Aerodynamics and Fluid Mechanics Commons^™

Bicycle Wheel Aerodynamics Predictions Using Cfd: Efficiency Using Blade Element Method, Drew Vigne

Honors Undergraduate Theses

The cycling industry has long relied on expensive wind tunnel testing when designing aerodynamic products, particularly in the context of wheels which account for 10 to 15 percent of a cyclist's total aerodynamic drag. With the recent advent of Computational Fluid Dynamics (CFD), the industry now has an economical tool to supplement the wheel design process; however, the complex nature of rotating spoked wheels requires high resolution meshes to model at acceptable fidelity. This research investigates an alternative CFD method that lowers the computational cost of modeling aerodynamic bicycle wheels by modeling spokes using Blade Element Method (BEM). Two CFD …

Numerical Modeling Of Shockwave Initiated Combustion Of A Hydrogen-Oxygen Mixture Within A Shock Tube, Reed Forehand

Electronic Theses and Dissertations, 2020-2023

Shock tubes are as close to an ideal reactor as most modern experiments can attain to examine chemical kinetics. As reaction temperatures drop, homogeneous combustion within a shock tube begins to exhibit inhomogeneous modes, which in a typical Hydrogen-Oxygen system are ex- pressed as deflagration to detonation transition. Experimental results of such a system in the Uni- versity of Central Florida's low-pressure shock tube have been collected through end and side-wall imaging to analyze flame structure and chemical kinetics. The purpose of this work is to con- duct a baselining of these results using both chemical and computational fluid dynamics …

Measurements Of Wind Turbine Wake Evolution And Trajectory During Morning Boundary Layer Transition And Under Wake Steering Conditions Via Unmanned Aerial Vehicles, Stewart Nelson

Theses and Dissertations--Mechanical and Aerospace Engineering

In July of 2019, a flight campaign was conducted using semi-autonomous Unmanned Aerial Vehicles (UAVs) at the Port Alma Kruger Energy wind farm in Ontario, Canada, to study various aspects of wind turbine wake evolution. Horizontal transects across the wakes were measured using modified fixed-wing aircraft fitted with a five-hole probe to measure the wind velocity vector. Reference boundary layer conditions were measured by an octocopter with an assortment of mounted sensors flying vertical profiles upstream of the turbines. Three experiments were conducted during the campaign, which consisted of a study on wake behavior during the morning boundary layer transition, …

Turbulence Suppression In An Axially Rotating Pipe, Alyn J. Smith

Theses and Dissertations--Mechanical and Aerospace Engineering

The phenomenon of turbulence suppression in a rotating pipe flow system has been well documented by past research and experimentation. Despite this, the methods that drive this phenomenon have not yet been effectively characterized, especially at higher Reynolds numbers. While many experiments have been performed to better understand swirling turbulent pipe flow, a difficulty that arises is how to test for high levels of rotation without reducing the Reynolds number. This thesis documents the design and construction of a new pressurized pipe flow system at the University of Kentucky aimed at achieving high Reynolds numbers without causing a reduction in …

Modeling Thin Layers In Material Response Solvers, Christen Setters

Theses and Dissertations--Mechanical and Aerospace Engineering

Thermal Protection Systems (TPS) are a necessary component for atmospheric entry. Most TPS contain thin layers of various materials such as ceramic coatings, pore sealers and bonding agents. When modeling TPS, these thin layers are often neglected due to the difference in scale between the TPS (centimeters) and the thin layers (micrometers). In this study, a volume-averaging flux-conservation method is implemented in the governing equations of a finite volume material response code. The model proposes the addition of a volume and area fraction coefficient which utilizes a weighted-averaging between the amount of thin layer and heat shield material in a …

A Computational Fluid-Structure Interaction Method For Simulating Supersonic Parachute Inflation, Jonathan Boustani

Theses and Dissertations--Mechanical and Aerospace Engineering

Following the successful landing of the Curiosity rover on the Martian surface in 2012, NASA/JPL conducted the low-density supersonic decelerator (LDSD) missions to develop large diameter parachutes to land the increasingly heavier payloads being sent to the Martian surface. Unexpectedly, both of the tested parachutes failed far below their design loads. It became clear that there was an inability to model and predict loads that occur during supersonic parachute inflation. In this dissertation, a new computational method that was developed to provide NASA with the capability to simulate supersonic parachute inflation is presented and validated. The method considers the loose …

Study Of The Mechanlsm Of Flow-Induced Vibrations Of A Cylinder In Proximity To A Wall, Jonathan M. Chambers

