Aerospace Engineering Commons^™

Static Pressure Measurements Of A Low Power Arcjet, Kevin P. Talley

Theses and Dissertations

The NASA Lewis 1.2 kilowatt arcjet has been used for a number of performance and lifetime studies. This design was modified to obtain static pressure measurements at several locations along the arcjet nozzle. These measurements were taken at various propellant flow rates over most of the operational envelope of the thruster. Measured static pressure distributions are considerably higher than predicted by ID models and are proportional to the arc power. A simple thermodynamic model is also compared to the data, and is shown to match the slope of the data while overpredicting the pressure.

High-Resolution Tvd Schemes For The Analysis Of 1. Inviscid Supersonic And Transonic Flows. 2. Viscous Flows With Shock-Induced Separation And Heat Transfer, Mark A. Driver

Theses and Dissertations

Application of TVD schemes to both inviscid and viscous flows is considered. The mathematical and physical bases of TVD schemes are discussed. First and second-order accurate TVD schemes and a second-order accurate Lax- Wendroff scheme are used to compute solutions to the Riemann problem in order to investigate the capability of each to resolve shocks, rarefactions, and contact surfaces. Second-order finite-volume and finite-difference TVD schemes are used to obtain solutions to inviscid supersonic and transonic cascade flow problems. TVD schemes are shown to be superior to the Lax-Wendroff family of schemes for both transient and steady-state computations. TVD methodology is …

Thermal Nonequilibrium Effects On Turbine Cascade Aerodynamics, Jill L. R. Shaw

Theses and Dissertations

The AFIT Total Variation Diminishing Euler Code (ATEC) was modified to include a thermal nonequilibrium model to investigate high temperature effects associated with vibrational relaxation in a transonic turbine cascade. Incorporation of this model into ATEC and creating ANTEC (AFIT Nonequilibrium TVD Euler Code) was accomplished in three steps. Steady-state solutions obtained with ANTEC were compared with those obtained with ATEC for various inlet and exit conditions. The Courant-Friedrichs-Levy criterion was held constant to ATEC; however, it required variation for ANTEC. Blade temperature profiles, temperature difference contours in the vicinity of the trailing edge and the value of the ratio …

A Comparative Study Of Numerical Versus Analytical Waverider Solutions, Gregory O. Stecklein

Theses and Dissertations

The WL/FIMM explicit, Roe flux-splitting Euler algorithm is applied to the inviscid hypersonic flow over a parabolic-top waverider configuration optimized for Mach 10 at zero degrees angle of attack. An on-design grid refinement study is conducted to determine the asymptotic nature of the optimized flight parameter L/D. A parametric study of off-design conditions is conducted to determine flow perturbation effects on HSDT waverider theory. A validation of the Euler code is conducted through a comparison of the numerical data to analytical results derived by Rasmussen. The grid refinement study shows little effect on the inviscid calculation of the optimized parameter …

Analysis Of An Advanced Fighter Aircraft Using Jet Flap Techniques And The Vortex Lattice Method, Steven P. Snyder

Theses and Dissertations

A computer code using the vortex lattice method with modified boundary conditions was used to determine the induced aerodynamic characteristics of high aspect ratio, vectoring, exhaust nozzles located at the wing root of a canard configured fighter aircraft. Comparison with existing wind tunnel data verified results of the method. The exhaust was modeled as a singularly blown jet flap at deflection angles of -10, 0, 10, 20, 30, and 40 degrees. Jet momentum coefficients were based on gross engine thrust for maximum afterburner and military power settings at a Mach number of 0.6 and an altitude of 20,000 ft. Lift, …

Robust Grasp Design Using Grasp Force Focus Positioning, Freddie D. Zayas

Theses and Dissertations

A three-finger precision grasp is used to rotate a cylindrical object about a threaded post. Three fingered grasps are unique in that the homogeneous solution for the contact forces produces a grasp force focus. Mapping of focus points which meet grasp stability and joint torque criteria results in a usable focus region. The effects of applied torque, contact location, and object position and orientation on usable regions are presented. Stability behavior about the region is also examined. Results are used to demonstrate a technique for robust grasp design. The versatility of robotic hands permit fine motion manipulation on a wide …

