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Articles 1 - 26 of 26
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Controlling Mechanical Properties Of Well-Defined Polymer Networks, Ipek Sacligil
Controlling Mechanical Properties Of Well-Defined Polymer Networks, Ipek Sacligil
Doctoral Dissertations
Polymer networks are one of the most versatile and highly studied material class that revolutionized many aspects of life. Connecting the final network properties to the molecular parameters of its building blocks remains a major research thrust. Recent advances in network synthesis techniques allowed for accurate predictions of elastic modulus in model networks. Tew Group has developed highly efficient, thiol-norbornene networks with controllable mechanical properties. Chapter 2 focuses on modifying the gel fracture energy predicted by Lake-Thomas theory by accounting for loop defects. This study allowed for a priori estimates of gel fracture energy by combining theory, experiments, and simulations. …
Numerical Simulations Of Cavitation In The Oil Pump And Thin-Fluid-Bearing For Automotive Applications, Jiaqi Xu
Electronic Theses and Dissertations
The cavitation in hydraulic pumps and fluid bearings could cause system instability, wearing, and failure. Modern commercial computational fluid dynamics (CFD) solvers such as Simerics Inc and GT-Suite have the capabilities of predicting cavitation. However, the fidelity and accuracy of those models require further evaluation. The aim of the thesis is to develop a methodology to improve the analysis of oil flow and cavitation in the oil circuit. The research project is conducted jointly by the University of Windsor and Politecnico di Torino. 3D CFD models of the vane pump and journal bearing are simulated using Simerics Inc to evaluate …
Improvements Of Renewable Energy: Cavitation Treatment And Optimization Of Hybrid System For Remote Areas, Mohammad Qandil
Improvements Of Renewable Energy: Cavitation Treatment And Optimization Of Hybrid System For Remote Areas, Mohammad Qandil
Theses and Dissertations
The optimization of turbines hydrofoils is to improve the efficiency and lifetime of the hydro turbines. Air treatment is one of the methods to reduce the cavitation effect and improve hydro turbines performance. It is necessary to utilize Computational Fluid Dynamics (CFD) analysis and to generate cavitation at different Angle of Attack (AoA) for the hydrofoil and test a variety of designs of air injection slots through the hydrofoil to optimize the best design. StarCCM+ software is used for CFD simulations. The hydrofoil is tested in a square water tunnel with water entering the tunnel at different velocities for each …
Effect Of Geometry And Fluid Viscosity On Dynamics Of Fluid-Filled Cracks: Insights From Analog Experimental Observations, Haitao Cao, Ezequiel F. Medici, Gregory P. Waite, Roohollah Askari
Effect Of Geometry And Fluid Viscosity On Dynamics Of Fluid-Filled Cracks: Insights From Analog Experimental Observations, Haitao Cao, Ezequiel F. Medici, Gregory P. Waite, Roohollah Askari
Michigan Tech Publications
Fluid-filled volumes in geological systems can change the local stress field in the host rock and may induce brittle deformation as well as crack propagation. Although the mechanisms relating fluid pressure perturbations and seismicity have been widely studied, the fluid-solid interaction inside the crack of a host rock is still not well understood. An analog experimental model of fluid intrusion in cracks between planar layers has been developed to study stress conditions at the margins and tips. A combined high-speed shadowgraph and a photoelasticity imaging system is used to visualize the fluid dynamics and induced stresses on the solid matrix. …
Change In Level Water In Pumping-Plant Intake, R.R. Ergashev, B.T. Xolbutayev
Change In Level Water In Pumping-Plant Intake, R.R. Ergashev, B.T. Xolbutayev
Irrigation and Melioration
A decrease in the water level in the pump chamber of the pumping stations leads to the formation of whirlpools in front of the suction pipes. As a result of air intake, the pump unit operates in cavitation mode and their intensive wear occurs. As the data obtained from the Karshi machine channel show, mainly a decrease in design water levels in the downstream waters is observed at the first pumping station. Depending on the number of simultaneously operating pumping units, the minimum water level in the head pumping station should be from 4.5 m to 5.7 m. The received …
Fundamental Understanding Of Plasma Discharge Formation In Liquid And Multiphase Configurations Through Multiphysics Modeling, Ali Charchi Aghdam
Fundamental Understanding Of Plasma Discharge Formation In Liquid And Multiphase Configurations Through Multiphysics Modeling, Ali Charchi Aghdam
Theses and Dissertations
