Engineering Commons^™

Design And Testing Of An H2/O2 Predetonator For A Simulated Rotating Detonation Engine Channel, Stephen J. Miller

Theses and Dissertations

A study is presented on the relationship between a pre-detonator and a detonation channel of an RDE. Testing was conducted on a straight narrow channel made of clear polycarbonate windows connected to an H2/O2 pre-detonator to simulate the RDE initiation scheme and allow for flow visualization. A comparison is made on decoupling distance and wave velocities for a range of pre-detonator designs, inclination angles, equivalence ratios and geometries placed within the simulated channel. Regardless of inclination angle or equivalence ratio the detonation wave decoupled within 25 mm from the pre-detonator exit into the channel. A step change in diameter 25 …

Axisymmetric Air Augmented Methanol/Gox Rocket Mixing Duct Experimental Thrust Study, Kyle Jacob Johnson

Master's Theses

A hot-flow axisymmetric Air Augmented Rocket (AAR) test apparatus was constructed to test various mixing duct configurations at static conditions. Primary flow for the AAR was provided through a liquid methanol-gaseous oxygen bipropellant rocket. Experimental thrust measurements were recorded and propellant mass flow rates and chamber conditions were calculated using an iterative solver dependant on recorded propellant line stagnation pressures. Primary rocket flow produced thrust ranging from 14 to 17.9lbf. Primary mass flow rate through testing ranged from 0.071 to 0.085lbm/s with calculated chamber pressures between 298-362psia. Calculated primary flow velocity ranged from 6,600ft/s to 8,000ft/s depending on propellant pressure …

Design And Performance Of Circulation Control Geometries, Rory Martin Golden

Master's Theses

With the pursuit of more advanced and environmentally-friendly technologies of today’s society, the airline industry has been pushed further to investigate solutions that will reduce airport noise and congestion, cut down on emissions, and improve the overall performance of aircraft. These items directly influence airport size (runway length), flight patterns in the community surrounding the airport, cruise speed, and many other aircraft design considerations which are setting the requirements for next generation aircraft. Leading the research in this movement is NASA, which has set specific goals for the next generation regional airliners and has categorized the designs that meet the …

Work Ethics For Sse-122: Satellites & Space Systems (Spring 2013), Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

PowerPoint presentation by Professor Bob Twiggs on work ethics for SSE-122: Satellites & Space Systems for the spring 2013 semester, created on February 28, 2013.

Equilibrium And Nonequilibrium Molecular Dynamics Simulations Of Thermal Conductance At Solid-Gas Interfaces, Zhi Liang, William Evans, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Thermal Conductance at Solid-Gas Interfaces with Different Interfacial Bonding Strengths is Calculated through Green-Kubo Equilibrium Molecular Dynamics (EMD) Simulations. Due to the Finite Size of the Simulation System, the Long-Time Integral of the Time Correlation Function of Heat Power Across the Solid-Gas Interface Exhibits an Exponential Decay, Which Contains the Information on Interfacial Thermal Conductance. If an Adsorbed Gas Layer is Formed on the Solid Surface, It is Found that the Solid-Gas Interface Needs to Be Defined at a Plane Outside the Adsorbed Layer So as to Obtain the Correct Result from the Green-Kubo Formula. the EMD Simulation Result …

Vtt Technical Research Centre Of Finland, Vtt Technical Research Centre

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation titled "VTT Technical Research Centre of Finland" from February 14, 2013.

Improvement Of Heat Transfer Efficiency At Solid-Gas Interfaces By Self-Assembled Monolayers, Zhi Liang, William Evans, Tapan Desai, Pawel Keblinski

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using Molecular Dynamics Simulations, We Demonstrate that the Efficiency of Heat Exchange between a Solid and a Gas Can Be Maximized by Functionalizing Solid Surface with Organic Self-Assembled Monolayers (SAMs). We Observe that for Bare Metal Surfaces, the Thermal Accommodation Coefficient (TAC) Strongly Depends on the Solid-Gas Interaction Strength. for Metal Surfaces Modified with Organic SAMs, the TAC is Close to its Theoretical Maximum and is Essentially Independent from the SAM-Gas Interaction Strength. the Analysis of the Simulation Results Indicates that Softer and Lighter SAMs, Compared to the Bare Metal Surfaces, Are Responsible for the Greatly Enhanced TAC. © 2013 …

