Aerospace Engineering Commons^™

Arliss Come Back Competition - Summary, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs on the "ARLISS Come Back Competition" from December 20, 2005.

Dynamic Aeroelastic Analysis Of Wing/Store Configurations, Gregory H. Parker

Theses and Dissertations

Limit-cycle oscillation, or LCO, is an aeroelastic phenomenon characterized by limited amplitude, self-sustaining oscillations produced by fluid-structure interactions. In order to study this phenomenon, code was developed to interface a modal structural model with a commercial computational fluid dynamics program. LCO was simulated for a rectangular wing, referred to as the Goland⁺ wing. It was determined that the aerodynamic nonlinearity responsible for LCO in the Goland+ wing was the combination of strong trailing-edge and lambda shocks which periodically appear and disappear. This mechanism limited the flow of energy into the structure which quenched the growth of the flutter, resulting …

Satellites In The Class Room, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Satellites in the Class Room" from December 2, 2005.

Numerical Study Of Chemically Reacting Viscous Flow Relevant To Pulsed Detonation Engines, Tae-Hyeong Yi

Mechanical and Aerospace Engineering Dissertations - Archive

A computational fluid dynamics code for two-dimensional, multi-species, laminar Navier-Stokes equations is developed to simulate a recently proposed engine concept for a pulsed detonation based propulsion system and to investigate the feasibility of the engine of the concept.The governing equations that include transport phenomena such as viscosity, thermal conduction and diffusion are coupled with chemical reactions. The gas is assumed to be thermally perfect and in chemically non-equilibrium. The stiffness due to coupling the fluid dynamics and the chemical kinetics is properly taken care of by using a time-operator splitting method and a variable coefficient ordinary differential equation solver. A …

Modular Multi-Scale Assembly System For Mems Packaging, Rakesh Murthy

Mechanical and Aerospace Engineering Theses - Archive

A multi-scale robotic assembly problem is approached here with focus on mechanical design for precision positioning at the microscale. The assembly system is characterized in terms of accuracy/repeatability and calibration via experiments. The MEMS packaging requirements are studied from an assembly point of view. The tolerance budget of the assembly ranges from 4 microns to 300 microns. The system components include robots, microstages, end-effectors and fixtures that accomplish the assembly tasks. Task assignment amongst this hardware has been accomplished based on precision and dexterity availability. Various end-effectors and fixtures have been designed for use with off-the-shelf hardware (robots and microstages) …

Design And Analysis Of Multi-Functional Laparoscopic Tool, Vadakkapattu Candadai Venkat Raghavan

Mechanical and Aerospace Engineering Theses - Archive

Laparoscopic tools have been developed over many years, but there is a need for a laparoscopic tool that can be used for multiple purposes without the need to be removed and reinserted in the body. This thesis discusses the design of such a multi-functional laparoscopic tool with the ability to independently actuate grasping and shearing mechanisms, and is modular enough to be easily adapted to robot assisted surgical techniques. The envisioned tool can be divided into three main sections - the surgeon interface, the transmission mechanism, and the end effector. The surgeon interface mainly consists of a handle and two …

Parametric Cycle Analysis For Pulse Detonation Engines, Haider Hekiri

Mechanical and Aerospace Engineering Theses - Archive

The performance of an ejector-driven pulse detonation engine (PDE) with an afterburner is analytically estimated. In the analysis, the PDE was modeled as a straight tube, closed at the front end and open at the other. A detonation wave starts to travel after it is ignited at the closed end, causing a Chapman-Jouguet detonation wave followed by a Taylor rarefaction to travel to the open end. At that point, rarefaction waves are reflected back to the closed end. The result is a high thrust due to both the primary and secondary flows of the ejector-driven PDE. A theoretical analysis is …

Airy Stress Function For Two Dimensional Inclusion Problems, Dharshini Rao Kavati

Mechanical and Aerospace Engineering Theses - Archive

This thesis addresses a problem of finding the elastic fields in a two-dimensional body containing an inhomogeneous inclusion using the Airy stress function which is determined so that the prescribed boundary condition at a far field and the continuity condition of the traction force and the displacement field at the interface are satisfied exactly. All the derivations and solving simultaneous equations are carried out using symbolic software.

