| Developing a Framework for Control of Agile Aircraft Platforms in Autonomous Hover |
Mar-2009 |
75 pages |
| Authors:
Kyle J Krogh; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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 | This thesis extends previous work on autonomous agile aircraft to develop a framework for control in both linear and non-linear flight profiles. Two dynamical systems are considered, a scale YAK-54 aerobatic remote control aircraft and the Flexrotor concept developed by Aerovel. Both models are capable of hover and level flight, requiring complex control transitions between the flight regimes. Linear controllers are developed for both models in a hover configuration. Open-loop ... |
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| Effects of Liquid Superheat on Droplet Disruption and Vaporization in Supersonic Conditions |
21 APR 2005 |
88 pages |
| Authors:
Mark R. Phariss; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| Individual neat 70mum diameter droplets of 1-propanol, ethanol, and methanol, were smoothly accelerated after injection into a convergent-free expansion test section of a draw-down supersonic wind tunnel to examine the effects of liquid superheat on droplet disruption and vaporization. Superheating of the initially unheated droplets was accomplished upon injection into the freely expanding jet as the static pressure dropped below the vapor pressures of the droplet fluids. The rate and ... |
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| Optical Tomography of the ZaP Flow Z-Pinch Plasma |
2005 |
154 pages |
| Authors:
Adam M. Madson; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| The ZaP Flow Z-Pinch Experiment forms a Z-pinch with an embedded axial flow that exhibits stability for 500 - 2000 times the instabililty growth time for a static Z-pinch. Two linear photodiode arrays placed orthogonal to each other measure chord-integrated emissivity of the plasma. Deconvolving these data produce time resolved 1-D and 2-D emission profiles of the Z-pinch cross-section during the stable quiescent period. These unfiltered emission profiles show that ... |
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| Combined Direct-Adjoint Approximations for Large-Scale Design-Oriented Structural-Acoustics Finite-Element Analysis |
2004 |
137 pages |
| Authors:
Eli Livine; Levent Coskuner; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| A second-order approximation method was developed for the design- oriented analysis and sensitivity approximations of large scale structural/ acoustic problems. The method is based on combined utilization of low-order approximations of both direct and adjoint problems. A variety of approximation techniques for the first-order model order reduction of the direct and adjoint structural acoustic problems were tested. The overall consistent accuracy level of the second order method over wide frequency ... |
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| Thermo-Viscoelastic Analysis of Composite Materials, |
JUN 1989 |
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| Authors:
Kuen Y. Lin; I. H. Hwang; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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 | The thermo-viscoelastic boundary value problem for anisotropic materials was formulated and a numerical procedure was developed for the efficient analysis of stress and deformation histories in composites. The procedure is based on the finite element method and is therefore applicable to composite laminates containing geometric discontinuities and complicated boundary conditions. Using the formulation, the time-dependent stress and strain distributions in both notched and unnotched graphite/epoxy composites were obtained. The effect ... |
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| A Void Growth Failure Criterion Applied to Dynamically and Statically Loaded Thin Rings. |
JUN 1980 |
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| Authors:
A. M. Rajendran; I. M. Fyfe; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| The introduction of inertia terms in the theoretical model of thin ring expansion shows that classical plastic instability concepts, defined in terms of the local strain in the necking region, no longer apply. However, in this report it is shown that, when the plastically incompressible constitutive model is replaced with a model applicable to porous plastic materials, a criterion based on critical void volume fraction provides an alternative means to ... |
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| Limits on Low Speed Wind Tunnel Tests of Rotors. |
27 SEP 1977 |
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| Authors:
William H. Rae Jr.; Shojiro Shindo; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| The low speed test limit of V/STOL aircraft wind tunnel testing has been investigated and two wall correction theories currently in use have been analyzed. The models used were either rotors or propellers acting as a rotor. In general the test limit based on tail data is more stringent than limits based on rotors. Corrections using Heyson's X sub eff are more accurate than traditional wall corrections. (Author) |
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| On the Calculation of Tidal Currents in Homogeneous Estuaries |
JUL 1977 |