Finite Element Analysis Of A Riveted Repair On A Curved Composite Panel, Scott A. Hamilton

Theses and Dissertations

To analyze the current Aircraft Battle Damage Repair (ABDR) techniques, a finite element model (FEM) of a curved composite panel with a center cutout section was developed and verified against previously obtained modal test results. The FEM was modified using different methods to exhibit the effects of riveting on an aluminum patch to repair the section. The different methods were contrasted against each other and previously obtained modal test results. The panel, a (0/-45/+45/90) sub s layup of AS4/3501 graphite epoxy measuring 12 inches in height and 12.19 inches across its arc length with a 2 by 4 inch cutout …

An Experimental Study Of A Sting-Mounted Circulation Control Wing, Steven J. Lacher

Theses and Dissertations

This wind tunnel study investigated the lift, drag, and pitching moment of a 20% thick, 8.5% camber, partial elliptical cross-section, single blowing slot, 2.325 aspect ratio, rectangular circulation control wing. The AFIT 5-foot wind tunnel was used. Lift and drag were referenced to the wind axis. The Reynolds number was 500,000 for all tests. Angle of attack was varied from -6 to 16 degrees and the effects of pulsed blowing were investigated. Effects of tripping the Coanda jet with a small flow barrier attached spanwise along the Coanda surface were also studied. Results indicate that there is a limit on …

Experimental Investigation Into The Effects Of Riblets On Compressor Cascade Performance, James A. Rothenflue

Theses and Dissertations

The effects of adding riblets to the blades of a subsonic, linear compressor cascade were investigated at the Air Force Institute of Technology. Three blade configurations were tested, including a set of unmodified NACA 64- A905 series blades, a set with riblets applied to the suction surface, and a set with riblets on the pressure surface. Performance was evaluated over a wide range of Reynolds numbers, and at low and high free stream turbulence levels. Cascade performance was evaluated in terms of total pressure loss coefficient, turning angle, and static pressure rise. No riblet configuration offered robust cascade performance improvements; …

The Effect Of Angle Of Incidence And Reynolds Number On Heat Transfer In A Linear Turbine Cascade, Steven G. Meschwitz

Theses and Dissertations

The AFIT linear Turbine Cascade Test Facility was used to study the effect of the small changes in the angle of incidence on turbine blade convective heat transfer. Other parameters studied were the model Reynolds number and the freestream turbulence level. Characterization tests, performed to determine the feasibility of the study were followed by a series of tests designed to separate the effects of the angle of incidence, Reynolds number, and freestream turbulence level on convective heat transfer. For any given freestream turbulence level or angle of incidence, there is an increase in the heat transfer coefficient for an increase …

Analysis Of The Effects Of Removing Nose Ballast From The F-15 Eagle, Richard L. Bennett

Theses and Dissertations

This study investigated the results of removing lead ballast from the nose section of the F-15 Air Superiority fighter. The goal of the investigation was to determine if aircraft handling qualities remained acceptable with the ballast removed, and also to determine what improvements in aircraft nose pointing authority resulted. Actual F-15 weight reports were used to calculate the worst case aft center of gravity location shift due to the ballast removal. Several configurations with different center of gravity locations (based on various amounts of lead weights removed) were used for comparison to the baseline aircraft. Moments of inertia were calculated …

Comparative Analysis Of Guidance Algorithms For The Hyper Velocity Missile And Afti/F-16, Edward G. Rice

Theses and Dissertations

This project has provided me with endless intrigue. In considering the problem of guiding a hyper-velocity missile from a moving platform to a moving target, a common perception said it was just another Kalman Filtration design challenge. I began with lofty intentions of running a full up extended Kalman filter simulation but I became enthralled with the limited work available on the physical limitations of basic guidance algorithms. This became the emphasis of this project. The best filter scheme cannot overcome a guidance algorithms physical limitation. Only with an understanding of these limitations can one effectively integrate a guidance scheme …

Application Of Mixed H2/H∞ Optimization, John J. Kusnierek

Theses and Dissertations

A non-conservative optimization technique is utilized to examine the problem of minimizing the 2 norm of one transfer function subject to an ∞-norm bound on another transfer function. For single exogenous input/ single exogenous output systems this non conservative mixed solution is shown to be up to 5% better in a specific example. For single exogenous input/two exogenous output systems the mixed solution is shown to be up to 27% better than a previous technique for a specific example. Finally, a two exogenous input/two exogenous output practical system is examined to demonstrate the utility of this mixed optimization technique.

