Engineering Commons^™

An Investigation Of Unsteady Vortex Flow Over A Maneuvering Delta Wing, Harry James Kowal

Doctoral Dissertations

An investigation of the vortex breakdown phenomenon using flow visualization qualitatively and quantitatively was conducted with a 70° delta wind under conditions of steady and unsteady pitch, roll and combinations of pitch and roll. Testing was carried out in the water tunnel located in the Mechanical Engineering Department of the Royal Military College of Canada, Kingston, Ontario.

Steady state roll experiments with the delta wing pitched at 30° showed that the behavior of vortex breakdown as a function of roll angle could be considered linear over the front half of the delta wing; however, the behavior beyond a certain critical …

Testing Of Solid Rocket Propellants With An Ultrasonic Transducer, Bryan Rasmussen

Honors Capstone Projects and Theses

No abstract provided.

Freezing Point Mobile Munitions Assessment Sytem: Thermal Chamber Redesign, Sara Gifford, Preston Harris

Undergraduate Honors Capstone Projects

The Army is actively investigating non-intrusive methods to identify six chemical weapons agents. The chemical munitions in question are often found scattered across military bases and other facilities. These non-stockpile munitions are specifically targeted for identification using the mobile munitions assessment system. This program is being administered by the Idaho National Engineering Laboratory.

The Pratt & Whitney 4060: Power For The Future, Gregory Sumner

Honors Theses

The Pratt & Whitney 4000 engine platform is considered the most economical turbofan engine in its class. It is advertised as providing the most efficient service and the most reliability for air carriers. United Airlines utilizes the company's engines. The paper begins with basic turbine engine theory and moves on to engine classifications, where the Pratt & Whitney 4060 is introduced. The systems are covered in detail. Maintenance areas of service and inspections are described to show how personnel may interact with the computers. Finally, a description of activities during the author's internship describe the interesting facets of a semester …

Three-Dimensional Aerodynamic Design Optimization Using Discrete Sensitivity Analysis And Parallel Computing, Amidu Olawale Oloso

Mechanical & Aerospace Engineering Theses & Dissertations

A hybrid automatic differentiation/incremental iterative method was implemented in the general purpose advanced computational fluid dynamics code (CFL3D Version 4.1) to yield a new code (CFL3D.ADII) that is capable of computing consistently discrete first order sensitivity derivatives for complex geometries. With the exception of unsteady problems, the new code retains all the useful features and capabilities of the original CFL3D flow analysis code. The superiority of the new code over a carefully applied method of finite-differences is demonstrated.

A coarse grain, scalable, distributed-memory, parallel version of CFL3D.ADII was developed based on "derivative stripmining". In this data-parallel approach, an identical copy …

Hybrid Rocket Powered Upper Stage Design Report, Imran Mukhtar

Honors Capstone Projects and Theses

No abstract provided.

The Design And Experimental Optimization Of A Wingtip Vortex Turbine For General Aviation Use, Andrew Roberts

Master's Theses - Daytona Beach

A wingtip vortex turbine (WVT) is an induced drag reduction device that straightens the vortex flow (reducing induced drag and wake turbulence) and also produces a thrust force component. The WVT also has the advantage of extracting the rotational energy of the vortex to turn a generator, which could be used to power onboard applications during normal or emergency flight operations. A 1/4-scale model of a thrust-producing WVT has been designed and tested in a wind tunnel for optimal drag reduction and power generation for general aviation aircraft — specifically, a Piper Cherokee — in both a stationary and a …

Development And Initial Evaluation Of An Acoustic Apparatus Used For Testing Of Farfield Noise Emitted By A Propeller In A Short Duct, R. Duane Oleson

Master's Theses - Daytona Beach

The purpose of this thesis was to design, construct and evaluate an apparatus which was used for testing of acoustic emissions by a propeller in a short duct. An apparatus was designed based on a combination of acoustic principles and a desire to be able apply the knowledge gained to a practical application such as an ultralight aircraft in an effort to reduce the overall noise levels emitted. The apparatus consisted of a 35 horsepower ultralight engine, a four bladed ultralight propeller, and a duct constructed of a foam core covered with fiberglass. Initial evaluations compared noise levels from the …

