Mechanical Engineering Commons^™

A New Atomization Paradigm: Smart Wave-Augmented Varicose Explosions, Daniel Mason Wilson

Doctoral Dissertations and Projects

The characterization of viscous, non-Newtonian slurry heating and atomization by means of internal wave excitation is presented for a twin-fluid injector. We detail mechanisms that enhance their disintegration in a novel process called “Wave-Augmented Varicose Explosions” (WAVE). Atomization of such fluids is challenging, especially at low gas-liquid mass ratios. Droplet production is further complicated when slurry viscosity varies widely; if viscosity levels are too high, atomization quality suffers, and an undesirable pressure drop restricts the flow. To mitigate, we introduce and demonstrate “Smart” atomization, a novel implementation of simultaneous proportional integral derivative (PID) control algorithms to accommodate dynamically and extensively …

Simulating Steam Jets Due To Rapid Plate Tectonics: A Computational Fluid Dynamics Analysis, Emilie Hatton

Senior Honors Theses

According to the Bible's account of earth's physical history, the majority of geological change from creation to the Ice Age is a consequence of the global Flood cataclysm described in Genesis 6-8. The changes included large-scale tectonic activity, recycling all pre-Flood ocean floor into the mantle, and generating all present-day igneous ocean floor by seafloor spreading at mid-ocean rift zones. Along the middle of these zones, strips of newly formed seafloor were present near the melting temperature of basaltic magma. Above these strips of extremely hot rock, intense jets of steam would almost certainly form. This research seeks to investigate …

Cfd Simulation Of Anaerobic Granular Sludge Reactors: A Review, Camila D' Bastiani, David Kennedy, Anthony Reynolds

Articles

Anaerobic digestion processes can generate renewable energy in the form of biogas while treating organic wastewater. The generation of biogas within anaerobic digestion systems is directly linked to the mixing conditions inside the reactors. In high-rate reactors such as the up-flow anaerobic sludge blanket (UASB) reactor, the expanded granular sludge bed (EGSB) reactor and the internal circulation (IC) reactor, the hydrodynamic behaviour will depend on the interactions between the wastewater, the biogas, and the biomass granules. Over the past few years, various researchers have used computational fluid dynamics (CFD) to study the hydrodynamic behaviour in these types of reactors. This …

Morton-Ordered Gpu Lattice Boltzmann Cfd Simulations With Application To Blood Flow, Gerald Gallagher, Fergal J. Boyle

Conference Papers

Computational fluid dynamics (CFD) is routinely used for numerically predicting cardiovascular-system medical device fluid flows. Most CFD simulations ignore the suspended cellular phases of blood due to computational constraints, which negatively affects simulation accuracy. A graphics processing unit (GPU) lattice Boltzmann-immersed boundary (LB-IB) CFD software package capable of accurately modelling blood flow is in development by the authors, focusing on the behaviour of plasma and stomatocyte, discocyte and echinocyte red blood cells during flow. Optimised memory ordering and layout schemes yield significant efficiency improvements for LB GPU simulations. In this work, comparisons of row-major-ordered Structure of Arrays (SoA) and Collected …

Effects Of Rotor-Airframe Interaction On The Aeromechanics And Wake Of A Quadcopter In Forward Flight, Denis-Gabriel Caprace, Andrew Ning, Philippe Chatelain, Grégoire Winckelmans

Faculty Publications

From small drones to large Urban Air Mobility vehicles, the market of vertical take-off and landing (VTOL) aircraft is currently booming. Modern VTOL designs feature a variety of configurations involving rotors, lifting surfaces and bluff bodies. The resulting aerodynamics are highly impacted by the interactions between those components and their wakes. This has consequences on the aircraft performance and on the downstream wake. Studying the effects of those interactions through CFD can inform the development of cheaper numerical models. In this work, we focus on the interaction between rotors and bluff bodies based on the example of a generic quadcopter …

Flowunsteady: An Interactional Aerodynamics Solver For Multirotor Aircraft And Wind Energy, Eduardo Alvarez, Judd Mehr, Andrew Ning

Faculty Publications

The ability to accurately and rapidly assess unsteady interactional aerodynamics is a shortcoming and bottleneck in the design of various next-generation aerospace systems: from electric vertical takeoff and landing (eVTOL) aircraft to airborne wind energy (AWE) and wind farms. In this study, we present a meshless CFD framework based on the reformulated vortex particle method (rVPM) for the analysis of complex interactional aerodynamics. The rVPM is a large eddy simulation (LES) solving the Navier-Stokes equations in their vorticity form. It uses a meshless Lagrangian scheme, which not only avoids the hurdles of mesh generation, but it also conserves the vortical …