Application Of Low Thrust Propulsion Techniques To Satellite Attitude Control Systems, Jeffrey J. Abbott

Theses and Dissertations

Equation of motion for a satellite controlled through continuous, low thrust propulsion systems are analyzed through numerical integration techniques. The equations of motion are derived using the Euler Moment Equations. The properties of the satellite model are based upon the Intelsat VII design of communications satellite. A simple rate and error feedback controller is used in providing active attitude control about two and three axes. Perturbation models are created and applied based upon the satellite model. Parameters varied include thrust levels and controller deadband widths. System response times, pointing accuracy, and total impulse required for attitude control are determined as …

Finite Element Frequency Domain Solution Of Nonlinear Panel Flutter With Temperature Effects And Fatigue Life Analysis, David Yongxiang Xue

Mechanical & Aerospace Engineering Theses & Dissertations

A frequency domain solution method for nonlinear panel flutter with thermal effects using a consistent finite element formulation has been developed. The von Karman nonlinear strain-displacement relation is used to account for large deflections, the quasi-steady first-order piston theory is employed for aerodynamic loading and the quasi-steady thermal stress theory is applied for the thermal stresses with a given change of the temperature distribution, ΔΤ (x, y, z). The equation of motion under a combined thermal-aerodynamic loading can be mathematically separated into two equations and then solved in sequence: (1) thermal-aerodynamic postbuckling and (2) limit-cycle oscillation. The Newton-Raphson iteration technique …

Linearized Dynamics Of Space Structures With Articulated Appendages, Gopichand Koganti

Mechanical & Aerospace Engineering Theses & Dissertations

The inherent difficulties of the conventional spacecraft design, which first considered the optimization with respect to structural variables and then with respect to control variables, have led to the concept of Controls-Structures Interactive Design. The success of the CSI design of Space structures without articulated appendages has prompted the extension of the CSI design to systems with articulated appendages. The presentation is of two parts, the first part deals with the derivations of the equations of motion and the second part deals with the eigenvalue/vector approximations.

Three approaches, namely: the multibody approach, the finite element based approach with hinge joints …

Higher-Order Thickness Expansions For Cylindrical Shells, Randy A. Smith

Theses and Dissertations

Eight variations of higher-order transverse shear deformation (HTSD) theory were developed for composite shells. Three attributes were varied to produce the eight variations. These attributes include the order of the thickness expansions used to approximate the shell shape factors and the assumed linear displacement field and the nonlinearity of transverse shear strain. Several cylindrical shell problems were investigated using SHELL, a finite- element code with a 36 degree of freedom cylindrical shell element. MACSYMA, a symbolic manipulation code, was used to formulate the element independent stiffness arrays for each variation of the theory. When all nonlinear strain- displacement terms for …

Investigation Of Advanced Aircraft Performance Measures Of Merit Including New Agility Metrics, Bruce A. Fox

Theses and Dissertations

Advanced aircraft performance measures of merit have been proposed and individually analyzed by various researchers. These metrics have been consolidated into a single computer code as part of this research effort. This code was used to study the relationships between the advanced metrics, aircraft design metrics and an aircraft's trajectory performance. The study found a linear relationship existed between the advanced metrics and the design metrics. This relationship was used to quantify the required levels of the advanced metrics which would give desired changes in trajectory performance. The results showed that advanced metrics could be applied only to very specific …

Model Identification And Control System Design For The Lambda Unmanned Research Vehicle, Gerald A. Swift