Master’s Theses

Flexible bluff bodies exposed to a uniform fluid flow undergo vibration due to vortex-shedding from the body. This phenomenon is known as vortex-induced vibration (VIV). Structural members, such as cables, conduits, and pipes, are susceptible to VIV. Vortex-induced vibrations result in structural stresses due to elastic structural deformation from the flow-induced loading. Cylindrical structures in proximity to planar surfaces can undergo vortex-induced vibrations when the gap between the cylinder and the planar surfaces is above a critical value. This laboratory study investigated the mechanism of vibration and planar wall proximity effect on the cylinder response to the vortex shedding process. …

Fluid-Wall Interactions In Pseudopotential Lattice Boltzmann Models, Cheng Peng, Luis F. Ayala, Orlando M. Ayala

Engineering Technology Faculty Publications

Designing proper fluid-wall interaction forces to achieve proper wetting conditions is an important area of interest in pseudopotential lattice Boltzmann models. In this paper, we propose a modified fluid-wall interaction force that applies for pseudopotential models of both single-component fluids and partially miscible multicomponent fluids, such as hydrocarbon mixtures. A reliable correlation that predicts the resulting liquid contact angle on a flat solid surface is also proposed. This correlation works well over a wide variety of pseudopotential lattice Boltzmann models and thermodynamic conditions.

Wind Tunnel Data Acquisition System Development Using Labview, Riley Bishop

Mahurin Honors College Capstone Experience/Thesis Projects

Utilizing an educational-purpose wind tunnel, a data acquisition system through LabVIEW was created to experimentally analyze the aerodynamic forces experienced by objects in uniform external flow by automatically performing trials and interpreting electrical measurement signals. To verify experimental results from pressure distribution data around an object, a force balance was designed to mount objects stationarily in the wind tunnel test section while directly measuring the total lift and drag forces, calculating the pitching moment (for airfoils), and monitoring the angle of attack. The force balance design includes three load cells, one for measuring drag force and two for measuring total …

Comparative Study On The Prediction Of Aerodynamic Characteristics Of Mini - Unmanned Aerial Vehicle With Turbulence Models, Somashekar V, Immanuel Selwyn Raj A

International Journal of Aviation, Aeronautics, and Aerospace

When dealing with CFD simulations the turbulent nature is seen on most of the engineering flows and these flows need to be solved. Reliable and applicable CFD outputs can be obtained from the accurate modelling of the turbulence as it is one of the most vital elements of CFD modelling. The RANS equations are extensively employed to analyse the complex flows over aircraft and for this purpose, a turbulence model is needed for turbulent flow analyses. Compatible turbulence must be chosen for the exact predictions of aircraft aerodynamic characteristics. In this report, numerical analyses of Mini-UAV are done to compare …

Design And Testing Of A Feed-Forward Control System For Deployable Vortex Generators Dependent On Angle Of Attack, Solomon B. Whitmire, Christopher J. Chapanar, Kirklin M. Anderson, Nickalus R. Amon, Daniel W. Chech

Williams Honors College, Honors Research Projects

A vortex generator (VG hereafter) is a common feature of an aircraft wing that disturbs the flow on the leading edge of the wing, thus energizing the boundary layer and reducing flow separation. For an aircraft experiencing flow separation, VGs can increase the lift-to-drag ratio of the wing and prevent stall; however, if flow separation isn’t an issue, the unnecessary frontal area of the VGs has the potential to produce parasitic drag. This study seeks to determine whether the use of a deployment system can improve the performance of VG’s by raising or lowering them depending on the angle of …

Oblique Shock Wave Diffuser Design, Noah Riggenbach

Williams Honors College, Honors Research Projects

In this Honors Research Project, I will investigate the aerodynamic drag on certain defined ramps and cone/cylinder geometries representing oblique shock wave diffusers. The goal is to develop an oblique shock wave diffuser that decelerates supersonic air while maintaining a limited aerodynamic drag profile. The aerodynamic drag will first be obtained by calculating the pressure coefficient and the skin friction coefficient using the fluid simulation software ANSYS Fluent (version 2019). Limiting drag is important for aircraft flight performance, especially at supersonic speeds. At flight speeds above Mach 1, shock waves form and the air passing through these waves experiences a …

Road Racing Aerodynamic Simulation + Testing, Jack Sawyer

Williams Honors College, Honors Research Projects

There are multiple goals for this project. The first goal of this project is to design, assemble and simulate additional aerodynamic components. Another goal is to create a product that can analyze various angles of attack of Aerodynamic components. The product will be used on, or off the track to determine the lift coefficients of vehicles at varying speeds. I will be using my 1992 Honda Civic for testing and compare my physical results to my simulated tests.

