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2011

Aerospace Engineering

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Articles 1 - 30 of 55

Full-Text Articles in Mechanical Engineering

Optimization Of A Low Reynolds Number 2-D Inflatable Airfoil Section, Todd A. Johansen Dec 2011

Optimization Of A Low Reynolds Number 2-D Inflatable Airfoil Section, Todd A. Johansen

All Graduate Theses and Dissertations

A stand-alone genetic algorithm (GA) and an surrogate-based optimization (SBO) combined with a GA were compared for accuracy and performance. Comparisons took place using the Ackley Function and Rastrigin's Function, two functions with multiple local maxima and minima that could cause problems for more traditional optimization methods, such as a gradient-based method. The GA and SBO with GA were applied to the functions through a fortran interface and it was found that the SBO could use the same number of function evaluations as the GA and achieve at least 5 orders of magnitude greater accuracy through the use of ...


Coherent Solid/Liquid Interface With Stress Relaxation In A Phase-Field Approach To The Melting/Solidification Transition, Valery I. Levitas, Kamran Samani Oct 2011

Coherent Solid/Liquid Interface With Stress Relaxation In A Phase-Field Approach To The Melting/Solidification Transition, Valery I. Levitas, Kamran Samani

Aerospace Engineering Publications

An advanced Ginzburg-Landau (GL) approach to melting and solidification coupled with mechanics is developed. It is based on the concept of a coherent solid-liquid interface with a transformation strain tensor, the deviatoric part of which is described by a thermodynamically consistent kinetic equation. Due to the relaxation of the elastic energy, a promoting contribution to the driving force for phase transformation in the GL equation appears, both for melting and solidification. Good agreement with known experiments is obtained for Al nanoparticles for the size-dependent melting temperature and temperature-dependent thickness of the surface molten layer. All types of interface stress distributions ...


Surface-Induced Phase Transformations: Multiple Scale And Mechanics Effects And Morphological Transitions, Valery I. Levitas, Mahdi Javanbakht Oct 2011

Surface-Induced Phase Transformations: Multiple Scale And Mechanics Effects And Morphological Transitions, Valery I. Levitas, Mahdi Javanbakht

Aerospace Engineering Publications

Strong, surprising, and multifaceted effects of the width of the external surface layer Δξ and internal stresses on surface-induced pretransformation and phase transformations (PTs) are revealed. Using our further developed phase-field approach, we found that above some critical Δξ*, a morphological transition from fully transformed layer to lack of surface pretransformation occurs for any transformation strain εt. It corresponds to a sharp transition to the universal (independent of εt), strongly increasing the master relationship of the critical thermodynamic driving force for PT Xc on Δξ. For large εt, with increasing Δξ, X ...


3d Simulation Of Wind Turbine Rotors At Full Scale. Part Ii: Fluid–Structure Interaction Modeling With Composite Blades, Y. Bazilevs, Ming-Chen Hsu, J. Kiendel, R. Wuchner, K. U. Bletzigner Oct 2011

3d Simulation Of Wind Turbine Rotors At Full Scale. Part Ii: Fluid–Structure Interaction Modeling With Composite Blades, Y. Bazilevs, Ming-Chen Hsu, J. Kiendel, R. Wuchner, K. U. Bletzigner

Ming-Chen Hsu

In this two-part paper, we present a collection of numerical methods combined into a single framework, which has the potential for a successful application to wind turbine rotor modeling and simulation. In Part 1 of this paper we focus on: 1. The basics of geometry modeling and analysis-suitable geometry construction for wind turbine rotors; 2. The fluid mechanics formulation and its suitability and accuracy for rotating turbulent flows; 3. The coupling of air flow and a rotating rigid body. In Part 2, we focus on the structural discretization for wind turbine blades and the details of the fluid–structure interaction ...


