Engineering Commons^™

Integrating Multidisciplinary Design In An Undergraduate Curriculum, Russell M. Cummings, H. Jo Anne Freeman

Aerospace Engineering

Multidisciplinary design and analysis has become the normal mode of operation within most aerospace companies, but the impact of these changes have largely not been reflected at many universities. In an effort to determine if the emergence of multidisciplinary design concepts should influence engineering curricula, NASA has asked several universities (Virginia Tech, Georgia Tech, Clemson, BYU, and Cal Poly) to investigate the practicality of introducing the concepts within their undergraduate curricula. A multidisciplinary team of faculty, students, and industry partners evaluated the aeronautical engineering curriculum at Cal Poly. A variety of ways were found to introduce multidisciplinary themes into the …

Behavior Of A Hypersonic Nozzle Using Finite Rate Chemistry, Guillermo Jose Hernandez Paul

Master's Theses - Daytona Beach

This study is concerned with the investigation of the behavior of a hypersonic nozzle with finite rate chemistry. First, equations describing steady one dimensional flow through a nozzle are presented. Solution methodologies for frozen, equilibrium and detailed chemistry flow are then discussed. A hydrogen-air chemical reaction mechanism, which is made up of fourteen different chemical species, and forty nine chemical reactions is used in this investigation for obtaining detailed chemistry flow solutions. The investigation also performs a sensitivity analysis on the reaction mechanism. Results from this may be used to eliminate a particular reaction from the chemical reaction mechanism that …

Numerical Analysis Of Two And Three Dimensional Recessed Flame Holders For Scramjet Applications, Douglas L. Davis

Theses and Dissertations

This study investigated the flame holding properties of recessed cavities in supersonic flow using numerical analysis techniques. A simplified analytical model indicated that an important property for flame holding was the lower residence time. Several chemical kinetic rate models for hydrogen and hydrocarbon combustion were compared. The perfectly stirred reactor model also indicated that trace species diffusion should increase flame spreading rate, and that heat loss reduces flame holding limits. After nonreacting calibration, two-dimensional simulations confirmed the perfectly stirred reactor results for blowout limits. Also, the effect of trace species diffusion on flame spreading was shown to be negligible, and …

Numerical Analysis Of Two And Three Dimensional Recessed Flame Holders For Scramjet Applications, Douglas L. Davis

Theses and Dissertations

This study investigated the flame holding properties of recessed cavities in supersonic flow using numerical analysis techniques. A simplified analytical model indicated that an important property for flame holding was the lower residence time. Several chemical kinetic rate models for hydrogen and hydrocarbon combustion were compared. The perfectly stirred reactor model also indicated that trace species diffusion should increase flame spreading rate, and that heat loss reduces flame holding limits. After nonreacting calibration, two-dimensional simulations confirmed the perfectly stirred reactor results for blowout limits. Also, the effect of trace species diffusion on flame spreading was shown to be negligible, and …

An Investigation Of The Relationships Between The Angle Of Mental Rotation Required For Spatial Orientation, Response Times, And Accuracy, Ronald D. Archer

Master's Theses - Daytona Beach

The purpose of this study is to investigate the relationship between the angles of mental rotation when attempting to spatially orientate and the resulting response times and levels of accuracy. By means of a computer program, participants were presented with 64 mental rotational trials. The mental rotational trials consisted of a triangle placed in the center of the screen with a standard stick symbol of an aircraft appearing at various headings and orientations around the triangle. The participants were required to imagine themselves inside the flight deck of the aircraft, and then respond as quickly and accurately as possible to …

Controlling Chaos In Dynamical Systems Described By Maps, Claire A. Marduel

Master's Theses - Daytona Beach

The purpose of this thesis is to study methods for the control of chaos in dynamical systems described by maps. Two simple model dynamical systems, a one-dimensional map, the logistic map and a two-dimensional map, the prey-predator map are treated first. A feedback control method is introduced, in which an independent parameter of the system is perturbed. The chaotic behavior is successfully suppressed and the maps are stabilized about an unstable fixed point. Next, a more complex two-dimensional map is studied: the dynamics of a marker particle advected by the flow field generated by a blinking vortex. This flow field …