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| Authors:
Carl E. Pearson; Donald F. Winter; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| This paper describes a new approach to the computation of tidal flow in homogeneous estuaries with irregualr boundary configurations and of arbitrary depth. The governing equations are the standard vertically integrated expressions of momentum and mass conservation including the effects of Coriolis acceleration, surface wind stress and bottom friction. The motion is assumed to be periodic and the original time-dependent equations are replaced by a set of modal equations obtained ... |
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| Propagation of a Laser Beam in a Plasma. |
OCT 1975 |
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| Authors:
John M. Chapman; Jirair Kevorkian; Loren C. Steinhauer; Juris Vagners; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| This paper shows that for a nonabsorbing medium with a prescribed index of refraction, the effects of beam stability, line focusing, and beam distortion can be predicted from simple ray optics. When the paraxial approximation is used, diffraction effects are examined for Gaussian, Lorentzian, and square beams. Most importantly, it is shown that for a Gaussian beam, diffraction effects can be included simply by adding imaginary solutions to the paraxial ... |
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| Transition to Transonic Flow in the Far Field for a Supersonic Airfoil in a Stratified Atmosphere. |
SEP 1975 |
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| Authors:
Georges A. Pechuzal; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| This paper deals with the steady frictionless, nonheat-conducting flow field of a thin airfoil in an atmosphere with a weak wind gradient. Because of this wind gradient, which is assumed to increase linearly with altitude, the flow gradually becomes transonic in the far field below the airfoil. This transition phenomenon also occurs in an atmosphere where the temperature decreases with altitude, and for certain cases of accelerating flights. In all ... |
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| Research in Resonance in Partial Differential Equations. |
1975 |
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| Authors:
Jirair Kevorkian; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| During the period covered in this report the principal investigator and collaborators have worked on the following three areas: (1) nonlinear acoustics, (2) nonlinear wave propagation, and (3) reentry roll resonance. |
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| An Experimental Investigation of Wind Tunnel Wall Corrections and Test Limits for V/STOL Vehicles. |
12 JUL 1973 |
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| Authors:
William H. Rae Jr.; Shojiro Shindo; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| The report deals with an experimental investigation of some of the problems associated with wind tunnel testing of V/STOL type aircraft. The models used in the study were either rotors or propellers acting as a rotor. Various size and shape wind tunnel test sections were simulated by the use of inserts installed within a larger main wind tunnel test section. The study investigated the application of wind tunnel wall corrections ... |
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| Developments in High Power Laser Research. |
JUN 1973 |
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| Authors:
A. Hertzberg; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| The effects of high-power laser technology programs on basic research activities in this country and abroad are described and analyzed. The particularly multidisciplinary nature of laser research which has had a special impact on physicists, fluid dynamicists and researchers in other branches of engineering science is highlighted. Also included to indicate the universal interest in the problem areas is the program of the Esfahan Symposium on Fundamental Laser Physics, held ... |
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| The Effect of Biaxial Strain Deformation on the Dynamic Fracture of 6061-T6 Aluminum. |
SEP 1972 |
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| Authors:
Ian M. Fyfe; Robert M. Schmidt; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| Fracture induced by the reflection of stress waves has been examined in the past using experiments which are characterized by uniaxial strain conditions, and where the maximum principal stress is normal to the fracture plane. This report describes dynamic fracture where the strains are biaxial and the maximum principal stress is tangential to the fracture surface. (Author) |
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| Dynamic Fracture in Metals under Biaxial Strain Conditions. |
OCT 1970 |
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| Authors:
Robert M. Schmidt; Ian M. Fyfe; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| An experiment to investigate the influence of biaxial strain on the dynamic fracture of metals is outlined. A hollow cylindrical specimen is loaded on the inner diameter by a polyethylene coated exploding wire which results in a circumferential spallation pattern. Prior to fracture, the spall plane undergoes biaxial deformation with a total hoop strain of the same order of magnitude as the total radial strain. The role of plastic pre-straining ... |