Cooperative Power-Limited Optimal Rendezvous Between Many Spacecraft, Virginie Guerre

Master's Theses - Daytona Beach

The minimum fuel rendezvous problem between several power-limited low-thrust spacecraft neighboring either a circular or an elliptic orbit is investigated. Both cooperative and non cooperative maneuvers are studied. The maximum principle of Pontryagin is applied to the optimal control rendezvous problem of several spacecraft. The gravitational field models investigated are the Clohessy-Wiltshire field and the inverse-square gravity field. Numerical solutions using a shooting method and the finite difference method are used in order to determine the trajectories of the spacecraft. Unlike previous investigations, this work is not restricted to a rendezvous of two spacecraft around a circular orbit, but a …

Aerodynamic Gradient-Based Optimization Using Computational Fluid Dynamics And Discrete Sensitivities For Practical Problems, Mohagna Jayendrarai Pandya

Mechanical & Aerospace Engineering Theses & Dissertations

A gradient-based shape optimization methodology based on quasi-analytical sensitivities has been developed for practical three-dimensional aerodynamic applications. The flow analysis has been rendered by a fully implicit, finite-volume formulation of the Euler and Thin Layer Navier-Stokes (TLNS) equations. The flow equations and aerodynamic sensitivity equation have been solved using an alternating-direction-implicit (ADI) algorithm for memory efficiency. A wing geometry model based on space-surface and planform parameterization has been utilized. The present methodology and its components have been tested via several comparisons.

Initially, the inviscid flow analysis for a wing has been compared with those obtained using an unfactored, Preconditioned Conjugate …

Input Design For Systems Under Identification Using Indirect And Direct Methods, Marco P. Schoen

Mechanical & Aerospace Engineering Theses & Dissertations

The motivation for system identification can be manifold. In this work, the provocation to identify unknown system characteristics is derived from the control engineering point of view. That is, one intends to design a control strategy based on the identified system properties. The used system identification methods are the Open-Loop Kalman filter System Identification method (OKID) and the Closed-Loop System Identification method (CLID). It is shown that the quantitative largest error of the system identification is given by its model representation, that is the attempt to describe a system with model parameters which poses a linear relationship with the input/output …

Nested Fork-Join Queuing Networks And Their Application To Mobility Airfield Operations Analysis, Craig J. Willits

Theses and Dissertations

A single-chain nested fork-join queuing network (FJQN) model of mobility airfield ground processing is proposed. In order to analyze the queuing network model, advances on two fronts are made. First, a general technique for decomposing nested FJQNs with probabilistic forks is proposed, which consists of incorporating feedback loops into the embedded Markov chain of the synchronization station, then using Marie's Method to decompose the network. Numerical studies show this strategy to be effective, with less than two percent relative error in the approximate performance measures in most realistic cases. The second contribution is the identification of a quick, efficient method …

Modern Flight Control Design, Implementation, And Flight Test, Phillip T. Edwards

Theses and Dissertations

This thesis addresses the application issues raised implementing flight control designs derived from optimal control theory and the challenges in obtaining acceptable handling qualities when using these techniques. Using the USAF TPS FCS project as the controller architecture, four controllers were designed using classical methods, and H2, H3, and mixed H2/H optimal control theory. These designs were implemented in the Calspan VSS II Learjet, simulating unstable aircraft longitudinal dynamics and a limited handling qualities flight test evaluation was performed. The design phase found the optimal control techniques, as applied, difficult to design to handling qualities specifications. The H2, H3 and …

Advances In Time-Domain Electromagnetic Simulation Capabilities Through The Use Of Overset Grids And Massively Parallel Computing, Douglas C. Blake

Theses and Dissertations

A new methodology is presented for conducting numerical simulations of electromagnetic scattering and wave propagation phenomena. Technologies from several scientific disciplines, including computational fluid dynamics, computational electromagnetics, and parallel computing, are uniquely combined to form a simulation capability that is both versatile and practical. In the process of creating this capability, work is accomplished to conduct the first study designed to quantify the effects of domain decomposition on the performance of a class of explicit hyperbolic partial differential equations solvers; to develop a new method of partitioning computational domains comprised of overset grids; and to provide the first detailed assessment …

