Influence Of Relative Density And Microstructural Anisotropy On The Global Elastic Properties Of Cellular Structures,
2017
University of Texas at Arlington
Influence Of Relative Density And Microstructural Anisotropy On The Global Elastic Properties Of Cellular Structures, Justin Compton
Mechanical and Aerospace Engineering Theses - Archive
The favorable strength-to-weight ratio of cellular solids makes them ideal for structural applications. With the advent of additive manufacturing, the fabrication of complex cellular structures is becoming a reality. It is therefore necessary to understand the mechanical properties of cellular structures. The global mechanical properties of cellular structures are governed by geometry and therefore, differ from the mechanical properties of the base material from which they are constructed. In this study, finite element models are developed to explore the effective elastic properties of honeycomb structures for isotropic and anisotropic microstructural material properties. Finite element models are generated for regular, hexagonal …
Refurbished And 3d Modeled Thermal Vacuum Chamber,
2017
California Polytechnic State University, San Luis Obispo
Refurbished And 3d Modeled Thermal Vacuum Chamber, Lauren M. Glenn
Master's Theses
Spacecraft testing includes acoustics, vibrations, and thermal vacuum. Cal Poly’s Space Environments Lab is equipped with multiple vacuum chambers, but no thermal vacuum chamber. The purpose of this thesis is to incorporate an ATS Chiller system with the HVEC vacuum chamber so students are able to experiment with a thermal vacuum chamber. The ATS Chiller had leaky pipes that needed to be refurbished and a shroud was implemented to improve thermal capabilities of the system. The full system was able to reach temperatures as low as -38ºC and as high as 58ºC at a pressure of 10-6 Torr. The ATS …
Actuator Disk Theory For Compressible Flow,
2017
California Polytechnic State University, San Luis Obispo
Actuator Disk Theory For Compressible Flow, Htet Htet Nwe Oo
Master's Theses
Because compressibility effects arise in real applications of propellers and turbines, the Actuator Disk Theory or Froude’s Momentum Theory was established for compressible, subsonic flow using the three laws of conservation and isentropic thermodynamics. The compressible Actuator Disk Theory was established for the unducted (bare) and ducted cases in which the disk was treated as the only assembly within the flow stream in the bare case and enclosed by a duct having a constant cross-sectional area equal to the disk area in the ducted case. The primary motivation of the current thesis was to predict the ideal performance of a …
Intensity Control Of Individual Dbd Plasma Filament. I. Experiment With A Needle Electrode,
2017
Missouri University of Science and Technology
Intensity Control Of Individual Dbd Plasma Filament. I. Experiment With A Needle Electrode, M. C. Paliwoda, J. L. Rovey
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Filamentary volume dielectric barrier discharge (DBD) produces patterned plasma structures that are currently being explored for reconfigurable metamaterial applications. In this work, the presence and intensity of a single filament (within an array of filaments) are controlled by biasing a low voltage needle electrode by less than 7% of the driving voltage. The current, voltage, and time-averaged normalized light intensity were measured while varying the needle voltage through self-biasing resistors. For a 7.5 kV, 3.2 kHz DBD in air, the needle-controlled filament intensity varies from 80% to 0% of the light intensity of surrounding filaments. When the biased voltage prevents …
Intensity Control Of Individual Dbd Plasma Filament. Ii. Fundamental Physical Mechanism,
2017
Missouri University of Science and Technology
Intensity Control Of Individual Dbd Plasma Filament. Ii. Fundamental Physical Mechanism, M. C. Paliwoda, J. L. Rovey
Mechanical and Aerospace Engineering Faculty Research & Creative Works
Filamentary volume dielectric barrier discharge (DBD) produces patterned plasma structures that are currently being explored for reconfigurable metamaterial applications. Previous work has demonstrated control of the presence and intensity of a single DBD plasma filament (within an array of filaments) by biasing a low voltage needle electrode. The results were attributed to redistributed charge inside the DBD due to the modified electric field created by the needle electrode. In the present work, results from a 3D electrodynamic field simulation bolster this argument. Results show that increasing needle bias voltage causes changes in the transverse electric field structure, resulting in redistribution …
