Aerospace Engineering Commons^™

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.

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 …

Stability And Power Optimality In Time-Periodic Flapping Wing Structures, Bret Stanford, Philip Beran, Richard Snyder, Mayuresh Patil

United States Air Force: Publications

This paper investigates the nonlinear dynamics of a vehicle with two flexible flapping wings. The body dynamics and the wings' deformation are monolithically grouped into a single system of equations, with aerodynamics accounted for by a quasi-steady blade element method. A periodic shooting method is then used to locate closed orbits of this non-autonomous system, and Floquet multipliers assess the linearized stability about the nonlinear orbit. This framework is then exposed to a gradient based optimizer, in order to quantify the role of wing planform variables, wing structure variables, and kinematic actuation variables in obtaining vehicles with superior open-loop stability …

Turbulence Modeling For Subsonic Separated Flows Over 2-D Airfoils And 3-D Wings, Aaron Michael Rosen

Open Access Theses

Accurate predictions of turbulent boundary layers and flow separation through computational fluid dynamics (CFD) are becoming more and more essential for the prediction of loads in the design of aerodynamic flight components. Standard eddy viscosity models used in many commercial codes today do not capture the nonequilibrium effects seen in a separated flow and thus do not generally make accurate separation predictions. Part of the reason for this is that under nonequilibrium conditions such as a strong adverse pressure gradient, the history effects of the flow play an important role in the growth and decay of turbulence. More recent turbulence …

Effect Of Aviation Fuel Type And Fuel Injection Conditions On The Spray Characteristics Of Pressure Swirl And Hybrid Air Blast Fuel Injectors, Rick Thomas Feddema

Open Access Theses

Feddema, Rick T. M.S.M.E., Purdue University, December 2013. Effect of Aviation Fuel Type and Fuel Injection Conditions on the Spray Characteristics of Pressure Swirl and Hybrid Air Blast Fuel Injectors. Major Professor: Dr. Paul E. Sojka, School of Mechanical Engineering

Spray performance of pressure swirl and hybrid air blast fuel injectors are central to combustion stability, combustor heat management, and pollutant formation in aviation gas turbine engines. Next generation aviation gas turbine engines will optimize spray atomization characteristics of the fuel injector in order to achieve engine efficiency and emissions requirements.

Fuel injector spray atomization performance is affected by the …

Effects Of Strain Energy Release Rate On Delamination In Temperature Environment, Venkata Naga Ravitej Sankarabatla

Mechanical and Aerospace Engineering Theses - Archive

Delamination is the weakest and major failure mode in laminated composites. Extensive efforts on initiation and growth of delamination under mechanical load have been investigated. A little emphasis was made earlier to account for the delamination in laminates under temperature loading. Strain energy release rate, a fracture mechanics parameter has been widely accepted to use for study the characteristics of delamination growth. In order to conduct a quick assessment of delamination growth, a closed form expression is developed to quantify the strain energy release rate of the laminate subjected to temperature environment. A finite element model is also developed to …

Investigation Of Side Wall Effects On An Inward Scramjet Inlet At Mach Number 8.6, Tiago Cavalcanti Rolim

Mechanical and Aerospace Engineering Dissertations - Archive

Experimental and computational studies were conducted to evaluate the performance of a scramjet inlet as the side cowl length is changed. A slender inward turning inlet with a total length of 304.8 mm, a span of 50.8 mm with a top and a bottom compression ramp each at 11.54 deg and a compression ratio of 4.79 was used. The side cowl lengths were of 0, 50.8 and 76.2 mm. The UTA Hypersonic Shock Tunnel facility was used in the reflected mode to test the inlet model. The model was instrumented with nine piezoelectric pressure transducers, for static and total pressure …

Development Of Artificial Neural Network Based Black Box Model Of A Data Center As A Temperature Predicting Tool As A Function Of Server Location, Dissipating Server Heat And Crac Fan Speed, Chinmay N. Date

Mechanical and Aerospace Engineering Theses - Archive

Modern data centers consume an astonishing 1.3\% power all around the world. As the number of data centers continue to grow, there is an increasing need and demand to develop new ways to reduce the power footprint. Several approaches are being made to achieve this. One of such several approaches is to develop control systems that would keep the data centers running energy efficiently. Various control theories have been developed throughout the world to achieve the optimal energy efficient state. However, during the synthesis of such control schemes, the CFD simulations take up excessive time for plotting the thermal map …

