Aerodynamics and Fluid Mechanics Commons^™

Conceptual Design Methodology For The Fan-In-Wing Vtol Aircraft, Brock Steinfeldt

Doctoral Dissertations and Master's Theses

The Fan-In-Wing (FIW) aircraft concept is one of the most compelling solutions for missions demanding jet-like cruise speeds and Vertical TakeOff and Landing (VTOL) capability. However, despite years of interest and documented improvements in lift-fan technology, there exists little in the way of an adequate theory for conceptual design of a fan-in-wing aircraft. To address this issue, a general conceptual design methodology has been developed as a source of guidance for the FIW designer. Through this work, the top-level requirements ranking the fan-in-wing concept above other VTOL aircraft have been defined, while a cross-comparison between the FIW concept and conventional …

Adaptive Control Of An Aeroelastic System For Active Flutter Suppression And Disturbance Rejection, Patrick Sterling Downs

Doctoral Dissertations and Master's Theses

The future of aircraft design strives for lighter weight, more aerodynamically efficient structures. These improvements may come with the drawback of increased structural flexibility and elevated aeroelastic effects, often resulting in a lower flutter speed. This motivates the implementation of advanced control methods to control aeroelastic systems over a range of flight conditions, suppress and delay the onset of flutter, and compensate for disturbances, actuator dynamics, and unmodeled nonlinear dynamics.

This dissertation first develops a novel method for constructing time-domain simulation models of two and three-dimensional aeroelastic systems, resulting in models that are suitable for the implementation of state-space control …

Development Of On-The-Fly Quasi-Steady State Approximation For Chemical Kinetics In Cfd, Abhinav Balamurugan

Doctoral Dissertations and Master's Theses

This study analyzes the feasibility of On-The-Fly Quasi-Steady-State Approximation (OTF-QSSA) application for solving chemical kinetics within Computational Fluid Dynamics (CFD) simulations, aiming to reduce the computational demand of detailed mechanisms. An algorithm that dynamically identifies and designates Quasi-Steady-State (QSS) species at specific grid locations and instances during the simulation was developed. With this information, our method pseudo-delays the advancement of concentrations for these QSS species—effectively setting their rate of concentration change to zero for a set number iteration before updating using the detailed mechanism and thereby omitting the computationally intensive processes typically required for their calculation during those skipped iteration. …

Numerical Study In Wind Energy Extraction From Controlled Limit-Cycle Oscillations In Modified Glauert Airfoil, Ethan L. Deweese

Doctoral Dissertations and Master's Theses

Typically, wind energy harvesting technology employs wind turbines. Towards the goal of meeting increasing energy needs with renewable energy sources a novel wind energy harvesting scheme is considered, utilizing a modified Glauert (MG) airfoil experiencing aeroelastic limit cycle oscillation (LCO) from which energy may be extracted. Synthetic jet actuators (SJA)s are used along with the unique geometry of the MG airfoil to control flow separation and amplify the LCO and energy generation potential of the system. The discussed wind energy harvesting scheme could provide flexibility in allowing installations previously unsuitable to wind turbines due to geometric or low wind velocity …

Mitigating Engine Unstart In Scramjets With Porous Bleeders, Ryan Lindley

Doctoral Dissertations and Master's Theses

The effectiveness of porous bleeders in mitigating unstart phenomena and enhancing isolator effectiveness in a hypersonic scramjet was investigated. Through computational fluid dynamics simulations, the impact of porous bleeder design parameters such as pressure jump coefficient and bleeder size on isolator effectiveness and unstart prevention was evaluated. Results indicated that porous bleeders delayed flow separation and reduced adverse pressure gradients, thereby enhancing isolator performance. Additionally, porous bleeders demonstrated promising capabilities in preventing full unstart events and mitigating oscillatory unstart phenomena.

Aerodynamic Investigation Of Naca 0020 Airfoil With Extended And Serrated Trailing Edge At Various Turbulent Intensities, Livya E

Theses and Dissertations

Lift (upward force) is a significant aerodynamic component that directly relates to the aerodynamic efficiency (lift-to-drag ratio) of the airfoil. Enhancement of airfoil lift is important for industries like wind turbines, aircraft, and turbo machinery. The present study investigates the NACA series airfoil by modifying the trailing edge in the form of extension and serration. The angle of attack was changed from 0° to 35° instep of 5°, and the airflow Reynolds number was fixed as 2.14 × 105. To figure out the flow behavior, surface pressure has been collected from the 50 pressure ports provided over the airfoil surface. …

Experimental Environmental Profiles And Sloshing Dynamics Aboard Zero-G Aircraft, Pedro J. Llanos, Sathya Gangadharan, Kevin Crosby