High-Performance Computing Of Wind Turbine Aerodynamics Using Isogeometric Analysis, Ming-Chen Hsu, Ido Akkerman, Yuri Bazilevs Oct 2011

High-Performance Computing Of Wind Turbine Aerodynamics Using Isogeometric Analysis, Ming-Chen Hsu, Ido Akkerman, Yuri Bazilevs

Ming-Chen Hsu

In this article we present a high-performance computing framework for advanced flow simulation and its application to wind energy based on the residual-based variational multiscale (RBVMS) method and isogeometric analysis. The RBVMS formulation and its suitability and accuracy for turbulent flow in a moving domain are presented. Particular emphasis is placed on the parallel implementation of the methodology and its scalability. Two challenging flow cases were considered: the turbulent Taylor–Couette flow and the NREL 5 MW offshore baseline wind turbine rotor at full scale. In both cases, flow quantities of interest from the simulation results compare favorably with the ...


A Multi-Regulator Sliding Mode Control Strategy For Output-Constrained Systems, Hanz Richter Oct 2011

A Multi-Regulator Sliding Mode Control Strategy For Output-Constrained Systems, Hanz Richter

Mechanical Engineering Faculty Publications

This paper proposes a multi-regulator control scheme for single-input systems, where the setpoint of a regulated output must be changed under the constraint that a set of minimum-phase outputs remain within prescribed bounds. The strategy is based on a max–min selector system frequently used in the aerospace field. The regulators used for the regulated and limited outputs are of the sliding mode type, where the sliding variable is defined as the difference between an output and its allowable limit. The paper establishes overall asymptotic stability, as well as invariance properties leading to limit protection. The design methodology is illustrated ...


Vortex Shedding From Elongated Bluff Bodies, Zachary J. Taylor Sep 2011

Vortex Shedding From Elongated Bluff Bodies, Zachary J. Taylor

Electronic Thesis and Dissertation Repository

As the spans of suspension bridges increase, the structures become inherently flexible. The flexibility of these structures, combined with the wind and particular aerodynamics, can lead to significant motions. From the collapse due to flutter of the Tacoma Narrows Bridge to the case of vortex-induced vibrations (VIV) of the Storebælt Bridge, it is evident that a better understanding of the aerodynamics of these geometries is necessary. The work herein is motivated by these two problems and is presented in two parts.

In the first part, the focus is on the physical mechanisms of vortex shedding. It is shown that the ...


Vibration-Based Health Monitoring Of Multiple-Stage Gear Train And Differential Planetary Transmission Involving Teeth Damage And Backlash Nonlinearity, Andrew Patrick Sommer Sep 2011

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 and Project Reports

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 ...


Apparatus For Focused Electric-Field Imprinting For Micron And Sub-Micron Patterns On Wavy Or Planar Surfaces, Abhijit Chandra, Ashraf F. Bastawros, Ambar K. Mitra, Charles A. Lemaire Aug 2011

Apparatus For Focused Electric-Field Imprinting For Micron And Sub-Micron Patterns On Wavy Or Planar Surfaces, Abhijit Chandra, Ashraf F. Bastawros, Ambar K. Mitra, Charles A. Lemaire

Aerospace Engineering Patents

A Focused Electric Field Imprinting (FEFI) process and apparatus provides a focused electric field to guide an unplating operation and/or a plating operation to form very fine-pitched metal patterns on a substrate. The process is a variation of the electrochemical unplating process, wherein the process is modified for imprinting range of patterns of around 2000 microns to 20 microns or less in width, and from about 0.1 microns or less to 10 microns or more in depth. Some embodiments curve a proton-exchange membrane whose shape is varied using suction on a backing fluid through a support mask. Other ...


Phase-Field Modeling Of Fracture In Liquid, Valery I. Levitas, Alexander V. Idesman, Ameeth K. Palakala Aug 2011

Phase-Field Modeling Of Fracture In Liquid, Valery I. Levitas, Alexander V. Idesman, Ameeth K. Palakala

Aerospace Engineering Publications

Phase-field theory for the description of the overdriven fracture in liquid (cavitation) in tensile pressure wave is developed. Various results from solid mechanics are transferred into mechanics of fluids. Thermodynamic potential is formulated that describes the desired tensile pressure–volumetric strain curve and for which the infinitesimal damage produces infinitesimal change in the equilibrium bulk modulus. It is shown that the gradient of the order parameter should not be included in the energy, in contrast to all known phase-field approaches for any material instability. Analytical analysis of the equations is performed. Problems relevant to the melt-dispersion mechanism of the reaction ...


