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Articles 1 - 19 of 19
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Study Of Low Speed Transitional Regime Gas Flows In Microchannels Using Information Preservation (Ip) Method, Umit Kursun
Study Of Low Speed Transitional Regime Gas Flows In Microchannels Using Information Preservation (Ip) Method, Umit Kursun
Electronic Theses and Dissertations
Proper design of thermal management solutions for future nano-scale electronics or photonics will require knowledge of flow and transport through micron-scale ducts. As in the macro-scale conventional counterparts, such micron-scale flow systems would require robust simulation tools for early-stage design iterations. It can be envisioned that an ideal Nanoscale thermal management (NSTM) solution will involve two-phase flow, liquid flow and gas flow. This study focuses on numerical simulation gas flow in microchannels as a fundamental thermal management technique in any future NSTM solution. A wellknown particle-based method, Direct Simulation Monte Carlo (DSMC) is selected as the simulation tool. Unlike continuum …
Design And Performance Evaluation Of An Integrated Miniature Single Stage Centrifugal Compressor And Permanent Magnet Synchronous Motor, Dipjyoti Acharya
Design And Performance Evaluation Of An Integrated Miniature Single Stage Centrifugal Compressor And Permanent Magnet Synchronous Motor, Dipjyoti Acharya
Electronic Theses and Dissertations
An attempt has been made in this present work to design, fabricate and performance evaluate an integrated single stage centrifugal compressor and permanent magnet synchronous motor which is a key component of the reverse brayton cycle cryocooler. An off the shelf compressor – the driven and electric motor – the driver was not available commercially to suffice the requirements of the reverse brayton cryocooler. The integrated compressor-motor system was designed and tested with air as the working fluid at mass flow rate of 7.3 grams per sec, with a compression ratio of 1.58 and driven by a 2 KW permanent …
Commissioning Of A Dynamic Mechanical Analyzerfor The Characterization Of Low Temperature Nitife Shape Memory Alloys, Maruthi Diwakar Nandiraju
Commissioning Of A Dynamic Mechanical Analyzerfor The Characterization Of Low Temperature Nitife Shape Memory Alloys, Maruthi Diwakar Nandiraju
Electronic Theses and Dissertations
NiTiFe shape memory alloys can undergo transformations between cubic, trigonal and monoclinic phases at low temperatures. The low hysteresis associated with the trigonal R-phase transformation make them candidates for actuator applications at low temperatures. However, the literature available on these alloys is limited and there is a need to establish processing structure-property correlations. This study was undertaken with the objective of determining and understanding such correlations in a Ni46.8Ti50Fe3.2 alloy. First, a dynamic mechanical analyzer (DMA) was successfully commissioned to facilitate mechanical testing between -150 and 600ºC. The experiments performed over selected ranges of stress and temperature probed a range …
Automated Adaptive Data Center Generation For Meshless Methods, Eric Mitteff
Automated Adaptive Data Center Generation For Meshless Methods, Eric Mitteff
Electronic Theses and Dissertations
Meshless methods have recently received much attention but are yet to reach their full potential as the required problem setup (i.e. collocation point distribution) is still significant and far from automated. The distribution of points still closely resembles the nodes of finite volume-type meshes and the free parameter, c, of the radial-basis expansion functions (RBF) still must be tailored specifically to a problem. The localized meshless collocation method investigated requires a local influence region, or topology, used as the expansion medium to produce the required field derivatives. Tests have shown a regular cartesian point distribution produces optimal results, however, in …
Novel Conceptual Design And Anlysis Of Polymer Derived Ceramic Mems Sensors For Gas Turbine Environment, Narasimha Nagaiah
Novel Conceptual Design And Anlysis Of Polymer Derived Ceramic Mems Sensors For Gas Turbine Environment, Narasimha Nagaiah
Electronic Theses and Dissertations
Technical challenges for developing micro sensors for Ultra High Temperature and turbine applications lie in that the sensors have to survive extremely harsh working conditions that exist when converting fuel to energy. These conditions include high temperatures (500-1500°C), elevated pressures (200-400 psi), pressure oscillations, corrosive environments (oxidizing conditions, gaseous alkali, and water vapors), surface coating or fouling, and high particulate loading. Several technologies are currently underdeveloped for measuring these parameters in turbine engines. One of them is an optical-based non-contact technology. However, these nondirective measuring technologies lack the necessary accuracy, at least at present state. An alternative way to measure …
Design And Implementation Of An Emission Spectroscopy Diagnostic In A High-Pressure Strand Burner For The Study Of Solid Propell, Jason Arvanetes
Design And Implementation Of An Emission Spectroscopy Diagnostic In A High-Pressure Strand Burner For The Study Of Solid Propell, Jason Arvanetes
Electronic Theses and Dissertations
The application of emission spectroscopy to monitor combustion products of solid rocket propellant combustion can potentially yield valuable data about reactions occurring within the volatile environment of a strand burner. This information can be applied in the solid rocket propellant industry. The current study details the implementation of a compact spectrometer and fiber optic cable to investigate the visible emission generated from three variations of solid propellants. The grating was blazed for a wavelength range from 200 to 800 nm, and the spectrometer system provides time resolutions on the order of 1 millisecond. One propellant formula contained a fine aluminum …