Theses and Dissertations

Research for this thesis centered on the Lambda Unmanned Research Vehicle (URV), an asset of the Flight Dynamics Directorate, Wright Laboratory Patterson AFB. The following tasks were accomplished: (1) a linear, state-space, small perturbation model was developed for both the longitudinal and lateral directional dynamics of the vehicles, and (2) pitch rate roll rate, and yaw rate flight controllers were designed using classical and multivariable feedback methods. The parameters of the linear, state space, small perturbation model were estimated from actual flight test data. Digital Datcom was first used to estimate stability and control derivatives from the vehicle's geometry. Maximum …

Integrated System Identification And Adaptive State Estimation For Control Of Flexible Space Structures, Chung-Wen Chen

Mechanical & Aerospace Engineering Theses & Dissertations

Accurate state information is crucial for control of flexible space structures in which the state feedback strategy is used. The performance of a state estimator relies on accurate knowledge about both the system and its disturbances, which are represented by system model and noise covariances respectively. For flexible space structures, due to their great flexibility, obtaining good models from ground testing is not possible. In addition, the characteristics of the systems in operation may vary due to temperature gradient, reorientation, and deterioration of material, etc. Moreover, the disturbances during operation are usually not known. Therefore, adaptive methods for system identification …

Finite Element Analysis Of Nonlinear Panel Flutter Of Rectangular Composite Plates Under A Uniform Thermal Load, Lain Ross Dixon

Mechanical & Aerospace Engineering Theses & Dissertations

A finite element formulation is developed to analyze large-amplitude panel flutter of arbitrarily laminated composite plates subjected to a uniform temperature change. The plates considered are anisotropic composite, thin rectangular panels. The aerodynamic pressure load is modeled through the use of the first-order piston theory. The equations of motion for the oscillating plate are determined from the principle of virtual work. Two different solution procedures are given to determine the panel motions. The first procedure, which considers only the aerodynamic load, solves the panel limit-cycle motions by employing the linearized updated-mode with a nonlinear time function (LUM/NTF) approximation. The second …

The Solution Of A Singular Integral Equation Arising From A Lifting Surface Theory For Rotating Blades, Mark H. Dunn

Mathematics & Statistics Theses & Dissertations

A technique is presented for the solution of a linear, two dimensional, singular, Volterra integral equation of the first kind. The integral equation, originally developed by Farassat and Myers, is derived from the basic equations of linearized acoustics and models the lifting force experienced by an infinitesimally thin surface moving tangent to itself. As a particular application, the motion of modern high speed aircraft propellers (Advanced Technology Propellers) is considered. The unknown propeller blade surface pressure distribution is approximated by a piecewise constant function and the integral equation is solved numerically by the method of collocation. Certain simplifying assumptions applied …

Application Of Sensitivity Analysis To The Euler Equations, Vamshi Mohan Korivi

Mechanical & Aerospace Engineering Theses & Dissertations

An approximation method is presented for efficiently predicting the changes which occur in a steady-state numerical solution of the Euler equations as a consequence of a small change in the geometric shape of the domain. The method is extended to develop a general procedure for calculating aerodynamic sensitivity derivatives with respect to variations of geometric shape. The techniques are implemented using an upwind cell centered finite volume formulation, and are applied to two test cases, (1) a subsonic nozzle (M_∞ = 0.85), and (2) a supersonic inlet (M_∞ = 2.0). Conventional numerical solutions are first obtained for flow …

An Experimental And Analytical Investigation Of Wing Flutter On A Trial Rotor V/Stol Aircraft, David L. Soistmann

Mechanical & Aerospace Engineering Theses & Dissertations

A wind tunnel model based on a trail rotor vehicle concept was tested for wing flutter in the subsonic flow regime. The wind tunnel model was flutter tested in the forward flight mode only. From this test it was determined that this conceptual vehicle may be susceptible to wing flutter. However, the flutter encountered was not catastrophic but was of the limited amplitude type. The trailing rotor blades were found to have a positive aerodynamic damping effect on flutter. The flutter mechanism for each flutter point was due to a coupling of the first wing bending and first wing torsion …

Cognitive Learning Styles And Their Relation To Air Traffic Control Screening And Training, Vincent P. Galotti

