Aerodynamics and Fluid Mechanics Commons^™

Accelerating Rans Cfd Convergence For Bluff Body Flows Using Surface-Vorticity Panel Solver Initialization, Trisha Babu

All Graduate Reports and Creative Projects, Fall 2023 to Present

Reynolds-Averaged Navier--Stokes (RANS) simulations are widely used for predicting aerodynamic performance in engineering applications but often require substantial computational time to achieve convergence, particularly for bluff-body flows characterized by large-scale separation and wake formation. Improving the initialization of CFD simulations offers a practical approach for reducing computational cost without modifying the underlying numerical algorithms. This study investigates the use of a surface-vorticity panel solver (FlightStream) to generate physically informed velocity fields for initializing steady RANS simulations in STAR-CCM+.

Two canonical bluff-body geometries are considered: a sphere at a Reynolds number of 5 X 10⁵ and an isolated cube at …

Effect Of Solid Particle Size And Density On Incipient Motion In A Turbulent Boundary Layer, Robert Bryan

Doctoral Dissertations and Master's Theses

Wind-blown sand and other instances of solid particles mobilized and suspended in gaseous turbulent boundary layers (TBLs) are seen in a wide variety of engineering contexts. An experimental framework was developed to study the incipient particle motion driven by external forcing within a turbulent boundary layer, which is provided by an airfoil section oscillating in the free-steam flow, resulting in a periodic disturbance in the near-wall region through production of synthetic large-scale structures at a fixed frequency. The incoming unsteady carrier-phase eddies were measured with a hot-film sensor upstream of a particle bed, and the particle motion was captured by …

Experimental-Motion-Driven Cfd Investigation Of Slosh Dynamics In Propellant Tanks Of Spacecraft And Launch Vehicles, Priyanshu Savaliya

Doctoral Dissertations and Master's Theses

Liquid sloshing in partially filled propellant tanks can generate transient forces and moments that affect spacecraft and launch vehicle stability, guidance, and control. This research develops a one-way experimental-to-Computational Fluid Dynamics (CFD) integration framework to investigate free-surface slosh behavior under realistic excitation conditions.

The overarching goal of this thesis is to develop and evaluate a one-way experimental-motion-driven computational framework for predicting liquid slosh response in a partially filled cylindrical tank. Rather than relying on idealized sinusoidal inputs, this work uses experimentally measured actuator-feedback motion as the prescribed excitation for high-fidelity CFD. The central objective is to establish the experimental and …

Optimal Integrated Cfd-Gnc Model For Drag-Based Reentry Dynamics, Sebastian Lopez

Doctoral Dissertations and Master's Theses

This research focuses on optimizing the control of a drag-maneuvering, Starship-class re-entry vehicle by closely integrating high-fidelity aerodynamic data derived from Computational Fluid Dynamics (CFD) simulations, specifically using StarCCM+. The aerodynamic models, tailored to the unique geometry of a drag-maneuvering body, are seamlessly incorporated into a guidance, navigation, and control (GNC) framework. This integration enables closed-loop CFD simulations with real-time control feedback, allowing for direct analysis and optimization of vehicle stability, trajectory, and control demands throughout the re-entry process.

Building upon the work of Gaglio and Bevilacqua, this advanced CFD-GNC model introduces high-order aerodynamic effects, such as aerodynamic moments and …

Numerical Investigation Of Shock-Induced Deformation Of Bubble-Laden Droplets, Juan Roldan

Doctoral Dissertations and Master's Theses

Rain impact can be a source of surface erosion on hypersonic vehicles, and the severity of each impact depends on droplet velocity, mass, and final shape, all of which are set by how the droplet breaks up under shock loading. Real droplets are expected to carry entrained non-condensable gas (NCG) nuclei from their formation. This dissertation investigates whether the purely mechanical, pressure-driven response of these nuclei, independent of vaporization, is large enough to measurably alter the internal pressure field and early deformation of a shock-loaded droplet.

The droplet and surrounding gas are modeled with a compressible, diffuse-interface, axisymmetric Eulerian framework …

Improving The Reliability And Performance Of A Supersonic Indraft Tube Wind Tunnel, Christian J. Kaml

Master's Theses

Access to supersonic testing is increasing in demand, and wind tunnels remain one of the safest and most cost-effective methods for gathering high-speed flow data. Despite being more economical than alternative options, supersonic wind tunnel facilities often require substantial investment to construct, operate, and maintain.