Single Network Adaptive Critics Networks-Development, Analysis, And Applications, Jie Ding, Ali Heydari, S. N. Balakrishnan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Solving infinite time optimal control problems in an approximate dynamic programing framework with two-network structure has become popular in recent years. In this chapter, an alternative to the two-network structure is provided. We develop single network adaptive critics (SNAC) which eliminate the need to have a separate action network to output control. Two versions of SNAC are presented. The first version, called SNAC outputs the costates and the second version called J-SNAC outputs the cost function values. Special structure called Finite-SNAC to efficiently solve finite time problems is also presented. Illustrative infinite time and finite time problems are considered; numerical …

Smaller Spacecraft For Flying Large Clusters Of Biological Space Experiments, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint presentation created by Professor Bob Twiggs titled "Smaller spacecraft for flying large clusters of biological space experiments" from February 5, 2013.

Would I Survive In Space?, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint presentation created by Professor Bob Twiggs titled "Would I survive in Space?" from February 4, 2013.

Smore Revision: Ignition And User Interface, Arash Mehrparvar

Aerospace Engineering

The Static Methanol Oxygen Rocket Engine (SMORE) has undergone several revisions since its inception. This latest revision aimed to increase startup reliability and user safety in the operation of the rocket. The implementation of maintenance procedures, safeguards in the ignition system, as well as construction of a new control box and redesign of the igniter itself have accomplished these goals while keeping costs down and without modifying the current rocket setup. Startup reliability has increased drastically, so long as all other rocket setup procedures are followed properly. 250 subsequent firings of the rocket have proven an igniter reliability of more …

Numerical Modeling Of Anti-Icing Using An Array Of Heated Synthetic Jets, Nikisha Maria Nagappan

Doctoral Dissertations and Master's Theses

A novel approach to icing control using an array of thermally activated synthetic jet actuators (SJAs) embedded in a wedge surface subject to a super-cooled flow is investigated numerically. The effects of SJA actuation with and without jet heating on ice accretion are studied using the FENSAP-ICE software. It is shown that the heated actuating SJAs can lead to a significant reduction in the amount of ice accreted on the surface. Additional parametric studies on several icing and SJA parameters are analyzed for their influence on the amount of ice accretion.

Validation Of Proposed Metrics For Two-Body Abrasion Scratch Test Analysis Standards: In Principle, Any Scratch Can Be Analyzed By This Method, Kenneth W. Street, Ryan L. Kobrick, David M. Klaus

Publications

Abrasion of mechanical components and fabrics by soil on Earth is typically minimized by the effects of atmosphere and water. Potentially abrasive particles lose sharp and pointed geometrical features through erosion. In environments where such erosion does not exist, such as the vacuum of the Moon, particles retain sharp geometries associated with fracturing of their parent particles by micrometeorite impacts. The relationship between hardness of the abrasive and that of the material being abraded is well understood, such that the abrasive ability of a material can be estimated as a function of the ratio of the hardness of the two …

Guided Wave-Based J-Integral Estimation For Dynamic Stress Intensity Factors Using 3d Scanning Laser Doppler Vibrometry, J. Ayers, Christopher Todd Owen, Eric D. Swenson, Anindya Ghoshal, V. Weiss

Faculty Publications

The application of guided waves to interrogate remote areas of structural components has been researched extensively in characterizing damage. However, there exists a sparsity of work in using piezoelectric transducer-generated guided waves as a method of assessing stress intensity factors (SIF). This quantitative information enables accurate estimation of the remaining life of metallic structures exhibiting cracks, such as military and commercial transport vehicles. The proposed full wavefield approach, based on 3D laser vibrometry and piezoelectric transducer-generated guided waves, provides a practical means for estimation of dynamic stress intensity factors (DSIF) through local strain energy mapping via the J-integral. Strain energies …

Electric Motor Modeling For Conceptual Aircraft Design, Robert A. Mcdonald

Aerospace Engineering

Electric motors have achieved very high efficiency and reliability; and in some cases, very high specific power. As the energy storage capabilities of batteries and fuel cells advance, these technologies are increasingly being considered for aircraft primary propulsion. In order to design electric aircraft, aircraft designers must be able to understand and model the performance characteristics of electric motors. Most electric machine modeling techniques either ignore potentially important phenomena or require an extreme level of detail undesirable for conceptual aircraft design. In this paper, a compromise approach is proposed which can capture the salient details of motor performance without requiring …

Enabling Rapid Conceptual Design Using Geometry-Based Multi-Fidelity Models In Vsp, Joel B. Belben, Robert A. Mcdonald

