Mechanical Engineering Commons^™

Parametric Study On A Novel Waste Heat Recovery System, Ghaleb Rustom Abdul Sater

Electronic Thesis and Dissertation Repository

The present thesis is based on an industry-sponsor project involving a novel waste heat-to-electricity conversion system. This proprietary system utilizes thermal energy from a low temperature heat sources to produce torque that drives an electric generator to produce electricity. The system needs to be studied through scientific research to help with optimizing the product development, component design, and overall system performance. The main objectives of this study are to develop simulation tools (numerical model) that will allow to simulate the thermo-fluid processes in various system components and to use this numerical model to study the heat transfer and phase-change processes …

Methods For Identifying Acoustic Emissions From The Front Face Of A Small Piezoelectric Blower, Brad K. Solomon

Theses and Dissertations

This thesis focuses on identifying acoustic noise generating components in piezoelectric blowers through transverse velocity measurements and the development of a numerical fluid model. Piezoelectric ceramics have proven useful for many industries and areas of research involving: high precision actuators, noise control, ultrasonic devices, and many other areas. As of late, a unique adaptation of piezoelectric ceramics is surfacing in the area of pumping and cooling. Air pumps that use these ceramics replace the traditional electric motor, resulting in lower power consumption, less moving parts, constant pressure gradients, lower overall weight, and a low profile. The current drawback of this …

Modelling Three-Phase Flow In Metallurgical Processes, Christoph Goniva, Gijsbert Wierink, Kari Heiskanen, Stefan Pirker, Christoph Kloss

Gijsbert Wierink

The interaction between gasses, liquids, and solids plays a critical role in many processes, such as coating, granulation and the blast furnace process. In this paper we present a comprehensive numerical model for three phase flow including droplets, particles and gas. By means of a coupled Computational Fluid Dynamics (CFD) - Discrete Element Method (DEM) approach the physical core phenomena are pictured at a detailed level. Sub-models for droplet deformation, breakup and coalescence as well as droplet-particle and wet particle-particle interaction are applied. The feasibility of this model approach is demonstrated by its application to a rotating drum coater. The …

Aerodynamic Analysis And Drag Coefficient Evaluation Of Time-Trial Bicycle Riders, Peter Nicholas Doval

Theses and Dissertations

Evaluation of drag coefficient often requires wind tunnel experiments and can be prohibitively expensive if not impossible for large objects or systems. Computational Fluid Dynamics (CFD) aerodynamic analysis offers an alternative approach and can be used as a very effective design tool in many industries: automotive, aerospace, marine, etc. The main objective of this research is to investigate feasibility of using non-contact digitizers for developing finite element models of large objects for subsequent CFD analysis. The developed methodology is applied to investigation of time-trial bicycle rider efficiency. Companies competing in this class of racing spend millions trying to optimize bicycle …

Investigation Of Heat Transfer And Flow Using Ribs Within Gas Turbine Blade Cooling Passage: Experimental And Hybrid Les/Rans Modeling, Sourabh Kumar

Theses and Dissertations

Gas turbines are extensively used for aircraft propulsion, land based power generation and various industrial applications. Developments in innovative gas turbine cooling technology enhance the efficiency and power output, with an increase in turbine rotor inlet temperatures. These advancements of turbine cooling have allowed engine design to exceed normal material temperature limits. For internal cooling design, techniques for heat extraction from the surfaces exposed to hot stream are based on the increase of heat transfer areas and on promotion of turbulence of the cooling flow. In this study, it is obtained by casting repeated continuous V and broken V shaped …

Design And Simulation Of Passive Thermal Management System For Lithium-Ion Battery Packs On An Unmanned Ground Vehicle, Kevin Kenneth Parsons

Master's Theses

The transient thermal response of a 15-cell, 48 volt, lithium-ion battery pack for an unmanned ground vehicle was simulated with ANSYS Fluent. Heat generation rates and specific heat capacity of a single cell were experimentally measured and used as input to the thermal model. A heat generation load was applied to each battery and natural convection film boundary conditions were applied to the exterior of the enclosure. The buoyancy-driven natural convection inside the enclosure was modeled along with the radiation heat transfer between internal components. The maximum temperature of the batteries reached 65.6 °C after 630 seconds of usage …

