Aerospace Engineering Commons^™

Numerical Simulation And Modeling Of Combustion In Scramjets, Ryan James Clark

Dissertations

In the last fifteen years the development of a viable scramjet has quickly approached the following long term goals: responsive sub-orbital space access; long-range, prompt global strike; and high-speed transportation. Nonetheless, there are significant challenges that need to be resolved. These challenges include high skin friction drag and high heat transfer rates, inherent to vehicles in sustained, hypersonic flight. Another challenge is sustaining combustion. Numerical simulation and modeling was performed to provide insight into reducing skin friction drag and sustaining combustion.

Numerical simulation was used to investigate boundary layer combustion, which has been shown to reduce skin friction drag. The …

Bayesian Statistics And Information Fusion For Gps-Denied Navigation, Brian Lee Copp

Mechanical and Aerospace Engineering Dissertations - Archive

It is well known that satellite navigation systems are vulnerable to disruption due to jamming, spoofing, or obstruction of the signal. The desire for robust navigation of aircraft in GPS-denied environments has motivated the development of feature-aided navigation systems, in which measurements of \textit{environmental features} are used to complement the dead reckoning solution produced by an inertial navigation system. Examples of environmental features which can be exploited for navigation include star positions, terrain elevation, terrestrial wireless signals, and features extracted from photographic data. Feature-aided navigation represents a particularly challenging estimation problem because the measurements are often strongly nonlinear, and the …

Two Phase Flow Cfd Analysis Of Refrigerants In A Condenser Pipe For Prediction Of Pressure Drop And Pumping Power, Aniket Ramchandra Kalambe

Mechanical and Aerospace Engineering Theses - Archive

With the ever growing need of achieving optimum cooling at chip level at the expense of low input pumping power and keeping in check the Global Warming Potential (GWP) & Ozone Depletion Potential (ODP) has given rise to “two-phase on chip cooling” with nature friendly refrigerants. Currently, “air-cooling” and “single-phase water on-chip cooling” using copper micro-channel coolers are being used but “two-phase on chip cooling” with refrigerants have a very large scale & long lasting advantages over the prior. However, due to the perceived complexity of modelling two-phase flow, this solution is not yet well understood. Modelling of two phase …

An Invastigation Of Band-Limited Fluid Damper Configuration Using Lumped Parameter Modeling, Ye Hong

Mechanical and Aerospace Engineering Theses - Archive

Vehicle suspension system is one of the key factors related to the vehicle dynamic characteristic. The fine tuning of suspension system between vehicle handling and ride comfort is not only a trade-off between these two aspects, but also, has its impact on vehicle safety and durability. For an optimal damper performance, the damper needs to generate sufficient damping force at maneuvering frequency (< 2 Hz); and it also needs to generate less damping force, which allow spring to filter the high frequency noise (> 2 Hz) generated by vehicle travels along rough road condition at speed. In order to achieve such performance, a lumped parameter model of Band-Limited Damper is proposed. Frequency response of both Conventional Damper and Band-Limited Damper are …

Computational Analysis Of Enhancing Heat Transfer In A 3-D Stacked Die Using Different Finned Heat Sink, Deekshith Pittala

Mechanical and Aerospace Engineering Theses - Archive

3D die stacking is an exciting new technology that increases the transistor’s density by integrating two or more dies vertically with a dense high – speed interface. The result of 3D die stacking is a significant reduction of interconnect both within a die and across dies in a system. The objective of the thermal design requirement for a 3D stacked die package is to maintain the junction temperatures of the devices at or below specified limits. Installing the Heat sink aid the heat transfer activity from a package. The extent of cooling and the junction temperatures vary if the designs …

Developing And Validating Thermodynamic Models For Evaporative Cooling Employed In Data Centers, Niravkumar Prabhatsinh Dodia

Mechanical and Aerospace Engineering Theses - Archive

Cooling of Data centers is of paramount importance for continuous and reliable operation of Servers housed by them. Considerable amount of total power is used to drive the cooling activity. Various different types of cooling methods have been implemented and are currently operating in various data centers. Evaporative (Indirect/Direct) Cooling is trending these days because of its ability to provide cooling at minimal cost. Previous studies have presented various cooling plants in data centers and studied them. A dedicated model for Evaporative cooling is developed and validated. The data is computed assuming the developed cooling model operating at a particular …

Experimental Study On Effects Of Segregated Cooling Provisioning On Thermal Performance Of Information Technology Servers In Air Cooled Data Centers, Ashwin Venugopal Siddarth

