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- Title
- Emission characteristics of a liquid spray sudden expansion combustor using computational fluid dynamics.
- Creator
- Rodriguez, Daniel, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A sudden expansion combustor (SUE) is analyzed using computation fluid dynamics (CFD). CO emissions and NOx emissions are computed for various operating conditions of the SUE combustor using a can type and an annular type geometrical configurations. The goal of this thesis is to see if the SUE combustor is a viable alternative to conventional combustors which utilize swirlers. It is found that for the can type combustor the NOx emissions were quite low compared to other combustor types but...
Show moreA sudden expansion combustor (SUE) is analyzed using computation fluid dynamics (CFD). CO emissions and NOx emissions are computed for various operating conditions of the SUE combustor using a can type and an annular type geometrical configurations. The goal of this thesis is to see if the SUE combustor is a viable alternative to conventional combustors which utilize swirlers. It is found that for the can type combustor the NOx emissions were quite low compared to other combustor types but the CO emissions were fairly high. The annular combustor shows better CO emissions compared to the can type, but the CO emissions are still high compared to other combustors. Emissions can be improved by providing better mixing in the primary combustion zone. The SUE combustor design needs to be further refined in order for it to be a viable alternative to conventional combustors with swirlers.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fcla/dt/3362574
- Subject Headings
- Fluid dynamics, Data processing, Fluid dynamics, Mathematical models, Computational fluid dynamics, Diffusers, Fluid dynamics
- Format
- Document (PDF)
- Title
- Effects of external disturbance on the flow development near the boundary of a work table.
- Creator
- Auche, Edouard Bernard., Florida Atlantic University, Su, Tsung-Chow
- Abstract/Description
-
This thesis addresses the issue of flow development near the boundary of a work table within a clean room. The flow is subjected to periodic external disturbance, either through the pulsation of a source of mass at fixed location, or a moving vortex. The global system consists of a flat table in a parallel oncoming laminar flow. The source of the disturbance is located in the vicinity of the boundary layer. The strength of disturbance is limited in order to apply the quasi-steady boundary...
Show moreThis thesis addresses the issue of flow development near the boundary of a work table within a clean room. The flow is subjected to periodic external disturbance, either through the pulsation of a source of mass at fixed location, or a moving vortex. The global system consists of a flat table in a parallel oncoming laminar flow. The source of the disturbance is located in the vicinity of the boundary layer. The strength of disturbance is limited in order to apply the quasi-steady boundary layer theory. Based on a quasi-steady assumption, a Thwaytes type integration was performed in order to evaluate the displacement thickness and the shear stress on the wall. A parametric study based upon the change of the pulsation, the location and the strength of the disturbance was included in the study. Thwaytes's deviation applied to unsteady cases proved to be successful, and worth being used in further developments.
Show less - Date Issued
- 1988
- PURL
- http://purl.flvc.org/fcla/dt/14461
- Subject Headings
- Boundary layer, Fluid dynamics
- Format
- Document (PDF)
- Title
- Settling of fine particles.
- Creator
- Kim, Hung Soo., Florida Atlantic University, Scarlatos, Panagiotis (Pete) D., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
This study pertaining to the settling of fine particles is developed using various models and formulas. The model considers two layers, i.e, the suspension zone dominated by perikinetic flocculation and the settling zone governed by gravitational force. In the suspension zone, floc formation of fine particles is simulated by the maximum chain model in which floc parameters and fractal dimension are compared with existing data. In addition, fractal dimension is compared with that of the...
Show moreThis study pertaining to the settling of fine particles is developed using various models and formulas. The model considers two layers, i.e, the suspension zone dominated by perikinetic flocculation and the settling zone governed by gravitational force. In the suspension zone, floc formation of fine particles is simulated by the maximum chain model in which floc parameters and fractal dimension are compared with existing data. In addition, fractal dimension is compared with that of the hierarchical model. The main assumption of the model is that any floc having sixteen particles outweighs Brownian force, and thus the floc starts falling down into the settling zone. The flocs moving from the suspension zone are considered as nonspherical particles in the settling zone. The study uses a dimensionless settling velocity, omega*, for estimation of the sedimentation of flocs. Settling causes aggregation of the depositing flocs. The form of these aggregates is analyzed by the fractal relationship P ~ L delta.
