Mechanical Engineering Commons^™

Numerical Analysis Of Internal Hydraulic Jump In Complex Topography, Dylan Macriner

Electronic Thesis and Dissertation Repository

Topographic effects on internal hydraulic jumps in stratified flow over complex geometry are studied. The simulations are motivated by flow conditions present in a channel in Hood Canal, Washington with continuous density profiles and constant inlet velocities.

Results show that mixing in the domain is typically increased by topographic variation, where isolated expansions saw an increase in mixing, but the associated velocity decrease in expansions had contrasting effects on mixing. Likewise, a contraction with an increased velocity caused more mixing, seeing geometry change and velocity acting as compounding factors. 2D results including along channel topographic variation modelled after Hood Canal's …

Direct Numerical Simulation Of Supercritical Co2 Mixing And Combustion, Syed Mohammad Ovais

All Dissertations

The supercritical CO₂ power cycle (sCO₂ ) is a relatively new technology, which promises to reduce CO₂ emissions with potentially higher efficiencies. However due to challenging conditions posed by supercritical pressures, the mixing and ignition phenomena in sCO₂ combustion is relatively less understood and studied. The primary objective of the current study is to investigate these fundamental processes using homogeneous ignition calculations (HMI) and direct numerical simulations (DNS). Broadly, the study is divided into two major parts. In the first part supercritical mixing in sCO₂ relevant conditions is investigated. To achieve this, DNS of temporally …

Complicating Factors In Hydraulic Jumps: The Effects Of Earth's Rotation, Muveno Pascoal Elias Mucaza

Electronic Thesis and Dissertation Repository

Hydraulic jumps at the interface of stratified rotating fluids are studied. The flow is de- fined with continuous density and velocity profiles, with the velocity in each layer changing (upstream shear). The study is conducted in jumps defined by an imposed velocity transition, and jumps developing over a topography.

The numerical simulations conducted showed the qualitative structure of the flow changing in the cross-width direction, as well as the size and amount of turbulence of the jumps. Mixing in these jumps was shown to increase towards the side of the domain where the jumps were larger and more turbulent. The …

An Analysis Of Perceptual Masking Between Stems In Manually-Mixed Multitrack Audio Using A Cross-Analytic Loudness Model, Brian H. Cofer

Audio Engineering Theses

In music production, there are many tools available to an audio engineer throughout the mixing process to bring a song to completion. Among the most common are level balancing, equalization (EQ), and compression. However, these tools still require the subjective judgments of human engineers to create the desired listening experience. While automated mixing algorithms have been increasingly studied, they have yet to match the skills of even an amateur mixing engineer, in major part, because the subjective mixing decisions of an engineer are difficult to replicate by automated systems. The following research was developed with the primary goal of objectively …

Listener Evaluation Of Common Drum Recording And Mixing Techniques, Tucker W. Arbuthnot

Audio Engineering Theses

This thesis explored whether listeners could perceive the differences between samples recorded and mixed according to methods reported by the so-called popular audio press and samples that did not utilize those methods. The three recording methods were: aligning multiple tracks to achieve a coherent phase relationship, microphone selection, and the style of recording. The three mixing methods were: inverting the bottom snare drum microphone to match the top snare drum microphone, having a pre-delay time on a reverb that matched the tempo of the sample, and routing the room microphones to the drummer’s perspective. ABX listening tests, preference surveys, and …

Physical Controllers Vs. Hand-And-Gesture Tracking: Evaluation Of Control Schemes For Vr Audio Mixing, Justin Bennington

Audio Engineering Theses

Alternative control schemes for affecting the characteristics of audio signals have been designed and evaluated within the audio research community. The medium of virtual reality (VR) presents a unique method of sound source visualization using a headset which displays a virtual environment to the user, allowing users to directly control sound sources with minimal intermediary interference with a variety of different controllers. In order to provide insight into the design and evaluation of VR systems for audio mixing, the differences in subject preference between physical controllers and hand-and-gesture detection controls were investigated. A VR audio mixing interface was iteratively developed …

The Effects Of Scale On Granular Mixing In A Double Screw Pyrolyzer, Breanna L. Marmur

Breanna L. Marmur

Granular mixing processes are important to many industries including the pharmaceutical, agricultural, and biotechnology industries. These processes often require both a high degree of homogeneity and a high degree of customizability. As granular mixing processes are so widely employed, a thorough understanding of the mixing dynamics is necessary to understand and control the resulting products. Research into granular mixing processes has been, thus far, largely focused on laboratory scale mixers with simple geometries, while actual industrial processes often require large mixers with complex geometries. Moreover, granular mixing processes are often very sensitive to changes in operating conditions and any solutions …

