Engineering Commons^™

Analysis Of Turbulent Flow Behavior In Helicopter Rotor Hub Wakes, Forrest Mobley

Masters Theses

The rotor hub is one of the most important features of all helicopters, as it provides the pilot a means for controlling the vehicle by changing the characteristics of the main and tail rotors. The hub also provides a structural foundation for the rotors and allows for the rotor blades to respond to aerodynamic forces while maintaining controllability and stability. Due to the inherent geometry and high rate of rotation, the rotor hub in its current form acts a large bluff body and is the primary source of parasite drag on the helicopter, despite its relatively small size. The rotor …

Fire Simulation And Analysis Of A Switchgear Cabinet Fire And Its Effects On Cable Trays, Yalcin Meraki

Masters Theses

Switchgear rooms are crucial in containing essential equipment such as cabinets and cable trays in case of a possible fire. There are three fire model classes which are algebraic models, zone model, and computation fluid dynamics model (CFD). PyroSim software, a visual user interface for the Fire Dynamics Simulator (FDS) developed at the National Institute of Standards and Technology (NIST), was used for simulation by using the CFD. Two different 464 kW and 1002 kW heat release rate (HRR) values were used under the same conditions for the fire scenario. By considering a fire scenario, the fire ignited due to …

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 …

A Parametric Computational Fluid Dynamics (Cfd) Study Of In-Line Horizontal Axis Wind Turbines (Hawts) With Yaw, North Alyster Yates

Masters Theses

Because of the constant use of non-renewable fossil fuels, and the enormous impact they have on global warming and pollution, there has been a push to use more eco-friendly and renewable sources for power. One such form is wind power via turbines. The most common form, Horizontal Axis Wind Turbines (HAWTs), can generate massive amounts of power. However, they also have a serious flaw in their design. As the wind passes through the swept area of the blades and past the tower, it creates massive disturbances in the airflow. These disturbances are called a ‘wake’. When trying to create a …

Cfd Analysis Of Subcutaneous Deposition And Dispersion Of Insulin In Adipose Tissue, Ryan C. Lubbers

Masters Theses

Drug delivery is the most important factor of many therapies, but a lack of technology and research have led to a very generalized understanding of drug kinetics. Insulin pump therapy for the treatment of Type 1 Diabetes depends on precise delivery of the hormone into the adipose region between the dermis and underlying muscle. The kinetics of insulin within the adipose tissue environment is not well understood and varies greatly case to case. The use of computation fluid dynamics (CFD) models to study insulin kinetics in relation to influential factors will lead to a better understanding of the characteristics of …

Nozzle Clogging Prevention And Analysis In Cold Spray, Alden Foelsche

Masters Theses

Cold spray is an additive manufacturing method in which powder particles are accelerated through a supersonic nozzle and impinged upon a nearby substrate, provided they reach their so-called critical velocity. True to its name, the cold spray process employs lower particle temperatures than other thermal spray processes while the particle velocities are comparably high. Because bonding occurs mostly in the solid state and at high speeds, cold spray deposits are distinguished for having low porosity and low residual stresses which nearly match those of the bulk material.

One complication with the cold spray process is the tendency for nozzles to …

Numerical Investigation Of Leading-Edge Modifications Of A Naca Airfoil, Anisur Rahman Ikram

Masters Theses

A parametric investigation was carried out to understand the flow characteristics of tubercle airfoils and to determine the best approach and parameters for designing a tubercle airfoil. For this purpose, a straight edge base airfoil (NACA 4414) and several tubercle airfoils, by modifying the leading edge of the base airfoil, were created in SolidWorks and tested with Computational Fluid Dynamics (CFD) application software Star CCM+.

Alternative tubercle airfoil with elliptical bumps demonstrated superior post-stall performance when compared to their straight edge counterparts; their post-stall lift did not decrease drastically. However, their pre-stall lift coefficients were always lower than the base …

Comparison Of Reynolds-Averaged Navier-Stokes Turbulence Models For Simulating Boundary Layers In Hypersonic Flows, Jorge-Valentino Kurose Bretzke

Masters Theses

“This study describes the use of Computational Fluid Dynamics (CFD) codes to simulate hypersonic boundary layers using several different turbulent closure models and comparing Reynolds-Averaged Navier-Stokes (RANS) simulations against Direct Numerical Simulations (DNS) of similar test cases. The test cases in this study consist of a flat plate in a Mach 8 freestream with a zero pressure gradient and wall recovery ratio of 0.48, as well as a Mach 8 axisymmetric nozzle also with a cold wall. The RANS models used in this study are the Spalart-Allmaras model, Baldwin-Lomax model, Menter K-Omega Baseline and Menter K-Omega Shear Stress Transport models. …

On The Fuel Spray Applications Of Multi-Phase Eulerian Cfd Techniques, Gabriel Lev Jacobsohn