Publications

This study presents the results of a parabolic flight experiment to study the sloshing dynamics of the magneto-active propellant management device experiment. This device utilizes a magnetoactive membrane and magnets located external to the tank to effectively damp the liquid free surface motion. This research work establishes a benchmark with sloshing analytical formulation and sensor calibration methods that can be used to characterize future research parabolic flights while providing important environmental profiles measured during flight, such as accelerations, pitch angle, velocity, temperature, total volatile content, carbon dioxide, relative humidity, magnetic field, and radiation. Correlation between these flight variables and the …

On Progress In Exploring Controlled Viscous Limit-Cycle Oscillations In Modified Glauert Airfoil, Ethan Deweese, Lap Nguyen, Erik Vataker, William Mackunis, Vladimir Golubev, Ron Efrati, Oksana Stalnov

Publications

The paper reports on the progress in the development of a novel robust, nonlinear flow control technology that employs an array of synthetic-jet actuators (SJAs) embedded in 2-DOF, elastically mounted, optimized Modified Glauert (MG) airfoil design in order to control limit cycle oscillations (LCO) at low subsonic flow regimes. The focus here is on the conceptual design of the wind energy harvesting system that employs, e.g., a piezoelectric device to extract energy from plunging LCO, with the closed-loop controller being capable to sustain the required LCO amplitudes over a wide range of wind speeds. The current high-fidelity studies first include …

Development Of Advanced Instrumentation For High-Enthalpy Flow Characterization For The Onr-Uta Arc-Jet ”Leste” Facility, Ian Raybon

Mechanical and Aerospace Engineering Dissertations - Archive

Sustained hypersonic flight is an exceedingly challenging task comprised of a myriad of complex physical processes. At hypersonic speeds, which is defined by the presence of unique phenomena like high-temperature nonequilibrium flow, viscous and vorticity interactions, and thin shock layers, which are not seen in supersonic, transonic, or subsonic vehicles, the vehicle design is principally driven by the high levels of aerodynamic heating caused by the conversion of kinetic energy to internal energy. Gaining an understanding of how these physical processes interact with each other is required to develop a design methodology for this class of vehicles. Arc-jet wind tunnels …

Two-Phase Flow Simulations With Plic-Vof Method And Dynamic Mesh Refinement, Vimalan Adaikalanathan

Mechanical and Aerospace Engineering Dissertations - Archive

Two-phase flows are critical in a variety of engineering applications that span multiple length scales. These applications encompass macroscopic phenomena, such as dam breakage and wave-structure interactions, as well as microscopic events, including droplet impacts and boiling, and mixed-scale issues like spray dynamics. Accurate representation of evolving interfaces is essential for numerical simulations of these problems, and the Volume of Fluid (VOF) method combined with the Piecewise Linear Interface Calculation (PLIC) approach is employed to fulfill this requirement. To tackle the computational challenges associated with high-resolution meshes in deforming two-phase flows, Adaptive Mesh Refinement (AMR) is utilized to enhance mesh …

Dynamics Of Separated Flows In Diffusers With Vortex Generators, Sandeep Eldho James

Mechanical and Aerospace Engineering Dissertations - Archive

Flow through curved diffusers is complicated due to the possibility of flow separation and secondary flows. Vortex generators (VGs) are a class of passive flow separation control devices used to improve the flow quality in curved diffusers by suppressing flow separation. However, the literature review demands an in-depth investigation on the physical mechanisms related to flow separation control. Thus, this study aims to improve the understanding of the underlying flow physics associated with VG-induced flow separation control in confined flows. The chosen geometry for this study is a well-documented asymmetric diffuser which exhibits a mild flow separation.

The theoretical formulation …

On The History And Semantics Of Burble In Aerodynamic Theory, Benjamin C. Moulton, Cory D. Goates, Troy A. Abraham

Mechanical and Aerospace Engineering Student Publications and Presentations

The term burble has been in use in aerodynamic theory for over a century. While burble may be unfamiliar to most contemporary aerodynamicists, the word has a rich history based in aerodynamic theory and experimentation. The present paper outlines the fluidity of burble's meaning over time. From analyzing subsonic flow over an airfoil, to the implementation of stochastic turbulence in aircraft carrier landing simulations, the term burble has had a significant impact on the study of aerodynamics. The term burble has fallen out of use in aerodynamic engineering circles. Why did this happen? And what can be learned from the …

Fundamental Chemical Kinetic Experiments Of Combustion Products Inside A Shock Tube, Alex-Abraham Pothen

Graduate Thesis and Dissertation 2023-2024

The use of lateral divert thrusters on hypersonic vehicles would allow for fine-tuned attitude control at high Mach numbers. However, the jet interaction effects of lateral thrusters on the hypersonic flow field have not been investigated thoroughly. Computational Fluid Dynamics (CFD) can provide preliminary modeling of the jet interaction, but several variables such as vehicle geometry, velocity, and altitude, result in computationally expensive modeling or loss in accuracy of the results. Therefore, the goal of chemical kinetics testing and chemical model verification is to enhance the fidelity of the jet interaction effects, specifically the plume reaction with air and the …