Modelling And Development Of An Automated Ldpe Autoclave Reactor In Cfd For Revealing Ethylene Hot Spots, Eric Turman

Masters Theses

Computational Fluid Dynamics (CFD) was employed to develop a rigorous model of a low-density polyethylene (LDPE) autoclave reactor. Different numerical settings within the solver were evaluated to minimize false diffusion and to reflect the sensitive heat generation taking place during free radical polymerization. The rigorous CFD model employed reaction kinetics, Proportional Integral Derivative (PID) automated thermal management, and a rotating stirrer shaft. Validation was carried out to determine the sensitivity to time-step size, turbulence model, and grid resolution. Data were compared to an industrial scale plant autoclave to guide the development of CFD. Time-step independence was confirmed by comparing the …

Development & Validation Of A Piv System For Obtaining Data From A Uasb Reactor, Camila D' Bastiani, Gerald Gallagher, David Kennedy, Anthony Reynolds

Conference Papers

Anaerobic digestion processes can generate energy in the form of biogas while treating organic wastewater. The efficiency of the treatment, and thus the generation of biogas, is closely linked to the type and design of the reactor, and the technology used. Granular anaerobic digestion technology offers advantages such as a higher loading rate and reduction of the space needed. However, the hydrodynamics inside this type of reactor can be complex due to the presence of solids (granules) and gas (biogas) phases along with the liquid phase (wastewater). This is one of the reasons why the study and optimization of reactors …

Incorporating High-Fidelity Aerostructural Analyses In Wind Turbine Rotor Optimization, Denis-Gabriel Caprace, Adam Cardoza, Andrew Ning, Marco Mangano, Sicheng He, Joaquim R. R. A. Martins

Faculty Publications

s demand grows for wind turbines with larger blades, the design of future wind turbines must account for multi-physical interactions and an ever-increasing number of design load conditions. One aspect, aerostructural coupling, calls for design tools that are both accurate and computationally efficient. In this paper, we present a combined-fidelity approach that couples high-fidelity computational fluid dynamics and computational solid mechanics simulations, with a conventional aeroelastic turbine modeling tool based on blade element momentum and beam theories. The approach is integrated into a multidisciplinary optimization framework. It takes advantage of the high-fidelity tightly-coupled aerostructural simulations to evaluate the rotor power …

Ignition Process And Flame Lift-Off Characteristics Of Dimethyl Ether (Dme) Reacting Spray, Khanh Duc Cung, Ahmed Abdul Moiz, Xiucheng Zhu, Seong-Young Lee

Michigan Tech Publications

Advanced combustion systems that utilize different combustion modes and alternative fuels have significantly improved combustion performance and emissions compared to conventional diesel or spark-ignited combustions. As an alternative fuel, dimethyl ether (DME) has been receiving much attention as it runs effectively under low-temperature combustion (LTC) modes such as homogeneous charge compression ignition (HCCI) and reactivity control combustion ignition (RCCI). Under compression-ignition (CI), DME can be injected as liquid fuel into a hot chamber, resulting in a diesel-like spray/combustion characteristic. With its high fuel reactivity and unique chemical formula, DME ignites easily but produces almost smokeless combustion. In the current study, …

Modeling And Simulation Of A Supercritical Co2-Liquid Sodium Compact Heat Exchanger For Sodium Fast Reactors, Hailei Wang, Sean M. Kissick

Mechanical and Aerospace Engineering Faculty Publications

The study focuses on modeling and simulations of sodium-sCO2 intermediary compact heat exchangers for sodium-cooled fast reactors (SFR). A simplified 1-D analytical model was developed in companion with a 3-D CFD model. Using classic heat transfer correlations for Nusselt number, some simulation results using the 1-D model have achieved reasonable match with the CFD simulation results for longer channels (i.e., 40 cm and 80 cm). However, for short channel (10 cm) when axial conduction within the sodium fluid is significant, the 1-D model significantly over-predicted the heat transfer effectiveness. By incorporating the temperature-jump model, the 1-D model can extend its …