Continuously Variable Rotorcraft Propulsion System: Modelling And Simulation, Naveen Kumar Vallabhaneni Aug 2011

Continuously Variable Rotorcraft Propulsion System: Modelling And Simulation, Naveen Kumar Vallabhaneni

Masters Theses

This study explores the variable speed operation and shift response of a prototype of a two speed single path CVT rotorcraft driveline system. Here a Comprehensive Variable Speed Rotorcraft Propulsion system Modeling (CVSRPM) tool is developed and utilized to simulate the drive system dynamics in steady forward speed condition. This investigation attempts to build upon previous variable speed rotorcraft propulsion studies by:

1) Including fully nonlinear first principles based transient gas-turbine engine model

2) Including shaft flexibility

3) Incorporating a basic flight dynamics model to account for interactions with the flight control system.

Through exploring the interactions between the various ...


Effects Of Supercooled Water Ingestion On Engine Performance, Rick Hutchings Aug 2011

Effects Of Supercooled Water Ingestion On Engine Performance, Rick Hutchings

Masters Theses

An aircraft will encounter freezing rain, snow, and ice during ground operation and flight. In cold conditions, ice may form on th einlet and internal stators and rotors of the gas turbine engine. When ice accumulates on blades (and/or stators), the aerodynamic characteristics of the blades change due to the altered size, shape, and roughness. This change causes the blade to no longer operate at its design point and decreases compressor performance. Therefore, characterization of the aerodynamic performance is required to define the associated losses due to the effects of supercooled liquid water ingestion. This characterization can be accomplished ...


The Biglobal Instability Of The Bidirectional Vortex, Joshua Will Batterson Aug 2011

The Biglobal Instability Of The Bidirectional Vortex, Joshua Will Batterson

Doctoral Dissertations

State of the art research in hydrodynamic stability analysis has moved from classic one-dimensional methods such as the local nonparallel approach and the parabolized stability equations to two-dimensional, biglobal, methods. The paradigm shift toward two dimensional techniques with the ability to accommodate fully three-dimensional base flows is a necessary step toward modeling complex, multidimensional flowfields in modern propulsive applications. Here, we employ a two-dimensional spatial waveform with sinusoidal temporal dependence to reduce the three-dimensional linearized Navier-Stokes equations to their biglobal form. Addressing hydrodynamic stability in this way circumvents the restrictive parallel-flow assumption and admits boundary conditions in the streamwise direction ...


Single-Shot Gas-Phase Thermometry Using Purerotational Hybrid Femtosecond/Picosecond Coherent Anti-Stokes Raman Scattering, Joseph D. Miller, Sukesh Roy, Mikhail N. Slipchenko, James R. Gord, Terrence R. Meyer Aug 2011

Single-Shot Gas-Phase Thermometry Using Purerotational Hybrid Femtosecond/Picosecond Coherent Anti-Stokes Raman Scattering, Joseph D. Miller, Sukesh Roy, Mikhail N. Slipchenko, James R. Gord, Terrence R. Meyer

Mechanical Engineering Publications

High-repetition-rate, single-laser-shot measurements are important for the investigation of unsteady flows where temperature and species concentrations can vary significantly. Here, we demonstrate singleshot, pure-rotational, hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps RCARS) thermometry based on a kHz-rate fs laser source. Interferences that can affect nanosecond (ns) and ps CARS, such as nonresonant background and collisional dephasing, are eliminated by selecting an appropriate time delay between the 100-fs pump/Stokes pulses and the pulse-shaped 8.4-ps probe. A time- and frequency-domain theoretical model is introduced to account for rotational-level dependent collisional dephasing and indicates that the optimal probe-pulse time ...


