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Pages
 Title
 Aerodynamic analysis of a propeller in a turbulent boundary layer flow.
 Creator
 Lachowski, Felipe Ferreira., Glegg, Stewart A. L., Graduate College
 Date Issued
 20130412
 PURL
 http://purl.flvc.org/fcla/dt/3361938
 Subject Headings
 Turbulent boundary layer, Propellers, Aerodynamics
 Format
 Document (PDF)
 Title
 Prediction of broadband selfnoise of an airfoil.
 Creator
 Gomez, Carlos L., Florida Atlantic University, Glegg, Stewart A. L.
 Abstract/Description

With the increase of air traffic and the introduction of larger aircraft and therefore larger engines, the noise generated by aircraft engines have become of greater importance. In order to address these problems, noise prediction codes must be developed in order to better understand the noise generating process. This thesis addresses important issues related to broadband selfnoise from ducted fans based on the prediction model developed by Glegg and Jochault [1]. By addressing issues...
Show moreWith the increase of air traffic and the introduction of larger aircraft and therefore larger engines, the noise generated by aircraft engines have become of greater importance. In order to address these problems, noise prediction codes must be developed in order to better understand the noise generating process. This thesis addresses important issues related to broadband selfnoise from ducted fans based on the prediction model developed by Glegg and Jochault [1]. By addressing issues regarding the prediction of broadband selfnoise from an isolated airfoil with the observer in the far field directly overhead (at 90° above), improvements can be made to Glegg and Jochault's approach for ducted fans. The prediction of broadband selfnoise at 90° above a single airfoil is done by considering boundary layer parameters, the results obtained are compared with theoretical approaches, as well as experimental results obtained by Brooks [2] in order to verify its accuracy.
Show less  Date Issued
 2006
 PURL
 http://purl.flvc.org/fcla/dt/13377
 Subject Headings
 AerofoilsNoise, Noise control, BladesNoise, RotorsNoise, Acoustical engineeringMathematical models, Acoustic models
 Format
 Document (PDF)
 Title
 Broadband blade self noise prediction for subsonic prop fans.
 Creator
 Jochault, Cyrille Andre., Florida Atlantic University, Glegg, Stewart A. L.
 Abstract/Description

Broadband selfnoise generated by rotating blades in a subsonic ducted propfan is studied for a hard walled cylindrical duct in a uniform flow. An expression for the induct sound power radiated by three selfnoise mechanisms is derived: the TurbulentBoundaryLayerTrailingEdge noise, the LaminarBoundaryLayerVortexShedding noise and the TrailingEdgeBluntness noise. The present theory uses NASA's selfnoise prediction methodology for an isolated airfoil. An efficient method of...
Show moreBroadband selfnoise generated by rotating blades in a subsonic ducted propfan is studied for a hard walled cylindrical duct in a uniform flow. An expression for the induct sound power radiated by three selfnoise mechanisms is derived: the TurbulentBoundaryLayerTrailingEdge noise, the LaminarBoundaryLayerVortexShedding noise and the TrailingEdgeBluntness noise. The present theory uses NASA's selfnoise prediction methodology for an isolated airfoil. An efficient method of programming is presented which reduces the time of computation for multiple radial modes. The results obtained are presented, discussed and compared with BladeTipBoundaryLayer fan noise predictions obtained using the SDPF code developed at FAU. The most important parameters which affect selfnoise are found to be the angle of attack, the effective Mach number and the chord length of the blade. For high angles of attack, the TBLTE noise gives significant amount of sound power especially at the low frequencies. For low effective Mach numbers and at certain angles of attack, the LBLVS noise can have high power levels in the mid and high frequencies. Trailing edge bluntness noise appeared to give insignificant amounts of energy over the whole spectrum compared to the other selfnoise mechanisms.
Show less  Date Issued
 1996
 PURL
 http://purl.flvc.org/fcla/dt/15255
 Subject Headings
 BladesNoise, RotorsNoise, Noise control, AerofoilsNoise
 Format
 Document (PDF)
 Title
 Modeling of shallow water ambient noise directionality using the effective depth approximation.
 Creator
 Galletta, Frank Anton., Florida Atlantic University, Glegg, Stewart A. L.
 Abstract/Description