Mechanical and Aerospace Engineering Theses - Archive

Modern Information Technology (IT) equipment are typically assumed to operate in quiescent airflow conditions in an uncontained data center facility. In this study, the multi-scaled thermal management strategies are reconsidered at the IT chassis and rack level for a containment system. For an ideal containment configuration of airflow provisioning the entirety of conditioned air provided by the Computer Room Air Conditioning (CRAC) unit would flow through the IT equipment and return back to the CRAC. But in actuality a lack of interfaced airflow distribution exists between the amount of conditioned air provisioned to the rack and the volume capacity ingested …

A Model Analysis Of Sand Insertion In Hydraulic Fractures, Ya Hao

Mechanical and Aerospace Engineering Theses - Archive

Hydraulic fracturing (fracking) is a well-stimulation technology to create large volume of fracture formation in rocks for gas and/or oil extraction. This technology has been applied to commercially exploit natural gas in unconventional shale reservoirs that contain immense quantity but low density of hydrocarbon sources. The productivity can be largely dependent on the connectivity of fractures that must stay open. However, upon initial hydraulic fracturing, the fractures would be closed due to high hydrostatic pressure deep inside the crust. Sand must be pumped into the fractures to keep them open. An in-depth understanding of the sand distribution and its dependence …

Magnetic Field Enhanced Thermal Conductivity Analysis Of Magnetic Nanofluids, Christopher Allen

Mechanical and Aerospace Engineering Theses - Archive

The magnetic properties of four water-based nanofluids consisting of Al2O3, CuO, Fe3O4, and SiO2 were exploited to analyze the effect of the application of an external magnetic field on the thermal conductivity of the nanofluid. When the magnetic field is applied, the magnetic dipole moments of the particles align and the particles come in contact with each other and form chains in the direction of the applied magnetic field. When parallel to the direction of heat flow, the magnetic field causes the effective thermal conductivity in the direction of the magnetic field to increase. A higher thermally conductive fluid can …

Spacecraft Trajectory Optimization Suite (Stops): Optimization Of Multiple Gravity Assist Spacecraft Trajectories Using Modern Optimization Techniques, Timothy J. Fitzgerald

Master's Theses

In trajectory optimization, a common objective is to minimize propellant mass via multiple gravity assist maneuvers (MGAs). Some computer programs have been developed to analyze MGA trajectories. One of these programs, Parallel Global Multiobjective Optimization (PaGMO), uses an interesting technique known as the Island Model Paradigm. This work provides the community with a MATLAB optimizer, STOpS, that utilizes this same Island Model Paradigm with five different optimization algorithms. STOpS allows optimization of a weighted combination of many parameters. This work contains a study on optimization algorithm performance and how each algorithm is affected by its available settings.

STOpS successfully found …

Inductive Monitoring Systems: A Cubesat Ground-Based Prototype, Michelle Haddock

Master's Theses

Inductive Monitoring Systems (IMS) are the newest form of health monitoring available to the aerospace industry. IMS is a program that builds a knowledge base of nominal state vectors from a nominal data set using data mining techniques. The nominal knowledge base is then used to monitor new data vectors for off-nominal conditions within the system. IMS is designed to replace the current health monitoring process, referred to as model-based reasoning, by automating the process of classifying healthy states and anomaly detection. An IMS prototype was designed and implemented in MATLAB. A verification analysis then determined if the IMS program …

Open Source Toolkit For Reentry Object Modeling, Christopher Lloyd Ostrom Ii

Master's Theses

Predicting the mass, position, and velocity of an object during its reentry are critical to satisfy NASA and ESA requirements. This thesis outlines a 3-D orbit and mass determination system for use on low earth orbit as applicable to general objects, of various material and size. The solution uses analytical models to calculate heat flux and aerodynamic drag, with some basic numerical models for simple orbit propagation and mass flow rate due to ablation. The system outlined in this thesis currently provides a framework for rough estimates of demise altitude and final mass, but also allows for many potential accuracy …

Divergent Plume Reduction Of A High-Efficiency Multistage Plasma Thruster, Christopher M. Barlog

Master's Theses

High Efficiency Multistage Plasma Thrusters (HEMPTs) are a relatively new form of electric propulsion that show promise for use on a variety of missions and have several advantages over their older EP competitors. One such advantage is their long predicted lifetime and minimal wall erosion due to a unique periodic permanent magnet system. A laboratory HEMPT was built and donated by JPL for testing at Cal Poly. Previous work was done to characterize the performance of this thruster and it was found to exhibit a large plume divergence, resulting in decreased thrust and specific impulse. This thesis explores the design …

A Study On Evaporative Cooling For Data Centers & Artificial Neural Network Modeling, Pritam Karmokar

Mechanical and Aerospace Engineering Theses - Archive

This study mainly aims at exploring how, one of the best “Green” solutions for IT equipment cooling aka Evaporative Cooling, can be optimized for better future deployment. Also, this study focuses on ways to deploy Artificial Neural Network models to Dynamic Systems. Today, SERVERS are one of most important devices that our technology driven world cannot do without. Efficiently cooling these delicate yet highly power dense beasts, while being environment friendly is one of our prime concerns. This study is a combination of two deceptively divergent works. First, on exploring the workings of this technique by investigating one such Evaporative …