Arc-Heated Gas Flow Experiments For Hypersonic Propulsion Applications, Christopher Matthew Roseberry

Mechanical and Aerospace Engineering Dissertations - Archive

Although hydrogen is an attractive fuel for a hypersonic air-breathing vehicle in terms of reaction rate, flame temperature, and energy content per unit mass, the substantial tank volume required to store hydrogen imposes a drag penalty to performance that tends to offset these advantages. An alternative approach is to carry a hydrocarbon fuel and convert it on-board into a hydrogen-rich gas mixture to be injected into the engine combustors. To investigate this approach, the UTA Arc-Heated Wind Tunnel facility was modified to run on methane rather than the normally used nitrogen. Previously, this facility was extensively developed for the purpose …

Reliability Of Lead-Free Solder Under Cyclic Bending, Fahad Zahedi

Mechanical and Aerospace Engineering Theses - Archive

To characterize particular compositions of lead free solder, four point cyclic bending test was conducted to study the affects of accelerated stress testing on the package to board interconnects. Nine CTBGA packages with 0.5 mm ball pitch and 12 x 12 mm package size were reflowed on 8 layered PWB's using solder balls with lead free composition alloys and different PWB copper pad finishes. The boards were subjected to test conditions based on proposed standards by JEDEC. Strain gages were mounted at different locations on the test boards as well as on bare boards in order to observe the difference …

Experimental Characterization Of Femtosecond Laser Micromachining For Silicon Mold Fabrication And Hot Embossing For Polymer Microreplication, Sunil Ranganath Belligundu

Mechanical and Aerospace Engineering Dissertations - Archive

Hot embossing is a fabrication technique employed for replicating microfeatures on a polymer surface that was primarily developed to fabricate MEMS devices for microfluidic applications. This manuscript deals with characterization of the femtosecond laser micromachining (FLM) and hot embossing (HEMM) processes for master mold fabrication on silicon and polymer replication respectively. Given the required size of the features to be fabricated or replicated, process parameters for FLM can be determined using the derived empirical equations, process parameters for the HEMM process can be established using the characteristic plots. A novel two-stage embossing process is developed and introduced that employs polymer …

Failure Analysis Of Composite Laminates With A Hole By Using Finite Element Method, Moumita Roy

Mechanical and Aerospace Engineering Theses - Archive

Predicting the strength of a given laminate has been extensively studied. There have been several fracture models proposed but still the immense tests of composite laminates are still needed. Different material systems or lay-ups exhibit different failure modes and failure mechanisms. This thesis focuses in investigation of the failure mechanism of the [±?/02]s and [02/±?]s laminates with a hole. ANSYS finite element models with and without a crack in vicinity of hole were developed to investigate the effect of the stress distribution due to the presence of the angle ply crack. The stress concentrations were obtained. It is found that …

Structural Optimization Using Ansys And Regulated Multiquadric Response Surface Model, Ajaykumar Menon

Mechanical and Aerospace Engineering Theses - Archive

The high computational expense of large non-linear and complex finite element analysis limits or often prohibits the use of conventional codes in engineering design and multidisciplinary optimization. Consequently alternate methods such as Design of experiments (DOE) and Response surface approximation are commonly used to minimize the computational cost of running such analysis and simulation. The basic approach of such methods is to construct a simplified mathematical approximation of the computationally expensive simulation and analysis code, which is then used in place of the original code to facilitate multidisciplinary optimization, design space exploration, reliability analysis etc. When such codes along with …

A Qualitative Modeling Method For Platform Design, Michael Van Wie, Robert B. Stone, Asli Sahin, Janis Terpenny, Fabrice Alizon, Steve Shooter, Timothy Simpson

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The development of a collection of related products sharing a common platform represents an important approach in modern product design. an ongoing problem is the application of design methods toward a limited set of evolving product data and archived design knowledge to search and explore alternative platform options. with the goal of maximizing the reuse of end item artifacts and supply chain elements, we propose a design modeling method using basic qualitative relationships among relevant performance, design, and noise parameters in the system of interest. by using qualitative models related to multiple levels of design data, the method provides a …

Modeling, Stability, And Control Of A Rotatable Tail On A Micro Air Vehicle, Travis J. Higgs

Theses and Dissertations

This research uses existing experimental wind tunnel data to develop a non-linear model that is used to characterize the stability of a flexible wing Micro Air Vehicle (MAV) with a rotatable tail. The experimental data are curve fit based on either angle of attack or angle of sideslip, and the coupled effect of tail rotation and tail deflection on the force and moment coefficients. Static optimization trims the input and state variables for Steady Level Unaccelerated Flight (SLUF). The resulting initial conditions are fed to an open loop non-linear Simulink/Matlab simulation. The study found that the bare MAV design is …

An Automated Optimal Design Of A Fan Blade Using An Integrated Cfd/Mdo Computer Environment, Uyi O. Idahosa

Master's Theses - Daytona Beach

The objective of the investigation is the development of more efficient design methodologies based on the applications of established design tools including Computational Fluid Dynamics (CFD) and non-linear Multidisciplinary Design Optimization (MDO) algorithms. Well known evolutionary type optimization algorithms include the Particle Swarm Optimization (PSO), Response Surface Optimization (RSO) and Genetic (GA) Algorithms. The benchmark case study is the optimal design of a low speed fan for an industrial air-conditioning application using the Response Surface Optimization (RSO) algorithm.

