused by a Boundary Layer: Inflow Measurements and Noise Predictions
… 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 wall in the …
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Real Airfoil Effects on Leading Edge Noise
… to determine the effects of airfoil shape on the unsteady loading spectrum on the different airfoils to attempt to explain the far-field noise. Measurements of the unsteady surface pressure on a single airfoil were made for a number of angles of attack to determine the effects of wind tunnel …
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High-Fidelity Modeling of eVTOL Rotor Unsteady Aerodynamic and Aeroacoustic Response to Time-Harmonic Gust
… aerodynamic and acoustic response of rotors to unsteady inflow represents a major uncertainty in community-noise assessment and certification. This thesis investigates the aerodynamic and aeroacoustic behavior of a representative eVTOL rotor subjected to time-harmonic inflow disturbances, …
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Forced response of a centrifugal compressor stage due to the impeller-diffuser interaction
The unsteady pressure field experienced by a centrifugal compressor stage can be dominated by of the impeller-diffuser interaction. The energy of the unsteady field, under certain aerodynamic and structural conditions, is capable of forcing the rotating impeller blades to vibrate excessively to the …
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Analytical Unsteady Aerodynamic Models for Horizontal Axis Wind Turbines
This thesis describes the development of unsteady aerodynamic models of wind turbines within the framework of blade element momentum theory. The main purpose is to build analytical models, and test them against available wind tunnel and field test data. The unsteady wake is modeled using vortex …
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Modification of Blade-Vortex Interactions Using Leading Edge Blowing
The interaction of an unsteady wake with a solid body can induce sizable loading of the structure, which has many detrimental side effects in both the structural and acoustic senses. These interactions are ubiquitous in nature and engineering. A flow control technique is sought to mitigate this …
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Propeller Noise Prediction of an Urban Air Mobility Vehicle in Urban Environment
… Air Mobility (UAM) vehicles operate in complex, unsteady aerodynamic environments where wake interactions, gust and turbulence significantly affect both performance and noise generation. Understanding these mechanisms is critical for developing quieter and more efficient eVTOL systems that meet …
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The Impact of Three Dimensional Flow Anisotropy and Transients on Turbulence Ingestion Noise in Open Rotors
… of the measurements taken. Overall the flow was unsteady, particularly in the outer region of the boundary layer. The sound radiated was shown to be tonal during the first half of the interaction, where the flow is dominated by a deterministic mean flow change, and attributed to a form of …
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A study of the application of air-jet vortex generators to intake ducts
… at the engine face, and hence, reduce the unsteady loading on the engine. Both vane and air jets have been tested experimentally as vortex generators and each has been found to reduce the flow distortion that would otherwise reach the engine face. The objective of this thesis was to …
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Influence of aspect ratio on dynamic stall of a finite wing
The influence of aspect ratio, AR, on the unsteady aerodynamics of pitching wings was examined by comparing experimental performance, flow measurements, and computational results across a range of different AR wings. Performance measurements were acquired for three wings of AR = 3, 4, 5, and an …
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Towards a silent fan: an investigation of low-speed fan aeroacoustics
… to inflow distortion of the mean flow (giving unsteady blade loading). This means that the product inlet must be designed very carefully to optimally condition the flow. Periodicity in the impeller outlet flow produces rotor-stator interaction tones even with a number of guide vanes chosen to …
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Large Eddy Simulation of Shear-Free Interaction of Homogeneous Turbulence with a Flat-Plate Cascade
… To validate our calculations, we computed the unsteady loading and radiated acoustic pressure field from flat plates interacting with vortical structures. We consider two fundamental problems: (1) A linear cascade of flat plates excited by a vortical wave (gust) given by a 2D Fourier mode, and …
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Unsteady Turbulence Interaction in a Tip Leakage Flow Downstream of a Simulated Axial Compressor Rotor
The unsteady behavior of a tip leakage flow downstream of a simulated axial compressor rotor has been studied. The Virginia Tech low speed linear cascade wind tunnel was adapted to model the unsteady tip leakage flow produced by a rotor operating in the vortical wakes of a set of stator vanes. The …
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