A theoretical model has been developed to compute the vertical array directional response for surface generated ambient noise in a shallow water environment. The cross spectrum function is based on a normal mode solution to the wave equation in which the effective depth approximation is used to yield closed form solutions for two distinct mode types. The effective depth modes encompass the shallowest grazing angles where the bottom reacts as a pressure release surface to the incident plane...
Show moreA theoretical model has been developed to compute the vertical array directional response for surface generated ambient noise in a shallow water environment. The cross spectrum function is based on a normal mode solution to the wave equation in which the effective depth approximation is used to yield closed form solutions for two distinct mode types. The effective depth modes encompass the shallowest grazing angles where the bottom reacts as a pressure release surface to the incident plane waves. The rigid bottom solution takes over as the grazing angle increases and attenuation becomes significant. The computed vertical array beam output was compared to other models including a fast field wavenumber integration method and a multipath eigenray method with mixed results. The results indicated good agreement for both comparisons with the realization that the effective depth model is sensitive to the approximation discontinuity at the mode transition point.
Show less  Date Issued
 1996
 PURL
 http://purl.flvc.org/fcla/dt/15237
 Subject Headings
 Underwater acousticsMeasurement, NoiseMeasurement, Acoustic surface waves
 Format
 Document (PDF)
 Title
 Model experiments for the acoustic field in a water column which includes the effects of shear in marine sediments.
 Creator
 Hundley, Allen John., Florida Atlantic University, Glegg, Stewart A. L.
 Abstract/Description

A scaled, horizontally stratified shallow water marine acoustic model is constructed for the purpose of investigating the sound field resulting from long range propagation. The characteristics of this sound field in the water column are strongly dependent upon properties of the surficial sediment. One effect is the conversion from compressional waves in the water column to shear waves in the sediment at grazing angles less than the critical. To model a shallow marine environment, concrete is...
Show moreA scaled, horizontally stratified shallow water marine acoustic model is constructed for the purpose of investigating the sound field resulting from long range propagation. The characteristics of this sound field in the water column are strongly dependent upon properties of the surficial sediment. One effect is the conversion from compressional waves in the water column to shear waves in the sediment at grazing angles less than the critical. To model a shallow marine environment, concrete is used as a substrate rock and laminating epoxy is used to model a surficial sediment. Preliminary tests of the effects of the model's environment are performed, and the range dependent sound field as a function of depth is measured for several CW frequencies. These sound field profiles are compared with an approximate predictive theory, and with a numerical solution which treats the sediment properties exactly.
Show less  Date Issued
 1990
 PURL
 http://purl.flvc.org/fcla/dt/14618
 Subject Headings
 Underwater acoustics, Marine sedimentsAcoustic properties
 Format
 Document (PDF)
 Title
 Modelling of underwater ambient noise due to whitecaps.
 Creator
 Elisseeff, Pierre., Florida Atlantic University, Glegg, Stewart A. L.
 Abstract/Description

A theoretical model accounting for underwater ambient noise due to whitecapgenerated bubbles and dropimpacts is developed to investigate the possible mechanisms of ocean noise generation. A general analysis is laid down, leading to expressions of the noise spectrum in an undefined environment. Subsequently the cases of isovelocity and stratified deep oceans are considered, and specific expressions are derived. The stratified deep ocean estimations of the directional spectrum are then...
Show moreA theoretical model accounting for underwater ambient noise due to whitecapgenerated bubbles and dropimpacts is developed to investigate the possible mechanisms of ocean noise generation. A general analysis is laid down, leading to expressions of the noise spectrum in an undefined environment. Subsequently the cases of isovelocity and stratified deep oceans are considered, and specific expressions are derived. The stratified deep ocean estimations of the directional spectrum are then compared to experimental data and a good agreement is found. Finally the absolute noise levels due to bubbles and drop impacts are discussed, and bubble noise is found to be larger than drop impact noise. The collective bubble oscillation hypothesis is also discussed, and although clues are given for and against this hypothesis no rigorous justification for this has been found.
Show less  Date Issued
 1992
 PURL
 http://purl.flvc.org/fcla/dt/14784
 Subject Headings
 Underwater acousticsMeasurement, Acoustic surface waves
 Format
 Document (PDF)
 Title
 Nonlinear convection of a vortex sheet past a cascade of airfoils.
 Creator
 van den Berg, Stanislas Franck., Florida Atlantic University, Glegg, Stewart A. L.
 Abstract/Description