During the last two decades, non-thermal plasma discharges in and in contact with liquids have received significant attention due to their wide range of applications including chemical analysis, medical, water treatment, fuel processing, etc. Despite the tremendous interest and advances attained in the experimental studies, modeling efforts providing a comprehensive understanding of the underlying physicochemical processes are limited. There is still no unified theory on plasma formation in dense medium and various theories have been proposed such as the presence of bubbles and tunneling which are topics of debate. In the first part of this study, a mathematical model is …
A New Synthesized Microalloys Steel Ods Of High Amplitude Ultrasonically Irradiation, Marzuki Silalahi, Hanif Abdurrahman Wicaksana, Ferhat Aziz, Syahfandi Ahda, Mohamad Riza Iskandar
A New Synthesized Microalloys Steel Ods Of High Amplitude Ultrasonically Irradiation, Marzuki Silalahi, Hanif Abdurrahman Wicaksana, Ferhat Aziz, Syahfandi Ahda, Mohamad Riza Iskandar
Makara Journal of Technology
Micropowders of oxide-dispersion-strengthened (ODS) steel have been synthesized using the ultrasonic irradiation method with variations in amplitude. The ultrasonic irradiation process is performed for 50 h at a frequency of 20 kHz with 40%, 50%, and 60% amplitudes in toluene solution. The formation of Fe-Cr microalloys in the preparation of Fe- 15Cr-0.5Y2O3 powder was analyzed using SEM-EDS, X-ray diffraction (XRD), and TEM-EDS. The percentage of Fe- Cr phase mass fraction of ODS steel micropowder formed during ultrasonic irradiation with 40%:50%:60% amplitude was 12.2%:34.1%:22.1%, with 25.67:77.02:38.51 nm crystallite size. The crystallite size at 50% amplitude was the largest, and the diffusion …
Investigation Of Performance And Cavitation Treatment In A Kaplan Hydro Turbine, Muhannad R. Al-Haddad
Investigation Of Performance And Cavitation Treatment In A Kaplan Hydro Turbine, Muhannad R. Al-Haddad
Theses and Dissertations
Cavitation is a phenomenon that occurs in various turbomachinery applications causing drawbacks on the. Some of these downsides are damaging the components of the system, generating noise and vibration, and loss of the turbine efficiency over time. Thus, it is imperative to address issue of cavitation to increase the life span of the equipment in addition to improve the system performance. This thesis introduces a method used to mitigate the cavitation phenomenon in a 3-inch Kaplan hydro turbine via injecting air at the leading edge of the rotor blades. The study is based on modeling the turbine using Computational Fluid …
Investigation Of Performance And Cavitation Treatment In A Kaplan Hydro Turbine, Muhannad R. Al-Haddad
Investigation Of Performance And Cavitation Treatment In A Kaplan Hydro Turbine, Muhannad R. Al-Haddad
Theses and Dissertations
Cavitation is a phenomenon that occurs in various turbomachinery applications causing drawbacks on the. Some of these downsides are damaging the components of the system, generating noise and vibration, and loss of the turbine efficiency over time. Thus, it is imperative to address issue of cavitation to increase the life span of the equipment in addition to improve the system performance. This thesis introduces a method used to mitigate the cavitation phenomenon in a 3-inch Kaplan hydro turbine via injecting air at the leading edge of the rotor blades. The study is based on modeling the turbine using Computational Fluid …
The Design And Optimization Of Jet-In-Cross-Flow (Jicf) For Engineering Applications: Thermal Uniformity In Gas-Turbines And Cavitation Treatment In Hydro-Turbines, Tarek Mahmoud Mohammed Elgammal
The Design And Optimization Of Jet-In-Cross-Flow (Jicf) For Engineering Applications: Thermal Uniformity In Gas-Turbines And Cavitation Treatment In Hydro-Turbines, Tarek Mahmoud Mohammed Elgammal
Theses and Dissertations
Jet-in-cross-flow (JICF) is a well-known term in thermal flows field. Ranging from the normal phenomenon like the volcano ash and dust plumes to the designed film cooling and air fuel mixing for combustion, JICF is always studied to understand its nature at different conditions. Realizing the behavior of interacting flows and importance of many variables lead to the process of reiterating the shapes and running conditions for better outcomes or minimizing the losses. Summarizing the process under the name of optimization, two JICF applications are analyzed based on the principles of thermodynamics and fluid mechanics, then some redesigns are proposed …
Effect Of Ultrasonic Treatment On The Microstructure And Mechanical Properties Of Al6061 And Composite, Ana S. Exime
Effect Of Ultrasonic Treatment On The Microstructure And Mechanical Properties Of Al6061 And Composite, Ana S. Exime
FIU Electronic Theses and Dissertations