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| Applicability of Stress-Strain Laws to Dynamic Problems. |
SEP 1970 |
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| Authors:
Ian M. Fyfe; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| An important problem in the dynamic response of solids is the establishment of the range and general applicability of proposed theories. An investigation of this problem can best be carried out with the introduction of a set of experiments that differ from those used to develop the theories originally. The experiments used in this study applied an exploding wire system as the loading mechanism to produce plane strain cylindrical stress ... |
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| A NON-GAUSSIAN TURBULENCE SIMULATION. |
NOV 1969 |
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| Authors:
Paul M. Reeves; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| A comparison of the statistical properties of low altitude atmospheric turbulence and the characteristics of presently used simulation techniques shows that these techniques do not satisfactorily account for the non-Gaussian nature of turbulence. A non-Gaussian turbulence simulation, intended to be used in conjunction with piloted flight simulators, is developed. The simulation produces three simultaneous random processes which represent the three orthogonal gust components. The probability distribution of each component is ... |
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| THE DYNAMIC PLASTIC RESPONSE OF ALUMINUM TO PLANE STRAIN CYLINDRICAL STRESS WAVES, |
JUL 1969 |
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| Authors:
Ian M. Fyfe; Robert P. Swift; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| The dynamic plastic behavior of hollow cylinders deformed radially by an exploding wire technique is used to consider the relative merits of possible constitutive equations. The experiments are of two distinct types, a finite-rise pressure pulse form of loading and a higher stress level impact test. An analytic study of these tests using in turn a linear elastic, a perfectly plastic incremental, and an elastic/viscoplastic constitutive model provided the means ... |
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| Finite Element Analysis of Fluid Flows |
OCT 1968 |
20 pages |
| Authors:
Harold C. Martin; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| The finite element method is applied to several simple cases of steady flow of a perfect, incompressible fluid. It is shown that the finite element representation accurately reflects the behavior of the classical flow equations. Finite elements form the basis for a versatile analysis procedure applicable to problems in several different fields. The earliest applications were to problems in structural mechanics. In recent years, nonstructural problems also have been treated ... |
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| AN EXPERIMENTAL STUDY OF ALLEVIATING THE LIMITS ON MINIMUM-SPEED V/STOL WIND-TUNNEL TESTS, |
JAN 1968 |
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| Authors:
Shojiro Shindo; William H. Rae Jr; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| An experimental study was made to investigate some means to alleviate flow breakdown by using a number of different strake or fence configurations. A total of 23 different configurations were studied in the 4 x 6 ft. insert with a 2 ft. diameter rigid rotor at about 7 psf disk loading. None of the strake configurations studied in the experiment completely eliminate the effect of flow breakdown. A further experimental ... |
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| OPTIMUM DEPTH - MINIMUM AREA DESIGN CHARTS FOR LATERALLY SUPPORTED STRUCTURAL BEAMS IN PURE BENDING. |
09 DEC 1965 |
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| Authors:
Peter St. Clair Christie; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| The investigation attempts to establish 'minimum' weight beam proportions, based on beam web elastic buckling criteria, for unstiffened I beams in pure bending. The investigation is basically a study of the parameters affecting beam weight for both strength and deflection designed beams. It is shown that an 'optimum' beam depth exists at which the beam cross sectional area will be 'minimum' for both strength designed and deflection designed beams. Design ... |
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| THE EFFECTS OF SHEAR ON STRESS WAVE PROPAGATION. |
AUG 1965 |
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| Authors:
I. M. Fyfe; R. R. Ensminger; R. Swift; WASHINGTON UNIV SEATTLE DEPT OF AERONAUTICS AND ASTRONAUTICS
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| The propagation of high-intensity stress waves in cylindrical geometries is considered as a means to obtain a measure of the shear stress effects on material behavior. A discontinuity theory is applied to show that when Hugoniots are used as equations of state, the Hugoniots must necessarily coincide for all geometric configurations. It is also shown that the simple equations of state of this type may accurately predict particular information that ... |
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