The interaction of rotor turbulence with the stator is currently believed to be the predominant mechanism of noise radiation from turbofans in aircraft engines. This thesis presents a general method to compute unsteady 2D potential flows past a cascade of airfoils. The procedure uses source and vortex distributions on the surface of the airfoils, creation of wakes downstream of the airfoils and nonlinear convection of the perturbed flow. These features are designed to satisfy a condition of...
Show moreThe interaction of rotor turbulence with the stator is currently believed to be the predominant mechanism of noise radiation from turbofans in aircraft engines. This thesis presents a general method to compute unsteady 2D potential flows past a cascade of airfoils. The procedure uses source and vortex distributions on the surface of the airfoils, creation of wakes downstream of the airfoils and nonlinear convection of the perturbed flow. These features are designed to satisfy a condition of noflow through the surface of the airfoils and the Kutta condition at the trailing edge of each of these airfoils. The investigation proves the importance of applying the Kutta condition. It was also shown that an infinite cascade is well approximated by a small number of airfoils and that the nonlinear rather than linear convection of vorticity has a large effect on the spectrum of the unsteady lift of an airfoil.
Show less  Date Issued
 1998
 PURL
 http://purl.flvc.org/fcla/dt/15586
 Subject Headings
 Vortexmotion, Cascades (Fluid dynamics), Unsteady flow (Fluid dynamics)
 Format
 Document (PDF)
 Title
 Radius distribution of ocean near surface bubbles.
 Creator
 Auffret, Yvan., Florida Atlantic University, Glegg, Stewart A. L.
 Abstract/Description

This study proposed to determine an ocean surface bubble radius distribution using theoretical noise models, experimental noise spectral data and a theoretical model for the bubble size distribution. The obtained distribution was compared to previous experimental distributions. A good agreement was found for the radius upper cutoff but the shape and the peak radius of the distribution are different from experimental observations. The most probable reasons for these differences were given....
Show moreThis study proposed to determine an ocean surface bubble radius distribution using theoretical noise models, experimental noise spectral data and a theoretical model for the bubble size distribution. The obtained distribution was compared to previous experimental distributions. A good agreement was found for the radius upper cutoff but the shape and the peak radius of the distribution are different from experimental observations. The most probable reasons for these differences were given. Moreover, the validity of recent theoretical bubble noise models was checked. Eventually, the main limitations of the study were pointed out and directions for future works were given.
Show less  Date Issued
 1993
 PURL
 http://purl.flvc.org/fcla/dt/14922
 Subject Headings
 Underwater acoustics, Acoustic surface waves, Bubbles
 Format
 Document (PDF)
 Title
 Response of a cascade of blades to an incoming turbulent flow.
 Creator
 Bocquillion, Olivier Christophe., Florida Atlantic University, Glegg, Stewart A. L.
 Abstract/Description

The purpose of this research is to study the modification of a turbulent flow as it passes through a cascade of flat plates. The results will then be compared with experimental results obtained in a companion experimental study being conducted at Virginia Tech. In a typical marine propulsor turbulent flow passes through a set of inlet guide vanes (IGVs) and then interacts with the propeller blades: this process creates unwanted vibration and sound. The purpose of this research is to determine...
Show moreThe purpose of this research is to study the modification of a turbulent flow as it passes through a cascade of flat plates. The results will then be compared with experimental results obtained in a companion experimental study being conducted at Virginia Tech. In a typical marine propulsor turbulent flow passes through a set of inlet guide vanes (IGVs) and then interacts with the propeller blades: this process creates unwanted vibration and sound. The purpose of this research is to determine if the arrangement of the IGVs can be used to reduce the propulsor noise generation. In this study the incoming flow to the propeller is modeled as homogeneous turbulence and the IGVs are represented by a cascade of flat plates. We will consider the equations, which describe the blade response to an incoming harmonic gust, and we will represent the turbulent flow using a modal description.
Show less  Date Issued
 2003
 PURL
 http://purl.flvc.org/fcla/dt/12971
 Subject Headings
 Blades, Turbulence, Cascades (Fluid dynamics)
 Format
 Document (PDF)
 Title
 The effects of sensor mislocation in vertical arrays.
 Creator
 Joy, David Raymond., Florida Atlantic University, Glegg, Stewart A. L.
 Abstract/Description