Phase Transition And Structure Of Silver Azide At High Pressure, Dongbin Hou, Fuxiang Zhang, Cheng Ji, Trevor Hannon, Hongyang Zhu, Jianzhe Wu, Valery I. Levitas, Yanzhang Ma Jul 2011

Phase Transition And Structure Of Silver Azide At High Pressure, Dongbin Hou, Fuxiang Zhang, Cheng Ji, Trevor Hannon, Hongyang Zhu, Jianzhe Wu, Valery I. Levitas, Yanzhang Ma

Aerospace Engineering Publications

ilver azide (AgN 3) was compressed up to 51.3 GPa. The results reveal a reversible second-order orthorhombic-to-tetragonal phase transformation starting from ambient pressure and completing at 2.7 GPa. The phase transition is accompanied by a proximity of cell parameters aand b, a 3° rotation of azide anions, and a change of coordination number from 4-4 (four short, four long) to eight fold. The crystal structure of the high pressure phase is determined to be inI4/mcm space group, with Ag at 4a, N1 at 4d, and N2 at 8h Wyckoff positions. Both of ...


Abstracts, Review Of Progress In Quantitative Nondestructive Evaluation (Burlington, Vermont, July 17-22, 2011), Center For Nondestructive Evaluation, Iowa State University Jul 2011

Abstracts, Review Of Progress In Quantitative Nondestructive Evaluation (Burlington, Vermont, July 17-22, 2011), Center For Nondestructive Evaluation, Iowa State University

Review of Progress in Quantitative Nondestructive Evaluation

Abstracts of papers presented at the 2011 Review of Progress in Quantitative Nondestructive Evaluation (QNDE) conference held in Burlington, Vermont from July 17–22, 2011.


A Study On Facility Planning Using Discrete Event Simulation: Case Study Of A Grain Delivery Terminal., Sarah M. Asio Jul 2011

A Study On Facility Planning Using Discrete Event Simulation: Case Study Of A Grain Delivery Terminal., Sarah M. Asio

Industrial and Management Systems Engineering -- Dissertations and Student Research

The application of traditional approaches to the design of efficient facilities can be tedious and time consuming when uncertainty and a number of constraints exist. Queuing models and mathematical programming techniques are not able to capture the complex interaction between resources, the environment and space constraints for dynamic stochastic processes. In the following study discrete event simulation is applied to the facility planning process for a grain delivery terminal. The discrete event simulation approach has been applied to studies such as capacity planning and facility layout for a gasoline station and evaluating the resource requirements for a manufacturing facility. To ...


Astro Camp Presentation, Get Away Special Team 2011 Jul 2011

Astro Camp Presentation, Get Away Special Team 2011

Education and Outreach

No abstract provided.


Model-Assisted Development Of A Laminography Inspection System, Robert J. Grandin, Joseph N. Gray Jul 2011

Model-Assisted Development Of A Laminography Inspection System, Robert J. Grandin, Joseph N. Gray

Center for Nondestructive Evaluation Conference Papers, Posters and Presentations

Traditional computed tomography (CT) is an effective method of determining the internal structure of an object through non-destructive means; however, inspection of certain objects, such as those with planar geometrics or with limited access, requires an alternate approach. An alternative is laminography and has been the focus of a number of researchers in the past decade for both medical and industrial inspections. Many research efforts rely on geometrically-simple analytical models, such as the Shepp-Logan phantom, for the development of their algorithms. Recent work at the Center for Non-Destructive Evaluation makes extensive use of a forward model, XRSIM, to study artifacts ...


A Quadrature-Based Kinetic Model For Dilute Non-Isothermal Granular Flows, Alberto Passalacqua, Janine E. Galvin, Prakash Vedula, Christine M. Hrenya, Rodney O. Fox Jul 2011

A Quadrature-Based Kinetic Model For Dilute Non-Isothermal Granular Flows, Alberto Passalacqua, Janine E. Galvin, Prakash Vedula, Christine M. Hrenya, Rodney O. Fox

Chemical and Biological Engineering Publications

A moment method with closures based on Gaussian quadrature formulas is proposed to solve the Boltzmann kinetic equation with a hard-sphere collision kernel for mono-dispersed particles. Different orders of accuracy in terms of the moments of the velocity distribution function are considered, accounting for moments up to seventh order. Quadrature-based closures for four different models for inelastic collisionthe Bhatnagar-Gross-Krook, ES-BGK, the Maxwell model for hard-sphere collisions, and the full Boltzmann hard-sphere collision integral-are derived and compared. The approach is validated studying a dilute non-isothermal granular flow of inelastic particles between two stationary Maxwellian walls. Results obtained from the kinetic models ...