Show less - Date Issued
- 1992
- PURL
- http://purl.flvc.org/fcla/dt/14872
- Subject Headings
- Fluid dynamics, Flow visualization
- Format
- Document (PDF)
- Title
- TWO DIMENSIONAL FLOW WITHIN A TRIANGULAR OSCILLATING CRACK (TURBULENCE, VORTEX STREET, TRANSITION FLOW, MIXING).
- Creator
- KIM, SOO YONG., Florida Atlantic University, Tennant, Jeffrey S., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The transition of two dimensional flow within a crack with oscillating wall is studied experimentally to establish the role of the parameters involved. Multiple instabilities in the fluid are produced by the motion of the oscillating wall. For a better understanding of the flow structure and displaying in the whole flow field at a time, flow visualization was used. Frequency, amplitude, and crack width were systematically varied. The present study shows that, in general, the frequency and...
Show moreThe transition of two dimensional flow within a crack with oscillating wall is studied experimentally to establish the role of the parameters involved. Multiple instabilities in the fluid are produced by the motion of the oscillating wall. For a better understanding of the flow structure and displaying in the whole flow field at a time, flow visualization was used. Frequency, amplitude, and crack width were systematically varied. The present study shows that, in general, the frequency and crack width play a role in the transition process at low frequencies of oscillations. However, amplitude becomes progressively important at its higher range. Results also show that the flow changes its character approximately after a Reynolds number 11420. After that the transition process continues until the Reynolds number 34322 which is the upper limit of variation of frequency (Reynolds number) in the present study.
Show less - Date Issued
- 1986
- PURL
- http://purl.flvc.org/fcla/dt/14312
- Subject Headings
- Fluid dynamics, Flow visualization
- Format
- Document (PDF)
- Title
- Synchronization and phase dynamics of oscillating foils.
- Creator
- Finkel, Cyndee L., Charles E. Schmidt College of Science, Department of Physics
- Abstract/Description
-
In this work, a two-dimensional model representing the vortices that animals produce, when they are flying/swimming, was constructed. A D{shaped cylinder and an oscillating airfoil were used to mimic these body{shed and wing{generated vortices, respectively. The parameters chosen are based on the Reynolds numbers similar to that which is observed in nature (104). In order to imitate the motion of ying/swimming, the entire system was suspended into a water channel from frictionless air...
Show moreIn this work, a two-dimensional model representing the vortices that animals produce, when they are flying/swimming, was constructed. A D{shaped cylinder and an oscillating airfoil were used to mimic these body{shed and wing{generated vortices, respectively. The parameters chosen are based on the Reynolds numbers similar to that which is observed in nature (104). In order to imitate the motion of ying/swimming, the entire system was suspended into a water channel from frictionless air{bearings. The position of the apparatus in the channel was regulated with a linear, closed loop PI controller. Thrust/drag forces were measured with strain gauges and particle image velocimetry (PIV) was used to examine the wake structure that develops. The Strouhal number of the oscillating airfoil was compared to the values observed in nature as the system transitions between the accelerated and steady states... As suggested by previous work, this self-regulation is a result of a limit cycle process that stems from nonlinear periodic oscillations. The limit cycles were used to examine the synchronous conditions due to the coupling of the foil and wake vortices. Noise is a factor that can mask details of the synchronization. In order to control its effect, we study the locking conditions using an analytic technique that only considers the phases.. The results suggest that Strouhal number selection in steady forward natural swimming and flying is the result of a limit cycle process and not actively controlled by an organism. An implication of this is that only relatively simple sensory and control hardware may be necessary to control the steady forward motion of man-made biomimetically propelled vehicles.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fcla/dt/3362333
- Subject Headings
- Mathematical physics, Fluid dynamics, Unsteady flow (Fluid dynamics), Aerofoils, Aerodynamics
- Format
- Document (PDF)
- Title
- Non-linear 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 2-D 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 non-linear 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 2-D 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 non-linear convection of the perturbed flow. These features are designed to satisfy a condition of no-flow 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 non-linear 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
- Vortex-motion, Cascades (Fluid dynamics), Unsteady flow (Fluid dynamics)
- Format
- Document (PDF)
- Title
- PRESSURE FLUCTUATION MEASUREMENT TECHNIQUES IN A CIRCULAR DUCT WITH INCOMPRESSIBLE TURBULENT FLOW (FREQUENCY-WAVENUMBER SPECTRA).
- Creator
- DAVIS, HARRY LEE., Florida Atlantic University, Cuschieri, Joseph M.