The Effects Of Elevator Rate Limiting And Stick Dynamics On Longitudinal Pilot-Induced Oscillations, Patrick J. Peters

Theses and Dissertations

This report presents the results of an investigation into the effects of elevator rate limiting and stick dynamics on longitudinal pilot-induced oscillations (PIO). A simulation study was conducted to prepare for the flight test, but also to gain insight into the effects of rate limiting and stick dynamics. Due to the non-numerical nature of the simulation results, a flexible three-phase flight test plan was developed, first varying the rate limits, then varying the stick dynamics, and finally flying a matrix determined in the first two phases. There were three major conclusions. First, the offset landing task flown was insufficient to …

Numerical And Experimental Investigation Of The Flowfield Near A Wrap-Around Fin, Carl P. Tilmann

Theses and Dissertations

A wall-mounted semi-cylindrical model fitted with a single wrap-around fin (WAF) has been investigated both numerically and experimentally, with the objective of characterizing the mean and turbulent flowfield in the vicinity of the fin. Numerical and experimental results are used to determine the nature of the flowfield and quantify the effects of fin curvature on the character of the flow near WAFs. This research has been motivated by the need to identify possible sources of a rolling moment reversal observed at high speeds in sub-scale flight tests. Detailed mean flow and turbulence measurements were obtained in the AFIT Mach 3 …

An Object Oriented Simulation Of The C-17 Wingtip Vortices In The Airdrop Environment, Hans J. Petry

Theses and Dissertations

This thesis effort focuses on the development of an object-oriented simulation of C-17 personnel airdrop operations and provides a tool for risk assessment of jumper and wingtip vortex interaction. Using the initial modeling efforts of the Wright Laboratory, this model expands those efforts to include random aircraft, wind and jumper movement within the simulation using MODSIM III as its language. Once the model was built, verified, and calibrated, it helped perform a preliminary analysis of jumper risk with varying element spacing and no crosswind. The results of the simulation provided 15 data points with which linear and logistic regression provided …

An Investigation Of The Hydrodynamic Effects Of Enteromorpha Clathrata Fouling On Hydrofoils, Brian J. Collino

Master's Theses - Daytona Beach

The purpose of this investigation was to determine the effects of biological fouling on hydrofoils. NACA 4412 and 4415 hydrofoil models with 6 inch chord and 8 inch span were used in this study. A water tunnel facility was designed and constructed to perform the tests, and the results were verified using computational fluid dynamic modeling. The CFD software package Fluent was used to create a two dimensional model of the water tunnel test section and hydrofoil. The model was meshed using a Laplacian grid smoothing technique that forced the structured grid lines to follow the same approximate contour as …

Development Of Radiation Shielding Materials For Space Applications, Stephen C. Ko

Dissertations, Theses, and Masters Projects

No abstract provided.

Discrete-Time Linear And Nonlinear Aerodynamic Impulse Responses For Efficient Cfd Analyses, Walter A. Silva

Dissertations, Theses, and Masters Projects

This dissertation discusses the mathematical existence and the numerical identification of linear and nonlinear aerodynamic impulse response functions. Differences between continuous-time and discrete-time system theories, which permit the identification and efficient use of these functions, will be detailed. Important input/output definitions and the concept of linear and nonlinear systems with memory will also be discussed. It will be shown that indicial (step or steady) responses (such as Wagner's function), forced harmonic responses (such as Theodorsen's function or those from doublet lattice theory), and responses to random inputs (such as gusts) can all be obtained from an aerodynamic impulse response function. …

Vehicle Performance Optimization Utilizing The Air Turbo-Ramjet Propulsion System; Methodology Development And Applications, Kirk Christensen

Doctoral Dissertations

"The ATR (Air TurboRocket) is an air breathing propulsion system in which the turbocompressor turbine is powered by a hot drive gas which is generated independently of the air flow through the compressor. The ATR has a lower specific impulse (Isp) and higher thrust compared to a similar size turbojet but a lower thrust and higher Isp compared to similar size solid rocket motor (SRM). This work defines the benefits of ATR propulsion for tactical vehicles.

ATR simulation codes were developed to support analysis of hypothetical ATR powered vehicles. Both turbojet powered and SRM powered vehicles were also evaluated against …