Interface Circuit For A Multiple-Beam Tuning-Fork Gyroscope With High Quality Factors, Ren Wang Jul 2011

Interface Circuit For A Multiple-Beam Tuning-Fork Gyroscope With High Quality Factors, Ren Wang

Mechanical & Aerospace Engineering Theses & Dissertations

This research work presents the design, theoretical analysis, fabrication, interface electronics, and experimental results of a Silicon-On-Insulator (SOI) based Multiple-Beam Tuning-Fork Gyroscope (MB-TFG). Based on a numerical model of Thermo-Elastic Damping (TED), a Multiple-Beam Tuning-Fork Structure (MB-TFS) is designed with high Quality factors (Qs) in its two operation modes. A comprehensive theoretical analysis of the MB-TFG design is conducted to relate the design parameters to its operation parameters and further performance parameters. In conjunction with a mask that defines the device through trenches to alleviate severe fabrication effect on anchor loss, a simple one-mask fabrication process is employed to implement ...


Rayleigh Test Apparatus Design Report, Josef Duller, Owen Raybould, James Nicovich Jun 2011

Rayleigh Test Apparatus Design Report, Josef Duller, Owen Raybould, James Nicovich

Mechanical Engineering

The Rayleigh Test Apparatus is a device that will be used to test the thermodynamic properties of Nitrous Oxide to assess the feasibility of using this fluid as a coolant for a hybrid rocket aero spike. The aero spike is intended to redirect the propulsion flow as it leaves the engine to create a more efficient flow pattern at low and high altitudes. However, there are issues of overheating which leads to melting of the aero spike. For this reason, the use of nitrous oxide (N2O) as a coolant is being explored. N20 is being considered because it is already ...


Port Flow Test System, Daniel Chairez, Chelsea E. Crawford, Daniel S. Welch Jun 2011

Port Flow Test System, Daniel Chairez, Chelsea E. Crawford, Daniel S. Welch

Mechanical Engineering

Solar Turbines Gas Compressor Engineering Division of San Diego, California called upon the Mechanical Engineering students of California Polytechnic University, San Luis Obispo to provide recommendations for optimization of compressor end cap port design. Various sizes of compressors have end caps with numerous ports that exchange fluids between the inside and outside of the working fluid pressure vessel. Because so many ports must exist on the end caps, unusual flow paths are created to supply the appropriate location within the compressor. These flow paths commonly consist of a drilled inlet hole which intersects with a sudden expansion. The sudden expansion ...


Design And Fabrication Of An Autonomous Solar Powered Airship, Mitchell Van Lee Jun 2011

Design And Fabrication Of An Autonomous Solar Powered Airship, Mitchell Van Lee

Honors Theses

The purpose of the project was to design and build a prototype small scale photovoltaic (PV) powered autonomous airship. The principle reason for the construction of the unmanned airship was to investigate the possibility of using self-guided, lighter-than-air aircraft as an alternative to earth observational satellites for the purposes of terrain mapping and imaging. The necessary electrical energy was produced by single crystal photovoltaic solar cells. The airship was designed to carry an onboard battery in order to provide power generation in the case of intermittent cloud coverage. It was also designed to interface with an Arduino prototyping board which ...


Cal Poly Human Powered Helicopter, Josiah Auer, Eric Behne, Dave Berry, Rebecca Hennings, James Koch, Ian Marquardt, Josiah Mayfield, Sean Miller Jun 2011

Cal Poly Human Powered Helicopter, Josiah Auer, Eric Behne, Dave Berry, Rebecca Hennings, James Koch, Ian Marquardt, Josiah Mayfield, Sean Miller

Mechanical Engineering

The following report encompasses the Cal Poly Human Powered Helicopter team’s efforts during the 2010-2011 academic year. The intention of this project is to further the knowledge of human powered helicopter design and to validate an ideal configuration through experimental tests and analysis.

