Aerospace Engineering Commons^™

Computational Solution Of Tail Buffet Response And Active Flow Control, Kaushik Laxmikant Joshi

Mechanical & Aerospace Engineering Theses & Dissertations

In this thesis, numerical simulation of the multidisciplinary method for prediction and control of vortex induced tail buffeting is studied using delta wing-single tail configuration. Flow conditions are chosen such that wing vortex cores experience vortex breakdown and the resulting wake flow impinges on the vertical tail. The aero/structure problem is solved sequentially using three sets of equations on a multi-block grid structure. To obtain aerodynamic loading on the tail, the fluid flow around the wing-tail assembly is computed by time-accurately solving unsteady, laminar, compressible Navier-Stokes equations using an implicit, upwind, flux-difference splitting finite volume scheme. Then the aeroelastic equations …

Pylon Effects On A Scramjet Cavity Flameholder Flowfield, Andrew B. Freeborn

Theses and Dissertations

Cavity flameholders in supersonic combustion ramjet (scramjet) combustors, while effective, fail to take advantage of the full combustor volume. Adding a pylon to the leading edge of a cavity flameholder generates a flowfield increasing mass exchange between the cavity and main combustor flow, increasing the mixing interface between flameholder products and main combustor flow, and exhibiting minimal Reynolds number effects. To demonstrate this modified flowfield driven by supersonic expansion behind the pylon, pylon-cavity flameholder flowfield data were obtained through a combination of wind tunnel experimentation and steady-state computational fluid dynamics (CFD). Flowfield effects of the pylon-cavity were examined at a …

Hypermixer Pylon Fuel Injection For Scramjet Combustors, Jason C. Doster

Theses and Dissertations

Fueling the core airflow of a circular or elliptical scramjet combustor cross-section often requires intrusive geometries. Intrusive geometries can distribute the fuel evenly across the combustor cross-section and act as a flameholder for the fuel/air mixture. Compared to conventional transverse or angled wall injection, intrusive geometries allow easier penetration into the core combustor airflow and reduced fuel injection pressures. The design and testing of an intrusive pylon geometry for scramjet combustor fueling is the subject of this research. Three pylon configurations are compared: a basic pylon, a ramp pylon, and an alternating wedge pylon. All three pylon configurations exhibit the …

Modeling And Parameter Estimation Of Spacecraft Lateral Fuel Slosh, Yadira Rodriguez Chatman

Master's Theses - Daytona Beach

Predicting the effect of fuel slosh on spacecraft and launch vehicle attitude control systems has been a very important and challenging task and has been the subject of considerable research over the past years. Analytic determination of the slosh analog parameters has been met with mixed success and is made more difficult by the introduction of propellant management devices such as elastomeric diaphragms. The experimental set-up in this research incorporates a diaphragm in a simulated spacecraft fuel tank subjected to lateral slosh behavior. This research focuses on the parameter estimation of a SimMechanics model of the simulated spacecraft propellant tank …

A Constraint Based Approach For Building Operationally Responsive Satellites, Mesut O. Kahraman

Theses and Dissertations

The Operational Responsive Space (ORS) program requires flexible and responsive satellites to meet user’s needs. Traditional satellite design methods are typically iterative processes that optimize individual components, subsystems, and ultimately the entire satellite. This study focuses on developing a new approach for creating Responsive Satellites (RS) from Plug-and-Play (PnP) components. The aim is to create an approach that quickly evaluates a wide variety of possible satellite configurations and identify the best configurations that meet the user’s needs and constraints. Satellite configurations are created by matching locations on the satellite structure with PnP components. Various constraints are derived from the user’s …

Hall Thruster Plume Diagnostics Utilizing Microwave Interferometry, Vipul Sharma

Theses and Dissertations

The fatigue behavior of two woven SiC-SiNC ceramic matrix composites (CMCs) was investigated at 1300 °C in laboratory air and in steam. The first composite (C1) consists of a PIP SiNC matrix reinforced with Sylramic (Syl) fibers woven in a five-harness satin weave fabric and coated with a proprietary dual-layer interface. The second composite (C2) consists of a modified PIP SiNC matrix reinforced with Sylramic-iBN (Syl-iBN) fibers woven in a five-harness satin weave fabric and coated with a proprietary dual-layer interface. The tensile stress-strain behavior was investigated and the tensile properties measured at 1300°C. Tension-tension fatigue behavior was studied for …

