Aerospace Engineering Commons^™

Performance Modeling And Experimental Investigations Of Rotating Detonation Engines, Andrew Ryan Mizener

Mechanical and Aerospace Engineering Dissertations - Archive

The rotating detonation engine (RDE) is a promising propulsion concept that has the potential to offer increased thermodynamic performance in a compact package with no moving parts. A series of analytical and experimental investigations was carried out on RDEs with the joint goal of investigating swirl, torque, and a range of other design parameters of interest. The model and experimental facility were then applied to related problems with the goal of advancing the understanding of RDE applications. A flexible, low-order, semi-empirical model for a rotating detonation engine was presented. The model was formulated to be able to run broad parametric …

Direct Numerical Simulation Of Homogeneous Isotropic Turbulence - A Methodology And Applications, Sarah Moussa Hussein

Mechanical and Aerospace Engineering Dissertations - Archive

Turbulence has been a topic of scientific research for years. Characterized by unorganized chaotic motion and irregular fluctuations, it persists as one of the most challenging topics in fluid mechanics despite volumes of documented research and crucial findings. This begs the question: What is turbulence and why is it so challenging? Turbulence research studies cover a wide spectrum of branches from fundamental flow propagation to different turbulence interactions. This research project investigates the simplest class of turbulent flow studies, homogeneous isotropic turbulence. In a quest to advance the fundamental understanding of turbulence physics, a direct numerical simulation tool is developed. …

Observation Of The Interaction Between A Transonic Shock Wave And A Wingtip Vortex||, Troy T. Bushmire

Mechanical and Aerospace Engineering Theses - Archive

The present study observes the interaction between two fundamental phenomena in fluid mechanics: the transonic shock wave and the wingtip vortex. While these are two areas of fluid mechanics in which extensive experimental and numerical research has been conducted, there is little information on the interaction between the two. The present study numerically simulates a wing with a NACA-0012 section at Mach 0.758 and observes the interaction between the transonic shock wave and wingtip vortex for various angles of attack. The focus of the study is on the surface flow topology and the flow exterior to the boundary layer. Results …

Reachable Set Computation And Analysis For Perturbed Linear Systems, Prabhjeet Singh Arora

Mechanical and Aerospace Engineering Theses - Archive

Determination of the set of all possible states, which a system can attain, plays an important role in safety for critical application. Prior knowledge of this set for the complete run-time provides critical information about how a system may evolve, providing accurate information of all the states, which could violate constraints. The knowledge of these states, helps in estimating control input, which can control the system, such that, these states are eliminated from the reachable set. Computation of reachable set of a dynamic system for a set of initial conditions can be easily performed, provided the analytical solution of the …

An Analytical Design Of Experiments Method For Fatigue Constrained Design Optimization Of A 3d Printed Structure, Ashish Pokharel

Mechanical and Aerospace Engineering Theses - Archive

A design of experiments approach has been used to analytically determine a low cycle fatigue (LCF) constraint for use in design optimization of 3D printed structures. In context of metal additive manufacturing, the process of melting, solidification and consolidation of metal powder introduces very high temperature gradient field within the build which in turn results in high compressive stresses at the core and tensile stresses at the outer surface of the part after it has cooled down to room temperature post build. An approach of finite element modeling in ANSYS Additive has been used to develop a residual stress profile …

Sensor Tasking For Satellite Tracking Utilizing Observability Measures, Mitchel T. Mcdonald

Mechanical and Aerospace Engineering Theses - Archive

In this thesis, novel observability-measure based sensor tasking methods are studied for satellite tracking applications. The tasking is performed by first computing the Hellinger Distance between ground/space based sensors and space objects, and then the measure is utilized for selecting the sensors that maximize observability. Several other measures such as the Fisher Information Gain, Largest Lyapunov Exponent, and Shannon Information Gain have also been utilized and the performance of these measures are computed against each other. The object's state estimates are obtained using nonlinear estimation techniques. The Extended Kalman Filter, Unscented Kalman Filter, and Bootstrap Particle Filter are compared within …

Design And Development Of Flexible Mems-Based Ph Sensor For Agricultural And Biomedical Applications, Shardul Sonu Pawar

Mechanical and Aerospace Engineering Theses - Archive

The purpose of this study is to demonstrate a novel method of using a flexible MEMS-based pH sensor for agricultural and biomedical applications. The first part of the thesis involves demonstration of the capability of our pH sensor for monitoring pH level change in the food product. The pH sensor we have developed consists of Iridium Oxide (IrOx) and Silver Chloride (AgCl) sensing electrodes. The sensor is designed to monitor and sustain long-term continuous usage, which makes it suitable for a wide variety of agricultural based applications. The electrochemical potential generated between IrOx and AgCl electrode is monitored and further …