The Extraction Of Shock Waves And Separation And Attachment Lines From Computational Fluid Dynamics Simulations Using Subjective Logic, Matthew C. Lively

Theses and Dissertations

The advancement of computational fluid dynamics to simulate highly complex fluid flow situations have allowed for simulations that require weeks of computation using expensive high performance clusters. These simulations often generate terabytes of data and hinder the design process by greatly increasing the post-processing time. This research discusses a method to extract shock waves and separation and attachment lines as the simulation is calculating and as a post-processing step. Software agents governed by subjective logic were used to make decisions about extracted features in converging and converged data sets. Two different extraction algorithms were incorporated for shock waves and separation …

Simulation Of Counterintuitive Pressure Drop In A Parallel Flow Design For A Specimen Basket For Use In The Advanced Test Reactor, Adam X. Zabriskie

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

To continue improving nuclear energy, new materials must be tested in testing reactors such as the Advanced Test Reactor (ATR) at Idaho National Laboratory. A new test cap section allowed coolant to contact specimens tested in the ATR. A parallel channel test cap section should reduce the pressure drop across this section compared to a single channel. A fluid experiment conducted by Idaho State University showed the pressure drop was actually greater. A Computation Fluid Dynamics simulation using STAR-CCM+ was conducted of the fluid experiment to explain the abnormal pressure drop. The simulation provided evidence of ow through the test …

Computational Fluid Dynamics Analysis Of Butterfly Valve Performance Factors, Adam Del Toro

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Butterfly valves are commonly used to control fluid flow inside of piping systems. A butterfly valve typically consists of a metal disc formed around a central shaft, which acts as its axis of rotation. As a butterfly valve is rotated open, fluid is able to more readily flow past the valve. A butterfly valve’s design is important to understand and is commonly characterized by its own performance factors. How a butterfly valve will perform, while in operation at different opening angles and under different types of flow, is critical information for individuals planning and installing piping systems involving the valve. …

Development And Verification Of A Navier-Stokes Solver With Vorticity Confinement Using Openfoam, Austin Barrett Kimbrell

Masters Theses

Vorticity Confinement (VC) is a numerical technique which enhances computation of fluid flows by acting as negative diffusion within the limit of vortical regions, preventing the inherent numerical dissipation present with conventional methods. VC shares similarities with large eddy simulation (LES), but its behavior is based on a stable negative dissipation of vortical structures controlled by the automatic balance between two parameters, μ [mu] and ε [epsilon].

In this thesis, three-dimensional, parallel-computing Navier-Stokes solvers with VC are developed using the OpenFOAM computational framework. OpenFOAM is an open-source collection of C++ libraries developed for computational fluid dynamics. Object-oriented programming concepts are …

Acceleration Of Cfd And Data Analysis Using Graphics Processors, Ali Khajeh Saeed

Open Access Dissertations

Graphics processing units function well as high performance computing devices for scientific computing. The non-standard processor architecture and high memory bandwidth allow graphics processing units (GPUs) to provide some of the best performance in terms of FLOPS per dollar. Recently these capabilities became accessible for general purpose computations with the CUDA programming environment on NVIDIA GPUs and ATI Stream Computing environment on ATI GPUs. Many applications in computational science are constrained by memory access speeds and can be accelerated significantly by using GPUs as the compute engine. Using graphics processing units as a compute engine gives the personal desktop computer …

Assessments And Computational Simulations In Support Of A Time-Varying Mass Flow Rate Measurement Technique For Pulsatile Gas Flow, Andrew Rice

Dissertations, Master's Theses and Master's Reports - Open

This thesis covers the correction, and verification, development, and implementation of a computational fluid dynamics (CFD) model for an orifice plate meter. Past results were corrected and further expanded on with compressibility effects of acoustic waves being taken into account. One dynamic pressure difference transducer measures the time-varying differential pressure across the orifice meter. A dynamic absolute pressure measurement is also taken at the inlet of the orifice meter, along with a suitable temperature measurement of the mean flow gas. Together these three measurements allow for an incompressible CFD simulation (using a well-tested and robust model) for the cross-section independent …