Takeoff And Landing Distance Measurement: An Evaluation Of Laser Altimetry For The Collection Of Absolute Aircraft Altitude,
2017
Florida Institute of Technology
Takeoff And Landing Distance Measurement: An Evaluation Of Laser Altimetry For The Collection Of Absolute Aircraft Altitude, Christopher John Kennedy
Theses and Dissertations
The measurement of takeoff and landing distance during flight testing of general aviation aircraft requires the accurate measurement of aircraft position over the ground and altitude up to 50 feet above surface elevation. Current methods of evaluating takeoff and landing distances include cinetheodolites, laser and radar trackers, and Differential Global Positioning Systems (DGPS). The use of laser altimetry to range altitude above the ground originated with military and agricultural aircraft. The AgLaser laser module was an infrared laser ranging unit designed for agricultural aircraft to gauge optimal spray height above a field. The AgLaser system has a stated accuracy of …
Flexsar Bistatic And Monostatic Circular Sar Collection,
2017
Space Dynamics Laboratory
Flexsar Bistatic And Monostatic Circular Sar Collection, Chad Knight, Mark Jensen, Trevor Jewkes, Jacob Gunther
Space Dynamics Laboratory Publications
Bistatic SAR data has advantages and disadvantages compared to monostatic data. This papers examines a combined bistatic and monostatic SAR data collection. The airborne platform used a monostatic radar system with two transmit and two receive channels in a pulsed spotlight mode. Another receive-only system was placed on an elevated mountaintop. The mountaintop receive system had two receive channels. The airborne asset flew in a full circle around several targets, exercising a large range of bistatic geometries. Various SAR modes were collected, including single-channel, quad-channel, and along-track interferometry (ATI) data for monostatic and bistatic modalities. This paper focuses on the …
Frequency Tuning Of Vibration Absorber Using Topology Optimization,
2017
University of Texas at Arlington
Frequency Tuning Of Vibration Absorber Using Topology Optimization, Swapnil Subhash Harel
Mechanical and Aerospace Engineering Theses - Archive
A tuned mass absorber is a system for reducing the amplitude in one oscillator by coupling it to a second oscillator. If tuned correctly, the maximum amplitude of the first oscillator in response to a periodic driver will be lowered, and much of the vibration will be ’transferred’ to the second oscillator. The tuned vibration absorber (TVA) has been utilized for vibration control purposes in many sectors of Civil/Automotive/Aerospace Engineering for many decades since its inception. Time and again we come across a situation in which a vibratory system is required to run near resonance. In the past, approaches have …
Numerical Investigation Of Vortex Generator Flow Control For External-Compression Supersonic Inlets,
2017
University of Texas at Arlington
Numerical Investigation Of Vortex Generator Flow Control For External-Compression Supersonic Inlets, Ezgihan Baydar
Mechanical and Aerospace Engineering Dissertations - Archive
Vortex generators (VGs) within external-compression supersonic inlets for Mach 1.6 were investigated to determine their ability to increase total pressure recovery and reduce total pressure distortion. Ramp and vane-type VGs were studied. The geometric factors of interest included height, length, spacing, angle-of-incidence, and positions upstream and downstream of the inlet terminal shock. The flow through the inlet was simulated numerically through the solution of the steady-state, Reynolds-averaged Navier-Stokes equations on multi-block, structured grids using the Wind-US flow solver. The inlet performance was characterized by the inlet total pressure recovery and the radial and circumferential total pressure distortion indices at the …
Integration Of Macro-Fiber Composite Material On A Low Cost Unmanned Aerial System,
2017
Embry-Riddle Aeronautical University
Integration Of Macro-Fiber Composite Material On A Low Cost Unmanned Aerial System, May Chong Chan
Doctoral Dissertations and Master's Theses