Master's Theses - Daytona Beach

The purpose of this study was to show a relationship between the type of cognitive learning style that an individual possesses and their subsequent success at simulated air traffic control practical exercises. Kolb's Learning Style Inventory was utilized to determine dominant learning styles of 30 college students enrolled in a laboratory-based air traffic control course. The instrument was administered during the first day of classes in the Fall of 1990. Students were placed in one of four groups for statistical purposes according to learning style. The scores of simulated micro-computer based air traffic control practical exercises given at semester's end …

Development Of A Personal Computer Simulation Program Of The Ln-94 Inertial Navigation System, Thomas E. Flynn

Theses and Dissertations

This thesis develops a simulation that emulates a Litton LN-94 INS. Real time simulation is achieved for a stationary navigation case and a straight-and-level flight trajectory are provided to exercise the simulation dynamics. The user interface is simple and requires little previous knowledge to operate. The communication link with the MILSTD 1553B bus provide a realistic environment in which to collect and analyze data. The simulation is processed on an 80386 IBM compatible personal computer. A 23-state INS error model is implemented and integration is performed by a fifth-order Kutta-Merson routine. The simulation is interfaced to a plotting routine and …

Experimental Evaluation Of Design Variables For Two-Dimensional Confined Jet Thrust Vector Control Nozzles, Timothy M. Hawkes

Theses and Dissertations

An experimental study of the axial and vectoring performance of two - dimensional (2-D) confined jet thrust vector control (CJTVC) nozzles was performed. The effects of adding secondary injection ports and changing exit height and secondary injection port location were studied on several 2-D CJTVC nozzles. The axial and vectoring performance results for these nozzles were measured over a range of pressure ratios. An analytical method for predicting flow separation was found to be applicable to these nozzles. Guidelines for designing 2-D CJTVC nozzles, that can be vectored using secondary injection, were established.

Fourier Transform Infrared (Ftir) Spectroscopy Analysis Of Combustion Aerosol, Gary Jacquin

Opportunities for Undergraduate Research Experience Program (OURE)

In conjunction with my co-op program at McDonnell-Douglas, my current OURE project is the analysis of combustion aerosols using Fourier Transform Infrared (FTIR) Spectroscopy. Aerosol science is a very important field as it is concerned with atmospheric chemistry, atmospheric physics, climate, public health, and environmental issues.

In the Cloud and Aerosol Sciences Laboratory (CASL) at UMR, combustion aerosols are generated by an in-house designed torch or burner. The fuels, JP4 and JP5, are provided by McDonnell-Douglas. Some other commercial fuels are also used. The primary objective of my OURE project was to generate and collect combustion aerosols for chemical analysis. …

A Computer Graphics Program For Displaying Water Molecules On A Dn3500 Apollo Workstation, Michael A. Stuller

Opportunities for Undergraduate Research Experience Program (OURE)

A computer graphics program is developed for displaying water molecule configurations on the screen of a DN3500 Apollo workstation. The motivation was to generate a fast display of output from molecular dynamics or Monte Carlo computer simulations. Input to the program consists of a listing of the Cartesian coordinates of the atomic constituents of the molecules. Options in the program include: 1) number of molecules; 2) plot size; 3) atomic radii; 4) superposition of substrate atomic positions; 5) viewing angle; and 6) color-coded and/or numbered atoms. The program is written in Fortran.

Investigation Of The Effects Of Geometry On The Efficiency Of The Double Lap Joint Of Unidirectional Fiberglass Composites, Joseph Anthony Musco

Master's Theses - Daytona Beach

The fracture toughness in shear mode (Mode II) has been studied for double lap adhesive joints where geometry of the joint is the major parameter. A unidirectional fiberglass - epoxy system was selected for experimental tests and theoretical analysis. Both rectangular and elliptical planform geometries were investigated. In order to evaluate the results, the adhesion area of the two geometries was purposely made identical. Through computer analysis, the effects on the stress concentration factor as a function of geometry was investigated. Then, using testing and fracture mechanics techniques, calibration factors for Mode II loading of the two geometries were obtained. …