A. Background

The Sikorsky Prize offered by the American Helicopter Society has been the catalyst for many attempts at Human Powered Helicopter (HPH) flight. The requirement to win the prize is a continuous, human powered flight of more than 60 seconds that stays within a 10 meter square box and reaches an altitude greater than 3 ...


Sae Aero Design Project, Angela N. Mclelland Jun 2011

Sae Aero Design Project, Angela N. Mclelland

Honors Theses

The Union College Flying Dutchmen Team aims to compete in the spring 2011, SAE Aero Design® East Competition. This regional event, hosted by the Society of Automotive Engineers International, is a threefold opportunity for teams from around the globe to showcase their understanding of engineering fundamentals. Competing in the SAE Aero Design® competition creates an arena for students to participate in hands-on design, to emphasize technological innovations in a competition setting, and to cooperate in a unique atmosphere where intellectual advancement and teamwork are championed above success. The underlying goal of the SAE Aero Design® competition is to design and ...


Development Of A Cubesat Instrument For Microgravity Particle Damper Performance Analysis, John Trevor Abel Jun 2011

Development Of A Cubesat Instrument For Microgravity Particle Damper Performance Analysis, John Trevor Abel

Master's Theses and Project Reports

Spacecraft pointing accuracy and structural longevity requirements often necessitate auxiliary vibration dissipation mechanisms. However, temperature sensitivity and material degradation limit the effectiveness of traditional damping techniques in space. Robust particle damping technology offers a potential solution, driving the need for microgravity characterization. A 1U cubesat satellite presents a low cost, low risk platform for the acquisition of data needed for this evaluation, but severely restricts available mass, volume, power and bandwidth resources. This paper details the development of an instrument subject to these constraints that is capable of capturing high resolution frequency response measurements of highly nonlinear particle damper dynamics.


Effect Of Unsteady Combustion On The Stability Of Rocket Engines, Tina Morina Rice May 2011

Effect Of Unsteady Combustion On The Stability Of Rocket Engines, Tina Morina Rice

Doctoral Dissertations

Combustion instability is a problem that has plagued the development of rocket-propelled devices since their conception. It is characterized by the occurrence of high-frequency nonlinear gas oscillations inside the combustion chamber. This phenomenon degrades system performance and can result in damage to both structure and instrumentation.

The goal of this dissertation is to clarify the role of unsteady combustion in the combustor instability problem by providing the first quantified estimates of its effect upon the stability of liquid rocket engines. The combination of this research with a new system energy balance method, accounting for all dynamic interactions within a system ...


Modeling And Analysis Of Turbojet Compressor Inlet Temperature Measurement System Performance, Brian A Binkley May 2011

Modeling And Analysis Of Turbojet Compressor Inlet Temperature Measurement System Performance, Brian A Binkley

Masters Theses

Accurate measurement of turbine engine compressor inlet total temperature is paramount for controlling engine speed and pressure ratio. Various methods exist for measuring compressor inlet total temperature on turbojet engines with hydromechanical control. One method involves the use of an ejector-diffuser system (eductor) to pull air from the engine inlet in order to measure the incoming total temperature. Analysis of historical test data has revealed that the inlet temperature measurement can be biased at certain flight conditions causing engine mis-scheduling and off-nominal engine operation. This bias is characterized primarily by adverse heat transfer effects and secondly by poor flow quality ...


Cross-Flow, Staggered-Tube Heat Exchanger Analysis For High Enthalpy Flows, Gary L. Hammock May 2011

Cross-Flow, Staggered-Tube Heat Exchanger Analysis For High Enthalpy Flows, Gary L. Hammock

Masters Theses

Cross flow heat exchangers are a fairly common apparatus employed throughout many industrial processes. For these types of systems, correlations have been extensively developed. However, there have been no correlations done for very high enthalpy flows as produced by Arnold Engineering Development Center’s (AEDC) H2 facility. The H2 facility uses a direct current electric arc to heat air which is then expanded through a converging-diverging nozzle to impart a supersonic velocity to the air. This high enthalpy, high temperature air must be cooled downstream by the use of a cross flow heat exchanger.

It is of interest to evaluate ...