- Abstract/Description
-
Turbulent pressure fluctuations and acoustical shock waves formed at pipe discontinuities are the primary source of flow noise. fhe pipe response is excited by the fluctuating forces associated with the turbulent pressure fluctuations. The forcing functions can be determined from the frequency-wavenumber spectrum of the pressure fluctuations. A procedure is developed here to obtain the frequency-wavenumber spectrum due to fully developed turbulent flow. The data analysis procedures developed...
Show moreTurbulent pressure fluctuations and acoustical shock waves formed at pipe discontinuities are the primary source of flow noise. fhe pipe response is excited by the fluctuating forces associated with the turbulent pressure fluctuations. The forcing functions can be determined from the frequency-wavenumber spectrum of the pressure fluctuations. A procedure is developed here to obtain the frequency-wavenumber spectrum due to fully developed turbulent flow. The data analysis procedures developed in this study to analyze the pressure fluctuations provide a good means to determine the frequency-wavenumber spectrum and represent this data in a clear form. Frequency-wavenumber spectra have been obtained for simulated pressure data. In the experimental system designed to collect turbulent pressure data, it was determined that a recessed transducer configuration cannot be used in water pipe flow turbulent pressure fluctuation studies because of the enhanced turbulence created by the upstream holes. Therefore, flush mounted transducers are required.
Show less - Date Issued
- 1986
- PURL
- http://purl.flvc.org/fcla/dt/14330
- Subject Headings
- Turbulence--Measurement, Fluid dynamics
- 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
- Separation flow around airfoil with upstream disturbance by discrete vortex method.
- Creator
- Li, Feng., Florida Atlantic University, Su, Tsung-Chow, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
The discrete vortex method was applied to the calculation of separation flow past NACA 4412 airfoil: Vortex panel was used to represent the body surface and discrete vortices were used to model the wake. Generally the uniform upstream condition is used in the calculation of separation flow. But actually an airfoil could move in wake of other airfoils or disturbed fluid. In this thesis, discrete vortices were used to model the upstream disturbance to investigate the effect of upstream...
Show moreThe discrete vortex method was applied to the calculation of separation flow past NACA 4412 airfoil: Vortex panel was used to represent the body surface and discrete vortices were used to model the wake. Generally the uniform upstream condition is used in the calculation of separation flow. But actually an airfoil could move in wake of other airfoils or disturbed fluid. In this thesis, discrete vortices were used to model the upstream disturbance to investigate the effect of upstream disturbance to the pressure, lift and drag coefficients around the airfoil. Also the animation of separation flow was made on HP workstation using "Starbase" computer graphic package to study the separation process.
Show less - Date Issued
- 1991
- PURL
- http://purl.flvc.org/fcla/dt/14739
- Subject Headings
- Vortex-motion, Fluid dynamics
- Format
- Document (PDF)
- Title
- Far-Field 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
- 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, non-uniform 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, non-uniform 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 aero-acoustic 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
- Rapid distortion theory for rotor inflows.
- Creator
- Kawashima, Emilia, Glegg, Stewart A. L., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
For aerospace and naval applications where low radiated noise levels are a requirement, rotor noise generated by inflow turbulence is of great interest. Inflow turbulence is stretched and distorted as it is ingested into a thrusting rotor which can have a significant impact on the noise source levels. This thesis studies the distortion of subsonic, high Reynolds number turbulent flow, with viscous effects ignored, that occur when a rotor is embedded in a turbulent boundary layer. The analysis...
Show moreFor aerospace and naval applications where low radiated noise levels are a requirement, rotor noise generated by inflow turbulence is of great interest. Inflow turbulence is stretched and distorted as it is ingested into a thrusting rotor which can have a significant impact on the noise source levels. This thesis studies the distortion of subsonic, high Reynolds number turbulent flow, with viscous effects ignored, that occur when a rotor is embedded in a turbulent boundary layer. The analysis is based on Rapid Distortion Theory (RDT), which describes the linear evolution of turbulent eddies as they are stretched by a mean flow distortion. Providing that the gust does not distort the mean flow streamlines the solution for a mean flow with shear is found to be the same as the solution for a mean potential flow with the addition of a potential flow gust. By investigating the inflow distortion of small-scale turbulence for various simple flows and rotor inflows with weak shear, it is shown that RDT can be applied to incompressible shear flows to determine the flow distortion. It is also shown that RDT can be applied to more complex flows modeled by the Reynolds Averaged Navier Stokes (RANS) equations.