Creep Behavior Of Oxide/Oxide Composites With Monazite Fiber Coating At 1100°C In Air And In Steam Environments, Tufan Yeleser

Theses and Dissertations

The creep behavior of six oxide-oxide ceramic-matrix composites (CMCs) was investigated at 1100 °C in laboratory air and in steam environments. The six CMC systems had an alumina ( Al2O3 ) matrix reinforced with Nextel^TM610 fibers. The CMC systems C1, C2 and C3 were reinforced with 10 uni-directional fiber layers in a symmetric cross-ply (0°/90°/0°/90°/0°)s orientation. In the case of composites C2 and C3, monazite (LaPO₄) fiber coating was applied to the fibers. Composite C1 contained no fiber coating. In the case of composites C1 and C2, alumina matrix was infiltrated with monazite. The CMC systems …

Inter-Frequency Bias Estimation For The Gps Monitor Station Network, Donny Holaschutz, Robert H. Bishop, R. Benjamin Harris, Brian Tolman

Mechanical Engineering Faculty Research and Publications

The inter-frequency bias (IFB) is present in all dual frequency combinations of GPS pseudorange and carrier phase observables. It is caused by the path dependent signal delays in both the satellite and receiver. That delay can be directly measured for a space vehicle prior to launch, or for a ground based receiver prior to its being used in the field. However the bias is known to drift, and monitoring the delay estimate by direct measurement is time consuming for ground based receivers and impossible for deployed space vehicles. Hansen (2002) examined the observability of IFB through a global model of …

Aerodynamic Analysis Of A Generic Fighter With A Chine Fuselage/Delta Wing Configuration Using Delayed Detached-Eddy Simulation, Tiger L. Jeans, David R. Mcdaniel, Russell M. Cummings, William H. Mason

Aerospace Engineering

The Modular Transonic Vortex Investigation (MTVI) program at NASA Langley Research Center investigated the transonic characteristics of generic fighter configurations with chined fuselages and delta wings. Previous experiments show that the fuselage and leading edge vortex interactions are detrimental to the vehicle’s aerodynamic characteristics for angles of attack greater than 23º at low angles of sideslip. This is largely due to abrupt asymmetric vortex breakdown, which leads to pronounced pitch-up and significant nonlinearities in lateral stability that could result in roll departure. An improved understanding of the exact origins of this nonlinear behavior would improve future fighter design, and predictive …

An Evaluation Of Proposed Formula 1 Aerodynamic Regulations Changes Using Computational Fluid Dynamics, Robert L. Perry, David D. Marshall

Aerospace Engineering

This report evaluates the proposed FIA Formula 1 World Championship aerodynamics rules changes intended to increase on track passing for the 2009 season. Two full Formula 1 cars were modeled under close drafting conditions, both under the current regulations and the proposed 2009 regulations to determine whether or not the FIA's goals of reducing down force by 50% and improving sensitivity to leading car wakes would be met. Under the current regulations, a car following another at 2.4 car lengths loses approximately 17% of it down force compared to isolation. The new regulations were counter productive and ineffective, failing both …

Raising The Dead, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

A Mathematical Model Development And Sensitivity Analysis Of Two Photon Polymerization For 3d Micro/Nano Fabrication, Nitin Uppal

Mechanical and Aerospace Engineering Dissertations - Archive

Two photon polymerization (2PP) is an effective technique for the fabrication of complex polymeric 3-D micro/nano features using ultrashort pulses from a NIR laser source. The photosensitive material absorbs two photons and initiates the chain polymerization reaction. The interaction of laser pulses with photo responsive resin creates a voxel (volumetric pixel) which defines the resolution of 2PP process. In this work, a mathematical model of the polymerization process that considers the effects of molecular diffusion and polymerization kinetics on the formation of voxel. The increase in temperature upon polymerization and their effect on the polymerization kinetics and molecular diffusion is …