Masters Theses

Eulerian-Eulerian Computational Fluid Dynamics (CFD) techniques continue to show promise for characterizing the internal flow and near-field spray for various fuel injection systems. These regions are difficult to observe experimentally, and simulations of such regions are limited by computational expense or reliance on empiricism using other methods. The physics governing spray atomization are first introduced. Impinging jet sprays and Gasoline Direct Injection (GDI) are selected as applications, and modern computational/experimental approaches to their study are reviewed. Two in-house CFD solvers are described and subsequently applied in several case studies. Accurate prediction of the liquid distribution in a like-doublet impinging jet …

Cfd Study Of Aerodynamic Drag Reduction Tool Of A Generic Sports Utility Vehicle (Suv), Samira Ishrat Jahan

Masters Theses

The Sports Utility Vehicle (SUV) has been a popular automobile choice in North America for over 50 years due to its seating and hauling versatility and good towing capacity. This widespread popularity has resulted in manufacturers pushing for increased horsepower and cabin size. Unfortunately, the limiting factor has been fuel economy which is governed by the vehicle aerodynamics. A reduction in aerodynamic drag can result in better fuel economy. The goal of this study is to reduce the aerodynamic drag of a generic SUV and the efficient application of drag reduction devices to control flow separation. An initial study has …

Study Of Cooling-Drag In A Generic Passenger Car Using Cfd And Wind Tunnel, Md Maruf Hossain

Masters Theses

The focus of the study is to explore aerodynamic aspects of cooling airflow. As a result of this study, an efficient multi-domain aero-thermal model was developed to analyze the cooling drag of a generic passenger vehicle. Cooling drag is described as the additional force that the production vehicle has to overcome while moving in comparison to the force if all the openings were closed. Though this model was developed based on the sedan class vehicle, the applied methodology could be generalized for other ground vehicle types. As a part of the presented model, a unique simplified geometric model is developed …

Development Of A Multi-Jointed Wing Surface Mover, Collin Arthur Strassburger

Masters Theses

The field of ornithopter research has reached a point where it has become commonplace for Computational Fluid Dynamics (CFD) solvers to have built-in capabilities for rigid solid body motion. This is suitable for micro air vehicles (MAVs) yet is often not exible enough to model wings with dynamic internal structure, such as the wings of birds and bats. There is currently no program available to perform the surface motion of a wing which has multiple independently moving joints. The code, detailed in this paper, provides the user with this type of capability. The bone lengths, joint angle properties, and thickening …

A Numerical Study Of The Limiting Cases Of Cylinder-Induced Shock Wave/Boundary Layer Interactions, Stefen Albert Lindorfer

Masters Theses

One of the limiting factors in the design of supersonic and hypersonic vehicles remains the prediction and control of the high aerodynamic, thermodynamic, acoustic, and structural loads generated by a shock wave/boundary layer interaction (SWBLI or SBLI). In conjunction with an experimental campaign produced within the research group, a numerical study was performed using a semi-infinite cylinder to generate a SWBLI at Mach 1.88 with both laminar and turbulent boundary layers. The goals were not only to better understand the complex flow surrounding the cylinder-induced turbulent interaction, but also to establish the interaction bounds of the limiting cases of a …

Effect Of Design Parameters On Thermal Performance Of A Vane Type Disc Brake Rotor, Yogesh Satish Dalal

Masters Theses

The ever-increasing need of effective transportation puts automobile manufacturers in a situation of continuous improvement and innovate the safety systems. The brake system of an automobile has always been considered as one of the most critical active safety systems. Thermal characteristics of the brake are an important aspect to consider for brake disc durability and performance. The convective cooling of a brake disc is an important factor since design changes in the brake rotor can significantly improve cooling characteristics. The focus of this research is to study and optimize the disc brake rotor for a given heat dissipation rate and …

Experimental And Numerical Study Of Dysphagia, Yash G. Potdar

Masters Theses

Dysphagia, meaning difficulty in swallowing, is a symptom of disease that occurs in young children and elderly people. It occurs particularly due to two reasons, weak neural network and/or deformities in oral section/s. The Helen DeVos Children’s Hospital’s Intensive Feeding Program takes care of children suffering from Dysphagia. In order to make the swallowing process easier and in some cases safer, thickener is added to the liquids. Depending on the requirement of thickness, the amount of thickener is varied. Although the directions to prepare the mixtures are given by the thickener product company, the required thickness is not achieved when …

Aerodynamics Of Race Car Wings: A Cfd Study, Simon Durrer

Masters Theses

Formula 1 racing is one of the most advanced technological sports. The aerodynamic on open wheel race cars is essential for the performance during a race. The front wing on a race car produces about 30 percent of the entire downforce of a race car. Several studies on front wings for open wheel race cars are conducted by various authors. A number of research studies include single element airfoils in ground effect and undisturbed flow. Numerical and experimental studies show that by decreasing the ground clearance, the downforce increases. The most efficient ground clearance is reported to be approximately 10 …