The novel indraft tube tunnel architecture was conceived as a high-speed flow testbed that incorporates features of both Ludwieg tubes and indraft wind tunnels to maintain costs low enough to be accessible even to small universities. This design was first developed and tested in 2018 at California Polytechnic State University, featuring a cost per test …

Design And Analysis Of A Customizable 6-Dof Force/Torque Sensor, Pyeongkang Kim

Master's Theses

This thesis presents the design, development, calibration, and testing of a novel customizable six-degree-of-freedom force/torque sensor, called the Kustom Force/Torque Sensor (KFTS), for use in the Cal Poly Low Speed Wind Tunnel (LSWT). The KFTS was developed as an alternative to commercial multi-axis force/torque sensors that feature fixed specifications. The swappable components and configurable structure of the KFTS enables changes to the sensor sensitivity, sensing range, and frequency response. Experimental testing verified that the sensor behaved as a linear time-invariant system, enabling calibration through the method of least squares and allowing the applied forces and moments to be reconstructed as …

Design And Optimization Of A Bluff Body For Energy Harvesting Of Transverse Galloping Induced By Low-Speed Wind Using Bernstein Polynomial Equations, Youssef Wael Abdelmoneim

Theses and Dissertations

In this thesis, a computational framework is proposed for optimizing the aerodynamic shape of bluff bodies used in galloping-based wind energy harvesters. The system targets low-wind speed environments, where normal wind turbines are not effective, offering a potential alternative to batteries used for powering small electronic devices such as wireless sensors. The design relies on the galloping effect, where airflow around a bluff body induces transverse oscillations that drive an energy conversion mechanism. To generate efficient bluff body geometry, the Class-Shape Transformation (CST) method is used to define a wide range of candidate shapes with minimal design parameters. These shapes …

A Higher Order Panel Method With Vortex Particle Wake, Luca Flick-Kaiser

Master's Theses

Panel codes were some of the earliest methods for computing the flow around aircraft. Despite the availability of higher fidelity CFD methods, panel methods remain an essential tool for the development of modern aircraft, allowing engineers to quickly iterate during the conceptual design phase.

This work develops and implements a high order panel method using Python. The wake is modeled using vortex particles, resulting in an accurate wake representation with minimal user input. The integration of the higher order singularity distributions has been extended to include the calculation of the velocity gradients necessary for the vortex particle implementation. The use …

Design And Development Of A Resonance Ignition System Using Gaseous Propellants, Benjamin J. Hoefer

Master's Theses

This work presents the development and experimental evaluation of a resonance igniter (RI) operating with premixed gaseous propellants. Resonance ignition is a non-electrical ignition concept in which an underexpanded jet impinges on a closed-end Hartmann–Sprenger tube (HST), generating cyclic compression and expansion waves that rapidly heat gas near the tube endwall. A modular experimental system was designed and built to investigate resonance ignition using methane–air and methane–oxygen mixtures. The system includes a supplemental configuration that may probe for mixture conditions favorable to ignition, informing RI testing. Pressure and temperature measurements were used to characterize pressure control, mixture pressure ratio (MPR), …

Aerodynamic And Acoustic Modeling For Evtol Rotor Noise Prediction, Daniella Bezuidenhout, Anastasios S. Lyrintzis, Vladimir V. Golubev

Doctoral Dissertations and Master's Theses

This thesis presents the development and validation of a methodology for predicting total acoustic emissions from a one-fifth scale electric vertical takeoff and landing (eVTOL) rotor in both hover and edgewise flight conditions. The approach couples sectional two-dimensional Reynolds-Averaged Navier-Stokes (2D-RANS) airfoil simulations with rotor loading predictions from the Comprehensive Hierarchical Aeromechanics Rotorcraft Model (CHARM), tonal noise calculations using the acoustic solver PSU-WOPWOP, and broadband noise predictions from the UCD-QuietFly framework. Boundary-layer inputs traditionally obtained from the viscous-inviscid solver, XFOIL, were replaced with higher-fidelity 2D-RANS results from OpenFOAM to better capture low-Reynolds-number flow physics, including laminar-turbulent transition and laminar separation …

Contributions To Ship-Airwake-Rotor Coupling Characterization Using Controlled Forcing, Guillermo Mazzilli

Doctoral Dissertations and Master's Theses

Shipboard helicopter operations occur within a highly unsteady environment referred to as the dynamic interface (DI), encompassing the coupled effects of the ship airwake, rotor wake, flight dynamics, and pilot response. A central aspect of the DI is the aerodynamic interaction between the ship airwake and the rotor wake, which degrades handling qualities and increases pilot workload, yet the underlying mechanisms governing ship-rotor coupling remain insufficiently understood. The ship-rotor aerodynamic coupling was examined using two canonical ship geometries, the NATO-GD and SFS2, together with a controlled experimental framework, the airflow-and-blade-frequency (ABF) system, which independently varied wake momentum flux and unsteady …