Low-Velocity Impact On Composite Sandwich Plates, Eric J. Herup

Theses and Dissertations

The objective of the research is to analytically model the response of composite sandwich plates to low velocity impact. A displacement based, plane stress, finite element code is modified for this purpose. Major new algorithms include 5th order Hermitian interpolation, three dimensional equilibrium integration for transverse stress calculations, sandwich core modeling as an elastic plastic foundation, loading by simulated contact with a spherical indentor, adaptive mesh, damage prediction, damage progression via stiffness reduction, and local-global analysis for displacement. An experimental effort is also included in which composite sandwich plates with graphite epoxy facesheets and Nomex honeycomb core are subjected to …

A Study Of The Numerical Implementation Of Multidisciplinary Design Optimization Strategies, Rodney A. Taylor

Mechanical & Aerospace Engineering Theses & Dissertations

Design optimization provides an organized, systematic, and efficient method for obtaining design improvements based upon a specified measure of design performance. In the multidisciplinary design optimization (MDO) environment efficient optimization techniques allow complex designs to be improved by managing conflicting disciplinary design goals so as to improve the global design. This thesis studies the implementation issues surrounding MDO techniques and strategies. To facilitate this investigation two testbed problems have been selected for study. These problems consider two approaches to the conceptual design of an aeroelastic wing. The first approach is based on an idealized, two-dimensional representation of an airfoil under …

Numerical Prediction Of Turbulent Diffusion Flames Formed By Cylindrical Tube Injector, Ali S. Kheireddine

Mechanical & Aerospace Engineering Theses & Dissertations

This work summarizes numerical results for a diffusion flame formed from a cylindrical tube fuel injector, issuing gaseous fuel jet vertically in a quiescent atmosphere. Both pure fuels as well as fuel mixtures are examined. The primary objective is to predict the flame base height as a function of the jet velocity. A finite volume scheme is used to discretize the time-averaged Navier-Stokes equations for the reacting flow, resulting from the turbulent fuel jet motion. The turbulent stresses, and heat and mass fluxes are computed from the Reynolds stress turbulence model. A chemical kinetics model involving a two-step chemical reaction …

A Progressive Damage Methodology For Residual Strength Predictions Of Center-Crack Tension Composite Panels, Timothy William Coats

Mechanical & Aerospace Engineering Theses & Dissertations

An investigation of translaminate fracture and a progressive damage methodology was conducted to evaluate and develop residual strength prediction capability for laminated composites with through penetration notches. This is relevant to the damage tolerance of an aircraft fuselage that might suffer an in-flight accident such as an uncontained engine failure. An experimental characterization of several composite materials systems revealed an R-curve type of behavior. Fractographic examinations led to the postulate that this crack growth resistance could be due to fiber bridging, defined here as fractured fibers of one ply bridged by intact fibers of an adjacent ply.

The progressive damage …

Analysis Of The Elements Of Drag In Three-Dimensional Viscous And Inviscid Flows, Russell M. Cummings, M. B. Giles, G. N. Shrinivas

Aerospace Engineering

This paper examines the analytical, experimental, and computational aspects of tlie determination of the drag acting on an aircraft in flight, with or without powered engines, for subsonic/transonic flow. Using a momentum approach, the drag is represented by an integral over a cross-flow plane at an arbitrary distance behind the aircraft Asymptotic evaluation of tlie integral shows tlie drag can be decomposed into three components corresponding to streamwise vorticity and variations in entropy and stagnation enthalpy. These are shown to be related to tlie established engineering concepts of induced drag, wave drag, profile drag and engine power and efficiency. This …

Residual Strength After Fatigue Of Unidirectional And Cross-Ply Metal Matrix Composites At Elevated Temperature, Sen-Tzer Chiou