Cae Analysis On A Ford Ecoboost Mustang Connecting Rod For Forged Steel, Aluminum 7075, Shiva Prasad Keralapura Basavaraju

Mechanical and Aerospace Engineering Theses - Archive

Connecting rod is high volume production critical component in an automobile engine. Every Internal combustion engine uses a connecting rod. Connecting rod must have highest possible rigidity with lowest possible weight. The major stress developed in the connecting rod are axial stress, due to combustion chamber pressure, and bending stress, due to centrifugal effect. Connecting rod mainly fails due to fatigue; according to survey, about 90% of the time the failure is due to fatigue. CAE analysis on Ford Eco boost Mustang connecting rod is carried out to validate the life of the connecting rod for forged steel and Aluminium7075. …

Computational Model For Steady State Simulation Of A Plate-Fin Heat Exchanger, Ajit Rajesh Desai

Mechanical and Aerospace Engineering Theses - Archive

High performance heat transfer devices are critical components in hybrid power generation systems. The design of a Recuperator for 'waste heat recovery' is crucial for reducing the operating cost of a hybrid system. Plate-fin heat exchangers occupy a special position among high performance heat exchangers because of the compactness, efficiency and flexibility they offer. The performance of these heat exchange devices is typically very sensitive to fluid property variations, axial conduction and heat losses to environment. This thesis presents a numerical model of a plate fin heat exchanger in which fluid property variations including temperature driven changes in specific heat …

Polyacrylonitrile Copolymers: Effects Of Molecular Weight, Polydispersity, Composition, And Sequencing On Thermal Ring-Closing Stabilization, Jeremy D. Moskowitz

Dissertations

Controlled polyacrylonitrile (PAN)-based carbon fiber precursors with defined molecular weights, polydispersities, compositions, and architectures have been prepared for their study on thermal ring-closing stabilization behavior. PAN and its copolymers of number average molecular weights exceeding 170,000 g/mol were successfully synthesized via low temperature reversible addition-fragmentation chain transfer (RAFT) polymerization. RAFT polymerizations of PAN-based precursors were compared to conventional free radical solution polymerizations with a focus on the effects of molecular weight and polydispersity on structural evolution and cyclization efficiency. When RAFT polymerization was extended to copolymers, it was found that RAFT copolymers achieved greater cyclization intensities and improved thermal stability …

The Impact Of Crystal Morphology On The Thermal Responses Of Ultrasonically-Excited Energetic Materials, J. K. Miller, J. O. Mares, I. E. Gunduz, Steven F. Son, Jeff Rhoads

Purdue Energetics Research Center Articles

The ability to detect explosive materials may be significantly enhanced with local increases in vapor pressure caused by an elevation of the materials'temperature. Recently, ultrasonic excitation has been shown to generate heat within plastic-bonded energetic materials. To investigate the impact of crystal morphology on this heating, samples of elastic binder are implanted with single ammonium perchlorate crystals of two distinct shape groups. Contact piezoelectric transducers are then used to excite the samples at ultrasonicfrequencies. The thermal responses of the crystals are recorded using infrared thermography, and the rate of heating is estimated. Surface temperature increases up to 15 °C …

Design Of Elastic Metamaterials, Yu-Chi Su

Open Access Dissertations

This study focused on the design and fabrication of a double negativity and three broadband single negativity elastic metamaterials using a 3D printer. We investigated dispersion curves and dynamic material properties of the metamaterials. Negative phase velocity in the double negativity metamaterial was also demonstrated.

For metamaterials with single negativity, three types of broadband metamaterials were designed from parametric studies. A comparison showed that using frame bending/stretching mode is more effective than applying beam bending mode to broaden bandgap. Furthermore, it is found that adding internal resonant components could enlarge the bandgap. The single negativity metamaterials were validated by numerical …

Direct Adaptive Control For Stability And Command Augmentation System Of An Air-Breathing Hypersonic Vehicle, Ron Aditya

Doctoral Dissertations and Master's Theses

In this paper we explore a Direct Adaptive Control scheme for stabilizing a non-linear, physics based model of the longitudinal dynamics for an air breathing hypersonic vehicle. The model, derived from first principles, captures the complex interactions between the propulsion system, aerodynamics, and structural dynamics. The linearized aircraft dynamics show unstable and non-minimum phase behavior. It also shows a strong short period coupling with the fuselage-bending mode. The value added by direct adaptive control and the theoretical requirements for stable convergent operation is displayed. One of the main benefits of the Directive Adaptive Control is that it can be implemented …