Turbulent Plenum Jet-Crossflow Validation Via Subgrid Scale Model Variation And Upstream Forcing Under Dynamic Hybrid Rans-Les, Cole W. Mccallum

Mechanical Engineering Undergraduate Honors Theses

In modern gas turbine design, film cooling has become ubiquitous as a method for limiting heat transfer between high temperature gases post-combustion and the surface of downstream blades. This paper validates the use of various computational fluid dynamics techniques in recreating an experiment measuring adiabatic effectiveness over a surface downstream of a compound-angle N2 plenum jet incident on a turbulent-air boundary layer [1]. To do this, both RANS and Dynamic Hybrid RANS-LES (DHRL) methods are implemented and compared to previous research [2]. The latter method is then modified through implementation of a different subgrid scale (SGS) model and through addition …

Analysis Of Oscillating Flow Over A 2-D Airfoil With Flow Reversal, Colter Couillard-Rodak

McKelvey School of Engineering Graduate Student Theses & Dissertations

Finite-state models are useful tools in modeling the aerodynamics of rotorcraft in flight simulators. 2-D and 3-D finite-state models have been developed and compared to closed form solutions, however these models are currently unable to handle situations where the freestream changes directions and the rotor re-enters its own wake. A 2-D finite state model was previously developed that includes a parameter that accounts for the change in free stream. This model, however, contains an inherent stability issue at the instant that the velocity changes direction.

The effects of this instability can be mitigated in certain flow conditions. A purely oscillatory …

Numerical Study Of Nutrient Mixing In Trabecular Bone In Microgravity, Disuse And Normogravity, Sagar Gharti

Doctoral Dissertations and Master's Theses

Mechanical loading is known to regulate bone remodeling by driving interstitial fluid flow which stimulates cells and drives nutrient transport within the trabecular network. In microgravity, the absence of mechanical stimulation or loading suppresses convective flow processes, causing diffusion-driven nutrient mixing and renewal, and accelerated bone loss. This thesis investigates how oscillation frequency and trabecular bone density jointly control nutrient mixing and wall shear stress within trabecular cavities.

A computational fluid dynamics (CFD) framework is developed in STAR-CCM+ using a soft-cap oscillation model that mimics cyclic compression. Three idealized trabecular morphologies are simulated across different frequencies to represent microgravity or …

Instrumentation And Control Of A Novel Device To Simulate A Hypersonic Environment, Andrew Marcello

Doctoral Dissertations and Master's Theses

The hypersonic flow regime poses several challenges regarding the design of hypersonic vehicles. Among them is the massive energy and economic expense associated with ground- testing evaluation of material responses within this extreme environment. In order to provide a low-cost, rapid option for preliminary material analysis within hypersonic applications, a novel device is under production to replicate this environment on the surface of these materials. This device has been designed to work in conjunction with Argonne National Laboratory (ANL) Advanced Photo Source (APS) synchrotron, to allow for in-situ characterization of ablation and oxidation on the sample surface.

To achieve this, …

Numerical Investigation Of Rotor-Gust Acoustic Interactions Using The Overflow Cfd Solver, Jordan Mills

Doctoral Dissertations and Master's Theses

The rapid expansion of Urban Air Mobility (UAM) necessitates high-fidelity modeling to predict and mitigate the noise signatures of electric vertical take-off and landing (eVTOL) aircraft within dense urban landscapes. A critical unknown in community-noise certification is the aeroacoustic response of rotors to unsteady inflow conditions. This research addresses this gap by investigating the aerodynamic and acoustic behavior of a representative rotor subjected to time-harmonic inflow disturbances. By establishing a robust numerical framework, this thesis quantifies the relationship between periodic atmospheric gusts and their impact on rotor performance, unsteady blade loading, and subsequent sound radiation. The research consists of a …

Effect Of Nozzle Pressure Ratio On Thrust And Flow Behavior In A Supersonic De Laval Nozzle, Esha Jain

Doctoral Dissertations and Master's Theses

Supersonic nozzles operate across a range of flow regimes. While an ideally expanded condition yields optimal thrust, practical propulsion systems rarely operate at this design point due to variations in altitude and engine operating conditions. As a result, nozzles frequently operate in off-design conditions. In overexpanded regime, where the exit pressure is lower than the ambient pressure, shock-induced separation may occur within the divergent section of the nozzle, potentially degrading nozzle performance. Understanding the aerodynamic behavior of nozzles operating under off-design conditions is therefore important for improving propulsion system performance and stability. In particular, direct thrust measurements provide a key …