Theses and Dissertations

This study investigated the residual strength of the unidirectional and cross-ply laminates of SCS-6 / Ti-15-3, metal matrix composite at elevated temperature 427°C (800°F) after under tension-tension load controlled mode. For this purpose, several specimens were fatigued to various fractions of the fatigue life and then loaded monotonically to failure. The purpose of this study was to determine the effects of different levels of fatigue damage on the composite's strength. The unidirectional specimens were cycled at a 900 MPa maximum stress at a frequency of 10 Hz, while, the cross-ply specimens were tested at both 300 MPa and 450 MPa …

Effect Of Transient Body Force On The Performance Of An Axial Grooved Heat Pipe, Wen-Lung Wang

Theses and Dissertations

An experimental investigation was performed to determine the effect of transient body forces on the performance of an ammonia/aluminum axial groove heat pipe. The effects of increased body forces on the dryout and rewet performance were simulated by tilting the heat pipe to different inclination angles. Theoretical calculations predicted the dryout length varied with different final inclination angles. The steady state experimental work was performed by tilting the heat pipe from 0 degrees to different final inclination angles for a long period of time until totally dryout occurred. Then, from the plot of the changing temperature at each location along …

An Investigation Of The Characteristics Of Regenerative Heat Exchangers, Timothy J. Murphy

Theses and Dissertations

The objective of the current research was to investigate the effects of reducing screen thickness on the volume and compactness factor of stacked, wire-screen regenerators. An improved transient step-change method was devised which integrated experimental data with a numerical model of the flow to determine the heat transfer coefficient and friction factor. The improvements to the approach are: (1) the measured inlet temperature trace is used, (2) the heat transfer coefficient is based on a parameter called the sponge effect delay time, and (3) the important effect of the tube surrounding the matrix is included in the numerical model. The …

Optimal Continuous-Thrust Orbit Transfers, James D. Thorne

Theses and Dissertations

The minimum time orbital transfer problem for spacecraft with steerable, continuous thrust of constant magnitude may be solved using Euler-Lagrange theory, which leads to the optimal control law in terms of Lagrange multipliers. However, the initial values of the Lagrange multipliers are not known from the orbital boundary conditions. Using analytical and empirical results, the optimal initial costates are modeled as functions of the problem parameters which are the initial thrust acceleration, A, and the final orbit radius, H, in canonical units. For circle to circle, coplanar orbit transfers, these approximate initial costate models lead to convergence in the shooting …

Direct Measurement Of Skin Friction In High Temperature And Impulsively Started Supersonic Flowfields, David M. Hazelton

Theses and Dissertations

This study further developed and improved a miniature plastic cantilever floating element gauge for direct measurement of skin friction in shock tunnel tests. Gauge durability and usability were improved, and potential sources of error were quantified. A high frequency 30 kHz gauge (compared to the baseline 10 kHz gauge) was constructed by using an I-beam cantilever rather than a round beam. A directional gauge was developed and demonstrated by measuring the flowfield about a fin in the AFIT shock tunnel. The 10 kHz and 30 kHz gauges were used in two scramjet test sequences conducted at Mach 14 enthalpy (stagnation …

Gain-Scheduled Aircraft Control Using Linear Parameter-Varying Feedback, Martin R. Breton

Theses and Dissertations

Systems which vary significantly over an operating envelope, such as fighter aircraft, generally cannot be controlled by a single linear time-invariant controller. As a result, gain-scheduling methods are employed to design control laws which can provide the desired performance. This thesis examines a relatively new approach to gain-scheduling, in which the varying controller is designed from the outset to guarantee robust performance, thereby avoiding the disadvantages of point designs. Specifically, the parameter-varying (LPV) aircraft model is linearized using linear fractional transformations (LFT's), and the resulting control problem is characterized as the solution to a set of four linear matrix inequalities …

Nonlinear Analysis Of Airfoil Flutter At Transonic Speeds, Scott A. Morton

Theses and Dissertations

Hopf-bifurcation analysis is used to determine flutter boundaries of a pitch and plunge airfoil (PAPA) at transonic Mach number conditions. The PAPA model is a coupling of the Euler equations and a two-degree-of-freedom structural model composed of linear and torsional springs. The Euler equations are discretized using an upwind total variation diminishing scheme (TVD) of Harten and Yee. Equilibrium solutions of the PAPA model are computed using Newton's method and dynamic solutions are explicitly integrated in time with first-order accuracy. The Hopf-bifurcation point, which models the flutter condition, is computed directly by solving an extended system of equilibrium equations following …