The development, deployment, and operation of Unmanned Aerial Systems (UAS) have grown exponentially in recent years and have provided researchers with the opportunity to gain hands-on experience with aircraft in a manner that was previously limited to institutions and companies with large budgets. This allows the generation and testing of UAS advanced technologies using low cost systems. The scope of this thesis does not aim to make vast improvements to the control strategy itself, but to expand upon previous UAV work carried out at Embry-Riddle by designing, implementing, and demonstrating a simulation environment for mechanical and Macro-Fiber Composite (MFC) actuated …
Performance Analysis Of A Coaxial Helicopter In Hover And Forward Flight,
2017
Embry-Riddle Aeronautical University
Performance Analysis Of A Coaxial Helicopter In Hover And Forward Flight, Stanrich D. Fernandes
Doctoral Dissertations and Master's Theses
The performance of a coaxial rotor system has been analyzed by establishing a proper basis of comparison between a conventional single rotor and coaxial rotor. An attempt has also been made to better understand the complicated aerodynamic interactions associated with coaxial rotor wakes by using a free-vortex methodology (FVM). The FVM is a Lagrangian-based wake convection methodology, which solves for the evolution of the vortical wake produced by the rotor blades under the influence of an external flow. The extent to which the two rotors interact with each other was found to be highly dependent on the inter-rotor spacing. To …
Battery Centric Serial Hybrid Aircraft Performance And Design Space,
2017
Embry-Riddle Aeronautical University
Battery Centric Serial Hybrid Aircraft Performance And Design Space, Lenny Gartenberg
Doctoral Dissertations and Master's Theses
The design space and flight envelope of a battery centric serial hybrid aircraft has been analytically derived. The formulation assumes cruising flight only and all energy available is used. The flight envelope can be generated for any conventional propeller driven serial hybrid aircraft. The advantageous combination of an electric motor and controllable-pitch electric propeller was also explored. The results are used to be able to control efficiency and noise at constant thrust and therefore constant airspeed. Manufacturer provided electric motor and propeller data is used for efficiency purposes. Since the electric motor is virtually silent compared to the propeller, published …
Structural Design Of A Business Jet Winglet,
2017
Embry-Riddle Aeronautical University
Structural Design Of A Business Jet Winglet, Jaime Gutierrez
Doctoral Dissertations and Master's Theses
Structural sizing of a winglet for the Falcon 10 was performed and is presented here. The aerodynamic profile of the winglet was taken from a previous study, which predicted an increase in range of 3.3% with an estimated weight increase of 52 kg. An investigation of the current structure layouts and materials used in the industry was conducted. Six loading cases were analyzed to identify the most critical for the winglet, found to be negative and positive sideslip and gust. A finite element model was developed and used to size the structure. A fabrication process and assembly is described and …
Comparison Of Rans Modeling To Dual-Plane Piv Measurements Of The Turbulent Tip Vortex Trailed From A Hovering Rotor,
2017
Embry-Riddle Aeronautical University
Comparison Of Rans Modeling To Dual-Plane Piv Measurements Of The Turbulent Tip Vortex Trailed From A Hovering Rotor, Zachary Lietzau
Doctoral Dissertations and Master's Theses
Numerical simulations using the Reynolds-Averaged Navier-Stokes (RANS) equations were conducted to study the development and turbulent decay of the tip vortices in the wake produced by a hovering rotor. The computational results were compared to detailed, dual plane Particle Image Velocimetry (PIV) measurements of a turbulent tip vortex trailed from a single-bladed rotor. The work investigated both the required mesh resolution and most suitable turbulence closure models with rotational/curvature corrections by assessing their predictions of the tip vortex properties and the overall physical nature of the rotor wake. It was found that even when using a higher-order accurate central differencing …
Extended Surface Heat Transfer Coefficients Via Endwall Temperature Measurements,
2017
Embry-Riddle Aeronautical University
Extended Surface Heat Transfer Coefficients Via Endwall Temperature Measurements, Yogesh Pai
Doctoral Dissertations and Master's Theses