The project did come with a list of design and manufacturing challenges along with additional finical cost which has resulted in some …

Microfluidics Design Considering Hyperuniformity And Cell Transport In Flow For Improved Circulating Tumor Cell Capture Efficiency, Michael Clarence Hood

Graduate Research Theses & Dissertations

Isolation of circulating tumor cells (CTCs) from patient derived blood samples for cancerdiagnostics and monitoring is challenging due to the extremely low CTC concentration. This thesis work evaluates the performance of passive microfluidics devices with different designs based on computational modeling. A new cell separation method is proposed based on velocity differentiation of varying cell sizes. All numerical studies were conducted in 2D based on a fluid structure interaction code where the fluid flow was solved based on the lattice Boltzmann method (LBM) implemented in Palabos, and the cell dynamics were simulated based on the molecular dynamics package LAMMPS, with …

Blood Flow Simulation In A Microvascular Network, Kacper Ostalowski

Graduate Research Theses & Dissertations

Cardiovascular disease such as heart attack or stroke has been the leading cause of death in the US for over 100 years. Understanding the blood cell transport physics in a vascular network is important in both fundamental research and clinical practices. In this study, 3Dnumerical simulations on blood flow in a complex retina vascular network were performed considering deformable red blood cells (RBCs), white blood cells (WBCs), and obstructed vessels. The blood was modeled as a mixture of RBCs and WBCs suspended in fluid. The fluid was solved using the lattice Boltzmann method (LBM), and blood cells were modeled by …

A Model For Inhalation Of Infectious Aerosol Contaminants In An Aircraft Passenger Cabin, Bert A. Silich

International Journal of Aviation, Aeronautics, and Aerospace

Aerosol contamination of an aircraft cabin by infectious passengers is a concern of passengers, aircrew and the aviation industry. This may be especially important during a pandemic, such as COVID-19, where the full extent of aerosol transmission is not well understood. A statistical method to determine the number of infectious passengers on board along with a mathematical model estimating the contaminant concentration of aerosols in the cabin and the number of inhaled infectious particles by passengers is presented. An example is used to demonstrated how the results can be estimated during normal operations and emergency conditions with malfunctions of the …

Numerical Analysis Of Aerospike Engine Nozzle Performance At Various Truncation Lengths, Sam Dakka Dr, Oliver Dennison

International Journal of Aviation, Aeronautics, and Aerospace

The aerospike engine was first devised in the early 1960s where it provided new means of reaching orbit in a single stage. The paper aimes to demonstrate the viability of the technology by showcasing the increased nozzle thrust efficiency over the conventional bell nozzle. Various truncations were applied to the nozzle and each was subjected to two conditions, an over-expansion and near optimum condition. The nozzle contour was developed using the simple approximation method and was chosen to replicate that of the XRS-2200. This anchored the data, thereby validating the computational fluid dynamics (CFD) simulation. Simulations were completed for at …

Aerodynamic Performance Analysis Of Co-Flow Jet Airfoil, C M Vigneswaran, Vishnu Kumar G C

International Journal of Aviation, Aeronautics, and Aerospace

The work in this paper aims to increase the maximum lift coefficient of the airfoil by implementing the co-flow jet concept on NACA 0018 airfoil and also to investigate the performance of co-flow jet (CFJ) airfoil. To conduct numerical solution, RANS equations have been solved for 2D incompressible and unsteady flow using the Spalart-Allmaras turbulence model. The suction surface of the airfoil is modified by placing the injection slot near the leading edge and the suction slot near the trailing edge. A small mass of air is withdrawn into the airfoil suction slot, pressurized by a pumping system located inside …

Identification Of Wind-Induced Hazard Zones Impacting Uas Bridge Inspection, Jack J. Green, John Mott

International Journal of Aviation, Aeronautics, and Aerospace

Unmanned Aerial Systems (UAS) continue to grow in both popularity and utility within the national airspace system. The use of commercial UAS for civil inspection, specifically that of bridge structures, is becoming commonplace among practitioners and academics alike. The development of an integrated bridge-inspection hazard model provides a way for UAS operators to prepare for and respond to changing environmental conditions that could otherwise prevent a successful UAS flight. The interaction of wind-induced airflow with bridge surfaces creates an aerodynamic wake that can result in hazardous conditions for a UAS platform operating in close proximity. An analysis of this airflow …

Albatross And Falcon Inspired Bionic Uav: An Aerodynamic Analysis, Bilji C. Mathew, Sagar K. Sahu, Prantik Dutta, Rushi Savale, Muruga Lal Jeyan Jv Dr.

International Journal of Aviation, Aeronautics, and Aerospace

The drone industry yearns for enhanced aerodynamic performance. In order to achieve this feat, researchers and engineers are trying to mimic the natural flyers due to their aerodynamic optimality. One such flyer, the Albatross is an inspiration for many marine drones due to its planform and aerodynamic efficiency. The wing of the plan form is designed and simulated to study its properties. The Bell-Shaped Lift Distribution is incorporated for higher efficiency and elimination of the total downwash produced in case of an Elliptical Lift Distribution. A blended wing body inspired by the Falcon is used for smoother airflow interactions. Furthermore, …