Enhancing Tensile Strength Of Fdm Parts Using Thermal Annealing And Uniaxial Pressure, Rhugdhrivya Rane

Mechanical and Aerospace Engineering Theses - Archive

Additive manufacturing has been a revolutionary and disruptive technological development in the field of design and manufacturing with Fused deposition modelling (FDM) being at the forefront of this technology. But it is seen that parts printed using FDM suffer from an inherent deficiency of weak tensile strength in the out of plane direction (z-direction) thus limiting their application. This issue of weak z-direction strength is due to the weak Inter-bead bond strength of adjacent polymer interfaces. The purpose of this work is to increase this Inter-Bead bond strength thus increasing the overall tensile strength of the part. In this work, …

Inducing Vibro-Tactile Sensation At Mesoscale, Sudip Hazra

Mechanical and Aerospace Engineering Theses - Archive

Haptics, the feeling of touch, has primarily been used to provide a person a general sensation such as vibration using a joystick or cellphone. But haptics has gradually developed to a stage where it is investigated for virtual and augmented reality environments. Vibro-tactile based feedback is a modality employed to provide a more realistic and localized sensation. This research focuses primarily on providing vibro-tactile feedback at the mesoscale level on the fingertips. A research platform for mesoscale vibro-tactile feedback has been investigated and developed. The software is based on LabVIEW and could generate a number of different and distinct waveform …

Minimizing Structural Jitter In Optical Sensor Systems Using Parametric Dynamic Response Optimization, Richard Lynn Scott

Mechanical and Aerospace Engineering Dissertations - Archive

Deployed in manned and unmanned aircraft, military and commercial ground vehicles, and security and monitoring systems, optical sensor systems are ubiquitous. Developing an optical sensor system includes calculating image motion due to structural dynamics—hereafter, “structural jitter”—and adjusting system design to reduce structural jitter and meet requirements. The current process for adjusting the structural design to reduce structural jitter is manual, labor intensive, and driven mostly by engineering judgment. This paper proposes a well-defined optimization process that provides a more explicit approach to the structural design and likely will reduce labor as the process matures. This project focuses on employing dynamic …

Electrospinning Approach For The Improvement Of Mechanical And Dielectric Properties Of Anisotropic Nanofiber Mat By Using A Novel Fiber Alignment Technique, Blesson Isaac

Mechanical and Aerospace Engineering Dissertations - Archive

Many advanced applications, including aerospace, can benefit from materials with superior mechanical and dielectric properties. For these applications, most fiber alignment electrospinning research has focused on either mechanical property improvement or dielectric property improvement, but not both simultaneously. Through an improved apparatus design and system parameter optimization, this work develops an electrospinning apparatus that produces an increased electrostatic force and more tightly controlled discharged particle path to enable a more uniform distribution and higher degree of alignment in deposited electrospun material, which results in simultaneous improvement of both mechanical and dielectric properties. The current state-of-the-art in aligned electrospinning techniques are …

Foil Thrust Bearing With Pocket Grooves And Tailored Bump Stiffness Distribution For Improved Static Performance, Nguyen Thao Latray

Mechanical and Aerospace Engineering Dissertations - Archive

Gas foil thrust bearing is one of few axial bearing options for high speed turbomachinery systems. Its advantages include low cost, light weight, generous allowance for component mis-alignment and runout. However, the bearing has low load carrying capacity comparing to other types such as rigid gas bearing and magnetic bearing. This work explores two non-traditional design aspects to improve gas foil thrust bearing’s static performance. The bearing bump foil is redesigned to tailor to the bearing pressure profile; hence induces a more uniform gas film thickness. Simulation using independent elastic foundation model predicts the new tailored bump foil thrust bearing …

Underdamped Motion Of A Microbead In Optical Tweezer And Its Relationship With The Reynolds Number, Vatsal Asitkumar Joshi

Mechanical and Aerospace Engineering Theses - Archive

Optical tweezers can hold and manipulate microscopic objects with the use of a highly focused laser beam. The radiation pressure acting on the object is generally in the range of piconewtons and can be attractive or repulsive based on the reflective indexes of the object and the surrounding medium. Though the advances in the field of Optical tweezers have been enormous in the past few years, only the object's planer motion can be analyzed with the motion capture technology available today. Due to the wide applications of Optical tweezers in the field of biology and physics, the ability to simulate …

Ultraviolet Imager Application For A Cube Satellite, Jason Grillo, Troy Hajjar, Brady Hill