Short pins are used for internal cooling of the trailing edge in a gas turbine blade. A novel method is described in this thesis which helps in simplifying the experimental process used to obtain average heat transfer data on the pin surface, at the expense of additional post processing complexity. The method is based on a unique, analytical solution of the longitudinal conduction equation with internal heat generation, allowing computation of heat transfer rates via pin base temperature measurements via Temperature Sensitive Paint, or similar non-intrusive methods. Verification of this method is done with comparisons to the solution of infinite …
The Effect Of Surface Materials And Morphology On Wingsuit Aerodynamics,
2017
Embry-Riddle Aeronautical University
The Effect Of Surface Materials And Morphology On Wingsuit Aerodynamics, Timothy Allen Sestak
Doctoral Dissertations and Master's Theses
This study examines the aerodynamic effects of the materials, textiles, and morphologies currently used in wingsuit design and construction. The experiment was a low-speed wind tunnel investigation using a rigid wing with an aspect ratio of 2, a NACA 4418 airfoil cross section and a smooth, polished painted surface as a baseline. The baseline wing was modified by covering the upper and lower surfaces with various textiles currently used in wingsuit construction. This study is the first step in continued research to design and build a wingsuit with superior glide performance compared to current designs. Surface textures and features on …
The Issues And Complexities Surrounding The Future Of Long Duration Spaceflight,
2017
Embry-Riddle Aeronautical University
The Issues And Complexities Surrounding The Future Of Long Duration Spaceflight, Solomon Miiro
Graduate Student Works
The Comprehensive Exam put forward by this proposal is intended to address the learning objectives covered by the Master of Aeronautical Science Degree with specializations in Aviation Aerospace Safety Systems and some limited aspects in Human Factors in Aviation Systems. This will be accomplished by researching the following topics: effects of long duration spaceflight on crew performance and functioning and the steps that should be taken to enable long term spaceflight mission crews in lieu of accomplishing important missions; a human factor analysis should current human-machine design interfaces be enhanced to make manual rendezvous and docking in space easier to …
Multidisciplinary Shape Optimization Of A Composite Blended Wing Body Aircraft,
2017
University of South Carolina
Multidisciplinary Shape Optimization Of A Composite Blended Wing Body Aircraft, Charles Maxwell Boozer
Theses and Dissertations
A multidisciplinary shape optimization tool coupling aerodynamics, structure, and performance was developed for battery powered aircraft. Utilizing high-fidelity computational fluid dynamics analysis tools and a structural wing weight tool, coupled based on the multidisciplinary feasible optimization architecture; aircraft geometry is modified in the optimization of the aircraft’s range or endurance. The developed tool is applied to three geometries: a hybrid blended wing body, delta wing UAS, the ONERA M6 wing, and a modified ONERA M6 wing. First, the optimization problem is presented with the objective function, constraints, and design vector. Next, the tool’s architecture and the analysis tools that are …
2017 Spring Graduate Recognition Program,
2017
The University of Alabama in Huntsville
2017 Spring Graduate Recognition Program, Propulsion Research Center, Robert Frederick
PRC Graduate Recognition
This program includes the graduate recognition program for spring 2017. Includes photographs, upcoming events, recent publications, and student profiles.
A Performance And Visualization Study On Inlet Geometries Of A Cross-Flow Fan.,
2017
University of Louisville
A Performance And Visualization Study On Inlet Geometries Of A Cross-Flow Fan., Yoel Tanquero
Electronic Theses and Dissertations
A study was conducted to characterize the flow-field in the suction region of different inlet geometries of a cross-flow fan. The characterization was accomplished by correlating the static performance curves measured for each fan-inlet configuration to the streamline plot obtained using a particle tracking velocimetry (PTV) measurement system at three constant flow rates (25, 40, and 55 CFM). The PTV measurement system used was developed by the author and uses helium bubbles as tracers, an LED light sheet, a slow motion camera, and a Matlab program. Four inlet geometry design variables were defined and independently studied to evaluate the effect …