In this study, the effect of ultrasonic treatment (UST) parameters such as amplitude, sonication time, and melt temperature on microstructure and microhardness of Al 6061 alloy is evaluated. The effect of UST on the dispersion of tungsten disulfide (WS2) and carbon nanotubes (CNT) as reinforcement particles in Al 6061 during casting is also studied. The cast Al 6061 with UST demonstrated 32% grain size reduction and 8% increase in the microhardness for optimum processing conditions. The cavitation process induced by UST is responsible for the refinement in microstructure and increase of hardness by enhancing the degassing and nucleation …
A Study Of Development Of A Micro Hydro Turbine System With A Rim Drive And Air Injection Treatment For Cavitation., Tomoki Sakamoto
A Study Of Development Of A Micro Hydro Turbine System With A Rim Drive And Air Injection Treatment For Cavitation., Tomoki Sakamoto
Theses and Dissertations
This thesis presents the study of Kaplan hydro turbines system at a very low head and air injection treatment to reduce cavitation happening around a turbine. Regarding the study of Kaplan hydroturbine system, optimization of hydro turbine system with a rim generator to gain a better performance was conducted by CFD and experiment. E-Motors, the partner of this research, is developing an integrated design to simplify manufacturing and installation. The integrated design includes a rim in the outside of the turbine runner to house the electrical generator rotor, namely rim drive. This approach enables a compact and simple assembly without …
Eulerian Cfd Modeling Of Multiphase Internal Injector Flow And External Sprays, Eli T. Baldwin
Eulerian Cfd Modeling Of Multiphase Internal Injector Flow And External Sprays, Eli T. Baldwin
Doctoral Dissertations
The improvement of combustion systems which use sprays to atomize liquid fuel requires an understanding of that atomization process. Although the secondary break up mechanisms for the far-field of an atomizing spray have been thoroughly studied and well understood for some time, understanding the internal nozzle flow and primary atomization on which the far-field spray depends has proven to be more of a challenge. Flow through fuel injector nozzles can be highly complex and heavily influenced by factors such as turbulence, needle motion, nozzle imperfections, nozzle asymmetry, and phase change. All of this occurs within metallic injectors, making experimental characterization …
Improving The Suction Performance And Stability Of An Inducer With An Integrated Inlet Cover Bleed System Known As A Stability Control Device, Ryan K. Lundgreen
Improving The Suction Performance And Stability Of An Inducer With An Integrated Inlet Cover Bleed System Known As A Stability Control Device, Ryan K. Lundgreen
Theses and Dissertations
The performance of an inducer with the integration of an inlet cover bleed system known as a stability control device (SCD) is investigated using computational fluid dynamics. Inducers are the first stage of high suction performance pumps and are designed to operate under cavitating conditions. Improvements in design have allowed inducers to operate stably with low inlet head conditions, however, cavitation instabilities ultimately lead to pump failure. It has been shown that inducers that employ an SCD fully suppress cavitation instabilities.The performance of an inducer is explored at both on- and off-design flow coefficients, where the flow coefficient is a …
An Investigation Of Off-Design Operation In High Suction Performance Inducers, Ryan Collins Cluff
An Investigation Of Off-Design Operation In High Suction Performance Inducers, Ryan Collins Cluff
Theses and Dissertations
Three-dimensional two-phase unsteady CFD simulations were run on three and four-blade inducers for the purpose of analyzing differences in cavitation stability at design and off-design flow rates. At design flow rates, there were very small differences between the breakdown curves for the three and four-bladed inducers. However, at lower cavitation numbers, the three-bladed inducer exhibited up to three times the rotor forces than the four-bladed inducer. When moving to off-design flow rates, both inducers experienced multiple modes of cavitation instabilities including rotating cavitation, alternate-blade cavitation, and cavitation surge. The four-bladed inducer began experiencing the formation of these modes of instability …
Cavitation In Vial Drop Subjected To Mechanical Shock, Houman Babazadehrokni
Cavitation In Vial Drop Subjected To Mechanical Shock, Houman Babazadehrokni
Electronic Theses and Dissertations
