Numerical Analysis Of Gun Barrel Pressure Blast Using Dynamic Mesh Adaption,
2011
Embry-Riddle Aeronautical University
Numerical Analysis Of Gun Barrel Pressure Blast Using Dynamic Mesh Adaption, Sathish Xavier
Doctoral Dissertations and Master's Theses
A Computational Fluid Dynamics (CFD) method has been applied to simulate the pressure blast of the projectile which is launched from a barrel and to investigate the pressure distribution and sound pressure level (dB) along different positions away from the gun axis and towards the fuselage of the aircraft. Fluent was employed to simulate the unsteady flow using dynamic mesh with moving boundary. Most CFD based ballistics-model requires additional thermodynamic functions which must be derived from the Noble-Abel equation of state. The unsteady, axisymmetric Navier Stokes equation systems were numerically solved using the Advection Upstream Splitting Method (AUSM) scheme; with …
Mars Carbon Dioxide Propulsion,
2011
Old Dominion University
Mars Carbon Dioxide Propulsion, Christopher Cushman Perry
Mechanical & Aerospace Engineering Theses & Dissertations
An experimental investigation was conducted to characterize the performance of a small-scale supersonic propulsion system using supercritical CO2 as a propellant intended for Mars surface applications. This research has focused on estimating the specific impulse behavior of high-pressure carbon dioxide propellant that can be produced by condensing dry ice out of Mars's atmosphere and heating it at constant volume to temperatures above its 31.1 ° C critical temperature. Since supercritical fluid was created by heating different dry ice-vapor mixtures to moderate temperatures, the nominal initial density and thermodynamic state within the pressure vessel could be controlled. The instrumented test …
A Fixed Robotic Mars Base Architecture,
2011
Old Dominion University
A Fixed Robotic Mars Base Architecture, Christie Angunette Alston
Mechanical & Aerospace Engineering Theses & Dissertations
This thesis proposes a fixed Mars base architecture consisting of the following interconnected elements: landing area, power generation, in-situ resource utilization (ISRU), robotic repair and assembly, and a scientific research laboratoiy. The base architecture that has been put forward can be expanded readily to include future elements such as a sustainable human habitat. The base architecture approach was developed assuming that serial Earth-launched lander missions were too expensive and too slow going forward in effecting the systematic exploration of a planet whose surface area constitutes nearly the same area as the land mass of Earth. The fixed base architecture facilitates …
Study Of The Role Of Pressure Relaxation In Inviscid, Incompressible Flows,
2011
Old Dominion University
Study Of The Role Of Pressure Relaxation In Inviscid, Incompressible Flows, Jonathan Strzelec
Mechanical & Aerospace Engineering Theses & Dissertations
This thesis has investigated the role of pressure relaxation in inviscid, incompressible flows. A modified form of the classical Bernoulli equation was developed from a vector form of the Navier-Stokes equation which includes pressure relaxation and bulk viscosity. This modified Bernoulli equation was utilized to compare two-dimensional potential flow pressure distributions over a sphere, cylinder, backward and forward facing steps. Finally, the modified Bernoulli equation was utilized to compare the theoretical bounding free streamline to an experimentally observed free streamline over a knife edge. Results of these comparisons show that the classical form of the Bernoulli equation can over-predict the …
Radiation Effects Basics For 7750,
2011
Morehead State University
Radiation Effects Basics For 7750, Robert J. Twiggs
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint presentation created by Professor Bob Twiggs on "Radiation Effects Basics for 7750" on September 25, 2011.
Design And Control Of Flapping Wing Micro Air Vehicles,
2011
Air Force Institute of Technology
Design And Control Of Flapping Wing Micro Air Vehicles, Michael L. Anderson
Theses and Dissertations
Flapping wing Micro Air Vehicles (MAVs) continues to be a growing field, with ongoing research into unsteady, low Re aerodynamics, micro-fabrication, and fluid-structure interaction. However, research into flapping wing control of such MAVs continues to lag. Existing research uniformly consists of proposed control laws that are validated by computer simulations of quasi-steady blade-element formulae. Such simulations use numerous assumptions and cannot be trusted to fully describe the flow physics. Instead, such control laws must be validated on hardware. Here, a novel control technique is proposed called Bi-harmonic Amplitude and Bias Modulation (BABM) which can generate forces and moments in 5 …
Evaluation Of Nanocomposites For Shielding Electromagnetic Interference,
2011
Air Force Institute of Technology
Evaluation Of Nanocomposites For Shielding Electromagnetic Interference, Kenneth Y. Chong
Theses and Dissertations
Numerous efforts are ongoing to research and develop nanocomposite materials for space applications. Current composite spacecraft materials are nonconductive and require costly shielding materials to be applied in order to protect spacecraft from the harmful effects caused by electromagnetic interference (EMI), which is a by-product of exposure to the space environment. Conductive fillers (nanofibers) are being employed in composites to produce nanocomposites to reduce the dry weight of space vehicles while providing sufficient protection against EMI. This eliminates the need to apply secondary shielding materials to spacecraft. This thesis studied a nanocomposite consisting of Cycom 5575-2 glass with multi-walled carbon …