Optimization Of High-Bypass Turbofan High-Pressure Compressor Blade – A Case Study, Adeel Khalid, Vlad Mandzyuk

The Kennesaw Journal of Undergraduate Research

This research determines the relationship between the High-Pressure Compressor (HPC) rotor blade design variables and compressor pressure ratio of a high bypass turbofan engine. Alterations in the HPC blades span, chord, taper, twist, number, and angle of incidence are performed and their effect on the HPC pressure ratio is observed. The objective is to determine key parameters that could maximize the performance of a high-pressure compressor for a given mission. Physics-based modeling, Computational Fluid Dynamics (CFD), and wind-tunnel testing are performed to compare and validate findings. Physics-based modeling is performed to serve as the benchmark for data obtained through other …

Winglet Vortex Optimization, Adeel Khalid, Anthony Gutierrez

The Kennesaw Journal of Undergraduate Research

The objective of this research is to determine the effect on aerodynamic performance due to changes of winglet design variables of the Boeing 737-700 aircraft. The various winglet types studied in this research include the blended, canted, wingtip fence and split scimitar. The variables include height, sweep angle, taper ratio, and inclination angle. These variables are altered in 5% increments from -15% to +15% of their original baseline values. Each altered winglet design only changes one variable at a time while keeping all other variables constant. The altered models are compared to the original by finding the aerodynamic efficiency through …

Design And Development Of Supersonic Free Jet Facility, Gowtham Sai Somaroutu

Mechanical and Aerospace Engineering Theses - Archive

High-speed wind tunnels are essential facilities for conducting research and testing in external and internal flows. This thesis details the design and development of a blow-down supersonic free-jet facility with a 3-inch square nozzle in the Mach number range of and unit Reynolds number ranging. Key aspects of the facility development include the detailed design of the gas supply system, control valve selection, plenum, nozzle, test section, and the selection of an exhaust silencer. CAD designs for all the components of the facility were also generated in this effort.

A new analytical approach was developed to design supersonic contoured nozzles …

Advancements In Elliptic Mesh Redistribution And Automated Overset Grid Generation For Computational Fluid Dynamics, Chase Ashby

Theses and Dissertations--Mathematics

Automated and robust structured curvilinear overset grid generation remains a significant challenge for the application of computational fluid dynamics. This thesis intro- duces a specialized anisotropic Mach cone aligned adaptation algorithm for low-boom simulations and an automated procedure for generating structured curvilinear overset grids for immersed boundary simulations. Results demonstrate that anisotropic mesh adaptation can reduce computational resource usage by over 50% while maintaining sonic boom prediction accuracy across the entire sonic boom domain compared to user-constructed Mach cone aligned grids. The proposed immersed overset grid gen- eration procedure eliminates the need for complex surface generation algorithms, producing grids suitable …

High-Fidelity Coupling For Studies Of Ablative Materials At Hypersonic Conditions, Aleksander Zibitsker

Theses and Dissertations--Mechanical and Aerospace Engineering

The development of accurate models and robust numerical tools for simulating ablative thermal protection materials (TPMs) in hypersonic flows is crucial for advancing atmospheric entry and hypersonic technologies. Traditional methods for simulating ablative materials often rely on heavy assumptions, such as equal heat and mass transfer coefficients and chemical equilibrium in the boundary layer, leading to conservative thermal protection system (TPS) designs and insufficient accuracy for certain in-flight ablation phenomena.

This work presents a high-fidelity and versatile coupled framework between hypersonic flow and material response solvers. The flow domain is modeled with an innovative overset CHAMPS NBS-Cart solver, which features …

Control Of Flow Instabilities With Acoustic Metamaterials, Jensen E. Mctighe

Open Access Master's Theses

Acoustic metamaterials (AMs) have been proposed for uses in flow control, as they offer a passive control method and can be engineered independently, without needing complex fluid structure interactions simulations. For example, AMs embedded into flat plate surfaces have been demonstrated to delay (or speed up) the onset of laminar-to-turbulent boundary layer transition by attenuating (or strengthening) Tollmein-Schlicting waves through numerical simulation. However, as of present, no experimental research has been conducted to study or demonstrate the behaviors of AMs designed to interact with flow structures. An experiment was performed in which an AM was embedded into a flat plate …

Uav To Carry Heavy Loads, Jacob Cannon, Robert Connor Downs, Anthony Orlando

Williams Honors College, Honors Research Projects

Our senior design project aims to develop an innovative Unmanned Aerial Vehicle (UAV) capable of carrying heavy payloads up to 50 lbs. This UAV will address the growing demand for efficient and autonomous cargo transportation, unlocking new possibilities in logistics and remote deliveries. The primary goal is to design, build, and test a robust UAV platform equipped with advanced propulsion systems, stabilizing mechanisms, and a secure payload attachment system. The heavy-lift UAV will be capable of transporting payloads in challenging environments, enhancing its versatility for various industries, including emergency response, disaster relief, and commercial logistics. For the extent of this …