Knowledge of the effects of sensor mislocation is necessary for interpreting the outputs from vertical acoustic receiver arrays deployed in the ocean. The first phase of this study consists of deriving a numerical method to determine the geometric shape of a flexible array cable, anchored at its upper end and displaced by horizontal ocean currents. Analytic methods to verify the numerical method are then derived. The second phase of this study considers measurements of a simple sound source...
Show moreKnowledge of the effects of sensor mislocation is necessary for interpreting the outputs from vertical acoustic receiver arrays deployed in the ocean. The first phase of this study consists of deriving a numerical method to determine the geometric shape of a flexible array cable, anchored at its upper end and displaced by horizontal ocean currents. Analytic methods to verify the numerical method are then derived. The second phase of this study considers measurements of a simple sound source by perturbed array cables. The results are compared with those from straight cables to ascertain the effect of the sensor mislocation. These effects are evaluated in terms of array cable curvature and tilt.
Show less  Date Issued
 1990
 PURL
 http://purl.flvc.org/fcla/dt/14595
 Subject Headings
 Underwater acoustics
 Format
 Document (PDF)
 Title
 A comparison of shallow water sound propagation measurements and computer model predictions.
 Creator
 Cichock, Joseph Arnold., Florida Atlantic University, Glegg, Stewart A. L.
 Abstract/Description

Highresolution sound propagation measurements were made on a 1/10000 thscale model of the Santa Lucia Escarpment, located off the Southern California coast. The tank was modified from previous experiments using a rubber coating on the tank bottom. High frequency, high resolution, Transmission Loss measurements were made on the SFTF range, Dania Florida. The Parabolic Equation Model RAM was used to validate these measurement sets. A new approach to account for shear wave effects on the...
Show moreHighresolution sound propagation measurements were made on a 1/10000 thscale model of the Santa Lucia Escarpment, located off the Southern California coast. The tank was modified from previous experiments using a rubber coating on the tank bottom. High frequency, high resolution, Transmission Loss measurements were made on the SFTF range, Dania Florida. The Parabolic Equation Model RAM was used to validate these measurement sets. A new approach to account for shear wave effects on the Transmission Loss for the RAM model was developed. Using this new approach, the scaled low frequency Santa Lucia measurements showed excellent agreement with the RAM calculated TL, but there were discrepancies in the predictions of the high frequency at sea measurements at ranges greater than 1 km.
Show less  Date Issued
 2000
 PURL
 http://purl.flvc.org/fcla/dt/12706
 Subject Headings
 Underwater acoustics, SoundTransmission
 Format
 Document (PDF)
 Title
 An experimental study of the response of circular plates subjected to fluid loading.
 Creator
 Coulson, Robert Kenneth., Florida Atlantic University, Glegg, Stewart A. L.
 Abstract/Description

The interaction between vibrating structures and fluids can have a profound influence upon the natural frequencies of the structure's vibration. This study examines one specific structure; a thin circular plate with the rarely studied free edge condition. It starts by considering a completely free plate in a vacuum and then, using receptance matching, utilises this result to determine the effects, on the natural frequencies, of a centrally located driving rod. Then, using the same technique,...
Show moreThe interaction between vibrating structures and fluids can have a profound influence upon the natural frequencies of the structure's vibration. This study examines one specific structure; a thin circular plate with the rarely studied free edge condition. It starts by considering a completely free plate in a vacuum and then, using receptance matching, utilises this result to determine the effects, on the natural frequencies, of a centrally located driving rod. Then, using the same technique, a result for the drive admittance of the fluid loaded plate is adapted to predict the natural frequencies of the same structure when subjected to significant fluid loading. All these results are then compared to those obtained from experiments.
Show less  Date Issued
 1990
 PURL
 http://purl.flvc.org/fcla/dt/14605
 Subject Headings
 Plates (Engineering)Vibration, Acoustical engineering
 Format
 Document (PDF)
 Title
 Lowfrequency source height measurements.
 Creator
 Armstrong, Joseph., Florida Atlantic University, Glegg, Stewart A. L.
 Abstract/Description