The optimization algorithm controls the variations of parameters that describe the three-dimensional geometry of the blade while applying performance and geometrical constraints …

Performance Measurements Of Direct Air Injection In A Cavity-Based Flameholder For A Supersonic Combustor, Scott G. Edens

Theses and Dissertations

For several years the Air Force Research Lab Propulsion Directorate has been studying the difficulties in fueling supersonic combustion ramjet engines with hydrocarbon based fuels. Recent investigations have focused on the use of direct air injection into a directly-fueled cavity-based flameholder. Direct air injection has been shown qualitatively to be a valuable tool for improving cavity combustion. Little quantitative data is available that characterizes the performance of cavity-based flameholders. The objective of this research was to quantitatively determine the specific advantages and disadvantages of the direct air injection scheme. This was accomplished via intrusive probing into a supersonic free stream …

Wind Tunnel Study Of Interference Effects Relating To Aft Supersonic Ejection Of A Store, Timothy P. Jung

Theses and Dissertations

An investigation into the issues surrounding the release of a store into a supersonic wake was conducted. A 10-degree half-angle cone was used to model the carrier vehicle as well as the store. The store was 42% than the vehicle. The experiments were conducted at a freestream Mach number of 2.93 and at zero degrees angle of attack. This study analyzed the effects of a support or strut mounted under the wind tunnel model. Research was conducted on the effects of a store at various positions in the wake, as well as the effects of a rear cavity in the …

Investigation Of Pool Boiling Heat Transfer With Nanofluids, Gilberto Moreno

Mechanical and Aerospace Engineering Theses - Archive

This investigation conducts pool boiling experiments under saturated conditions (Tsat=60°C) using nanofluids as coolants. Four different nanofluids were tested including zinc oxide (ZnO)-water, aluminum oxide (Al2O3)-water, aluminum oxide (Al2O3)-water+ethylene glycol (ethylene glycol solution) and gold (Au)-water. At saturation (Tsat=60 °C), the pool boiling performance of Al2O3-water and ZnO-water nanofluids were similar. The maximum CHF enhancement as compared to predicted Zuber's [1] CHF evaluated at an equivalent saturation temperature is about 180% for Al2O3-water nanofluids and about 240% for ZnO-water nanofluids. In both cases, no degradation in the boiling heat transfer rate was observed for lower nanoparticle concentrations. The dispersion of …

The Thermal Characteristics Of Liquid-Heat-Spreader, Sang Muk Kwark

Mechanical and Aerospace Engineering Theses - Archive

The present study is an experimental research of a liquid-heat-spreader (LHS) with saturated water at ~2.29 psia. A LHS, indirect liquid cooling module, was successfully fabricated using thin copper blocks and copper tubes using solder. Three types of LHS, Flat-type, L-type, and T-type, were developed for different orientations and were compared with solid metal blocks such as aluminum and copper. The Flat-type LHS, 100 (W) × 254 (L) × 3 (T) mm3, was designed for vertical orientation. It showed a remarkable thermal performance by dissipating heat flux of 119 W/cm2 with below 100? chip temperature at the typical condition. The …

Repeatable Nanostructures In Dielectrics By Femtosecond Laser Pulse Trains, Lan Jiang, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Using the plasma model recent developed by the authors, this study predicts the existence of a constant ablation-depth zone with respect to fluence in femtosecond laser ablation of dielectrics, which has also been observed experimentally. It is found that the value of the constant ablation depth is significantly decreased by the pulse train technology. Repeatable nanostructures can be achieved with the parameters in the constant ablation-depth zone of a femtosecond pulse train, even when the laser system is subject to fluctuations in fluences.

Tools For Analysis Of Complex Geometries For A Combined Cycle Scram Jet / Rocket, James Moss

Master's Theses - Daytona Beach

A preliminary design for a variable geometry combined cycle supersonic combustion ram jet (SCRAM jet) / rocket was developed. A precise geometry was selected by parametric analysis and the resultant geometry was analyzed using a computational fluid dynamics (CFD) code developed by Dr. Eric Perrell, and modified by, among others, the author.

