Digital Commons Network^™

Dynamic Aeroelastic Analysis Of Wing/Store Configurations, Gregory H. Parker

Theses and Dissertations

Limit-cycle oscillation, or LCO, is an aeroelastic phenomenon characterized by limited amplitude, self-sustaining oscillations produced by fluid-structure interactions. In order to study this phenomenon, code was developed to interface a modal structural model with a commercial computational fluid dynamics program. LCO was simulated for a rectangular wing, referred to as the Goland⁺ wing. It was determined that the aerodynamic nonlinearity responsible for LCO in the Goland+ wing was the combination of strong trailing-edge and lambda shocks which periodically appear and disappear. This mechanism limited the flow of energy into the structure which quenched the growth of the flutter, resulting …

An Automated Optimal Design Of A Fan Blade Using An Integrated Cfd/Mdo Computer Environment, Uyi O. Idahosa

Master's Theses - Daytona Beach

The objective of the investigation is the development of more efficient design methodologies based on the applications of established design tools including Computational Fluid Dynamics (CFD) and non-linear Multidisciplinary Design Optimization (MDO) algorithms. Well known evolutionary type optimization algorithms include the Particle Swarm Optimization (PSO), Response Surface Optimization (RSO) and Genetic (GA) Algorithms. The benchmark case study is the optimal design of a low speed fan for an industrial air-conditioning application using the Response Surface Optimization (RSO) algorithm.

The optimization algorithm controls the variations of parameters that describe the three-dimensional geometry of the blade while applying performance and geometrical constraints …

Experimental Aerodynamic Analysis Of A Wing-Flap System With Delta Vortex Generators, Charles Roy Mcconnell

Masters Theses

The principle idea upon which the use of vortex generators (VGs) is based has been to control flow separation. The characteristic of VGs has been used to improve lift and alter the stall characteristics of aircraft and has been a relatively common practice for many years. Due to the seemingly limitless range of VG geometries and arrangements, which are largely dependant upon the desired aerodynamic performance, there has been a broad investigation into VG application.

The purpose of this experimental investigation has been to collect data to be used to establish the effects of various delta shaped vortex generators (delta-VGs) …

Viscosity Measurement Technique By Merging Liquid Drops Aboard The International Space Station, Daniel Aaron Lehman

Masters Theses

The efforts reported in this thesis has been to analyze the data from two "Fluid Merging Viscosity Measurement" experiments in order to validate this as a viable method for measuring the viscosity of fluids with known surface tensions. This method involves simultaneously using a numerical analysis code and experimental data to produce matching curves of contact radius versus time and from that a determination of viscosity. Two experiments that were performed, used different liquids (glycerin and 125 Poise silicon oil) and different size ratios between the two drops ( 1 to 1 and O. 3 3 to 1 respectively). The …

Wind Tunnel Study Of Interference Effects Relating To Aft Supersonic Ejection Of A Store, Timothy P. Jung

Theses and Dissertations

An investigation into the issues surrounding the release of a store into a supersonic wake was conducted. A 10-degree half-angle cone was used to model the carrier vehicle as well as the store. The store was 42% than the vehicle. The experiments were conducted at a freestream Mach number of 2.93 and at zero degrees angle of attack. This study analyzed the effects of a support or strut mounted under the wind tunnel model. Research was conducted on the effects of a store at various positions in the wake, as well as the effects of a rear cavity in the …

Performance Measurements Of Direct Air Injection In A Cavity-Based Flameholder For A Supersonic Combustor, Scott G. Edens

Theses and Dissertations

For several years the Air Force Research Lab Propulsion Directorate has been studying the difficulties in fueling supersonic combustion ramjet engines with hydrocarbon based fuels. Recent investigations have focused on the use of direct air injection into a directly-fueled cavity-based flameholder. Direct air injection has been shown qualitatively to be a valuable tool for improving cavity combustion. Little quantitative data is available that characterizes the performance of cavity-based flameholders. The objective of this research was to quantitatively determine the specific advantages and disadvantages of the direct air injection scheme. This was accomplished via intrusive probing into a supersonic free stream …

Modeling, Stability, And Control Of A Rotatable Tail On A Micro Air Vehicle, Travis J. Higgs

Theses and Dissertations

This research uses existing experimental wind tunnel data to develop a non-linear model that is used to characterize the stability of a flexible wing Micro Air Vehicle (MAV) with a rotatable tail. The experimental data are curve fit based on either angle of attack or angle of sideslip, and the coupled effect of tail rotation and tail deflection on the force and moment coefficients. Static optimization trims the input and state variables for Steady Level Unaccelerated Flight (SLUF). The resulting initial conditions are fed to an open loop non-linear Simulink/Matlab simulation. The study found that the bare MAV design is …

Propeller Development Process: Conflict And Cooperation Between The Department Of Defense And Civil Aviation, Nathan Grant Neblett

Masters Theses

The purpose of this thesis was to compare and contrast the acquisition of the Electronic Propeller Control System through both the Department of Defense and Civil Aviation processes controlled by the Federal Aviation Administration (FAA). The author was a planner and participant in the Department of Defense (DoD) process. Information about the Civil Aviation process was obtained via email and telephone communication with participants, some of whom aided both processes.