Cavitation is a phenomenon that occurs when the local pressure falls down below the critical pressure. Previous work from the Randolph lab demonstrated that protein aggregates can form when a vial of therapeutic solution is dropped onto a hard surface. The process by which this occurs is most likely shock induced cavitation. During this process, hot spots can be created with temperatures and pressures reaching thousands of Kelvin and hundreds of atmospheres, respectively, leading to degradation of protein therapeutics. This work will extend previous efforts by exploring differences generated by change in vial materials, solutions, drop methods and fill volumes. …
Characterizing Cryogenic Propellant Flow Behavior Through A Cavitating Venturi In Comparison To Alternative Flow Control Mechanisms, Marjorie Adele Ingle
Characterizing Cryogenic Propellant Flow Behavior Through A Cavitating Venturi In Comparison To Alternative Flow Control Mechanisms, Marjorie Adele Ingle
Open Access Theses & Dissertations
The work detailed is an investigation of the use of a cavitating venturi as both a flow control and metering device. This was achieved through the combination of actual experimentation and numerical modeling of the fluid behavior of both liquid water and liquid methane as it passes through the test article designed, developed, and validated here within this study. The discharge coefficient of the cavitating venturi was determined through weigh flow calibration testing to determine an average mass flow rate. Turbine flow meter flow rate readings were used as a point of comparison and the discharge coefficient was computed. The …
Mechanisms Of Microstructure Formation Under The Influence Of Ultrasonic Vibrations, Milan Rakita
Mechanisms Of Microstructure Formation Under The Influence Of Ultrasonic Vibrations, Milan Rakita
Open Access Dissertations
Positive effects of ultrasound on crystallization have been known for almost 90 years. Application of ultrasound has been very successful in many industries, most notably in chemistry, creating a new branch of science - sonochemistry. However, ultrasonication has not found wide commercial application in the solidification processing. The reason for that is the complexity of underlying phenomena and the lack of predicting models which correlate processing parameters with the properties of a product. The purpose of this study is to give some contribution toward better understanding of mechanisms that lead to changes in the solidifying microstructure. It has been found …
Fluid-Structure Interactions With Flexible And Rigid Bodies, David J. Daily
Fluid-Structure Interactions With Flexible And Rigid Bodies, David J. Daily
Theses and Dissertations
Fluid structure interactions occur to some extent in nearly every type of fluid flow. Understanding how structures interact with fluids and visa-versa is of vital importance in many engineering applications. The purpose of this research is to explore how fluids interact with flexible and rigid structures. A computational model was used to model the fluid structure interactions of vibrating synthetic vocal folds. The model simulated the coupling of the fluid and solid domains using a fluid-structure interface boundary condition. The fluid domain used a slightly compressible flow solver to allow for the possibility of acoustic coupling with the subglottal geometry …
A Hybrid Constitutive Model For Creep, Fatigue, And Creep-Fatigue Damage, Calvin Stewart
A Hybrid Constitutive Model For Creep, Fatigue, And Creep-Fatigue Damage, Calvin Stewart
Electronic Theses and Dissertations
In the combustion zone of industrial- and aero- gas turbines, thermomechanical fatigue (TMF) is the dominant damage mechanism. Thermomechanical fatigue is a coupling of independent creep, fatigue, and oxidation damage mechanisms that interact and accelerate microstructural degradation. A mixture of intergranular cracking due to creep, transgranular cracking due to fatigue, and surface embrittlement due to oxidation is often observed in gas turbine components removed from service. The current maintenance scheme for gas turbines is to remove components from service when any criteria (elongation, stress-rupture, crack length, etc.) exceed the designed maximum allowable. Experimental, theoretical, and numerical analyses are performed to …
Cavitation In Pharmaceutical Manufacturing And Shipping, Donn Sederstrom
Cavitation In Pharmaceutical Manufacturing And Shipping, Donn Sederstrom
Electronic Theses and Dissertations
Therapeutic proteins are used to successfully treat hemophilia, Crohn's Disease, diabetes, and cancer. Recent product recalls have occurred because of sub-visible particle formation resulting from the inherent instability of proteins. It has been suggested that particle formation is associated with late stage processing steps of filling, shipping, and delivery. Previous work at the University of Denver demonstrated that fluid cavitation can generate a large number of sub-visible protein particles in ultra clean formulations, but that mitigation can be achieved with fluid property manipulation. The goal of this research was to (1) assess the risk of cavitation under common pharmaceutical manufacturing …