Two-Dimensional, Time-Dependent Plasma Structures Of A Hall Effect Thruster,
2011
Air Force Institute of Technology
Two-Dimensional, Time-Dependent Plasma Structures Of A Hall Effect Thruster, David Liu
Theses and Dissertations
The Hall thruster is a type of electric propulsion utilized by satellites to perform a wide variety of missions ranging from station keeping, orbital maneuvers, and even deep space propulsion. In order to accommodate the multitude of missions it also has a wide assortment of sizes and power configurations which can range from approximately an inch in diameter at 20 W to a couple of feet in diameter at 1.5 kW. Additionally, this electro-static device provides high specific impulse without the added weight penalty associated with conventional chemical thrusters. It supplies this high specific impulse by ionizing a gas such …
Stochastic Real-Time Optimal Control: A Pseudospectral Approach For Bearing-Only Trajectory Optimization,
2011
Air Force Institute of Technology
Stochastic Real-Time Optimal Control: A Pseudospectral Approach For Bearing-Only Trajectory Optimization, Steven M. Ross
Theses and Dissertations
A method is presented to couple and solve the optimal control and the optimal estimation problems simultaneously, allowing systems with bearing-only sensors to maneuver to obtain observability for relative navigation without unnecessarily detracting from a primary mission. A fundamentally new approach to trajectory optimization and the dual control problem is developed, constraining polynomial approximations of the Fisher Information Matrix to provide an information gradient and allow prescription of the level of future estimation certainty required for mission accomplishment. Disturbances, modeling deficiencies, and corrupted measurements are addressed with recursive updating of the target estimate with an Unscented Kalman Filter and the …
Increasing The Performance Of A Sliding Discharge Actuator Through The Application Of Multiple Potentials,
2011
Air Force Institute of Technology
Increasing The Performance Of A Sliding Discharge Actuator Through The Application Of Multiple Potentials, Steven D. Seney Jr.
Theses and Dissertations
This work encompasses a comparison between a sliding discharge DBD actuator with grounded and AC biased sliding electrode driven at kHz frequency. The induced velocity in the bulk flow was recorded with PIV and compared for multiple potential splits between two test configurations and a baseline sliding discharge actuator over three test phases. In the first test phase, varying potential splits were examined between the primary and secondary electrode with the sliding electrode grounded. The potential splits induced a thicker induced jet than the baseline case with similar peak velocities on the order of 1.25 m/s at the 61 mm …
Effect Of The Thickness Of Undoped Gan Interlayers Between Multiple Quantum Wells And The P-Doped Layer On The Performance Of Gan Light-Emitting Diodes,
2011
Missouri University of Science and Technology
Effect Of The Thickness Of Undoped Gan Interlayers Between Multiple Quantum Wells And The P-Doped Layer On The Performance Of Gan Light-Emitting Diodes, T. Lu, S. Li, K. Zhang, C. Liu, Y. Yin, L. Wu, H. Wang, Xiaodong Yang, G. Xiao, Y. Zhou
Mechanical and Aerospace Engineering Faculty Research & Creative Works
InGaN based light-emitting diodes (LEDs) with undoped GaN interlayer of variant thicknesses grown by metal-organic chemical vapor deposition technique have been investigated. It was found that the thickness of undoped GaN interlayers affected LEDs' performance greatly. The LED with 50 nm undoped GaN interlayer showed higher light output power and lower reverse-leakage current compared with the others at 20 mA. Based on electrical and optical characteristics analysis and numerical simulation, these improvements are mainly attributed to the improvement of the quality of depletion region by inserting an undoped GaN layer, as well as reduction of the Shockley-Read-Hall recombination in InGaN/GaN …
Space Environment-Iii Lecture - Powerpoint Presentation,
2011
Morehead State University
Space Environment-Iii Lecture - Powerpoint Presentation, Robert J. Twiggs
Robert "Bob" Twiggs STEM Education Collection
Professor Bob Twiggs' lecture on Space Environment-III PowerPoint presentation delivered on September 2, 2011.
Space Environment - A Review,
2011
Morehead State University
Space Environment - A Review, Robert J. Twiggs
Robert "Bob" Twiggs STEM Education Collection
A PowerPoint presentation created by Professor Bob Twiggs on "Space Environment" on September 2, 2011.
Mission Performance Considered As Point Performance In Aircraft Design,
2011
California Polytechnic State University, San Luis Obispo
Mission Performance Considered As Point Performance In Aircraft Design, Robert A. Mcdonald
Aerospace Engineering
The cruise or loiter performance of an aircraft is intimately tied to its wing loading and its thrust-to-weight ratio. Paradoxically, mission performance is often not considered when these fundamental aircraft parameters are determined in conceptual design. In this paper, the traditional constraint diagram is extended to include contours of range or endurance parameter. These performance metrics represent the mission-performance capability of the aircraft without sizing the aircraft to a particular mission. This gives the designer an immediate and intuitive understanding of the tradeoff between the point and mission performance of the aircraft. The potential freedom for the designer to choose …
Designing Propulsion Systems For Future Aerospace Applications,
2011
Minnesota State University - Mankato
Designing Propulsion Systems For Future Aerospace Applications, Nihad E. Daidzic
Aviation Department Publications
No abstract provided.