Study Of Heat Transfer Characteristics Of Impinging Air Jet Using Pressure Andn Temperature Sensitive Luminescent Paint, Quan Liu
Electronic Theses and Dissertations
Luminescent coating measurement system is a relatively new technology for quantitative pressure and temperature measurement. Usually referred to as Pressure Sensitive Paint (PSP) and Temperature Sensitive Paint (TSP), luminescent coatings contain sensor molecules, which undergoes a luminescent transition when excited with light of proper wavelength. The reaction is pressure and/or temperature sensitive. The image of TSP or PSP coated model surface can be captured with a scientific grade camera and then processed to obtain full field temperature and pressure distribution with very high fidelity. The preparation time of the technique is short. The measurement system offers an economic alternative to …
System Identification And Fault Detection Of Complex Systems, Dapeng Luo
System Identification And Fault Detection Of Complex Systems, Dapeng Luo
Electronic Theses and Dissertations
The proposed research is devoted to devising system identification and fault detection approaches and algorithms for a system characterized by nonlinear dynamics. Mathematical models of dynamical systems and fault models are built based on observed data from systems. In particular, we will focus on statistical subspace instrumental variable methods which allow the consideration of an appealing mathematical model in many control applications consisting of a nonlinear feedback system with nonlinearities at both inputs and outputs. Different solutions within the proposed framework are presented to solve the system identification and fault detection problems. Specifically, Augmented Subspace Instrumental Variable Identification (ASIVID) approaches …
Efficient Large Scale Transient Heat Conduction Analysis Using A Parallelized Boundary Element Method, Kevin Erhart
Efficient Large Scale Transient Heat Conduction Analysis Using A Parallelized Boundary Element Method, Kevin Erhart
Electronic Theses and Dissertations
A parallel domain decomposition Laplace transform Boundary Element Method, BEM, algorithm for the solution of large-scale transient heat conduction problems will be developed. This is accomplished by building on previous work by the author and including several new additions (most note-worthy is the extension to 3-D) aimed at extending the scope and improving the efficiency of this technique for large-scale problems. A Laplace transform method is utilized to avoid time marching and a Proper Orthogonal Decomposition, POD, interpolation scheme is used to improve the efficiency of the numerical Laplace inversion process. A detailed analysis of the Stehfest Transform (numerical Laplace …
Study Of Discharge Coefficient And Trends In Film Cooling Effectiveness Of Conical Holes With Increasing Diffusion Angles, Humberto Zuniga,
Study Of Discharge Coefficient And Trends In Film Cooling Effectiveness Of Conical Holes With Increasing Diffusion Angles, Humberto Zuniga,
Electronic Theses and Dissertations
Previous studies indicate that increasing the diffusion angle in conical film-cooling holes leads to an improvement in their film cooling effectiveness. Discharge coefficient and film cooling effectiveness measurements are conducted to characterize this behavior. Part of the focus of this investigation is to find out how this trend develops and attempt to ascertain the optimum cone angle, if possible. Six test plates, each with one row of eight conical-shaped cooling holes of equal diffusion angles of 0, 1, 2, 3, 6, or 8 [degrees], with respect to the hole axis are used in this study. The ratios of the hole …
Experiments In Pool Boiling Heat Transfer And Nucleationdynamics Of High Pressure Refrigerants, Daniel Joo
Experiments In Pool Boiling Heat Transfer And Nucleationdynamics Of High Pressure Refrigerants, Daniel Joo
Electronic Theses and Dissertations
A high pressure pool boiling experiment of pressurized R134a is designed and built, utilizing thermochromatic liquid crystal techniques. Liquid crystals thermo-chromatography uses encapsulated liquid crystals that are sensitive to temperature. When exposed to hot temperatures the crystal reflect a blue/violet color, and when exposed to cooler temperatures it reflects a red/orange color. The color value or hue is proportional to its temperature. Using this technique this experiment is capable of studying the physics and thermodynamics of refrigerants under nucleate pool boiling. The main objective of this experiment was the design of the experimental setup. Various designs were tested and validated, …
Preliminary Study On The Impact Of Impingement On The Effectiveness Of Film Cooling In The Presence Of Gas Path Pressure Gradient, Anil Peravali
Preliminary Study On The Impact Of Impingement On The Effectiveness Of Film Cooling In The Presence Of Gas Path Pressure Gradient, Anil Peravali
Electronic Theses and Dissertations
Impingement is the most commonly used method of cooling in the hot stages of gas turbines. This is often combined with film cooling to further increase the cooling performance. The mainstream flow where in the coolant films discharge often has large stream wise pressure variations. All existing studies on coupled film and impingement cooling concentrated on the effect of the film depletion on the impingement heat transfer. This study investigates the impact of impingement on film cooling, where the jets impinging on a flat plate are depleted through arrays of film cooling holes in the presence of pressure gradient in …
A Fluid Structure Interaction Model Of Intracoronary Atherosclerotic Plaque Rupture, Eric Teuma-Melago
A Fluid Structure Interaction Model Of Intracoronary Atherosclerotic Plaque Rupture, Eric Teuma-Melago
