Aerospace Engineering Commons^™

Cfd Modeling Of Smoke Movement In An Atrium, Robin Wu

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this paper is to better understand the behavior of smoke movement in an atrium. Thus gives first responders and civilians in and out of building a better understanding

With the advancements of modern technology, computers and softwares make simulation models possible such as fire models to simulate fire and smoke movements. In this paper, a computational fluid dynamic (CFD) software Fire Dynamic Simulator (FDS) is used to conduct a series of atrium tests to investigate the effectiveness of smoke exhaust systems. FDS solves the Navier-Stokes equations appropriate for low speed flows (Ma < 0.3) with an emphasis on smoke, heat transport and CO2 concentrations from fires. The default turbulence model used in FDS simulation is the Large Eddy Simulation (LES), which is the solution of Navier-Stokes equations at low speed.

The compartment tested was 9 …

Effects Of Secondary Stall And Unsteady Free-Stream On Blade Drag And Pitching Moments, Michael Malick

McKelvey School of Engineering Graduate Student Theses & Dissertations

Dynamic stall is a complex aerodynamic phenomenon occurring in helicopter rotors, limiting the flight envelope and causing control linkage damage and instabilities. The Peters-Modarres semi-empirical dynamic stall model is extended to simulate pitching moment and drag in unsteady freestream and yawed flow, including the effects of secondary stall. The aerodynamics are implemented as a state-space model, suitable for time-marching or aeroelastic analyses. With small modifications to the original stall model, secondary stall effects and unsteady freestream can be simulated without adding additional states. An optimization routine determines sets of parameters that minimize the error between the modeled solution and experimental …

Rotating Mount For Complex Fluid Flow Research, Kirsten Murphy

Honors Theses

Fluid flow around rotating objects is mathematically complex and there is currently limited experimental data on the subject. To make Western Michigan University capable of this research, a rotating wind tunnel mount was developed. The mount design was integrated into the existing setup at the Applied Aerodynamics Laboratory (AAL) to allow seamless transitions between different research projects. Non-rotating and rotating disk prototypes were created from 3D-printed materials to test the mount’s capabilities. Experimental data gathered from utilizing this rotating mount was analyzed to understand the aerodynamic effects on rotating disks in a fluid stream. From testing the rotating disk prototype …

Rotating Mount For Complex Fluid Flow Research, Kirsten Murphy

Honors Theses

Fluid flow around rotating objects is mathematically complex and there is currently limited experimental data on the subject. To make Western Michigan University capable of this research, a rotating wind tunnel mount was developed. The mount design was integrated into the existing setup at the Applied Aerodynamics Laboratory (AAL) to allow seamless transitions between different research projects. Non-rotating and rotating disk prototypes were created from 3D-printed materials to test the mount’s capabilities. Experimental data gathered from utilizing this rotating mount was analyzed to understand the aerodynamic effects on rotating disks in a fluid stream. From testing the rotating disk prototype …

Nonupdating Methods For The Characterization Of Nonlinear Stress-Strain And Delamination Fracture Properties Of Fiber Reinforced Composites, Bastiaan Corstiaan Van Der Vossen

Mechanical and Aerospace Engineering Dissertations - Archive

Efforts to develop strength and life prediction analysis tools for aircraft composite structures have shown a great need to understand the complexity and interaction of failure modes. Many failure models are highly sensitive to transverse nonlinear shear stress-strain and delamination fracture properties, which are notoriously hard to measure. Without proper input parameters, life predictions analyses will not be successful. The objective of this work was to accurately characterize these mechanical properties of carbon fiber reinforced polymer composites through advanced experimental methods. Full-field noncontact deformation measurements using Digital Image Correlation are used to quantify all surface strains components, enabling the design …

Evaporative Hotspot Cooling Of Microprocessors Using Electrowetting On Dielectric (Ewod), Arvind Venkatesan

Mechanical and Aerospace Engineering Dissertations - Archive

The increased use of smart devices and great strides in fabrication technologies have resulted in densely packed electronics. Combined with 3D packaging, high heat uxes have become the norm. The need for advanced thermal management solutions has risen. Most devices based on their load pro le and architecture are susceptible to non-uniformities in heat uxes. These non-uniformities with very high heat uxes are known as hotspots. Mitigation of hotspots is very important for the normal functioning and long term reliability of microprocessors. Multiple attempts have been made at developing microscale thermal solutions. Most prominent among them are microchannels and heat …

Design Principles For Large Foil Bearings Based On Scaling Laws: Analyses And Experiment, Srikanth Honavara Prasad

Mechanical and Aerospace Engineering Dissertations - Archive

Gas foil bearings are used for supporting high speed turbomachinery systems. They are characterized by complex physical and thermal interactions between the lubricating fluid and the structural elements. Mathematically, the behavior of such systems is governed by nonlinear partial differential equations and pose substantial computational challenges. However, their potential applications in aerospace systems and power generation systems have renewed research and development efforts aimed at simplifying their design and analyses methods. Commercialization of gas foil bearings in Mega Watt scale applications necessitate the development of simple tools for estimating bearing design parameters such as load capacity, radial clearance, and support …

Surface Roughness Formation During Tensile Plastic Deformation Of Nickel Polycrystals, Kranthi Balusu

Mechanical and Aerospace Engineering Dissertations - Archive

Understanding the formation of surface roughness could help better diagnose a metal component’s health and could potentially help in making better microstructure design decisions. Both of these, in turn, contribute to the design of efficient structural components. In this work, the research objective is to understand the relationship between the surface microstructure (i.e., grain orientations) and the surface-height changes in nickel polycrystals undergoing small amounts of tensile plastic deformation. The secondary objective is to determine the relationship between surface height and strain localization. Primarily simulations were used, along with experimental surface roughness observations, to validate the simulation results. Discrete dislocation …

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 …