Mechanical Engineering

This document serves as the final design review (FDR) report for the 2018 Cal Poly CubeSat Ultraviolet Imager senior project, sponsored by UC Berkeley Space Sciences Laboratories (SSL). SSL wants to monitor the ionosphere above Earth to gain a better understanding of its properties and particle interactions. Far Ultraviolet (FUV) imaging is a good way to obtain high quality images of the ionosphere and the Earth's auroras, and advancement in optic technologies have made cube satellites (CubeSats) an ideal vessel for a FUV imager, as they are relatively low-cost, lightweight, and can be repeatedly deployed. These CubeSat FUV imagers could …

Effect Of Aerogel On The Thermal Performance Of Corrugated Composite Sandwich Structures, Jacob Dillon Chess

Master's Theses

Current insulation solutions across multiple industries, especially the commercial sector, can be bulky and ineffective when considering their volume. Aerogels are excellent insulators, exhibiting low thermal conductivities and low densities with a porosity of around 95%. Such characteristics make aerogels effective in decreasing conductive heat transfer within a solid. These requirements are crucial for aerospace and spaceflight applications, where sensitive components exist among extreme temperature environments. When implemented into insulation applications, aerogel can perform better than existing technology while using less material, which limits the amount of volume allocated for insulation. The application of these materials into composites can result …

Generating Exploration Mission-3 Trajectories To A 9:2 Nrho Using Machine Learning, Esteban Guzman

Master's Theses

The purpose of this thesis is to design a machine learning algorithm platform that provides expanded knowledge of mission availability through a launch season by improving trajectory resolution and introducing launch mission forecasting. The specific scenario addressed in this paper is one in which data is provided for four deterministic translational maneuvers through a mission to a Near Rectilinear Halo Orbit (NRHO) with a 9:2 synodic frequency. Current launch availability knowledge under NASA’s Orion Orbit Performance Team is established by altering optimization variables associated to given reference launch epochs. This current method can be an abstract task and relies on …

Micro-Nozzle Simulation And Test For An Electrothermal Plasma Thruster, Tyler J. Croteau

Master's Theses

With an increased demand in Cube Satellite (CubeSat) development for low cost science and exploration missions, a push for the development of micro-propulsion technology has emerged, which seeks to increase CubeSat capabilities for novel mission concepts. One type of micro-propulsion system currently under development, known as Pocket Rocket, is an electrothermal plasma micro-thruster.

Pocket Rocket uses a capacitively coupled plasma, generated by radio-frequency, in order to provide neutral gas heating via ion-neutral collisions within a gas discharge tube. When compared to a cold-gas thruster of similar size, this gas heating mechanism allows Pocket Rocket to increase the exit thermal velocity …

Investigating The Effect Of An Upstream Spheroid On Tandem Hydrofoils, Joel Tynan Guerra

Master's Theses

This thesis documents a series of three dimensional unsteady Reynolds Averaged Navier-Stokes CFD simulations used to investigate the influence of an upstream prolate spheroid body on tandem pitching hydrofoils. The model is validated by performing separate CFD simulations on the body and pitching hydrofoils and comparing results to existing experimental data. The simulations were run for a range of Strouhal numbers (0.2-0.5) and phase differences (0-π). Results were compared to identical simulations without an upstream body to determine how the body affects thrust generation and the unsteady flow field.

The combined time-averaged thrust increases with Strouhal number, and is highest …

Energy Harvesting Device Using Ferrofluids Slugs In Microchannels, Omkar Amar Pawar

Mechanical and Aerospace Engineering Theses - Archive

This research proposes a new concept of energy harvesting with the help of oscillating slugs of ferrofluid in microchannels. Ferrofluids are colloidal suspension of paramagnetic nanoparticles which get magnetized in the presence of magnetic field. They can conform to any shape and can be injected easily in intricate spaces. A change in the magnetic flux through the solenoid area produces electromotive force per Faraday’s law. To prove the concept of harvesting energy by having a change in magnetic flux with the help of ferrofluids, several ferrofluid slugs were made to pass through a multi turn solenoid wound around a glass …

Process Calibration For Elastically Scaled 3d Printed Models Using Fused Deposition Modeling, Edgar Bernardo Mares

Mechanical and Aerospace Engineering Theses - Archive

With the increase in additive manufacturing capabilities the use of 3D printed models characterize a critical point for evaluating aerodynamic and aeroelastic properties on aircraft configuration. An experimental and computational approach beginning with elastically scaled 3D printed models enables for a case to be defined, developed, and extracted to match aeroelastic test behavior. The basis of this work is supported by aeroelastic tailoring and scaling methods in the application of 3D printed models. To accomplish this, stiffened 3D printed plates are scaled from elastically scaled 3D printed models for stiffness through geometric configurations, different build orientations, and bead thickness as …