A Least-Squares/Galerkin Split Finite Element Method For Incompressible And Compressible Navier-Stokes Equations, Rajeev Kumar

Mechanical and Aerospace Engineering Dissertations - Archive

Over the years Galerkin finite element method along with its variants has been used to solve incompressible and compressible Navier-Stokes equations. The Galerkin method which is more suited for self-adjoint type system of equations like in solid mechanics and heat conduction struggles when applied to non self-adjoint type systems like one encountered in fluid dynamics. Velocity and pressure variables have to be approximated using functions which belong to different spaces and must satisfy the tough LBB condition. The least-squares finite element method (LSFEM), which is based on minimizing the l2-norm of the residual, has many attractive advantages over Galerkin finite …

The Development And Testing Of Pulsed Detonation Engine Ground Demonstrators, Philip Koshy Panicker

Mechanical and Aerospace Engineering Dissertations - Archive

The successful implementation of a PDE running on fuel and air mixtures will require fast-acting fuel-air injection and mixing techniques, detonation initiation techniques such as DDT enhancing devices or a pre-detonator, an effective ignition system that can sustain repeated firing at high rates and a fast and capable, closed-loop control system. The control system requires high-speed transducers for real-time monitoring of the PDE and the detection of the detonation wave speed. It is widely accepted that the detonation properties predicted by C-J detonation relations are fairly accurate in comparison to experimental values. The post-detonation flow properties can also be expressed …

Analytical Thermal Model Of A Generic Multi-Layer Spacerless 3d Package, Erantha Nuwan Rodrigo

Mechanical and Aerospace Engineering Theses - Archive

Analytical Thermal Model of a Generic Multi-Layer Spacerless 3D Package Abstract The need for more functions in a single device has lead to die stacking architecture. Although the number of functional die increases further to accommodate package functionality, the overall package dimensions have not increased, they have stayed the same or decreased. Recently, Samsung announce a 16 die stacked device. In order to keep the same package height, alternate stacking structures need to be investigated. One suck opportunity is spacerless die stacking architecture. Using dummy silicon spacers add cost to a package and do not increase the memory of functionality. …

The Lattice Boltzmann Method For Computational Fluid Dynamics Applications, Chinmay Adhvaryu

Mechanical and Aerospace Engineering Theses - Archive

An analysis of lattice Boltzmann method is presented in this thesis. This analysis contrast with the traditional lattice Boltzmann work, where complex fluids are considered with extended properties. Focus of the current thesis is on the validation and use of lattice Boltzmann method for traditional fluid dynamics. In first part of the document a historical and theoretical background of lattice Boltzmann method is presented. In this part some conclusions are drawn about the stability and other physical characteristics of the lattice Boltzmann method. Second part deals with the computer implementation of the LBM. It also discusses some aspect about practical …

The Development Of A Finite Element Tool For The Calculation Of Beam Cross Section Properties, Bryan Dale Mixon

Mechanical and Aerospace Engineering Theses - Archive

Cross section properties are crucial in the analysis and design of beams as they play a key role in the determination of the stress state encountered. The development of an FEM tool in MATLAB for the calculation of beam cross section properties will be discussed. Properties of interest include general cross section properties as well as the non-trivial warping-dependent properties for both the unrestrained and restrained cross section conditions for solid and hollow, open and closed sections.

Flip Chip Back End Design Parameters To Reduce Bump Electromigration, Vishal Nagaraj

Mechanical and Aerospace Engineering Theses - Archive

The advancement in flip chip technology has enabled us to meet the requirement of smaller die size along with the increased functionality. Due to this development in flip chip packaging technology along with higher current carrying requirement of solder bumps, electromigration has now become a reliability concern. In this research, a commercially available finite element tool is adopted in order to study the distribution of current density in eutectic solder bump for variety of back end design parameters. Geometries needed were generated by using Pro/Engineer® Wildfire 3.0 as a Computer-Aided-Design (CAD) tool and were transferred to ANSYS® 10.0, where meshed …

