Mechanical Engineering Commons^™

Numerical Simulations Of Premixed Flames Of Multi Component Fuels/Air Mixtures And Their Applications, Essa Kh I J Salem

Theses and Dissertations--Mechanical Engineering

Combustion has been used for a long time as a means of energy extraction. However, in the recent years there has been further increase in air pollution, through pollutants such as nitrogen oxides, acid rain etc. To solve this problem, there is a need to reduce carbon and nitrogen oxides through lean burning, fuel dilution and usage of bi-product fuel gases. A numerical analysis has been carried out to investigate the effectiveness of several reduced mechanisms, in terms of computational time and accuracy. The cases were tested for the combustion of hydrocarbons diluted with hydrogen, syngas, and bi-product fuel in …

Experimental And Numerical Characterization Of Multiphase Subsurface Oil Release, Feng Gao

Dissertations

Subsurface oil release is commonly encountered in the natural environment and engineering applications and has received the substantial attention of researchers after the disastrous Deepwater Horizon Blowout oil spill in 2009. The main focus on the present research is to systematically study the hydrodynamics of underwater oil jet under a variety of conditions, including the effect of dispersant and different gas to oil ratios (GOR) by using experimental measurement as well as a Computational Fluid Dynamics (CFD) approach, from which the measured turbulent characteristics (e.g., velocity, turbulent kinetic energy, turbulence dissipation rate, etc.) of underwater oil jet are thoroughly examined …

Performance Of C2H4 Reductant In Activated-Carbon-Supported Mnox-Based Scr Catalyst At Low Temperatures, Guangli Liu, Dongtai Han, Jie Cheng, Yongshi Feng, Wenbin Quan, Li Yang, Kozo Saito

Mechanical Engineering Faculty Publications

Hydrocarbons as reductants show promising results for replacing NH₃ in SCR technology. Therefore, considerable interest exists for developing low-temperature (< 200 °C) and environmentally friendly HC-SCR catalysts. Hence, C₂H₄ was examined as a reductant using activated-carbon-supported MnOx-based catalyst in low-temperature SCR operation. Its sensitivity to Mn concentration and operating temperature was parametrically studied, the results of which showed that the catalyst activity followed the order of 130 °C > 150 °C > 180 °C with an optimized Mn concentration near 3.0 wt.%. However, rapid deactivation of catalytic activity also occurred when using C₂H₄ as the reductant. The mechanism of deactivation was explored and is …

Modeling And Simulation Of The Thermoforming Process In Thermoplastic-Matrix Composite Materials, Philip M. Bean

Electronic Theses and Dissertations

Thermoplastic-matrix composite materials have unique advantages over traditional thermosets including faster processing, improved fracture toughness, and recyclability. These and other benefits have caused increasing interest in the use of these materials in both aerospace and automotive industries. Due to the differences in behavior, these materials require a different type of manufacturing process to thermoset matrix composites. This manufacturing process generally involves using pre manufactured tape-layers. These layers, containing both thermoplastic-matrix and fiber-reinforcement, are aligned to the desired orientation, and stacked up into a “tailored blank” using an automated tape layup machine. They are then heated to the thermoplastic melting temperature …

Metal Thin Film Stiffness Extraction Technique For Surface Acoustic Wave Filters, Travis R. Weismeyer

Electronic Theses and Dissertations

Accurate knowledge of the surface acoustic wave (SAW) properties propagating at the surface of a piezoelectric substrate with thin films, electrodes or temperature compensated films, is critical in SAW filter design to meet the target frequency response, power durability and performance prior to device fabrication. While reliable material constants exist for substrates such as LiNbO3 used in SAW filters, the absolute elastic constants associated with operational thin films used for electrodes or temperature compensation do not exist. Although the bulk values of the constituent materials are known, the composite film/substrate properties are difficult to predict since they depend strongly on …

Feasible Form Parameter Design Of Complex Ship Hull Form Geometry, Thomas L. Mcculloch

University of New Orleans Theses and Dissertations

This thesis introduces a new methodology for robust form parameter design of complex hull form geometry via constraint programming, automatic differentiation, interval arithmetic, and truncated hierarchical B- splines. To date, there has been no clearly stated methodology for assuring consistency of general (equality and inequality) constraints across an entire geometric form parameter ship hull design space. In contrast, the method to be given here can be used to produce guaranteed narrowing of the design space, such that infeasible portions are eliminated. Furthermore, we can guarantee that any set of form parameters generated by our method will be self consistent. It …