Development Of Multi-Element Active Aerodynamics For The Formula Sae Car, James Patrick Merkel

Mechanical and Aerospace Engineering Theses - Archive

This thesis focuses on the design, development, and implementation of an active aerodynamics system on 2013 Formula SAE car. The aerodynamics package itself consists of five element front and rear wings as well as an under body diffuser. Five element wings produce significant amounts of drag which is a compromise between the cornering ability of the car and the acceleration capability on straights. The active aerodynamics system allows for the wing angle of attack to dynamically change their configuration on track based on sensory data to optimize the wings for any given scenario. The wings are studied using computational fluid …

The Samara Spacecraft: Design And Development Of A Self-Stabilizing, Auto-Rotating, Distributed Sensing System, Amit Desai Lalloobhai

Mechanical and Aerospace Engineering Theses - Archive

The scope of this research is the design and development of a self-stabilizing re-entry vehicle that closely resembles naturally occurring seeds in nature. It was hypothesized that a femto-satellite with a shape of a samara could self stabilize and passively generate lift, as well as transmit a signal during its descent through the atmosphere. The research included a conceptual design phase and a preliminary design phase that entailed analytic simulations, and an experimental demonstration. The goal was to investigate the feasibility of developing the above-mentioned femto-vehicle that could increase the range capability of its descent to maximize data capture.

Development And Operation Of An Integrated Sampling Probe And Gas Analyzer For Turbulent Mixing Studies In Complex Supersonic Flows, John D. Wiswall

Mechanical and Aerospace Engineering Theses - Archive

For many aerospace applications, mixing enhancement between co-flowing streams has been identified as a critical and enabling technology. Due to short fuel residence times in scramjet combustors, combustion is limited by the molecular mixing of hydrogen (fuel) and air. Determining the mixedness of fuel and air in these complex supersonic flowfields is critical to the advancement of novel injection schemes currently being developed at UTA in collaboration with NASA Langley and intended to be used on a future two-stage to orbit (~Mach 16) hypersonic air-breathing vehicle for space access.Expanding on previous work, an instrument has been designed, fabricated, and tested …

Numerical Study Of Incompressible Fluid Flow In A Vertically Dropping Pool With And Without End Sill, Vimal Ramanuj

Mechanical and Aerospace Engineering Theses - Archive

The study involves numerical analysis of flow field for three different flow regimes taking place in a vertically dropping pool. In general, a vertically dropping flow generates a skimming flow regime with one recirculation zone along with a developing shear layer. The presence of an obstacle (end sill) results in the formation of another recirculation zone downstream of the impinging jet. Based on the nature of these zones, the flow is categorized as napped, periodically oscillatory and skimming. The type of flow regime depends on the flow parameters like velocity and depth of flow which are controlled by Froude number. …

3-D Fracture Study Of The Beol Cu/Low-K Stack To Assess And Mitigate The Cpi Risk During The Reflow Process, Zaeem Baig

Mechanical and Aerospace Engineering Theses - Archive

As scaling of components continues, using SiO2 as a dielectric in the Back-End-Of-Line (BEoL) is no longer a viable option and can be replaced with low-k and ultralow-k (ULK) dielectric materials for advanced integrated circuits (IC) packaging solutions. The low-k materials improve performance by reducing parasitic capacitance and crosstalk between adjacent metal lines. However, low-k dielectrics have lower modulus, lower fracture toughness, higher coefficient of thermal expansion (CTE), and poor adhesion as compared to SiO2. Thus, low-k dielectric integration in the contemporary IC packages poses a significant reliability challenge. Delamination along the metal-dielectric interfaces and crack propagation in the dielectric …

A Novel Approach For Two-Dimensional Inclusion/Hole Problems Using The Airy Stress Function Method, Manikandan Madhavan

Mechanical and Aerospace Engineering Theses - Archive

This thesis demonstrates the application of the Airy stress function in solving plane elasticity problems. An Airy stress function is determined for two-dimensional infinite plates containing a circular inclusion embedded with a circular hole subjected to tensile loading and the traction and displacement functions for various boundary conditions satisfy the equilibrium and continuity conditions. Mathematica was useful for solving the complex expressions and to calculate the elastic fields for a variety of elastic problems in this study.