Strong similarities existed in system design and prototype manufacture for both processes. A large portion of developmental flight test was similar, if not identical. In particular, both the DoD and …

Bio-Derived Fuels For Hybrid Rocket Motors, Joshua David Scholes

Masters Theses

Two bio-derived fuels have been successfully tested in a laboratory scale hybrid rocket combustion chamber located at the University of Tennessee, Knoxville. Pure lard soaked in an open cell sponge matrix and beeswax were both tested using gaseous oxygen as the oxidizer. Given similar testing conditions, these fuels exhibit higher regression rates than the common hybrid rocket propellant HTPB (hydroxyl-terminated polybutadiene), thus overcoming one of the main shortcomings of hybrid rocket fuels. These fuels also have similar or higher regression rates than paraffin-based fuels recently tested by a Stanford University/NASA Ames team. Measured thrusts ranged from 20-140 Newtons, and calculated …

An Experimental Study Of Axisymmetric Cavity Oscillations In Low Speed Incompressible Flow, Jeremy David Brice Smith

Masters Theses

This study is the latest increment of an ongoing research effort at the University of Tennessee Space Institute with the goal of accomplishing a greater understanding of cavity instabilities and or making use of the instabilities to amplify their effects on the flows. An experimental procedure was designed to examine the unsteady pressure pulses that occur when an incompressible fluid (water) flows through an axisymmetric cavity. The length to depth ratios (L/D) examined ranged from about 0.69 to about 6.2, and the average flow Reynolds numbers ranged from 0 to 1.2 million.

Results show that large amplitude oscillations are generated …

Approaches For Autonomous Vehicles In Civil Airspace: Giving Sight To The Blind, Nicholas Scott Hardman

Masters Theses

The growing prevalence of unmanned aerial vehicles (UAVs) brings great potential for public benefit, but in order to fly in civil airspace UAVs must avoid traffic without the benefit of an onboard human. Developing this capability presents many system integration challenges.

This report examines the integration of automated detect, see, and avoid (DSA) systems on aircraft. For context, the need for UAV operations is reviewed. The report then examines how DSA fits into the entire framework for aviation safety. The research, test results, and conclusions that follow provide the necessary information to decide:

• how to test and evaluate new …

Managing The Remaining Service Life Of The T-34c Aircraft, John Howard Rousseau

Masters Theses

The T-34C Airplane has been the primary trainer aircraft of the United States Navy for more than twenty-five years and is reaching the end of its service life. The Navy has delayed the procurement of the replacement T-6A Texan II aircraft for five years, yet does not expect the future training requirements to diminish. This delay in T-6A procurement along with recent observed increases in primary trainer aircraft usage have resulted in the need for the Navy to pay considerable attention to the remaining service life of the T-34C aircraft.

This thesis will discuss the methodology used to determine future …

Flightlines, Vol. 13, No. 1, Jeffrey A. Johnson

Flightlines Newsletter

No abstract provided.

Tools For Analysis Of Complex Geometries For A Combined Cycle Scram Jet / Rocket, James Moss

Master's Theses - Daytona Beach

A preliminary design for a variable geometry combined cycle supersonic combustion ram jet (SCRAM jet) / rocket was developed. A precise geometry was selected by parametric analysis and the resultant geometry was analyzed using a computational fluid dynamics (CFD) code developed by Dr. Eric Perrell, and modified by, among others, the author.

This paper is broken into several sections discussing, separately, the design innovations used to permit the geometry of the craft to be adjusted to conform to its flight conditions, the 2D analysis tool developed for the parametric analysis, development of the grid for CFD analysis, and modifications made …

Repeatable Nanostructures In Dielectrics By Femtosecond Laser Pulse Trains, Lan Jiang, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using the plasma model recent developed by the authors, this study predicts the existence of a constant ablation-depth zone with respect to fluence in femtosecond laser ablation of dielectrics, which has also been observed experimentally. It is found that the value of the constant ablation depth is significantly decreased by the pulse train technology. Repeatable nanostructures can be achieved with the parameters in the constant ablation-depth zone of a femtosecond pulse train, even when the laser system is subject to fluctuations in fluences.