Electronic Theses and Dissertations
Plaque rupture with superimposed thrombosis is the primary cause of acute coronary syndromes of unstable angina, myocardial infarction and sudden death. Although intensive studies in the past decade have shed light on the mechanism that causes unstable atheroma, none has directly addressed the clinical observation that most myocardial infarction (MI) patients have moderate stenoses (less than 50%). Considering the important role the arterial wall compliance and pulsitile blood flow play in atheroma rupture, fluid-structure interaction (FSI) phenomenon has been of interest in recent studies. In this thesis, the impact is investigated numerically of coupled blood flow and structural dynamics on …
Design Optimization Of Solid Rocket Motor Grains For Internal Ballistic Performance, Roger Hainline
Design Optimization Of Solid Rocket Motor Grains For Internal Ballistic Performance, Roger Hainline
Electronic Theses and Dissertations
The work presented in this thesis deals with the application of optimization tools to the design of solid rocket motor grains per internal ballistic requirements. Research concentrated on the development of an optimization strategy capable of efficiently and consistently optimizing virtually an unlimited range of radial burning solid rocket motor grain geometries. Optimization tools were applied to the design process of solid rocket motor grains through an optimization framework developed to interface optimization tools with the solid rocket motor design system. This was done within a programming architecture common to the grain design system, AML. This commonality in conjunction with …
Rapid Prototyping Of Microfluidic Packages, Michael Pepper
Rapid Prototyping Of Microfluidic Packages, Michael Pepper
Electronic Theses and Dissertations
In the area of MEMS there exists a tremendous need for communication between the micro-device and the macro world. A standard protocol or at least multiple standards would be of great use. Electrical connections have been standardized for many uses and configurations by the integrated circuit industry. Standardization in the IC industry has created a marketplace for digital devices unprecedented. In addition to the number of "off the shelf" products available, there exists the possibility for consumers to mix and match many devices from many different manufacturers. This research proposes some similar solutions as those for integrated circuits for fluid …
Annular Beam Shaping And Optical Trepanning, Danyong Zeng
Annular Beam Shaping And Optical Trepanning, Danyong Zeng
Electronic Theses and Dissertations
Percussion drilling and trepanning are two laser drilling methods. Percussion drilling is accomplished by focusing the laser beam to approximately the required diameter of the hole, exposing the material to one or a series of laser pulses at the same spot to melt and vaporize the material. Drilling by trepanning involves cutting a hole by rotating a laser beam with an optical element or an xy galvo-scanner. Optical trepanning is a new laser drilling method using an annular beam. The annular beams allow numerous irradiance profiles to supply laser energy to the workpiece and thus provide more flexibility in affecting …
Lattice Vibration Study Of Silica Nanoparticle In Suspension, Parveen Sachdeva
Lattice Vibration Study Of Silica Nanoparticle In Suspension, Parveen Sachdeva
Electronic Theses and Dissertations
In recent years considerable research has been done in the area of "nanofluids". Nanofluids are colloidal suspensions of nanometer size metallic or oxide particles in a base fluid such as water, ethylene glycol. Nanofluids show enhanced heat transfer characteristics compared to the base fluid. The thermal transport properties of nanofluids depend on various parameters e.g. interfacial resistance, Brownian motion of particles, liquid layering at the solid-liquid interface and clustering of nanoparticles. In this work atomic scale simulation has been used to study possible mechanisms affecting the heat transfer characteristics of nanofluids. Molecular dynamics simulation for a single silica nanoparticle surrounded …
Oscillatory Flow As A Means Of Enhanced Species Separation: A Three Dimensional Time-Accurate Cfd Analysis, Jennifer Crain
Oscillatory Flow As A Means Of Enhanced Species Separation: A Three Dimensional Time-Accurate Cfd Analysis, Jennifer Crain
Electronic Theses and Dissertations
A fluid that contains species in the presence of a concentration gradient generates unusual phenomena when it is forced into pulsatile motion. For example, each species in the fluid has an enhanced mass transport due to pure molecular diffusion. This enhancement takes place even if there is no net total flow over a cycle of the pulsatile motion. When more than one species in dilute amounts is present in an otherwise pure fluid, called a carrier, each species is transported at a different rate thereby causing a partial separation of the species. This idea traces back to hyperventilation studies done …
Driver-Gas Tailoring For Test-Time Extension Using Unconventional Driver Mixtures, Anthony Amadio
Driver-Gas Tailoring For Test-Time Extension Using Unconventional Driver Mixtures, Anthony Amadio
Electronic Theses and Dissertations
To study combustion chemistry at low temperatures in a shock tube, it is of great importance to increase experimental test times, and this can be done by tailoring the interface between the driver and driven gases. Using unconventional driver-gas tailoring with the assistance of tailoring curves, shock-tube test times were increased from 1 to 15 ms for reflected-shock temperatures below 1000 K. Provided in this thesis is the introduction of tailoring curves, produced from a 1-D perfect gas model for a wide range of driver gases and the production and demonstration of successful driver mixtures containing helium combined with either …