Show less - Date Issued
- 2013
- PURL
- http://purl.flvc.org/fau/fd/FA0004030
- Subject Headings
- Computational fluid dynamics, Fluid dynamic measurements, Fluid mechanics -- Mathematical models, Turbulence -- Computer simulation, Turbulence -- Mathematical models
- Format
- Document (PDF)
- Title
- Upwind return flow in a coastal lagoon: Seasonal-scale barotropic transport.
- Creator
- Pitts, Patrick A., Harbor Branch Oceanographic Institute
- Date Issued
- 1989
- PURL
- http://purl.flvc.org/FCLA/DT/3174021
- Subject Headings
- Lagoons, Fluid dynamics, Estuaries, Geomorphology, Tides
- Format
- Document (PDF)
- Title
- Estimates of water turbine noise levels.
- Creator
- Guerra, Julian., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
This work seeks to understand water turbine noise generation and to make preliminary estimations of the noise levels. Any structure attached to a turbine upstream its blades will generate unsteady fluctuating loads on the blade's surface, which are proportional to the radiated acoustic pressure. The noise levels of a simplified turbine based on existing designs surpass the ambient noise levels of the ocean at low frequencies ( 30 Hz).
Show moreThis work seeks to understand water turbine noise generation and to make preliminary estimations of the noise levels. Any structure attached to a turbine upstream its blades will generate unsteady fluctuating loads on the blade's surface, which are proportional to the radiated acoustic pressure. The noise levels of a simplified turbine based on existing designs surpass the ambient noise levels of the ocean at low frequencies (< 20 Hz) by approximately 50 dB ref 1 μPa and stay under the ambient noise levels at higher frequencies for a blade-passing frequency of 0.83 Hz and point of observation (100 m, 45 degrees, 45 degrees) from the hub. Streamlining the cross-section of the upstream structure as well as reducing its width decrease the noise levels by approximately 40 dB ref 1 μPa, at low frequencies and moderately increase them at higher frequencies. Increasing the structure-rotor distance decreases the noise levels with increasing frequencies (> 30 Hz).
Show less - Date Issued
- 2011
- PURL
- http://purl.flvc.org/FAU/3170958
- Subject Headings
- Turbines, Vibration, Testing, Underwater acoustics, Fluid dynamics
- Format
- Document (PDF)
- Title
- HYDRODYNAMIC PERFORMANCE OF AN UNMANNED CATAMARAN VEHICLE IN HEAD SEAS.
- Creator
- Prasad, Bijoy, Dhanak, Manhar, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
This study analyzes the hydrodynamic performance of an advanced catamaran vehicle using computational fluid dynamics (CFD) simulations and experimental testing data in support of system identification and development of a physics-based control system for unmanned surface vehicle (USV) operations in coastal waters. A series of steps based on increasing complexity are considered sequentially in this study. First the steady flow past the static vehicle, then the vehicle with a fixed orientation...
Show moreThis study analyzes the hydrodynamic performance of an advanced catamaran vehicle using computational fluid dynamics (CFD) simulations and experimental testing data in support of system identification and development of a physics-based control system for unmanned surface vehicle (USV) operations in coastal waters. A series of steps based on increasing complexity are considered sequentially in this study. First the steady flow past the static vehicle, then the vehicle with a fixed orientation advancing in calm water, and finally the vehicle moving with two degrees of freedom (DOF) in calm water as well as head seas. The main objective of the study is to assess the role of general multiphase unsteady Reynolds Averaged Navier Stokes (RANS) as a predictive tool for the hydrodynamic performance of an USV. A parametric analysis of the vehicle performance at different Froude number and wave steepness in shallow waters is conducted. The characteristics of the wave resistance, heaving and pitching motion, wave-hull interactions, and free surface flow patterns are investigated. The study will aid in the design of a robust physics-based control system for the vehicle and provide a tool for prediction of its performance.
Show less - Date Issued
- 2019
- PURL
- http://purl.flvc.org/fau/fd/FA00013404
- Subject Headings
- Catamarans, Computational fluid dynamics, Water waves
- Format
- Document (PDF)
- Title
- Design and evaluation of a swirling flow combustion system.
- Creator
- Li, Ceji., Florida Atlantic University, Moslemian, Davood, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
A swirling flow combustion system has been designed and constructed. An integral laser Doppler velocimeter is constructed for the investigations of fluid mechanics aspects of a swirling flow combustor. The combustor consists of one fuel flow and two swirled air flows. The inner air flow has a fixed swirling strength and the outer air flow has an adjustable swirler. Both counterswirl and coswirl flows with variable swirl strength can be generated. Premixed or non-premixed combustion can be...