The Federal Highway Administration's development of a new highway noise prediction model (TNM) necessitated the collection of equivalent source height data on moving highway vehicles as a function of frequency. An original method developed by Glegg and Yoon was used in the initial collection of this data. Analysis of this data indicated the measured source height was overestimated at frequencies below 500 Hz. In order to improve the equivalent source height estimates below this frequency two...
Show moreThe Federal Highway Administration's development of a new highway noise prediction model (TNM) necessitated the collection of equivalent source height data on moving highway vehicles as a function of frequency. An original method developed by Glegg and Yoon was used in the initial collection of this data. Analysis of this data indicated the measured source height was overestimated at frequencies below 500 Hz. In order to improve the equivalent source height estimates below this frequency two alternative methods were investigated. The first method made use of the coherence function to remove noise from the autospectral density estimate for an array element through the cross spectra of two other elements. This method is called the noise extraction method and was found to be ineffective for this application. However, the second method used matchedfield processing, and a significant improvement in the estimated equivalent source heights was achieved for frequencies below 500 Hz.
Show less  Date Issued
 1996
 PURL
 http://purl.flvc.org/fcla/dt/15333
 Subject Headings
 Noise barriersEvaluation, Underwater acoustics
 Format
 Document (PDF)
 Title
 A passive platform for tracking underwater vehicles.
 Creator
 Dufour, Emmanuel R., Florida Atlantic University, Glegg, Stewart A. L.
 Abstract/Description

Over recent years, the trend in Autonomous Underwater Vehicle (AUV) design has been to reduce vehicle size and cost. On board navigation systems are both large and expensive so alternate solutions for vehicle positioning are required. The thesis explores the performance of a passive platform, the Ambient Noise Sonar (ANS), in remotely detecting, localizing and tracking submersible vessels. This task is achieved by exploiting communication signatures emitted by the moving submersible. The...
Show moreOver recent years, the trend in Autonomous Underwater Vehicle (AUV) design has been to reduce vehicle size and cost. On board navigation systems are both large and expensive so alternate solutions for vehicle positioning are required. The thesis explores the performance of a passive platform, the Ambient Noise Sonar (ANS), in remotely detecting, localizing and tracking submersible vessels. This task is achieved by exploiting communication signatures emitted by the moving submersible. The utility modem integrated on the AUV can be operated in a PSK and a MFSK mode. It was demonstrated that the ANS successfully tracks AUVs in both cases. First, the thesis presents the sonar beamformer and shows its potential for tracking by using the AUV communication signals. It describes a scheme developed to enhance the processor performance in a multitarget configuration and clutter. Then, it discusses promising tracking results from experiments conducted in summer and fall 1998, off the coast of South Florida.
Show less  Date Issued
 1999
 PURL
 http://purl.flvc.org/fcla/dt/15671
 Subject Headings
 Oceanographic submersiblesAutomatic control, Underwater acoustics, Acoustical engineering
 Format
 Document (PDF)
 Title
 Investigating the effects of measured noise source heights on the predicted insertion loss of noise barriers in the new TNM software.
 Creator
 Glynn, Charles D., Florida Atlantic University, Glegg, Stewart A. L.
 Abstract/Description

At the present time the Federal Highway Administration is developing a new highway noise prediction model called TNM that is anticipated to be a superior model than its predecessor STAMINA 2.0. TNM will use frequency dependent measured noise source heights as a function of speed, acceleration, pavement type, road grade and vehicle class in its propagation loss and insertion loss calculations. Also, TNM will split the equivalent source height into two subsources at specified heights and...
Show moreAt the present time the Federal Highway Administration is developing a new highway noise prediction model called TNM that is anticipated to be a superior model than its predecessor STAMINA 2.0. TNM will use frequency dependent measured noise source heights as a function of speed, acceleration, pavement type, road grade and vehicle class in its propagation loss and insertion loss calculations. Also, TNM will split the equivalent source height into two subsources at specified heights and calculate the insertion loss of noise barriers from these two subsources. The accuracy of this concept is investigated in this thesis, and it is found that on the average the two subsource approach is less accurate than the single equivalent source approximation but will overestimate the attenuated levels, thus a conservative barrier height can be designed from this result.
Show less  Date Issued
 1997
 PURL
 http://purl.flvc.org/fcla/dt/15411
 Subject Headings
 Traffic noiseMathematical models, Noise barriersMathematical models
 Format
 Document (PDF)
 Title
 FarField Noise From a Rotor in a Wind Tunnel.
 Creator
 Grant, Justin Alexander, Glegg, Stewart A. L., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