Vortex Shedding Dynamics In Long Aspect-Ratio Aerodynamics Bodies, Liu Chen

Dissertations, Master's Theses and Master's Reports - Open

The focus of the current dissertation is to study qualitatively the underlying physics of vortex-shedding and wake dynamics in long aspect-ratio aerodynamics in incompressible viscous flow through the use of the KLE method. We carried out a long series of numerical experiments in the cases of flow around the cylinder at low Reynolds numbers. The study of flow at low Reynolds numbers provides an insight in the fluid physics and also plays a critical role when applying to stalled turbine rotors. Many of the conclusions about the qualitative nature of the physical mechanisms characterizing vortex formation, shedding and further interaction …

Computational Investigation Of Ethanol And Bifuel Feasibility In Solstice Engine, Adam Michael Blake

Browse all Theses and Dissertations

A Gasoline Direct Injection (GDI) engine enables an increased fuel efficiency and higher power output than a conventional Port Fuel Injection (PFI) system. By injecting pressurized fuel straight into each cylinder of an internal-combustion engine, the degree of fuel atomization is increased, as well as the fuel vaporization rate. In order to further harness the effects of direct injection, ethanol is implemented as a fuel. The cooling effect of ethanol fuel droplets changing to vapor inside the combustion chamber facilitates a higher compression ratio, thus increasing engine power and efficiency. Three dimensional computational simulation is used to investigate the feasibility …

Feature-Based Neuro-Symbolic Networks For Global Diagnostics, Tracy Lynn Schantz

Electronic Theses and Dissertations

Engineered system diagnostics have been researched over the years with many successful results. From transportation systems to office technologies, many have been equipped with self-diagnostic capabilities and are called Smart Machines. In spite of these advances, current diagnostic systems are driven by direct sensory information without much concern for patterns of the system behavior or features associated with them. For large-scale systems with complex dynamics, global as well as local diagnostics become of great importance, where sensory information is used as input for the local diagnostics, and patterns of behavior or features are utilized for global diagnostics.

The main objective …

Numerical Simulation Of Buoyancy-Driven Turbulent Ventilation In Attic Space Under Winter Conditions, Shimin Wang, Zhigang Shen, Linxia Gu

Department of Mechanical and Materials Engineering: Faculty Publications

Attic design and construction have significant impacts on residential buildings’ energy performance. In order to understand how passive ventilation rates affect ridge-vent attic’s performance, a two-dimensional steady-state finite volume model is employed to simulate the buoyancy-driven turbulent ventilation and heat transfer in a triangular attic space of a gable-roof residential building under winter conditions. The modeled attic has a pitch of 5/12 and a passive ventilation system, consisting of continuous ridge and soffit vents. The v2f model is used to analyze the turbulent air flow and natural convection heat transfer inside the attic. The effects of ambient air temperature, vent …

Simulation Of Whistle Noise Using Computational Fluid Dynamics And Acoustic Finite Element Simulation, Jiawei Liu

Theses and Dissertations--Mechanical Engineering

The prediction of sound generated from fluid flow has always been a difficult subject due to the nonlinearities in the governing equations. However, flow noise can now be simulated with the help of modern computation techniques and super computers. The research presented in this thesis uses the computational fluid dynamics (CFD) and the acoustic finite element method (FEM) in order to simulate the whistle noise caused by vortex shedding. The acoustic results were compared to both analytical solutions and experimental results to better understand the effects of turbulence models, fluid compressibility, and wall boundary meshes on the acoustic frequency response. …

Computational Study On Micro-Pilot Flame Ignition Strategy For A Direct Injection Stratified Charge Rotary Engine, Zachary Steven Votaw

Browse all Theses and Dissertations

The Office of Security of Defense's Assured Fuels Initiative has recently been pressing for a single fuel battle space. This endeavor requires modifying many of the vehicle power plants currently in operation throughout the Armed Forces. The RQ-7 Shadow, an unmanned aerial vehicle (UAV) utilized by the Marine Corp and Army for reconnaissance purposes, is powered by UEL's AR741 rotary engine and functions on aviation fuel. One effort underway has been focused on developing this rotary engine system to operate on heavy fuels using direct injection technology and charge stratification. Although the rotary engine has many advantages over standard reciprocating …