Optimization Of Torquer Coil Design For Use With The Small Satellite Attitude Control Simulator, David Deloyd Anderson

Undergraduate Honors Capstone Projects

This paper presents a procedure used to optimize the performance of a ferromagnetic core magnetic torquer coil design for use on the Space Dynamics Laboratory (Logan, UT) Small Satellite Attitude Control Simulator. The items of optimization include the primary goal of maximizing the coil 's magnetic moment while reducing power consumption and system mass within given power, mass, and dimensional constraints. The optimization process makes use of several simple equations to determine a few starting points for design, after which an iterative approach based on experimentation is used to produce the final design. It is found that optimal magnetic moment …

Space Trajectory Simulation For The Internet, Michael Selby, Patrick Newton

Honors Capstone Projects and Theses

No abstract provided.

Geometric Stiffness Effects On Data Recovery Of An Idealized Mast/Blanket Model, Paul A. Bosela, D. R. Ludwiczak

Civil and Environmental Engineering Faculty Publications

The photovoltaic arrays for the international space station consist of a pre-tensioned blanket of solar collectors and a deployable mast. NASA uses the MSC/NASTRAN finite element program for modeling the dynamic response of the structure due to various loading conditions, such as plume impingement during shuttle docking. This finite element program uses the updated stiffness matrix (elastic plus geometric, or initial stress stiffness matrix) in determining the natural frequencies and mode shapes, as well as the dynamic response, of a pre-loaded structure. However, during the data recovery phase, when the moment and shear at the supports, and internal stresses are …

The Airline Quality Rating 1996, Brent D. Bowen, Dean Headley, Uno Aviation Institute

Faculty Books and Monographs

UNOAI Report 96-4

The Airline Quality Rating (AQR) was developed and first announced in early 1991 as an objective method of comparing airline performance on combined multiple factors important to consumers. Development history and calculation details for the AQR rating system are detailed in The Airline Quality Rating issued in April, 1991, by the National Institute for Aviation Research at Wichita State University. This current report, Airline Quality Rating 1996, contains monthly Airline Quality Rating scores for 1995. Additional copies are available by contacting Wichita State University or the University of Nebraska at Omaha.

The Airline Quality Rating 1996, contains …

A Comparison Of Two Geo-Centric Attitude Indicators As Aids To Unusual Attitude Recovery: Pictorial Vs. Symbolic Displays, Christopher Cohoes

Master's Theses - Daytona Beach

Aircraft require high cognitive quality aircraft attitude information. Evidence will be presented on aircrew decision-making performance on an unusual attitude recovery task using three different types of attitude displays. Results indicated that among a sample of low-flight time student pilots attending Embry-Riddle Aeronautical University, mean reaction times were significantly faster and error rates significantly lower using an outside-in pictorial display than with either an outside-in symbolic display or an attitude gyro. This is attributed to the pictorial display being a more intuitive display by providing a more natural or realistic representation of aircraft orientation than the other two displays. The …

Evaluation Of A Display With Both Quickened And Status Information For Control Of A Second Order System, Matthew J. Neal

Master's Theses - Daytona Beach

Quickened displays have a severe limitation in that they do not give any indication of status information, and therefore no indication of actual error. It was hypothesized in this study that a display with both quickened and status information would enable the operator to make more effective control responses than either a status alone display, or a quickened alone display.

A horizontal axis pursuit tracking task was developed and controlled by eighteen participants with three display types: (1) a status alone display; (2) a quickened alone display; and (3) a status and quickened combined display.

The primary hypothesis was only …

The Design, Fabrication, And Evaluation Of A Low-Speed, Low-Turbulence, Anechoic Wind Tunnel, Brian J. Kaplan

Master's Theses - Daytona Beach

In order to provide a means for testing noise reduction techniques in propellers and fans, a low-speed, low-turbulence, anechoic wind tunnel was designed, fabricated and evaluated at Embry-Riddle Aeronautical University.