Open Source 3-D Printed Nutating Mixer, Dhwani K. Trivedi, Joshua M. Pearce

Joshua M. Pearce

As the open source development of additive manufacturing has led to low-cost desktop three-dimensional (3-D) printing, a number of scientists throughout the world have begun to share digital designs of free and open source scientific hardware. Open source scientific hardware enables custom experimentation, laboratory control, rapid upgrading, transparent maintenance, and lower costs in general. To aid in this trend, this study describes the development, design, assembly, and operation of a 3-D printable open source desktop nutating mixer, which provides a fixed 20° platform tilt angle for a gentle three-dimensional (gyrating) agitation of chemical or biological samples (e.g., DNA or blood …

Open Source 3-D Printed Nutating Mixer, Dhwani K. Trivedi, Joshua M. Pearce

Department of Materials Science and Engineering Publications

As the open source development of additive manufacturing has led to low-cost desktop three-dimensional (3-D) printing, a number of scientists throughout the world have begun to share digital designs of free and open source scientific hardware. Open source scientific hardware enables custom experimentation, laboratory control, rapid upgrading, transparent maintenance, and lower costs in general. To aid in this trend, this study describes the development, design, assembly, and operation of a 3-D printable open source desktop nutating mixer, which provides a fixed 20° platform tilt angle for a gentle three-dimensional (gyrating) agitation of chemical or biological samples (e.g., DNA or blood …

Media Mixing Apparatus, Nick Colt, Eric Depew, Kurt Thoele, Chris Ward

Capstone Design Expo Posters

The purpose of this project is to reduce the physical exertion and radiological exposure of the maintenance worker by reducing mixing time of water and resin beads when replacing resin beads in a shipboard tank. Presently, a maintenance worker empties ⅓ cubic foot of resin media into a bucket, and fills the bucket with about 1-⅓ gallons of water. Then the water and resin media is mixed with a paddle by hand, until it appears homogeneous, creating a slurry. The slurry is dumped into a funnel after the mixing process and introduced to the system after the discharge valve is …

Experimental And Theoretical Investigation Of Powder-Binder Mixing Mechanism For Metal Injection Molding

Faculty of Engineering University of Malaya

Metallic powder and binder mixing mechanism plays a vital role in the quality of molded parts in metal injection molding. The present study is intended for experimental and theoretical investigation of powder-binder mixing mechanism to investigate the functional correlation among mixing parameters and performance characteristics for different composition of feedstocks. Powder loading and shear rate are considered as input parameter. Fuzzy expert system is adopted to test the validity of the experimental results by analyzing different numerical error criteria using the viscosity as output with respect to input parameters. The mean relative error and correlation coefficient for type A and …

Dimensionless Criteria For Selecting Tidally-Influenced Advective-Dispersive Desalination Brine Mixing Plume Characterization Models, Alireza Shahvari

Civil & Environmental Engineering Theses & Dissertations

The very nature of requirements for implementing a desalination process is highly spatial due to the need to secure both a source for the operation and sink for brine dilution. Thus, the applicable coastal location is bound to natural tidal mixing characteristics and subjected to a near- or a far-field availability for source and sink. Mixing characteristics of coastal waters are very different from one point to another due to the spatiotemporal tidal characteristic in loco in a manner that it can vary from being highly advective to completely dispersive dominant. Once a location is identified, estimation of corresponding water …

Optimization Of Mixing In A Simulated Biomass Bed Reactor With A Center Feeding Tube, Michael T. Blatnik

Masters Theses 1911 - February 2014

Producing gasoline-type fuels from lignocellulosic biomass has two advantages over producing alcohol-type fuels from plant sugars: gasoline has superior fuel characteristics and plant lignin/cellulose does not compete with human food supplies. A promising technology for converting lignocellulose to fuel is catalytic fast pyrolysis (CFP). The process involves injecting finely ground biomass into a fluidized bed reactor (FBR) at high temperatures, which reduce the biomass to gases that react inside the catalyst particles. This entails complex hydrodynamics to efficiently mix a stream of biomass into a catalyst bed that is fluidized by a separate stream of inert gas. Understanding the hydrodynamics …

Electrokinetic Mixing And Separation In Microfluidic Systems, Fang Yang

Theses and Dissertations

Electrokinetics involves the study of liquid or particle motion under the action of an electric field; it includes electroosmosis, electrophoresis, dielectrophoresis, and electrowetting, etc. The applications of electrokinetics in the development of microfluidic devices have been widely attractive in the past decade. Electrokinetic devices generally require no external mechanical moving parts and can be made portable by replacing the power supply by small battery. Therefore, electrokinetic based microfluidic systems can serve as a viable tool in creating a lab-on-a-chip (LOC) for use in biological and chemical assays. Here we present our works of electrokenitic based mixing and separation in microfluidics …