Mechanical Engineering News, Georgia Southern University

Mechanical Engineering News (2013-2023)

• Georgia Southern Research Focus Prompts R2 Carnegie Designation

Development And Thermodynamic Analysis Of An Integrated Mild/Partial Gasification Combined Cycle (Impgc) Under Green And Brown Field Conditions With And Without Carbon Capture, Henry A. Long Iii

University of New Orleans Theses and Dissertations

Coal is a very prominent energy source in the world, but it is environmentally unattractive due to its high sulfur and ash content as well as its alleged contribution towards climate change, but it is affordable, abundant, and has high energy content. Thus, utilizing coal in a cleaner and more efficient way has become necessary. One promising clean coal technology involves fully gasifying coal into synthesis gas, cleaning it, and feeding it into a high-efficiency combined cycle, such as an Integrated Gasification Combined Cycle (IGCC). Inspired by the recent success of warn gas cleanup (WGCU), mild and partial gasification are …

Dynamic Response Of A Hingeless Helicopter Rotor Blade At Hovering And Forward Flights, Pratik Sarker

University of New Orleans Theses and Dissertations

The helicopter possesses the unrivaled capacity for vertical takeoff and landing which has made the helicopter suitable for numerous tasks such as carrying passengers and equipment, providing air medical services, firefighting, and other military and civil tasks. The nature of the aerodynamic environment surrounding the helicopter gives rise to a significant amount of vibration to its whole body. Among different sources of vibrations, the main rotor blade is the major contributor. The dynamic characteristics of the hingeless rotor consisting of elastic blades are of particular interest because of the strongly coupled equations of motion. The elastic rotor blades are subjected …

Multi-Grid Acceleration Scheme For Neutron Transport Calculations Using Optimally Diffusive Cmfd Method, Lakshay Jain, Ramamoorthy Karthikeyan, Umasankari Kannan

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

Method of characteristics (MOC) is one of the most efficient deterministic techniques for high fidelity neutronic analysis of complex and heterogeneous reactor problems. However, the conventional MOC inner-outer iteration scheme suffers from poor convergence speeds for problems with large scattering to transport cross-section ratio and/or large dominance ratio. This creates a serious hindrance for its effective application to realistic reactor problems. A High Order – Low Order (HO-LO) multi-grid scheme using optimally diffusive coarse mesh finite difference (odCMFD) method has been introduced for improving the performance of code DIAMOND, an assembly level neutronic analysis code based on MOC and unstructured …

Xenon Dynamics Of Ahwr, Arindam Chakraborty, Baltej Singh

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

Large core reactors where the core dimension is significantly large compared to the migration length of neutron are more susceptible to xenon instability due to local perturbations. Advanced Heavy Water Reactor (AHWR) is being designed for on-power refueling. Therefore, refueling or movement of control devices in AHWR causes local perturbation. Preliminary modal analysis of AHWR equilibrium core also showed that the eigenvalue separation between fundamental mode and 1st azimuthal mode is small indicating its susceptibility to xenon oscillation in azimuthal plane. Therefore, xenon dynamic studies for AHWR with explicit xenon calculations were carried out using diffusion theory based computer code …

Transient Simulation Of Lbe Cooled Chtr Under Natural Circulation With 3d Multi-Physics Code Arch-Th, D. K. Dwivedi, Anurag Gupta, Umasankari Kannan

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

India is developing a 100kWth Compact High Temperature Reactor (CHTR) to facilitate demonstration of technologies for high temperature process heat applications. CHTR is being designed as thorium based TRISO fueled and beryllium oxide moderated prismatic block type vertical core cooled with lead-bismuth eutectic (LBE) under natural circulation for 1000°C outlet. The new concept of high temperature core requires multi-physics multi-scale modeling based tools for investigating the normal operational behavior as well as anticipated transients of CHTR. In view of that, 3D multi-physics code ARCH-TH is being indigenously developed and validated for coupled neutronics-thermal hydraulic benchmarks. The multi-group diffusion based neutron …

Flow And Thermal Effects Of Blockages In A Nano-Fluid Cooled Nuclear Fuel Subassembly, Shubham Mandot, N. Govindha Rasu