Three-Phase Hydrodynamic Simulation And Experimental Validation Of An Upflow Anaerobic Sludge Blanket Reactor, Camila D' Bastiani, Jéferson Luis Alba, Gabriel Tomazzoni Mazzarotto, Severino Rodrigues De Farias Neto, Anthony Reynolds, David Kennedy, Lademir Luiz Beal

Articles

This research focuses on performing multiphase solid/liquid/gas CFD simulations of a UASB reactor in order to obtain a validated model that provides a clearer understanding of the hydrodynamic behaviour of the three phases in UASB reactors. Eulerian–Eulerian, laminar, three-dimensional, multiphase simulations are carried out using Fluent 16.2. The liquid phase velocity and flow profile are validated through PIV experiments. A liquid mean velocity difference of 8.45% is found between the experimental and numerical results, thus validating the CFD model. Shadowgraphy is applied successfully to validate the biogas phase velocity and bubble size. Based on the hydrodynamic analysis results, the reactor …

Toward A Fast And Accurate Modeling Strategy For Thermal Management In Air-Cooled Data Centers, Long Tran Bao Phan

FIU Electronic Theses and Dissertations

Computational fluid dynamics (CFD) has become a popular tool compared to experimental measurement for thermal management in data centers. However, it is very time-consuming and resource-intensive when used to model large-scale data centers, and may not be ready for real-time thermal monitoring. In this thesis, the two main goals are first to develop rapid flow simulation to reduce the computing time while maintaining good accuracy, and second, to develop a whole building energy simulation (BES) strategy for data center modeling. To achieve this end, hybrid modeling and model training methodologies are investigated for rapid flow simulation, and a multi-zone model …

Cavitation Number As A Function Of Disk Cavitator Radius: A Numerical Analysis Of Natural Supercavitation, Reid Prichard

Senior Honors Theses

Due to the greater viscosity and density of water compared to air, the maximum speed of underwater travel is severely limited compared to other methods of transportation. However, a technology called supercavitation – which uses a disk-shaped cavitator to envelop a vehicle in a bubble of steam – promises to greatly decrease skin friction drag. While a large cavitator enables the occurrence of supercavitation at low velocities, it adds substantial unnecessary drag at higher speeds. Based on CFD results, a relationship between cavitator diameter and cavitation number is developed, and it is substituted into an existing equation relating drag coefficient …

Cfd/Fea Of A Steam Methane Reforming Tube, Matthew Wegener

Research Opportunities for Engineering Undergraduates (ROEU) Program 2017-18

Steam methane reforming is the primary method by which hydrogen is produced; increased efficiency in hydrogen production could enable hydrogen’s usage as an alternative fuel. The objectives of this project are to construct a robust CFD/FEA model of a steam methane reforming tube, and to perform CFD/FEA analysis in both steady and transient operational states, comparing thermal stresses/strains in the tube wall in the two states and relating tube stresses/strains to properties of the process controller.

Cfd Evaluation Of Mixing Processes For High-Level Nuclear Waste Tanks, Maximiliano Edrei

FIU Electronic Theses and Dissertations

Computational Fluid Dynamics (CFD) has been applied to investigate two aspects of a mixing process for high level nuclear waste tanks. Through CFD the applicability of Poreh’s correlations that are currently used to describe the radial wall jets in the Pulse Jet Mixing (PJM) process were assessed. In addition, simulations were conducted in order to investigate mean hydrodynamic characteristics of sparged non-Newtonian fluids for the use in the PJM process.

Three single phase turbulent simulations using the commercial package STAR-CCM+ were successively conducted. A model validated with experimental data was developed and successively altered to see effects of low characteristic …

Computational Fluid Dynamic Analysis Of Microbubble Drag Reduction Systems At High Reynolds Number, John D. Goolcharan

FIU Electronic Theses and Dissertations

Microbubble drag reduction (MBDR) is an effective method to improve the efficiency of fluid systems. MBDR is a field that has been extensively studied in the past, and experimental values of up to 80% to 90% drag reduction have been obtained. The effectiveness and simplicity of MBDR makes it a viable method for real world applications, particularly in naval applications where it can reduce the drag between the surface of ships and the surrounding water. A two dimensional single phase model was created in ANSYS Fluent to effectively model the behavior of bubble laden flow over a flat plate. This …

Comparison Of Airfoil Precomputational Analysis Methods For Optimization Of Wind Turbine Blades, Ryan Barrett, Andrew Ning