Design And Analysis Of An Axisymmetric Aerospike Supersonic Micro-Nozzle For A Refrigerant-Based Cold-Gas Propulsion System For Small Satellites, Abdalla Ali Bani

Masters Theses

"The cold-gas propulsion system being developed by M-SAT requires improvements to its original nozzle design. This study documents the research, design, and analysis of a supersonic plug nozzle concept that could be integrated to the refrigerant-based cold-gas propulsion system to possibly improve its performance. As documented in this thesis, CFD analysis showed that the outlined nozzle design method resulted in a feasible nozzle concept that has the ability to out-perform a conventional nozzle of the same area ratio. The flow-fields and thrust of the aerospike nozzle, for the full and truncated nozzles, were investigated. The purpose of this study is …

Cfd Simulation Of The Flow Around Nrel Phase Vi Wind Turbine, Yang Song

Masters Theses

The simulation of the turbulent and potentially separating flow around a rotating, twisted, and tapered airfoil is a challenging task for CFD simulations. This thesis describes CFD simulations of the NREL Phase VI turbine that was experimentally characterized in the 24.4m X 36.6m NREL/NASA Ames wind tunnel. All computations in this research are performed on the experimental base configuration of 0^o yaw angle, 3^o tip pitch angle, and a rotation rate of 72 rpm. The significance of specific mesh resolution regions to the accuracy of the CFD prediction is discussed. The ability of CFD to capture bulk quantities, …

Multidimensional Cfd Modeling Of A Liquid Salt Pebble Bed Heat Transfer Loop, Richard B. Cunningham

Masters Theses

The Pebble Bed Advanced High Temperature Reactor (PB-AHTR) is a next generation reactor design proposed by the University of California at Berkeley. Oak Ridge National Laboratory’s Liquid Salt Test Loop (LSTL) is designed to simulate AHTR operating conditions for component testing. In this study, COMSOL Multiphysics is used to model the LSTL. Full 3D modeling of the LSTL is computationally expensive. However, COMSOL allows users to combine 1D, 2D, and 3D fluid flow physics in order to design models that are both representative and efficient. 1D pipe flow calculations are used for the piping sections. COMSOL’s porous media module is …

Analysis Of A Ventilation Network In A Multiple Fans Limestone Mine, Ali Haghighat

Masters Theses

"As mining progresses the total resistance of an excavation is increased, the mine characteristic curve becomes steeper, and the operating point moves up the fan curve, reducing the total air quantity and increasing the system pressure. For multi-level ventilation networks with a number of fans the process can be tedious, and on a count of numerous dependent factors the optimal combination of fans is very hard to be achieved. The design of a ventilation network in conjunction with multi surface fans and booster fans entails a complex procedure.

The objective of this study is to provide a plan to improve …

Development Of Cfd Models For The Purposes Of Exploring Free Surface Wave Phenomena, Leonard P. Stoehr

Masters Theses

With the push for finding alternative, green energy sources, the harnessing of energy from ocean and lake waves is becoming a more researched field. To fully understand the behavior of wave interactions and optimize designs to extract this energy, it is necessary to develop computer models that can accurately replicate this behavior. A case is presented in which previous work done using the wave tank found in the Western Michigan University fluids lab is examined. The case involves harnessing the energy generated by ocean waves through the usage of plates of different shapes resting horizontally on the water’s surface. The …

Computational Analysis Of A Wing Oscillator, Ryne Derrick Radermacher

Masters Theses

An analysis of a newly proposed wind power extraction device called a wing oscillator was performed using computational fluid dynamics (CFD). A wing oscillator is a device that consists of two airfoils attached to a central pivot by means of a frame or shaft. Oscillatory motion is produced by controlling the angle of attack of the airfoils as a fluid flow is passed over the device. A robust mathematical scheme was developed to investigate the performance of the wing oscillator and was hooked to the CFD software package FLUENT through User Defined Functions (UDFs). Using the dynamic meshing analysis methods …

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 …

Evaluation Of Geometric Scale Effects For Scramjet Isolators, Jaime Enrique Perez

Masters Theses

A numerical analysis was conducted to study the effects of geometrically scaling scramjet inlet-combustor isolators. Three-dimensional fully viscous numerical simulation of the flow inside constant area rectangular ducts, with a downstream back pressure condition, was analyzed using the SolidWorks Flow Simulation software. The baseline, or 1X, isolator configuration has a 1” x 2.67” cross section and 20” length. This baseline configuration was scaled up based on the 1X configuration mass flow to 10X and 100X configurations, with ten and one hundred times the mass flow rate, respectively. The isolator aspect ratio of 2.67 was held constant for all configurations. To …