Vibration-Based Health Monitoring Of Multiple-Stage Gear Train And Differential Planetary Transmission Involving Teeth Damage And Backlash Nonlinearity,
2011
California Polytechnic State University, San Luis Obispo
Vibration-Based Health Monitoring Of Multiple-Stage Gear Train And Differential Planetary Transmission Involving Teeth Damage And Backlash Nonlinearity, Andrew Patrick Sommer
Master's Theses
The objective of this thesis is to develop vibration-based fault detection strategies for on-line condition monitoring of gear transmission systems. The study divides the thesis into three sections. First of all, the local stresses created by a root fatigue crack on a pinion spur gear are analyzed using a quasi-static finite element model and non-linear contact mechanics simulation. Backlash between gear teeth which is essential to provide better lubrication on tooth surfaces and to eliminate interference is included as a defect and a necessary part of transmission design. The second section is dedicated to fixed axis power trains. Torsional vibration …
Stoichiometric H2ice With Water Injection And Exhaust And Coolant Heat Recovery Through Organic Rankine Cycles,
2011
Missouri University of Science and Technology
Stoichiometric H2ice With Water Injection And Exhaust And Coolant Heat Recovery Through Organic Rankine Cycles, Alberto Boretti
Mechanical and Aerospace Engineering Faculty Research & Creative Works
High power density, stoichiometric, turbocharged, directly injected engines with water injection and a three-way catalytic converter after treatment have been proposed as one of the most promising H2ICE [1]. These throttle-controlled engines have top brake efficiencies exceeding 40%, but large penalties in efficiency reducing the load with 1 bar BMEP values approaching 10%. Recovery of the large amount of fuel energy lost in the coolant especially at low loads as well as the fuel energy lost in the exhaust that is significant at high loads and speeds may push not only the top brake efficiencies to exceed the 45% mark, …
Advances In Hydrogen Compression Ignition Internal Combustion Engines,
2011
Missouri University of Science and Technology
Advances In Hydrogen Compression Ignition Internal Combustion Engines, Alberto Boretti
Mechanical and Aerospace Engineering Faculty Research & Creative Works
The turbocharged direct injection lean burn Diesel engine is the most efficient engine now in production for transport applications within heavy duty trucks applications full load brake engine thermal efficiencies up to 45% and reduced penalties in brake engine thermal efficiencies reducing the load by the quantity of fuel injected. the secrets of this engine's performances are the high compression ratio and the lean bulk combustion mostly diffusion controlled in addition to the partial recovery of the exhaust energy to boost the charging efficiency. the major downfalls of this engine are the carbon dioxide emissions and the depletion of natural …
Flow Characteristics Of The Renovated Cal Poly 3 X 4 Ft Subsonic Wind Tunnel,
2011
California Polytechnic State University, San Luis Obispo
Flow Characteristics Of The Renovated Cal Poly 3 X 4 Ft Subsonic Wind Tunnel, Mathew L. Thomas, Dorian V. Pandey, Jason N. Nguyen
Aerospace Engineering
This paper investigates the flow characteristics of the renovated Cal Poly 3 x 4 ft subsonic wind tunnel. The IFA 300 constant-temperature anemometer along with a cross-plane X-wire dual-sensor probe was used to measure the mean velocity and turbulence intensity of the tunnel flow and part of the turbulent boundary layer at one section of the tunnel. Because of the malfunction of one channel of the IFA 300, only one wire of the dual sensor probe was calibrated for the measurements. The probe was then placed in a streamlined probe holder mounting on the traverse inside the wind tunnel. The …
Femtosecond Laser Fabricated All-Optical Fiber Sensors With Ultrahigh Refractive Index Sensitivity: Modeling And Experiment,
2011
Missouri University of Science and Technology
Femtosecond Laser Fabricated All-Optical Fiber Sensors With Ultrahigh Refractive Index Sensitivity: Modeling And Experiment, Lan Jiang, Longjiang Zhao, Sumei Wang, Jinpeng Yang, Hai Xiao
Mechanical and Aerospace Engineering Faculty Research & Creative Works
All-optical fiber sensors based on ultracompact fiber inline Mach-Zehnder interferometer (MZI) are fabricated by side-ablating a Ushape microcavity in a single-mode optical fiber with the fiber core partially removed using femtosecond (fs) laser pulses, in which the two light paths are accordingly formed in the remaining D-type fiber core and the U-shape microcavity. Beam propagation method (BPM) analysis is utilized to illustrate the dependences of good transmission spectra on parameters including the ablation depth, ablation length and the refractive index of Ushape microcavity, which gives some guidelines to optimize parameters for fs laser micromachining and predicts RI (refractive index) sensitivities …