Quantification Of The Depth-Of-Field In A Self-Aligned Focusing Schlieren System, Alexander Ephraim

Doctoral Dissertations and Master's Theses

This thesis investigates self-aligned focusing schlieren (SAFS) as a step toward future volumetric and quantitative measurements of three-dimensional compressible flows. Conventional schlieren imaging provides valuable visualization of density gradients, but it records only a line-of-sight projection and therefore does not directly resolve the spatial distribution of structures through the depth of the flowfield. SAFS addresses part of this limitation by introducing depth sensitivity, but its depth response has not been well characterized quantitatively. To help lay the foundation for future volumetric and quantitative SAFS methods, this work addresses two related problems. First, calibrated quantitative schlieren imaging is applied to an …

Influence Of The Sst K-Ω Stress-Limiter Coefficient On Transonic Shock Buffet Prediction For The Oat15a Supercritical Airfoil, Melinawo Vowotor

College of Graduate Studies: Theses & Dissertations

Transonic shock buffet predictions using the Shear Stress Transport (SST) k–ω turbulence model are known to be sensitive to the stress-limiter coefficient a₁, yet no systematic investigation of this sensitivity exists. This thesis presents a parametric study of a₁ for two-dimensional URANS simulation of shock buffet on the OAT15A supercritical airfoil at M = 0.73 and Re = 3 × 10⁶. Eleven a₁ values (0.25–0.37) are examined at α = 3.5°, and a matrix of five a₁ values across five angles of attack (3.0°–3.9°) maps the interaction with incidence. The results reveal that a₁ acts as a bifurcation parameter: a …

Multiphysics Transport In Porous Thermal Protection Systems: Experimental Characterization Of Gas Permeability And Radiative Properties, Yejajul Hakim

Theses and Dissertations--Mechanical and Aerospace Engineering

Porous thermal protection systems (TPS) used in hypersonic vehicles exhibit coupled gas and radiative transport across multiple regimes and length scales. Accurate performance prediction requires reliable characterization of permeability, slip-flow behavior, and radiative transport properties, particularly for low-permeability and charred materials where existing data are limited. This dissertation presents experimental methods for characterizing multiphysics transport in porous TPS materials. A modular flow system was developed to measure permeability and slip behavior in both virgin and charred materials under relevant environments. A transient pressure decay method enables accurate permeability estimation in low-permeability regimes and provides insight into effective pore structure. Results …

Development And Integration Of A Liquid Rocket Propulsion System For A High-Power Rocket, Matthew A. Dipofi, Christina Griggy, Jonathan Armbrust, Jackson Frame

Williams Honors College, Honors Research Projects

The goal of this project is to integrate the Stinger liquid rocket engine, a regeneratively cooled LOX/ethanol engine developed by the Akronauts Rocket Design Team, into the Copperhead launch vehicle. The objective is to design, build, and test a complete propulsion system including electronics, software, pressurization, tanks, and instrumentation capable of flight. A key innovation is the electronic pressure regulation system, which replaces mechanical regulators with servo-actuated valves running PID loops for precision and an extra degree of control.

The Stinger engine, under development since Fall 2023, has undergone nine hot-fire tests, with further testing planned to qualify the new …

Aeroelastic Simulation Of Shape Adaptive Wing, Allan Alfred Kozich Iii

Honors Undergraduate Theses

Morphing wings provide aerodynamic qualities that normal fixed wings cannot, such as the ability to improve endurance yet maintain maneuverability, overcome strong gusts, vibrations, and shocks, and handle both ideal flight for both high and low speeds. A critical application of the new generation of morphing wings is the ability to overcome and affect the onset flutter, a self-excited oscillatory instability that has led to the destruction of aircrafts. This work investigates aeroelastic behavior and measurement of a meta-material structured "smart" wing and its attempt to delay the effect of flutter. The variable wing tip model is analyzed through finite …

On The Vibrational Dynamics Of Wind Turbine Blades: The Oscillatory Response To Gust Pulses, And The Physical Mechanisms Behind Them, North A. Yates

Dissertations, Master's Theses and Master's Reports

An easily noticed trend in the utility-scale wind turbine industry is that the size of the machines has continued to increase over time. While this may have benefits in terms of increasing the power generation for a single turbine, a major drawback is the rate with which the weight of the turbine blades grow. To ensure these larger machines can be utilized, efforts are being put forth to create lighter blades. This may fix the weight issue, but brings on a new one; these lighter blades can also be more flexible than previously studied ones. It is, therefore, vitally important …