This project is intended to demonstrate the current state of knowledge in the prediction of the tonal and broadband noise radiation from a Sevik rotor. The rotor measurements were made at the Virginia Tech Stability Wind Tunnel. Details of the rotor noise and flow measurements were presented by Wisda et al(2014) and Murray et al(2015) respectively. This study presents predictions based on an approach detailed by Glegg et al(2015) for the broadband noise generated by a rotor in an...
Show moreThis project is intended to demonstrate the current state of knowledge in the prediction of the tonal and broadband noise radiation from a Sevik rotor. The rotor measurements were made at the Virginia Tech Stability Wind Tunnel. Details of the rotor noise and flow measurements were presented by Wisda et al(2014) and Murray et al(2015) respectively. This study presents predictions based on an approach detailed by Glegg et al(2015) for the broadband noise generated by a rotor in an inhomogeneous flow, and compares them to measured noise radiated from the rotor at prescribed observer locations. Discrepancies between the measurements and predictions led to comprehensive study of the flow in the wind tunnel and the discovery of a vortex upstream of the rotor at low advance ratios. The study presents results of RANS simulations. The static pressure and velocity profile in the domain near the rotor's tip gap region were compared to measurements obtained from a pressure port array and a PIV visualization of the rotor in the wind tunnel.
Show less  Date Issued
 2015
 PURL
 http://purl.flvc.org/fau/fd/FA00004501, http://purl.flvc.org/fau/fd/FA00004501
 Subject Headings
 Aerodynamic noise, Computational fluid dynamics, Fluid dynamic measurement, Fluid mechanics  Mathematical models, Fluid structure interactioin, Turbomachines  Fluid dynamics, Turbulence  Mathematical models, Unsteady flow (Fluid dynamics)
 Format
 Document (PDF)
 Title
 On the Low Order Model of Turbulence in the Wake of a Cylinder and Airfoil – URANS Approach.
 Creator
 Whelchel, Jeremiah Mark, Glegg, Stewart A. L., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

This thesis has described a Reynolds Averaged Navier Stokes approach to modeling turbulence in the wake of a cylinder and airfoil. The mean flow, cross stresses, and twopoint space time correlation structure was analyzed for an untripped cylinder with a Reynolds number based on the cylinder diameter and freestream velocity of 60,000. The same features were also analyzed using this approach for an untripped NACA 0012 airfoil with a Reynolds number based on the airfoil chord and freestream...
Show moreThis thesis has described a Reynolds Averaged Navier Stokes approach to modeling turbulence in the wake of a cylinder and airfoil. The mean flow, cross stresses, and twopoint space time correlation structure was analyzed for an untripped cylinder with a Reynolds number based on the cylinder diameter and freestream velocity of 60,000. The same features were also analyzed using this approach for an untripped NACA 0012 airfoil with a Reynolds number based on the airfoil chord and freestream velocity of 328,000. These simulation results were compared to experimental and newly developed models for validation. The ultimate goal of this present study was to create the twopoint space time correlation function of a cylinder and airfoil wake using RANS calculations which contributes to a larger study where the sound radiated by an open rotor due to ingestion of turbulence.
Show less  Date Issued
 2018
 PURL
 http://purl.flvc.org/fau/fd/FA00013105
 Subject Headings
 TurbulenceNoiseMathematical models., Aerodynamic noise., Wakes (Aerodynamics)., Reynolds number.
 Format
 Document (PDF)
 Title
 Noise Radiation From A Cylindrical Embossment Immersed In Turbulent Boundary Layer Flow.
 Creator
 Bryan, Benjamin Skyler, Glegg, Stewart A. L., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