Reinforcement Learning Based Dual-Control Methodology For Complex Nonlinear Discrete-Time Systems With Application To Spark Engine Egr Operation, Peter Shih, Brian C. Kaul, Jagannathan Sarangapani, J. A. Drallmeier

Electrical and Computer Engineering Faculty Research & Creative Works

A novel reinforcement-learning-based dual-control methodology adaptive neural network (NN) controller is developed to deliver a desired tracking performance for a class of complex feedback nonlinear discrete-time systems, which consists of a second-order nonlinear discrete-time system in nonstrict feedback form and an affine nonlinear discrete-time system, in the presence of bounded and unknown disturbances. For example, the exhaust gas recirculation (EGR) operation of a spark ignition (SI) engine is modeled by using such a complex nonlinear discrete-time system. A dual-controller approach is undertaken where primary adaptive critic NN controller is designed for the nonstrict feedback nonlinear discrete-time system whereas the secondary …

Analysis And Design Of A Hypersonic Scramjet Engine With A Starting Mach Number Of 4.00, Kristen Nicole Roberts

Mechanical and Aerospace Engineering Theses - Archive

When pressures and temperatures become so high in supersonic flight that it is no longer efficient to slow the oncoming flow to subsonic speeds for combustion, a scramjet (supersonic combustion ramjet) is used in place of a ramjet. Currently, the transition to supersonic combustion generally occurs at a freestream Mach number around 5.0 to 6.0. This research details analysis completed towards extending scramjet operability to lower Mach numbers, while maintaining performance at higher Mach numbers within the same flowpath as detailed in the Air Force solicitation AF073-058. The specific goal is to determine whether the scramjet starting Mach number can …

Issues On Stability Of Adp Feedback Controllers For Dynamical Systems, S. N. Balakrishnan, Jie Ding, F. L. Lewis

Mechanical and Aerospace Engineering Faculty Research & Creative Works

This paper traces the development of neural-network (NN)-based feedback controllers that are derived from the principle of adaptive/approximate dynamic programming (ADP) and discusses their closed-loop stability. Different versions of NN structures in the literature, which embed mathematical mappings related to solutions of the ADP-formulated problems called “adaptive critics” or “action-critic” networks, are discussed. Distinction between the two classes of ADP applications is pointed out. Furthermore, papers in “model-free” development and model-based neurocontrollers are reviewed in terms of their contributions to stability issues. Recent literature suggests that work in ADP-based feedback controllers with assured stability is growing in diverse forms.

Book Review: Tourists In Space: A Practical Guide, T. D. Oswalt

Publications

This document is Dr. Oswalt’s review of Tourists in Space : a Practical Guide by Erik Seedhouse. Springer/Praxis, 2008 314p, 9780387746432 $34.95

An Undergraduate Computational Aerodynamics Curriculum, Keith Bergeron, Russell M. Cummings, Capt Robert Decker, Maj Jacob Freeman, Capt Charlie Hoke, Jurgen Seidel, Scott A. Morton, David M. Mcdaniel

Aerospace Engineering

Modeling and Simulation (M&S) as part of the Aeronautical Engineering major at the United States Air Force Academy (USAFA) has grown from a one course introduction to an integrated and essential component for developing future aerospace leaders. This paper documents the progress the USAFA Department of Aeronautics (DFAN) has made since 2003 to teach cadets, through a 2-course sequence, how to gain an understanding of aerodynamic phenomena using computational methods made possible with Department of Defense (DoD) High Performance Computing Modernization Program (HPCMP) resources. The first course in of the sequence builds upon demonstrations, made in early core coursework, to …

Numerical Prediction And Wind Tunnel Experiment For A Pitching Unmanned Combat Air Vehicle, Russell M. Cummings, Scott A. Morton, Stefan G. Siegel

Aerospace Engineering

The low-speed flowfield for a generic unmanned combat air vehicle (UCAV) is investigated both experimentally and numerically. A wind tunnel experiment was conducted with the Boeing 1301 UCAV at a variety of angles of attack up to 70 degrees, both statically and with various frequencies of pitch oscillation (0.5, 1.0, and 2.0 Hz). In addition, pitching was performed about three longitudinal locations on the configuration (the nose, 35% MAC, and the tail). Solutions to the unsteady, laminar, compressible Navier–Stokes equations were obtained on an unstructured mesh to match results from the static and dynamic experiments. The computational results are compared …