A Prediction Code For The Thrust Performance Of Two-Dimensional, Non-Axisynnetric, Converging Diverging Nozzles, Angela M. Geatz

Theses and Dissertations

The objective of this research is to develop a prediction code for the Air Force Research Laboratory Propulsion Directorate that can accurately determine the gross thrust coefficient for a user defined nonaxisymmetric two-dimensional converging diverging nozzle. The code includes the effects of friction, angularity, and expansion losses on nozzle efficiency. To demonstrate the prediction method, the generated computational results were compared to experimental data, as well as computational results from other existing nozzle performance codes, for a number of different nozzle geometries. The nozzle internal performance prediction code showed excellent agreement with experimental data in predicting the gross thrust performance …

Experimental Investigation Of A Lift Augmented Ground Effect Platform, Roberto T. Igue

Theses and Dissertations

This experimental study investigated the feasibility of applying the concept of a skirtless hovercraft into the production of an operational vehicle. A 0.255 m diameter prototype was designed, built and tested. An air bearing table was used as a testing platform, virtually eliminating the influence of friction and providing one degree of freedom for the experiments. Static tests were performed at various heights and craft configurations, providing a wide range of data for comparison. Lift, torque and efficiency were measured and calculated for each setting. Pressure and velocity information was also collected at specific points around the craft when operating …

The Effect Of Aerodynamic Surfaces Versus Thrust Maneuvers On Reentry Vehicles, Meredith M. Albrecht

Theses and Dissertations

This research effort analyzes the effect of aerodynamic surfaces versus thrust maneuvers on a reentry vehicle. At high altitudes the effect of aerodynamic surfaces on the reentry vehicle is small due to low atmospheric density; however as the vehicle reaches lower altitudes a lift maneuver is very successful in deflecting the vehicle and creating a large impact footprint. When a continuous thrust maneuver is input in the place of a lift maneuver the results are very similar at the highest maneuver altitudes, although the impact footprint shrinks rapidly as the maneuver altitude decreases. Additionally, when the thrust maneuver is along …

Operator State Estimation For Adaptive Aiding In Uninhabited Combat Air Vehicles, Christopher A. Russell

Theses and Dissertations

This research demonstrated the first closed-loop implementation of adaptive automation using operator functional state in an operationally relevant environment. In the Uninhabited Combat Air Vehicle (UCAV) environment, operators can become cognitively overloaded and their performance may decrease during mission critical events. This research demonstrates an unprecedented closed-loop system, one that adaptively aids UCAV operators based on their cognitive functional state A series of experiments were conducted to 1) determine the best classifiers for estimating operator functional state, 2) determine if physiological measures can be used to develop multiple cognitive models based on information processing demands and task type, 3) determine …

Nonlinear Regression Methods For Estimation, Eric B. Nelson

Theses and Dissertations

Regression techniques are developed for batch estimation and applied to three specific areas, namely, ballistic trajectory launch point estimation, adaptive flight control, and radio-frequency target triangulation. Specifically, linear regression with an intercept is considered in detail. An augmentation formulation is developed. Extensions of theory are applied to nonlinear regression as well. The intercept parameter estimate within the linear regression is used to identify the effects of trim change that are associated with the occurrence of a control surface failure. These estimates are used to adjust the inner loop control gains via a feed-forward command, hence providing an automatic reconfigurable retrim …

Characterization Of The Global Hawk Low Pressure Turbine First Rotor, Timothy L. Garmoe

Theses and Dissertations

The Air Force Research Laboratory, Propulsion Directorate at Wright Patterson Air Force Base has studied the performance of turbine blade geometries utilizing a large scale, low speed, drawdown wind tunnel in an effort to better understand gas turbine blade aerodynamics. Currently, the Air Force's Unmanned Aerial Vehicle (UAV) Global Hawk has been operated primarily at flight conditions other than the design point of its Allison AE3007H turbofan engine. This off design condition decreased the Reynolds number at the low pressure turbine causing losses in efficiency and loading. Two different blades were studied to maximize performance of the Global Hawk turbine. …

Effects Of Boundary Layer Flow Control Using Plasma Actuator Discharges, Jeffrey M. Newcamp

Theses and Dissertations

This study addresses the usage and effects of atmospheric plasma discharges on the near wall flow conditions for a Pak-B low-pressure turbine blade. A plasma actuator was built normal to the freestream flow in a low-speed wind tunnel. The test section of the wind tunnel had a contoured upper wall geometry designed to mimic the suction side of a Pak-B turbine blade. A high frequency ac voltage source supplied three voltages in the kilovolt range at four Reynolds numbers in the experiment, between 10,000 and 103,000. The effect of the plasma on the near-wall boundary layer conditions was evaluated at …

Investigation Of The Performance Characteristics Of Re-Entry Vehicles, Charles A. Bilbey Jr.