Faculty Publications

The objective of this research was to develop and compare various airfoil precomputational parameterization and analysis techniques for aerostructural optimization of wind turbine blades. The airfoils along the blade were added as optimization design variables through pre-computational parameterization methods using thickness-to-chord ratios and blended airfoil family factors. The airfoils' aerodynamic performance was analyzed with three methods of increasing fidelity: a panel method (XFOIL), Navier-Stokes based computational fluid dynamics (RANS CFD), and wind tunnel data. The optimizations minimized mass over annual energy production (m/AEP) and thereby approximated the minimization of cost of energy. The results were compared to the NREL 5-MW …

Experimental And Computational Study Of Gas Bubble Removal In A Microfluidic System Using Nanofibrous Membranes, Hamed Gholami Derami, Ravindra Vundavilli, Jeff Darabi

SIUE Faculty Research, Scholarship, and Creative Activity

This paper presents a simple and efficient method for removing gas bubbles from a microfluidic system. This bubble removal system uses a T-junction configuration to generate gas bubbles within a water-filled microchannel. The generated bubbles are then transported to a bubble removal region and vented through a hydrophobic nanofibrous membrane. Four different hydrophobic Polytetrafluorethylene (PTFE) membranes with different pore sizes ranging from 0.45 to 3 μm are tested to study the effect of membrane structure on the system performance. The fluidic channel width is 500 μm and channel height ranges from 100 to 300 μm. Additionally, a 3D computational fluid …

Experimental Validation Data For Cfd Of Transient Convection From Forced To Natural With Flow Reversal On A Vertical Flat Plate, Blake W. Lance, Barton L. Smith

Engineering Datasets

Transient convection was investigated experimentally for the purpose of providing Computational Fluid Dynamics (CFD) validation data. A specialized facility for validation experiments called the Rotatable Buoyancy Tunnel was used to acquire thermal and velocity measurements of flow over a smooth, vertical heated plate. The initial condition was forced convection downward with subsequent transition to mixed convection, ending with natural convection upward after a flow reversal. Data acquisition through the transient was repeated for ensemble-averaged results. With simple flow geometry, validation data were acquired at the benchmark level. All boundary conditions (BCs) were measured and their uncertainties quantified. Temperature profiles on …

Evaluation Of The Mass Transfer Effect Of The Stalk Contraction-Relaxation Cycle Of Vorticella Convallaria, Jiazhong Zhou

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Vorticella convallaria is a genus of protozoa living in fresh water. It has a bell-shaped zooid equipped with adoral ciliary bands and a contractile stalk tethering the zooid to a substrate. Vorticella is regarded as a biological spring because its contractile stalk can pull the zooid towards the substrate at a remarkably high speed and then relaxes to its extended state much more slowly. However, reasons for Vorticella’s stalk contraction are still unknown. It is presumed that the flow field induced by the contraction-relaxation cycle of Vorticella would augment mass transfer effect near the substrate. We investigated this hypothesis …

Extended Formation Flight At Transonic Speeds, Andrew Ning, Ilan Kroo, Michael Aftosmis, Marian Nemec, James Kless

Faculty Publications

Aircraft flown in formation can realize significant reductions in induced drag by flying in regions of wake upwash. However, most transports fly at transonic speeds where the impact of compressibility on formation flight is not well understood. This study utilizes an Euler solver to analyze the inviscid aerodynamic forces and moments of transonic wing/body configurations flying in a two-aircraft formation. Formations with large streamwise separation distances (10-50 wingspans) are considered.

This work indicates that compressibility-related drag penalties in formation flight may be eliminated by slowing 2-3% below the nominal out-of-formation cruise Mach number (either at fixed lift coefficient or fixed …

Inviscid Analysis Of Extended Formation Flight, James Kless, Michael Aftosmis, Andrew Ning, Marian Nemec

Faculty Publications

Flying airplanes in extended formations, with separation distances of tens of wingspans, significantly improves safety while maintaining most of the fuel savings achieved in close formations. The present study investigates the impact of roll trim and compressibility at a fixed lift coefficient on the benefits of extended formation flight. An Euler solver with adjoint-based mesh refinement combined with a wake propagation model is used to analyze a two-body echelon formation at a separation distance of 30 spans. Two geometries are examined: a simple wing and a wing-body geometry. Energy savings, quantified by both formation drag fraction and span efficiency factor, …

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 …