Flow Distribution And Heat Transfer Coefficients Inside Gas Holes Discharging, Amirhossein Eshtiaghi

LSU Master's Theses

Fluid flow and heat transfer coefficient associated with flow inside short holes (L/D=1) discharging orthogonally into a crossflow was investigated experimentally and numerically for (Re) ̅ ranging from 0.5×105 to 2×105, and blowing ratio ranging from 1.3 to 3.2. The basic configuration studied consists of a feed tube with five orthogonally located gas holes. Four different hole configurations were studied. The transient heat transfer study employs an IR-camera to determine the local heat transfer coefficient inside each hole. Velocity measurements and numerical flow simulation were used to better understand the measured heat transfer distribution inside the hole. The Nusselt number …

Design And Scale-Up Of Production Scale Stirred Tank Fermentors, Ryan Z. Davis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

In the bio/pharmaceutical industry, fermentation is extremely important in pharmaceutical development, and in microbial research. However, new fermentor designs are needed to improve production and reduce costs of complex systems such as cultivation of mammalian cells and genetically engineered micro-organisms. Traditionally, stirred tank design is driven by the oxygen transfer capability needed to achieve cell growth. However, design methodologies available for stirred tank fermentors are insufficient and many times contain errors. The aim of this research is to improve the design of production scale stirred tank fermentors through the development of dimensionless correlations and by providing information on aspects of …

Computational Fluid Dynamic Optimization And Design For The Airborne Laser System, Matthew James Opgenorth

Electronic Theses and Dissertations

The Airborne Laser (ABL) was designed to destroy any ballistic missile shortly after launch that could be a threat to the United States and its allies. The ABL uses several lasers to accomplish the destruction of the ballistic missile, most notably the high powered Chemical Oxygen Iodine Laser (COIL). The COIL is a complex device that could be improved upon in several areas that will result in overall weight reduction, refinement of beam quality, and increased magazine capacity.

This dissertation presents novel design and optimization techniques coupled with fluid dynamics to improve the performance of the COIL system. The focus …

Macroinstability And Perturbation In Turbulent Stirred Tank Flows, Somnath Roy

LSU Doctoral Dissertations

Impeller stirred tank reactors (STRs) are commonly used in the chemical processing industries for a variety of mixing and blending technologies. In this research, a numerical study of flow and mixing inside turbulently agitated STRs are carried out. An immersed boundary method (IBM) is utilized to represent moving impeller geometries in the background of multi-block structured curvilinear fluid. The IBM This curvilinear-IBM methodology is further combined with the large eddy simulation (LES) technique to address the issue of modeling unsteady turbulent flows in the STR. Verification of the combined IBM-LES implementation strategy in curvilinear coordinates is done through comparisons with …

Mixing Effectiveness Of Various Damper-Plenum Configurations, Harry J. Sauer, Pankaj Hande, Fathi Finaish

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Improper mixing of outside air and return air streams in building air conditioning systems has been recognized for years. The problems may lead to nuisance cycling, frequent freeze-stat trips and serious consequences of a frozen or ruptured conditioning coil. It was thought that typical solutions for the problem usually consist of preferred placement of outside air and return air duct penetrations to the mixing box, manipulation of the inlet damper angles and velocity ratio between the outside air and return air streams and the insertion of static flow mixers in the mixing box to help improve the thermal stratification. This …

Active Control Of Spray Combustion, Onur Tuncer

LSU Doctoral Dissertations

Effect of a forced dilution air jet on air-fuel spray mixing and emissions has been investigated. Temperature measurements have been made at a number of forcing frequencies in the range of 100-1100 Hz and blowing ratios between 6-15. Open-loop flame response to forcing has also been acquired by recording pressure and heat release spectra. The results show that the mean temperature field inside the flame can be altered due to jet modulation. Significant effects are observed by forcing at locations close to the dump plane. Enhancements in temperature of the order of 100–200 ˚C, and reduction in pattern factor of …

Numerical Studies On Supersonic Mixing And Combustion Phenomena, Tarek M. Abdel-Salam

Mechanical & Aerospace Engineering Theses & Dissertations

A numerical study is conducted to investigate the mixing, combustion, and flow characteristics of different scramjet-combustor configurations. Three-dimensional models for the combustors have been used. Numerical results are obtained using a finite volume computational fluid dynamics (CFD) code with unstructured grids with sizes between 200,000 and 400,000 cells.

In the first part of the current study, the effects of the side angle of the fuel injectors in both mixing and combustion processes are investigated. Raised (compression) and relieved (expansion) wall-mounted ramps are used with side angles of 0 (unswept), 5, and 10 degrees. Results are obtained for nonreacting flows as …