This paper is broken into several sections discussing, separately, the design innovations used to permit the geometry of the craft to be adjusted to conform to its flight conditions, the 2D analysis tool developed for the parametric analysis, development of the grid for CFD analysis, and modifications made …

Sonic Boom Prediction Using Euler/Full Potential Methodology, Isik Ali Ozcer

Mechanical & Aerospace Engineering Theses & Dissertations

Sonic Booms of two different bodies, a double cone configuration and a modified F-SE aircraft, are predicted using Euler solvers for the near field, and a Full Potential Propagation method for the far field. The problem is considered inviscid since viscous effects in high Reynolds number flows are negligible in Sonic Boom propagation. To enhance the accuracy of the predictions, elaborate shock fitting and grid adaptation routines are developed that can handle complicated shock topologies. The far field propagation code using the full potential equation is the first three-dimensional computational fluid dynamics code in literature that can march the solution …

Contemporary-Classical Sequential Loop Design With Parameter Uncertainty, Donghyuk Jeong

Mechanical & Aerospace Engineering Theses & Dissertations

Standard sequential loop closure design based on Evans root migration concepts is a well accepted, insightful and effective technique for meeting nominal performance objectives and traditional gain-phase stability margin requirements. Unfortunately, assessment of closed-loop variations resulting from parameter error is a post-process, implying an undesirable design-assess-redesign procedure is necessary if variations are found unacceptable. Further, the modem parameter uncertainty assessment framework is often inconsistent, both quantitatively and qualitatively, with the redesign task. Specifically, the parameter uncertainty assessment variables are not readily apparent in the sequential loop design framework, and these variables provide little guidance for the redesign strategy. Therefore, enhancing …

Numerical Integration Strategy For Generating Root Migration Diagrams, Deepak H. Panduranga

Mechanical & Aerospace Engineering Theses & Dissertations

Evans root locus is a graphical method for analyzing or designing the stability and performance of a single channel closed-loop system. The method consists of plotting the locus of closed-loop characteristic equation roots in the complex plane as the loop gain parameter is varied over a wide range of values. Several methods for plotting the root locus graph exist and can be mainly classified into two types: analytical methods and numerical methods. The most common numerical method is based on polynomial factoring or root solving. A less common, alternative method for generating the root locus graph is based on numerical …

New Methodology For Robust Control System Design And Analysis For Single Parameter Uncertain Systems, Charles J. Player

Mechanical & Aerospace Engineering Theses & Dissertations

Due to the conservative nature of the standard singular value robustness tests there is ambiguity in the results that they provide. The tests only establish a sufficient condition and therefore provide little insight to the stability robustness of a system that fails the test. However, for a single parameter uncertain system that is modeled using structured uncertainty, an Evans root locus can be derived that shows how system closed-loop poles change with the magnitude of the single parameter uncertainty. This technique provides clear stability robustness insight. Further, another Evans root locus can be derived that shows how system closed-loop zeros …

Hands-On, Go Do It Program, Robert J. Twiggs

Robert "Bob" Twiggs STEM Education Collection

A PowerPoint Presentation created by Professor Bob Twiggs titled "Hands-On, Go Do It Program" from September 14, 2005.

Effects Of Boundary Layer Flow Control Using Plasma Actuator Discharges, Jeffrey M. Newcamp

Theses and Dissertations

This study addresses the usage and effects of atmospheric plasma discharges on the near wall flow conditions for a Pak-B low-pressure turbine blade. A plasma actuator was built normal to the freestream flow in a low-speed wind tunnel. The test section of the wind tunnel had a contoured upper wall geometry designed to mimic the suction side of a Pak-B turbine blade. A high frequency ac voltage source supplied three voltages in the kilovolt range at four Reynolds numbers in the experiment, between 10,000 and 103,000. The effect of the plasma on the near-wall boundary layer conditions was evaluated at …

Experimental Investigation Of A Lift Augmented Ground Effect Platform, Roberto T. Igue

Theses and Dissertations

This experimental study investigated the feasibility of applying the concept of a skirtless hovercraft into the production of an operational vehicle. A 0.255 m diameter prototype was designed, built and tested. An air bearing table was used as a testing platform, virtually eliminating the influence of friction and providing one degree of freedom for the experiments. Static tests were performed at various heights and craft configurations, providing a wide range of data for comparison. Lift, torque and efficiency were measured and calculated for each setting. Pressure and velocity information was also collected at specific points around the craft when operating …

The Effect Of Aerodynamic Surfaces Versus Thrust Maneuvers On Reentry Vehicles, Meredith M. Albrecht

Theses and Dissertations

This research effort analyzes the effect of aerodynamic surfaces versus thrust maneuvers on a reentry vehicle. At high altitudes the effect of aerodynamic surfaces on the reentry vehicle is small due to low atmospheric density; however as the vehicle reaches lower altitudes a lift maneuver is very successful in deflecting the vehicle and creating a large impact footprint. When a continuous thrust maneuver is input in the place of a lift maneuver the results are very similar at the highest maneuver altitudes, although the impact footprint shrinks rapidly as the maneuver altitude decreases. Additionally, when the thrust maneuver is along …