Aerospace Engineering

Four types of reduced fidelity or degenerate geometric representations have been defined and implemented in VSP for the purpose bridging the gap between conceptual design and analysis. They are Degenerate Surface, Degenerate Plate, Degenerate Stick, and Degenerate Point, corresponding to three-, two-, one-, and zero-dimensional representations of underlying geometry, respectively. The information contained in these representations was targeted specifically at lifting line theory, vortex lattice, equivalent beam, and equivalent plate methods, but could be used for other analysis techniques. The ability to output this information in both csv and Matlab file formats has been implemented in VSP. Ongoing work seeks …

Flow Uniformity Calibration Of Amelia's Circulation Control Wings, Eric N. Paciano, Johnathan A. Lichtwardt, David D. Marshall, Kristina K. Jameson, Robert K. Fong

Aerospace Engineering

This paper details the extensive effort required to achieve uniform now from the AMELIA wind tunnel model's circulation control wings. Performed in September of 2011 in the Fluid Mechanics Lab at NASA Ames Research Center, the calibration required a 500hp instrument-quality air compressor capable of delivering 250 CFM at pressures greater than 70 psL It was found that the geometery within AMELIA's circulation control supply plenums produced highly vortlcal flow, resulting in poor circulation control performance as measured by traversing external and stationary internal total pressure probes, as well as surface oil now. Adjustments were made within AMELIA to the …

Stol Performance Of Cal Poly's Amelia, Johnathan A. Lichtwardt, Eric N. Paciano, David D. Marshall, Kristina K. Jameson

Aerospace Engineering

Results from Cal Poly's recent wind tunnel test in the 40-by 80-foot test section at the National Full-Scale Aerodynamics Complex (NFAC) at NASA Ames Research Center are presented. AMELIA, the Advanced Model for Extreme Lift and Improved Aeroacoustics, is the first full-span cruise efficient short take-off and landing (CESTOL) model incorporating leading-and trailing-edge blowing wing circulation control and over-the-wing mounted turbine propulsion simulators (TPS) to date. Testing of the 10 foot span model proved successful and was the result of a 5-year NASA Fundamental Aeronautics Program Research Announcement. All of the results associated with Cal Poly's effort will be available …

Cal Poly's Amelia 10 Foot Span Hybrid Wing-Body Low Noise Cestol Aircraft Wing Tunnel Test And Experimental Results Overview, Kristina K. Jameson, David D. Marshall, Robert Ehrmann, Jonathon A. Lichtwardt, Eric N. Paciano, Robert J. Englar, William C. Hornes

Aerospace Engineering

A collaboration between California Polytechnic Corporation with Georgia Tech Research Institute (GTRI) and DHC Engineering worked on a NASA NRA to develop predictive capabilities for the design and performance of Cruise Efficient, Short Take-Off and Landing (CESTOL) subsonic aircraft. The work presented in this paper gives details of a large scale wind tunnel effort to validate predictive capabilities for this NRA for aerodynamic and acoustic performance during takeoff and landing. The model, Advanced Model for Extreme Lift and Improved Aeroacoustics {AMELIA), was designed as a 100 passenger, N+2 generation, regional, cruise efficient short takeoff and land (CESTOL) airliner with hybrid …

Solar Energy Collection Analysis Tool For Conceptual Aircraft Design, Grant M. Glazebrook, Robert A. Mcdonald

Aerospace Engineering

As battery energy storage and solar cell technology improve, solar aircraft are increasingly being considered for high altitude long endurance missions. Although solar vehicles may theoretically remain on station indefinitely using the sun as a power source, their design and feasibility is sensitive to mission planning details as specific as the time history of the vehicle’s deck orientation relative to the sun; the energy available for capture by the on-board solar array is governed by the solar incidence angle, and at certain orientations, the vehicle may cast shadows on itself and further reduce its energy capture capabilities. To quantify these …

Spacecraft Payloads, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs on "Spacecraft Payloads" on January 5, 2013.

Systems Engineering, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs on "System Engineering" on January 5, 2013.

Akin's Laws Of Spacecraft Design, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A document use in class by Professor Bob Twiggs titled "Akin's Law of Spacecraft Design" from January 5, 2013.