This dissertation will consider the sound radiation from forwardfacing steps and a three dimensional cylindrical embossment of very low aspect ratio mounted on a plate. Glegg et al (2014) outlined a theory for predicting the sound radiation from separated flows and applied the method to predicting the sound from forwardfacing steps. In order to validate this theory it has been applied to the results of Catlett et al (2014) and Ji and Wang (2010). This validation study revealed that the...
Show moreThis dissertation will consider the sound radiation from forwardfacing steps and a three dimensional cylindrical embossment of very low aspect ratio mounted on a plate. Glegg et al (2014) outlined a theory for predicting the sound radiation from separated flows and applied the method to predicting the sound from forwardfacing steps. In order to validate this theory it has been applied to the results of Catlett et al (2014) and Ji and Wang (2010). This validation study revealed that the original theory could be adjusted to include a mixed scaling which gives a better prediction. RANS simulations have been performed and used to support the similarities between the forwardfacing step and the cylindrical embossment. The simulations revealed that the cylindrical embossment exhibits a separation zone similar to that of the forwardfacing step. This separation zone has been shown to be the dominant source of noise on the forwardfacing step in previous works and therefore was expected to be the major source of sound from the cylindrical embossment. The sensitivity of this separation zone to the different parameters of the flow has been investigated by performing several simulations with different conditions and geometries. The separation zone was seen to be independent of Reynolds number based on boundary layer thickness but was directly dependent on the height of the cylinder. The theory outlined in Glegg et al (2014) was then reformulated for use with a cylindrical embossment and the predictions have been compared with wind tunnel measurements. The final predictions show good agreement with the wind tunnel measurements and the farfield sound shows a clearly defined directionality that is similar to an axial dipole at low frequencies.
Show less  Date Issued
 2015
 PURL
 http://purl.flvc.org/fau/fd/FA00004484, http://purl.flvc.org/fau/fd/FA00004484
 Subject Headings
 Acoustic models, Aerodynamic noise, Computational fluid dynamcs, Fluid structure interaction, Structural dynamics, Turbulence  Mathematical models
 Format
 Document (PDF)
 Title
 Predicting the flow & noise of a rotor in a turbulent boundary layer using an actuator disk – Rans approach.
 Creator
 Buono, Armand C., Glegg, Stewart A. L., Florida Atlantic University, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

The numerical method presented in this study attempts to predict the mean, nonuniform flow field upstream of a propeller partially immersed in a thick turbulent boundary layer with an actuator disk using CFD based on RANS in ANSYS FLUENT. Three different configurations, involving an infinitely thin actuator disk in the freestream (Configuration 1), an actuator disk near a wall with a turbulent boundary layer (Configuration 2), and an actuator disk with a hub near a wall with a turbulent...
Show moreThe numerical method presented in this study attempts to predict the mean, nonuniform flow field upstream of a propeller partially immersed in a thick turbulent boundary layer with an actuator disk using CFD based on RANS in ANSYS FLUENT. Three different configurations, involving an infinitely thin actuator disk in the freestream (Configuration 1), an actuator disk near a wall with a turbulent boundary layer (Configuration 2), and an actuator disk with a hub near a wall with a turbulent boundary layer (Configuration 3), were analyzed for a variety of advance ratios ranging from J = 0.48 to J =1.44. CFD results are shown to be in agreement with previous works and validated with experimental data of reverse flow occurring within the boundary layer above the flat plate upstream of a rotor in the Virginia Tech’s Stability Wind Tunnel facility. Results from Configuration 3 will be used in future aeroacoustic computations.
Show less  Date Issued
 2014
 PURL
 http://purl.flvc.org/fau/fd/FA00004269, http://purl.flvc.org/fau/fd/FA00004269
 Subject Headings
 Aeroelasticity, Computational fluid dynamics, Fluid dynamic measurements, Fluid mechanics  Mathematical models, Turbomachines  Fluid dynamics, Turbulence  Mathematical models
 Format
 Document (PDF)
 Title
 ACOUSTIC SOURCE ASSESSMENT USING SOURCE BREAKDOWN.
 Creator
 SMART, RICHARD C., Florida Atlantic University, Glegg, Stewart A. L., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
 Abstract/Description

Knowledge of vehicle source heights is necessary for noise barrier design, but currently, no reliable method exists to measure this parameter. This study involves the development of system to evaluate source heights using a method known as the source breakdown technique. The first phase of this study consists of the demonstration of the source breakdown technique on loudspeakers in an anechoic chamber. The second phase involves tests outdoors using loudspeakers in the presence of ground...
Show moreKnowledge of vehicle source heights is necessary for noise barrier design, but currently, no reliable method exists to measure this parameter. This study involves the development of system to evaluate source heights using a method known as the source breakdown technique. The first phase of this study consists of the demonstration of the source breakdown technique on loudspeakers in an anechoic chamber. The second phase involves tests outdoors using loudspeakers in the presence of ground reflections. The third phase consists of an assessment of sources on a single vehicle. In the first two phases, source breakdown results are compared with actual measurements for verification. Noise and source mislocation errors are considered, as well as methods to reduce their detrimental effects.
Show less  Date Issued
 1987
 PURL
 http://purl.flvc.org/fcla/dt/14393
 Subject Headings
 Traffic noiseMeasurement
 Format
 Document (PDF)