Show moreA swirling flow combustion system has been designed and constructed. An integral laser Doppler velocimeter is constructed for the investigations of fluid mechanics aspects of a swirling flow combustor. The combustor consists of one fuel flow and two swirled air flows. The inner air flow has a fixed swirling strength and the outer air flow has an adjustable swirler. Both counterswirl and coswirl flows with variable swirl strength can be generated. Premixed or non-premixed combustion can be investigated on this system. Evaluation of the swirling combustion system and performance check of the velocity measurement system are conducted. Detailed time mean and fluctuating flow measurements are obtained for coswirl and counterswirl conditions with the LDV system. A central recirculation zone is observed in both swirl conditions, but the size in counterswirl is much smaller. The reasons for the difference are discussed.
Show less - Date Issued
- 1991
- PURL
- http://purl.flvc.org/fcla/dt/14767
- Subject Headings
- Fluid dynamics, Vortex-motion, Combustion chambers
- Format
- Document (PDF)
- Title
- Vortex street wakes downstream of truncated and full cylinders in a rotating fluid.
- Creator
- Leader, Bram., Florida Atlantic University, Marshall, Jeffrey S., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
- Abstract/Description
-
An experimental study has been conducted to examine the flow field about and the wake behind truncated cylindrical obstacles of varying height, which are towed through a fluid with a free surface in a rotating system. The results show the development of a vortex street-type wake downstream of the obstacle for retrograde (westward) flows, even for very small ratios of obstacle height to water layer depth. For short obstacles, a pronounced backward flowing jet is observed, which impinges on the...
Show moreAn experimental study has been conducted to examine the flow field about and the wake behind truncated cylindrical obstacles of varying height, which are towed through a fluid with a free surface in a rotating system. The results show the development of a vortex street-type wake downstream of the obstacle for retrograde (westward) flows, even for very small ratios of obstacle height to water layer depth. For short obstacles, a pronounced backward flowing jet is observed, which impinges on the Taylor column from downstream. Prograde (eastward) flows are found to have a meandering wake that extends farther than eight obstacle diameters downstream and do not exhibit backjetting or vortex street formation. Upwelling is believed to occur within the side boundary layers of the Taylor column, which could play a significant role in deep water production in the ocean.
Show less - Date Issued
- 1992
- PURL
- http://purl.flvc.org/fcla/dt/14827
- Subject Headings
- Taylor vortices, Fluid dynamics, Vortex-motion
- Format
- Document (PDF)
- Title
- HYDRODYNAMIC PERFORMANCE AND SEAKEEPING ANALYSIS OF A CATAMARAN IN TRANSFORMING NEAR-SHORE HEAD AND FOLLOWING SEAS.
- Creator
- Ulgen, Kayhan, Dhanak, Manhar R., Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
-
A computational investigation of the hydrodynamic and seakeeping performance of a catamaran in calm, and in the presence of transforming head and following seas in waters of constant and varying depths is described. Parametric studies were conducted for a selected WAM-V 16 catamaran geometry using OpenFOAM® to uncover the physical phenomena. In the process a methodology has been developed for simulating the interactions between the vehicle and the shallow water environment akin to that in the...
Show moreA computational investigation of the hydrodynamic and seakeeping performance of a catamaran in calm, and in the presence of transforming head and following seas in waters of constant and varying depths is described. Parametric studies were conducted for a selected WAM-V 16 catamaran geometry using OpenFOAM® to uncover the physical phenomena. In the process a methodology has been developed for simulating the interactions between the vehicle and the shallow water environment akin to that in the coastal environment. The multiphase flow around the catamaran, including the six degrees-of-freedom motion of the vehicle, was modeled using a Volume of Fluid (VoF) method and solved using a dynamic mesh. The numerical approach was validated through computing benchmark cases and comparing the results with previous work. It is found that in a calm shallow water environment the total resistance, dynamic trim and sinkage of a catamaran in motion can be significantly impacted by the local water depth. The variations of the impact with depth and length-based Froude numbers are characterized. The impact varies as the vehicle moves from shallow waters to deep water or vice versa. In the presence of head and following small-amplitude seas, interesting interactions between incident waves and those generated by the vehicle are observed and are characterized for their variation with Froude number and water depth.