Comparison Of Models For Mixture Transport Properties For Numerical Simulations Of Ablative Heat-Shields, Hicham Alkandry, Iain D. Boyd, Alexandre Martin

Mechanical Engineering Faculty Publications

The goal of this study is to evaluate the effects of different models for calculating the mixture transport properties on flowfield predictions of ablative heat-shields. The Stardust sample return capsule at four different trajectory conditions is used as a test case for this study. In the first part of the study, the results predicted using Wilke's mixing rule with species viscosities calculated using Blottner's curve fits and species thermal conductivities determined using Eucken's relation are compared to the results obtained using Gupta's mixing rule with collision cross-section (CCS) data. The Wilke/Blottner/Eucken model overpredicts the heat transfer to the surface relative …

Investigation Of Turbulent Structure Modification By Momentum Injection Into Turbulent Flow Over A Rough Surface, Mark A. Miller, Huaibao Zhang, Alexandre Martin, Sean C. C. Bailey

Mechanical Engineering Faculty Publications

Utilizing a turbulent channel flow facility, experiments were performed to determine the modifications made to the temporal and spatial structure of turbulence over a sinusoidally rough surface due to momentum injection through the surface. As expected, when compared to the smooth-walled conditions, it was found that the surface roughness increased wall shear stress, decreased the turbulence energy content near the wall, and shifted that energy content to wavelengths on the order of the roughness elements. The addition of momentum injection was found to produce further modifications analogous to increasing the roughness height by increasing the wall shear stress and further …

Modeling Of Chemical Nonequilibrium Effects In A Charring Ablator, Alexandre Martin

Mechanical Engineering Faculty Publications

Charring ablators remain the premium choice for space exploration missions that involve atmospheric re-entry. These type of ablative material are composed of a carbon matrix, usually made of fibers, which is then impregnated with a resin. During re-entry, the high heat flux produced by convective heating causes the material to chemically react. First, the resin pyrolyzes, and is vaporized into a gas that travels through the material, and is eventually ejected at the surface. Since the composition of the gas at the surface greatly affects the heat flux, and therefore the surface temperature, it is thus important to be able …

Robust Parafoil Terminal Guidance Using Massively Parallel Processing, Jonathan Rogers, Nathan Slegers

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

Terminal guidance of autonomous parafoils is a difficult problem in which wind uncertainty and system underactuation are major challenges. Existing strategies almost exclusively use impact error as the criterion for optimality. Practical airdrop systems, however, must also include other criteria that maybe even more important than impact error for some missions, such as ground speed at impact or constraints imposed by drop zones with restrictions on flight patterns. Furthermore, existing guidance schemes determine terminal trajectories using deterministic wind information and may result in a solution that works in ideal wind but may be sensitive to variations. The work described here …

Projectile Fire-Control Algorithm In A Spatially Varying Wind Field, Lakmal Kaviratna, Mark Costello, Nathan Slegers

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

The fire-control solution is an important element of any modern weapon system, providing precise aiming of the gun to enable highly accurate projectile impact. To be practical, the fire-control solution must be computed rapidly and reliably while simultaneously including all pertinent physical effects that can alter the trajectory and impact point. Current fire-control solutions account for the effect of atmospheric wind in a rudimentary manner, typically assuming a constant crosswind that is estimated in the field or measured at the firing site. With the advent of advanced wind-measurement systems (light detection and ranging, for example), it is now possible to …

Investigation Of Astm E 238 Bearing Pin Properties For Various Aerospace Alloys, Trevor J. Lee

Master's Theses

Aircraft are often designed with numbers determined by testing in a lab, rather than by repeatedly building prototypes. These lab tests conform to testing specifications so that the numbers can be compared between manufacturers, suppliers, and lab technicians. One such specification is ASTM specification E238 – 84(08), and it is used to determine important properties of a bearing pin joint like hinges, bolt holes, and rivet joints. The properties determined from this fastener-through-plate method are bearing strength, bearing yield strength, and bearing stiffness.

Adhering to the methods outlined in ASTM E238, a study was performed, looking at the effects that …

Reducing Uncertainty In Fatigue Life Limits Of Turbine Engine Alloys, J M. Larson, S K. Jha, C J. Szczepanski, M J. Caton, R John, A H. Rosenberger, D J. Buchanan, P J. Golden, J R. Jira

United States Air Force: Publications

In probabilistic design of materials for fracture-critical components in modern military turbine engines, a typical maximum design target risk (DTR) is 5 X 10^-8 component failures/engine flight hour. This metric underscores the essential role of safety in a design process that simultaneously strives to achieve performance, efficiency, reliability, and affordability throughout the life cycle of the engine. Traditionally, the design and life management approaches for engine materials have typically relied on extensive testing programs to produce large databases of fatigue data, from which statistically based life limits are derived by extrapolation from the mean fatigue behavior. However, we …