Computational Study Of Rotating Detonation Combustors, Aditya Balasubramaniam

Mechanical and Aerospace Engineering Theses

Rotating detonation combustors (RDCs) are pressure-gain combustion devices that sustain one or more continuously rotating detonation waves, offering potential thermodynamic and performance advantages over conventional deflagration-based systems. Their behavior depends strongly on combustor geometry and operating conditions. Understanding these effects is therefore essential for the design and optimization of practical RDCs. Accordingly, this thesis numerically investigates annular RDCs with two primary objectives: (1) to evaluate the effects of propellant mass flux and (2) to assess the influence of annular width on detonation-wave dynamics and combustor performance.

A finite-volume framework is used to solve the compressible reactive Euler equations with hydrogen–air …

Active Altitude Control For High Powered Rockets, Henry Allen, Jason Secora, Charles Williams, Donavon Sanchez, Caleb Nedoma

Williams Honors College, Honors Research Projects

The International Rocket Engineering Competition (IREC) is the premier collegiate high power rocketry competition in the world hosted by the Experimental Sounding Rocket Association (ESRA). The Akronauts Rocket Design team has been competing in IREC since 2015 and have won several awards. The main goal of IREC is to launch a rocket to a specified altitude of 10k, 30k, or 45k ft while carrying a payload and successfully recover with little to no damage.

The control of a typical high-powered rocket is purely passive; the center of pressure of the rocket must be behind the center of gravity with respect …

Breaking The Vapor Barrier And Scale: Revolutionizing Steel Quenching With Ultrasound Technology, Anthony O. Santos

Williams Honors College, Honors Research Projects

The quenching process is a fundamental heat treatment used to enhance material properties by heating steel to its austenitizing temperature and rapidly cooling it to form high-strength martensite. However, this process is often hindered by two surface barriers: the Leidenfrost effect (vapor blanket) and oxide scale. These cooling limitations restrict the use of steel in high-performance aerospace applications due to inconsistent material properties and unpredictable engineering properties. This research investigates the use of fully submersible, 50-watt 40 kHz ultrasound technology to improve cooling rates in a Jominy test [4]. Through numerical simulations and experimental validation, the study demonstrates that acoustic …

Thermal Radiation Effects On Particles From Plasma Arc Radiation, Reece Davis, Joseph Mcgee

Williams Honors College, Honors Research Projects

Understanding the radiation heating and transport of both microparticles and nanoparticles is a phenomenon that is critical for both space and Earth sciences. In space, these particles are heated by plasma arcs within ionized space clouds or solar flares and can be present the path of deep space missions and orbital satellites. While on Earth, processes such as forest fires, nuclear fusion, and microchip manufacturing include the plasma arc heating of particles. These particles lay within the Mie Scattering Regime and Rayleigh Scattering Regime and emit radiation differently based on their diameter. New mathematical and computational modeling has been conducted …

Development Of A Hypersonic Aerodynamic Analysis Methodology For Conceptual Design, Stephen Atkins

Mechanical and Aerospace Engineering Theses

This research promotes the advancement of the Aerospace Vehicle Design Synthesis (AVDS) system through the development of a low order numerical hypersonic aerodynamic analysis methodology. The AVDS methodology outlines how to utilize disciplinary tools and relies on the careful selection or development of those tools to carry out the aerospace vehicle sizing and evaluation processes. An overview of the aerodynamic analysis process from both industrial and academic perspectives is presented to provide context for the present work. The different philosophies of design are discussed insofar as they dictate how aerodynamic tools are used in the design process. Next, a literature …

Effects Of Hydrogen Enrichment And Premixing On Flame Stability In A High-Pressure Axial-Stage Combustor, Alexandre Fernandes C. Santiago Filho

Honors Undergraduate Theses

The addition of hydrogen to conventional fuels enhances reactivity and can increase the risk of flashback in premixed gas turbine combustors. This study investigates the effects of premixing length and hydrogen concentration on flame stability in a high-pressure axial-stage combustor. Experiments were conducted at the UCF Propulsion and Energy Research Laboratory using a two-stage configuration, where the primary stage provided a high-temperature vitiated crossflow using a hydrogen-piloted, premixed methane–air mixture, and hydrogen-enriched methane–air mixtures were injected through a concentric fuel-tube injector in the axial stage. Premixing length was varied for pure hydrogen flames, and hydrogen concentration was varied at a …