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

Nanofluids have a great impact on heat transfer characteristics due to increased thermal conductivity and heat transfer coefficient. In this study, Titanium nanoparticles mixed in liquid sodium has been chosen for analyzing the effect of Nanofluid coolant for a Nuclear Sub- assembly. This study is conducted to observe the effect of nanoparticles on the flow properties and heat transfer characteristics such as velocity, heat transfer coefficient, clad temperature, coolant temperature etc. These effects have been observed for varying nanoparticle concentration and different flow blockage sizes. For this study, 7-pin fuel bundle with and without blockage has been modeled and analyzed …

Transient Analysis Of Primary Feed Pump Trip For 700 Mwe Iphwr, S. Phani Krishna, S. Pahari, S. Hajela, M. Singhal

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

700 MWe Indian Pressurized Heavy Water Reactor (IPHWR) is a horizontal channel type reactor with two loops of Primary Heat Transport (PHTS) system. Three (two operating and one stand by) main boiler feed water pumps (BFP) supply feed water to Steam Generators (SGs). In the event of one of the running BFP trip, standby comes on line on auto. Transient analysis for this event is performed using in- house computer code ATMIKA.T .The transient has been initiated by tripping one of the pumps.

Two cases are postulated:

1: BFP Trip and Standby BFP available on auto
2: BFP Trip and …

Heavy Water Concentration Measurement In Air, A. Gupta, D. V. Uduapa, A. Topkar, A. K. Mohanty

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

The heavy water in PHWRs flows at high temperature and pressure, hence leaks in the heat transport system are not uncommon. The loss of heavy water due to such leaks can lead to spreading of radioactivity and it also contributes to operating cost of the nuclear reactor. It is advantageous to detect small leaks, because if remains undetected, they may develop into a severe leak, which may lead to reactor shutdown. None of the sensors which are currently in use can meet all the requirement of high sensitivity, and real time measurement which is free from interference from other gamma …

Design And Evaluation Of A 3d Printed Filar Micrometer, Emily M. Rull

ELAIA

Background Double stars are celestial objects that allow for calculating the mass of stars by assessing their orbits. Stellar mass affects every current model of stellar evolution, but the most accurate double star orbits can take decades to record. Due to the long-term nature of such observations and lack of groundbreaking research in double star studies, professional astronomers are no longer focused on making these measurements, so amateur astronomers can pick up where professionals have left off. Amateurs can only do this if they can get the equipment that they need at prices they can afford. A personally-manufactured filar micrometer …

Thermal Stratification In Liquid Metal Pools Under Cold Transients, Brendan Ward, Hitesh Bindra

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

Experimental results are presented for understanding the thermal stratification or mixing in a low Prandtl number, Pr, pool due to the injection of a colder (higher density) jet at the bottom of the pool. In liquid metals (Pr<<1), the higher volumetric thermal expansion enhances buoyant forces, aiding in thermal stratification while the low Pr extends the thermal boundary layer. Rayleigh backscattering with swept wavelength interferometry is used to generate the high fidelity distributed temperature data. The high spatial and temporal resolution of the sensors are required to capture the temperature gradient and fluctuations of temperature allowing more …

Non-Optical Imaging Of Flow, Boiling, And Salt Deposition In A Simulated Debris Bed, Molly Ross, Alan Cebula, Steven Eckels, D. S. Mcgregor, Hitesh Bindra

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

Determining flow and heat transfer characteristics in a debris bed or a packed bed is difficult due to the lack of optical access. Non-optical imaging methods, such as x-ray or neutron imaging, can be used to observe flow characteristics and particle deposition, as well as boiling in a packed bed. An amorphous Silicon detector based digital radiography camera can be used to image with either x-rays or neutrons at up to 100 frames per second. The digital radiography camera, coupled with digital image analysis techniques was used to characterize fluid fraction and flow rates in a simulated debris bed. A …

Enhancements To The Discrete Generalized Multigroup Method, R. L. Reed, J. A. Roberts

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

This work seeks to improve the practicality of the discrete generalized multigroup (DGM) method. The DGM method divides a fine-group energy domain into a set of coarse groups. Fine-group fluxes within each coarse group are expanded in an orthogonal basis, and cross section moments are defined to preserve the reaction rates of the fine-group solution. Previous implementations of DGM suffered from large memory requirements, so this work work explores options to reduce the memory footprint by (a) homogenizing cross-section moments over coarse regions and (b) representing discrete-angle dependence through truncated Legendre expansions. Tests were performed using a 1-D, discrete ordinates …