Show less - Date Issued
- 2022
- PURL
- http://purl.flvc.org/fau/fd/FA00013942
- Subject Headings
- Seakeeping, Catamarans, Hydrodynamics, Computational fluid dynamics
- Format
- Document (PDF)
- Title
- FLOW-MEDIATED NAVIGATION AND COORDINATION OF ARTIFICIAL SWIMMERS USING DEEP REINFORCEMENT LEARNING.
- Creator
- Nair, Aishwarya, Verma, Siddhartha, Florida Atlantic University, Department of Ocean and Mechanical Engineering, College of Engineering and Computer Science
- Abstract/Description
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Aquatic organisms are able to achieve swimming efficiencies that are much higher than any underwater vehicle that has been designed by humans. This is mainly due to the adaptive swimming patterns that they display in response to changes in their environment and their behaviors, i.e., hunting, fleeing, or foraging. In this work, we explore these adaptations from a hydrodynamics standpoint, using numerical simulations to emulate self-propelled artificial swimmers in various flow fields. Apart...
Show moreAquatic organisms are able to achieve swimming efficiencies that are much higher than any underwater vehicle that has been designed by humans. This is mainly due to the adaptive swimming patterns that they display in response to changes in their environment and their behaviors, i.e., hunting, fleeing, or foraging. In this work, we explore these adaptations from a hydrodynamics standpoint, using numerical simulations to emulate self-propelled artificial swimmers in various flow fields. Apart from still or uniform flow, the most likely flow field encountered by swimmers are those formed by the wakes of solid objects, such as roots of aquatic vegetation, or underwater structures. Therefore, a simplified bio-inspired design of porous structures consisting of nine cylinders was considered to identify arrangements that could produce wakes of varying velocities and enstrophy, which in turn might provide beneficial environments for underwater swimmers. These structures were analyzed using a combination of numerical simulations and experiments, and the underlying flow physics was examined using a variety of data-analysis techniques. Subsequently, in order to recreate the adaptations of natural swimmers in different flow regimes, artificial swimmers were positioned in each of these different types of flow fields and then trained to optimize their movements to maximize swimming efficiency using deep reinforcement learning. These artificial swimmers utilize a sensory input system that allows them to detect the velocity field and pressure on the surface of their body, which is similar to the lateral line sensing system in biological fish. The results demonstrate that the information gleaned from the simplified lateral line system was sufficient for the swimmer to replicate naturally found behaviors such as K´arm´an gaiting. The phenomenon of schooling in underwater organisms is similarly thought to provide opportunities for swimmers to increase their energy efficiency, along with the other associated benefits. Thus, multiple swimmers were trained using multi-agent reinforcement learning to discover optimal swimming patterns at the group level as well as the individual level.
Show less - Date Issued
- 2024
- PURL
- http://purl.flvc.org/fau/fd/FA00014413
- Subject Headings
- Reinforcement learning, Hydrodynamics, Computational fluid dynamics, .
- Format
- Document (PDF)
- Title
- Data gateway for prognostic health monitoring of ocean-based power generation.
- Creator
- Gundel, Joseph., College of Engineering and Computer Science, Department of Computer and Electrical Engineering and Computer Science
- Abstract/Description
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On August 5, 2010 the U.S. Department of Energy (DOE) has designated the Center for Ocean Energy Technology (COET) at Florida Atlantic University (FAU) as a national center for ocean energy research and development. Their focus is the research and development of open-ocean current systems and associated infrastructure needed to development and testing prototypes. The generation of power is achieved by using a specialized electric generator with a rotor called a turbine. As with all machines,...
Show moreOn August 5, 2010 the U.S. Department of Energy (DOE) has designated the Center for Ocean Energy Technology (COET) at Florida Atlantic University (FAU) as a national center for ocean energy research and development. Their focus is the research and development of open-ocean current systems and associated infrastructure needed to development and testing prototypes. The generation of power is achieved by using a specialized electric generator with a rotor called a turbine. As with all machines, the turbines will need maintenance and replacement as they near the end of their lifecycle. This prognostic health monitoring (PHM) requires data to be collected, stored, and analyzed in order to maximize the lifespan, reduce downtime and predict when failure is eminent. This thesis explores the use of a data gateway which will separate high level software with low level hardware including sensors and actuators. The gateway will v standardize and store the data collected from various sensors with different speeds, formats, and interfaces allowing an easy and uniform transition to a database system for analysis.
Show less - Date Issued
- 2012
- PURL
- http://purl.flvc.org/FAU/3342111
- Subject Headings
- Machinery, Monitoring, Marine turbines, Mathematical models, Fluid dynamics, Structural dynamics
- Format
- Document (PDF)