Comparison Of Cooling Performance Of Overhead And Underfloor Supply With Rear Door Heat Exchanger In High Density Data Center Clusters, Ravi K. Udakeri

Mechanical and Aerospace Engineering Theses - Archive

The power trend for server systems continues to grow thereby making thermal management of Data centers a very challenging task. Although various configurations exist, the raised floor plenum with Computer Room Air Conditioners (CRACs) providing cold air is a popular operating strategy. In prior work, numerous data center layouts employing raised floor plenum and the impact of design parameters such as plenum depth, ceiling height, cold isle location, tile openings and others on thermal performance of data center was presented. The air cooling of data center however, may not address the situation where more energy is expended in cooling infrastructure …

Thermo-Mechanical Solutions In Electronic Packaging: Component To System Level, Aalok Trivedi

Mechanical and Aerospace Engineering Theses - Archive

Since the advent of the transistor and integrated circuit, the performance of electronic equipment has increased significantly while footprint of systems at all levels continues to decrease. Recently, the number of transistors on a high end microprocessor has exceeded a billion. All of the above has necessitated considerable improvement in cooling technology and associated reliability. In this era of high heat fluxes, air cooling still remains the primary cooling solution mainly due to its cost and ease of installation and operation. The primary goal of a good thermal design is to ensure that the chip can function at its rated …

Structural Optimization Using Matlab Partial Differential Equation Toolbox And Radial Basis Function Based Response Surface Model, Faisal Tanveer Mosharrof

Mechanical and Aerospace Engineering Theses - Archive

As a decision making tool, optimization has become an inseparable part of the modern design process. However, in spite of the advances in computer capacity and speed, the computational time for some complex problems is too high to use conventional solution approach. In order to reduce the computational effort and the cost associated with such type of problems, approximation methods such as response surface methodology (RSM) along with design of experiments (DOE) are used in engineering design optimization. The main idea involves replacing the expensive simulation model during the design and optimization process with a simplified mathematical approximation of the …

Modeling, Analysis And Testing Of A Semi-Active Control System For Landing Gear Applications, David James Majko

Master's Theses - Daytona Beach

There have been several recent studies on the potential benefits of controllable dampers. Controllable dampers can use a fluid with controllable properties, such as Magneto - Rheological fluid (MR fluid), or control the damping force by changing orifice size. For this project, controllable dampers were created using MR fluid. When exposed to a magnetic fluid, the viscosity of MR fluid can change significantly. By replacing the standard damper oil in an aircraft landing gear and exposing the system to an appropriate magnetic field, the damping coefficients of the system can be changed almost instantaneously to accommodate nearly any situation. This …

Image Processing Technique For Runway Segmentation Using Color Spaces, Naresh Reddy Reddy

Electrical & Computer Engineering Theses & Dissertations

Aircrafts of the future now face the challenge of growing demand for safety which will require a more significant level of pilot assistance than is available today. During an approach to the airport runway, an algorithm that continuously segments the runway from the rest of the background with very little human intervention is very useful for both enhancing the landing safety and reducing the pilot's work load. This thesis presents a novel method for segmenting airport runways on a clear day and in poor visibility conditions using the color space components. In this thesis, collages were formed for both runway …

Detecting Portable Electronic Devices Onboard Commercial Aircraft, Randy Woods

Electrical & Computer Engineering Theses & Dissertations

The need to detect unauthorized usage of intentionally transmitting portable electronic devices (PEDs) onboard commercial aircraft is growing while still allowing passengers to use selected unintentionally transmitting devices, such as laptop computers and CD players, during non-critical stages of flight. This thesis presents the development and testing of an installed system for detecting PEDs over multiple frequency bands. Additionally, the advantages of a fixed versus mobile system are discussed.

Data is presented to cover the frequency range of 20 MHz to 6.5 GHz with special attention given to the cellular and PCS telephone bands, Bluetooth, and the family radio service …