This open circuit wind tunnel was designed using several other existing wind tunnels as a guide and incorporated an open jet test section. The tunnel, which was built almost entirely out of wood and fiberglass, is powered by a 15 hp centrifugal fan.

Tufts of yarn, a pitot-static tube, and a hot film anemoter were used to determine the flow characteristics in the test section of this wind tunnel. From …

Unsteady, Transonic Flow Around Delta Wings Undergoing Coupled And Natural Modes Response: A Multidisciplinary Problem, Margaret Anne Menzies

Mechanical & Aerospace Engineering Theses & Dissertations

The unsteady, three-dimensional Navier-Stokes equations coupled with the Euler equations of rigid-body dynamics are sequentially solved to simulate and analyze the aerodynamic response of a high angle of attack delta wing undergoing oscillatory motion. The governing equations of fluid flow and dynamics of the multidisciplinary problem are solved using a time-accurate solution of the laminar, unsteady, compressible, full Navier-Stokes equations with the implicit, upwind, Roe flux-difference splitting, finite-volume scheme and a four-state Runge-Kutta scheme, respectively. The primary model under consideration consists of a 65° swept, sharp-edged, cropped delta wing of zero thickness at 20° angle of attack. In a freestream …

Sensitivity Analysis And Optimization Of Aerodynamic Configurations With Blend Surfaces, Almuttil Mathew Thomas

Mechanical & Aerospace Engineering Theses & Dissertations

A novel (geometrical) parametrization procedure using solutions to a suitably chosen fourth order partial differential equation is used to define a class of airplane configurations. Inclusive in this definition are surface grids, volume grids, and grid sensitivity. The general airplane configuration has wing, fuselage, vertical tail and horizontal tail. The design variables are incorporated into the boundary conditions, and the solution is expressed as a Fourier series. The fuselage has circular cross section, and the radius is an algebraic function of four design parameters and an independent computational variable. Volume grids are obtained through an application of the Control Point …

An Approach For Multidisciplinary Design Optimization, Robert V. Krueger

Mechanical & Aerospace Engineering Theses & Dissertations

Multidisciplinary Design Optimization (MDO) is an optimization technique that allows complex designs to be improved by managing conflicting goals in such a fashion so as to improve the overall design. This thesis presents a nonhierarchic MDO formulation and gives a general explanation of how it is to be applied to various appropriate problems. In addition, this thesis evaluates the viability of this MDO technique by applying it to two distinct, multidisciplinary problems that have been used as examples in other literature. The first example problem is a combined aerodynamic/structural problem and the second example is an alkylation process problem. First, …

Study Of Surface Heat Exchangers For High-Altitude Atmospheric Research Aircraft, Te-Kang Wang

Mechanical & Aerospace Engineering Theses & Dissertations

A flush-mounted heat exchanger concept, using the wing surface to dissipate heat, is investigated as a lower drag alternative to conventional ducted plate-fin radiators. A feasibility analysis is made for an unmanned high-altitude aircraft which will reach altitudes up to 25 kilometers. A computer code is used to calculate approximate heat transfer coefficients over the airfoil's surface. A model is tested in the Old Dominion University subsonic wind tunnel to verify the results of the computer code. The results indicate that a flush mounted heat exchanger design is able to provide 20 to 100 percent of the required heat dissipation …

A Total Systems Analysis Method For The Conceptual Design Of Spacecraft: An Application To Remote Sensing Imager Systems, Knut I. Oxnevad

Engineering Management & Systems Engineering Theses & Dissertations

Increased emphasis is being placed on improving the performance of space projects, within tighter budgets and shorter development times. This has led to a need for more efficient space system design methods. The research described here represents an effort to develop and evaluate such a method.

Systems engineering and concurrent engineering together provide the theoretical foundation for the method. The method, derived from both this theoretical foundation and ideas from experts in the space industry, emphasizes a total systems analysis approach, taking into account given mission requirements, and the mathematical modeling of interactions between system variables and between subsystems. The …