Theses and Dissertations

When a non-US spacecraft reenters the Earth's atmosphere, having the ability to accurately determine its performance characteristics is a primary concern. This study investigated the atmospheric re-entry profiles of a maneuverable re-entry vehicle. The re-entry vehicle was modeled as a point mass with aerodynamic properties. Equations of motion were numerically integrated, giving the time histories of position, velocity and flight path angle. The algorithm is able to generate a complete and feasible entry trajectory of a approximately 25-minute flight time in about 5 to 10 seconds on a desktop computer, given the entry conditions and values of constraint parameters. This …

Privatization Of Space Ventures: Proposing A Proven Regulatory Theory For Future Extraterrestral Appropriation, Jonathan Thomas

Brigham Young University International Law & Management Review

No abstract provided.

Adaptive Control Of A Projectile Fin Using Piezoelectric Elastic Beam, Smitha Mani, Sahjendra N. Singh, Surya Kiran Parimi, Woosoon Yim, Mohamed B. Trabia

Mechanical Engineering Faculty Research

No abstract provided.

Variable Structure Control Of Unsteady Nonlinear Aeroelastic System, With Partial State Information, Sushma Gujjula, Sahjendra N. Singh

Electrical & Computer Engineering Faculty Research

This paper treats the question of control of a two-degree-of-freedom unsteady aeroelastic system with partial state information in the presence of uncertainties. The chosen model describes the plunge and pitch motion of a wing and a single trailing-edge control surface is utilized for the purpose of control. Based on the Lyapunov approach, a variable structure control law is derived. For the control law derivation, the system is treated as the interconnection of two subsystems in which the subsystem associated with the unsteady aerodynamics is input-to-state stable. The stability property of this subsystem is exploited to generate a dominating signal for …

The Role Of Simulation In The Test And Evaluation Of A Man In The Loop Weapon System, Keith Matthew Henry

Masters Theses

The Department of Defense has attempted to use recent advances in modeling and simulation to improve the acquisition process for weapons systems. This Simulation Based Acquisition brought advances in the process, but considerable disagreement remains over the universal applicability of this approach. This paper focuses on the challenges of applying modeling and simulation to the Test and Evaluation of a weapon system with significant Pilot-Vehicle interface concerns.

The Standoff Land Attack Missile Expanded Response (SLAM ER) is an aircraft-launched missile with GPS/INS guidance for navigation to the target area and Man In The Loop (MITL) control in the terminal phase. …

The Increased Costs Of Restricting The Procurement Of New Capability In Aircraft Modernisation, Michael Roy Barker

Masters Theses

As an element of the Government of Canada, the Canadian Forces are constrained by many financial and administrative regulations intended to ensure that public funds are expended judiciously. When these regulations restrict the acquisition of an improved capability, they may force program managers to accept a less capable product than could be obtained were only a simple cap on the total program cost imposed.

The CP-140 Aurora Navigation and Flight Instruments Modernisation Project is studied, highlighting specific areas where restrictions upon which capabilities could be improved or added, rather than simply how much money could be spent, resulted in program …

An Investigation Of The Rotor Tip Path Height Of The Mh-60s Helicopter In View Of Forklift Clearance In Support Of The United States Navy Medium Lift Shipboard Logistics Mission, Jonathan Patrick Kline

Masters Theses

The purpose of this paper is to summarize Department of the Navy tests performed to measure rotor tip path height of the MH-60S helicopter and present an analysis of collected data to determine if safe cargo loading operations on the MH-60S can be conducted with a forklift while the rotor is engaged. Testing was conducted to measure the dynamic height of the rotor tip path plane during incremental cyclic displacements, rotor response to external disturbances, and pilot tendencies when centering the cyclic control stick. Additional information was gathered on representative forklifts in use on U.S. Navy ships, and shipboard operating …

Large It Project Implementation - A Police Application Perspective, Venkateswar P. Oruganti

Venkateswar P Oruganti FIETE FIE PMP

A comprehensive Police Information System has the paramount objective to computerize activities related to Crime control, administrative support functions and interactions with other co-functionary government departments such as Judiciary, Road Transport Authority, Prisons, Hospitals, immigration etc., apart from providing timely and accurate information to citizens.

Effective implementation of such system depends primarily on the environment, processes, infrastructure, and continuity measures. The implementation of such systems will bring in an Organizational Transformation bridging the digital divide in a department in particular and in the government in general.