Cavitation Of A Water Jet In Water, Michael Marshall Wright
Cavitation Of A Water Jet In Water, Michael Marshall Wright
Theses and Dissertations
Cavitation is a phenomenon that occurs in liquids when the pressure drops below the vapor pressure of the liquid. Previous research has verified that cavitation bubble collapse is a dynamic and destructive process. An understanding of the behavior of cavitation is necessary to implement this destructive mechanism from an axisymmetric jet for underwater material removal. This work investigates the influence of jet pressure and nozzle diameter on the behavior of a cloud of cavitation bubbles generated by a submerged high-pressure water jet. First, this investigation is put into context with a condensed historical background of cavitation research. Second, a description …
Experimental Characterization Of Baffle Plate Influence On Turbulent And Cavitation Induced Vibrations In Pipe Flow, Gavin J. Holt
Experimental Characterization Of Baffle Plate Influence On Turbulent And Cavitation Induced Vibrations In Pipe Flow, Gavin J. Holt
Theses and Dissertations
Turbulent and cavitation induced pipe vibration is a large problem in industry often resulting in pipe failures. This thesis provides an experimental investigation on turbulent flow and cavitation induced pipe vibration caused by sharp edged baffle plates. Due to large pressure losses across a baffle plate, cavitation can result. Cavitation can be destructive to pipe flow in the form of induced pipe wall vibration and cavitation inception. Incipient and critical cavitation numbers are design points that are often used in designing baffle plate type geometries. This investigation presents how these design limits vary with the influencing parameters by exploring a …
The Effect Of Static Pressure On The Inertial Cavitation Threshold And Collapse Strength, Kenneth Bryan Bader
The Effect Of Static Pressure On The Inertial Cavitation Threshold And Collapse Strength, Kenneth Bryan Bader
Electronic Theses and Dissertations
The amplitude of the acoustic pressure required to nucleate a gas and/or vapor bubble in a fluid, and to have that bubble undergo an inertial collapse, is termed the inertial cavitation threshold. The hydrostatic dependence of the inertial cavitation threshold was measured up to 30 MPa in ultrapure water using a high quality factor spherical resonator. The threshold increased linearly with the hydrostatic pressure and was found to be temperature dependent. The strength of the bubble collapse at the threshold was measured in terms of shock waves and light emissions. The shock amplitudes increased linearly with the hydrostatic pressure, while …
Experimental Investigation Of Cavitation Signatures In An Automotive Torque Converter Using A Microwave Telemetry Technique, Carl L. Anderson, L. Zeng, P. O. Sweger, Amitabh Narain, Jason R. Blough
Experimental Investigation Of Cavitation Signatures In An Automotive Torque Converter Using A Microwave Telemetry Technique, Carl L. Anderson, L. Zeng, P. O. Sweger, Amitabh Narain, Jason R. Blough
Department of Mechanical Engineering-Engineering Mechanics Publications
A unique experimental investigation of cavitation signatures in an automotive torque converter under stall conditions is reported. A quantitative criterion is proposed for predicting early and advanced cavitation in terms of suitable nondimensional pump speeds. The dimensionless pump speed that marks early cavitation is obtained by relating this parameter to the appearance of charge-pressure–dependent pressure fluctuations in the differential pressure transducer readings. The differential pressure transducers were mounted at well-defined locations in the pump passage of a torque converter. The data were transmitted by a wireless telemetry system mounted on the pump housing. Data were received and processed by a …
Interface Cavitation Damage In Polycrystalline Copper, Brent L. Adams, David P. Field
Interface Cavitation Damage In Polycrystalline Copper, Brent L. Adams, David P. Field
Faculty Publications
The authors acknowledge the support of the Office of Basic Energy Sciences of the United States Department of Energy. Determination of an interface damage function (IDF) from a stereological procedure similar to that presented by Hilliard is described. The mathematical and experimental simplicity of the method is utilized in measuring an IDF for polycrystalline copper crept at 0.6T sub m under uniaxial tension. Whereas previous work focused on a five parameter description of the local state of a grain boundary, the domain of the IDF is increased to eight degrees of freedom in the present study to include the complete …