Matryoshka Inspired Statistical Surrogate For Turbulent Mixing, Abhinav Gairola, Hitesh Bindra

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

Thermalhydraulics of reactor plena is often the most challenging problem due to turbulent mixing, role of jets and stratified flows. Due to which, the safety analysis of the overall reactor vessel or reactor system become complex. Inability of the system level analysis codes to accurately model the role of tur- bulent mixing in scalar transport leads to a major source of uncertainties. The computational cost of accurate CFD models renders the sensitivity studies using those for reactor safety ineffective. Reduced order models are needed which can effectively capture the effects of turbulent mixing and can be used for parametric studies …

Progress In Micro-Layered Fast Neutron Detectors, Priyarshini Ghosh, W. Fu, Mark J. Harrison, Patrick K. Doyle, Jeremy A. Roberts, D. S. Mcgregor

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

The study of accident tolerant fuels is ongoing at the Transient Reactor Test Facility (TREAT) at Idaho National Laboratory. The TREAT Facility provides quick, high-energy neutron pulses that simulate various accident conditions. These neutron pulses are presently detected using an array of fast-neutron detectors called Hornyak buttons. Hornyak buttons suffer from poor detection efficiency and significant Ĉerenkov radiation contamination in the signal. A new enabling technology, the micro-layered fast-neutron detector (MLFD), is presented to monitor neutron flux changes during mild-to-severe reactor accidents. The MLFD was designed to overcome the shortcomings of the Hornyak buttons and to improve detection efficiency. The …

Cfd Simulation Of Hydrodynamics And Scrubbing Behaviour Of Iodine Vapors In A Self-Priming Venturi Scrubber, Paridhi Goel, A. K. Nayak

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

In a severe accident scenario, the inadequate heat removal in a nuclear reactor can lead to over pressurization of the containment thus challenging its integrity. If not controlled, this can lead to release of radionuclides and high pressure steam in the environment. To ensure that the containment building remains intact and the reactor depressurizes, the vent line from the reactor is directed to a scrubber tank consisting of multiple venturi scrubbers, metal fiber filter and demister pad (known as Filtered Containment Venting System (FCVS)). This is a passive safety measure suggested for installation in advanced and existing nuclear reactors post …

Critical Heat Flux And Power Transients At Low-Pressure Low-Flow Conditions In Vertical Flow Boiling, S. R.G. Vadlamudi, A. K. Nayak

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

In the advanced boiling water reactor concepts such as AHWR and ESBWR, the recirculation pumps are eliminated in order to simplify the design. During the start-up of such reactors, to establish the natural circulation, the primary coolant has to be heated up slowly in steady steps; it is quite important to determine the characteristics of boiling and critical heat flux (CHF) values in order to establish operational limits. Flow boiling experiments were conducted in an annular channel at very low flow rates and atmospheric pressure varying the inlet subcooling from 20 to 400 C. CHF occurred during the oscillatory flow …

Experimental Evaluation Of Critical Heat Flux In Downward-Facing Boiling On Flat Plate Relevant To In-Vessel Retention In Indian Phwrs, Sumit V. Prasad, A. K. Nayak

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

Retention of corium inside the CV and cool it by calandria vault water is essential to mitigate severe accidents in PHWRs. The thermal failure of CV can be prevented by effective decay heat removal on the outer surface of CV using vault water, which depends on the heat transfer behaviour from the outer surface of CV to the vault water. Determination of limiting heat removal capability of vault water through outer surface of calandria vessel is very important. Since, the calandria vessel has a very large diameter and length, the bottom most part of the calandria vessel almost behaves as …

A Review Of Core Catchers For Advanced Reactors, Samyak Munot, A. K. Nayak

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

In order to address the challenges of severe accident and to ensure safety of people and environment, a core retention device called as “core catcher” has been incorporated in the present and future reactor designs. The concept of core catcher came into existence as early as in early nineties. It is the system which is placed inside the reactor in such a manner that even in the severe accidental scenario, it will retain the corium, quench it and then sustain the coolability of the debris formed due to corium water interactions. From then various approaches to development of core catchers …

Preliminary Assessment Of Steady-State And Transient Reaction-Rate Measurements At The University Of Wisconsin Nuclear Reactor, J. A. Roberts, T. R. Ochs, D. M. Nichols, W. Fu, Y. Cheng, J. C. Boyington, D. S. Mcgregor, P. P.H. Wilson, R. J. Agasie, C. S. Edwards, Y-H. Park

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

Recently, a number of reactor-physics experiments were conducted at the University of Wisconsin Nuclear Reactor (UWNR) using a set of 7 micro-pocket fission detector (MPFD) probes and 3 resistance temperature detector (RTD) probes. The UWNR core is a TRIGA-fueled, MTR conversion using 2x2 fuel bundles separated by coolant channels. Each MPFD probe contained 4 detectors, and each RTD probe contained 6 detectors, all arranged uniformly along the active fuel height. These probes were placed in four different configurations to measure fluxes and temperatures in every accessible coolant channel for a variety of steady-state and transient operations. Relative fluxes can be …

Additive Manufacturing Of Ti6al4v Alloy: A Review, Shunyu Liu, Yung C. Shin

School of Mechanical Engineering Faculty Publications

In this paper, the recent progress on Ti6Al4V fabricated by three mostly developed additive manufacturing (AM) techniques-directed energy deposition (DED), selective laser melting (SLM) and electron beammelting (EBM)-is thoroughly investigated and compared. Fundamental knowledge is provided for the creation of links between processing parameters, resultant microstructures and associated mechanical properties. Room temperature tensile and fatigue properties are also reviewed and compared to traditionally manufactured Ti6Al4V parts. The presence of defects in as-builtAMTi6Al4V components and the influences of these defects on mechanical performances are also critically discussed.

Micro Structured Sensors For Neutron Detection, D. S. Mcgregor, S. L. Bellinger, J. C. Boyington, Y. Cheng, R. G. Fronk, W. Fu, L. C. Henson, J. D. Hewitt, C. W. Hilger, R. M. Hutchins, K. E. Kellogg, J. A. Medina, D. M. Nichols, T. R. Ochs, M. A. Reichenberger, J. A. Roberts, S. R. Stevenson, T. M. Swope, T. C. Unruh

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

The shortage of ³He gas, identified as a problem several years ago, initiated research into alternative neutron detectors for various applications. One such technology is the microstructured semiconductor neutron detector (MSND). These compact detectors have microstructures etched deeply into the substrates that are subsequently backfilled with neutron reactive material. Single sided devices typically have thermal neutron detection efficiencies exceeding 30%, while double sided microstructured semiconductor neutron detectors (DS-MSND) have yielded >69% thermal neutron detection efficiency. Both MSNDs and DS-MSNDs have been integrated into compact low-noise and low-power electronics modules. Dosimetry calculations indicate that these detectors can be used as …

Stratification And Mixing In The Hot Plena Of Liquid Metal-Cooled Reactors, Hitesh Bindra, Brendan Ward, Graham Wilson, Abhinav Gairola

Symposium on Advanced Sensors and Modeling Techniques for Nuclear Reactor Safety

Understanding or modeling the role of stratification and mixing in the plena or containments of nuclear reactors is of prime significance to their safety analysis. Particularly, in case of liquid metal-cooled reactors, thermal stratification in the hot pools under off-normal transients is one of the least understood problems that have multi-physics effects on thermo- mechanics and reactor physics. This is primarily due to lack of high fidelity experimental data for validating CFD or system scale models, which are essential for improved understanding. A scaled liquid metal thermal-hydraulic facility with a scaled hot plenum has been developed at Kansas State University …

Elevated Temperature Progressive Damage And Failure Of Duplex Stainless Steel, Darren P. Luke

Civil Engineering ETDs

Ductile failure of metals has been the focus of research efforts within academia and industry for many years since it is tremendously important for understanding the failure of structures under extreme loading conditions. However, limited research has been dedicated to elevated temperature ductile failure, which is critical for evaluating catastrophic events such as industrial, structural or shipping vessel fires. A detailed investigation was conducted on the structural response of Duplex Stainless Steel at elevated temperatures. The temperature dependence of elastic modulus, yield strength, ultimate strength, and ductility was measured up to 1000°C and a continuum damage plasticity model was developed. …