Browsing by Subject "Aerospace engineering"
Now showing items 1-20 of 22
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A General-Purpose Simulator for Evaluating Astronaut Radiation Exposure
(2021)Purpose: Current Monte Carlo simulations modeling space radiation exposure typically use simplistic human phantoms with low anatomical detail and minimal variability in physical characteristics. This thesis describes the ... -
A New Approach to Model Order Reduction of the Navier-Stokes Equations
(2012)A new method of stabilizing low-order, proper orthogonal decomposition based reduced-order models of the Navier Stokes equations is proposed. Unlike traditional approaches, this method does not rely on empirical turbulence ... -
A New Hybrid Free-Wake Model for Wind Turbine Aerodynamics with Application to Wake Steering
(2017)Wind energy has emerged as one of the most promising and rapidly growing renewable energy technologies in the United States and over the world. The offshore wind energy is of special interest because it has more consistent ... -
A Theoretical and Computational Study of Limit Cycle Oscillations in High Performance Aircraft
(2015)High performance fighter aircraft such as the F-16 experience aeroelastic Limit Cycle Oscillations (LCO) when they carry certain combinations of under-wing stores. This `store-induced LCO' causes serious problems including ... -
Aerodynamic Optimization of Helicopter Rotors using a Harmonic Balance Lifting Surface Technique
(2018)This thesis concerns the optimization of the aerodynamic performance of conventional helicopter rotors, given a set of design variables to control the rotor's pitching angle, twist and chord distributions. Two models are ... -
Aeroelastic and Flight Dynamics Analysis of Folding Wing Systems
(2013)This dissertation explores the aeroelastic stability of a folding wing using both theoretical and experimental methods. The theoretical model is based on the existing clamped-wing aeroelastic model that uses beam theory ... -
Aeroelastic Modeling of Blade Vibration and its Effect on the Trim and Optimal Performance of Helicopter Rotors using a Harmonic Balance Approach
(2020)This dissertation concerns the optimization of the aeroelastic performance of conventionalhelicopter rotors, considering various design variables such cyclic and higherharmonic controls. A nite element model is introduced ... -
Aeroelasticity and Enforced Motion Frequency Lock-in Associated with Non-Synchronous Vibrations in Turbomachinery
(2022)One of the most complex challenges in our world today is the interaction between fluids and structures. This complicated meeting is one of the focal points in the design and manufacturing of turbomachinery, whether in jet ... -
An Aeroelastic Evaluation of the Flexible Thermal Protection System for an Inflatable Aerodynamic Decelerator
(2015)The purpose of this dissertation is to study the aeroelastic stability of a proposed flexible thermal protection system (FTPS) for the NASA Hypersonic Inflatable Aerodynamic Decelerator (HIAD). A flat, square FTPS coupon ... -
Computational Studies of Buffet and Fluid-Structure Interaction in Various Flow Regimes
(2020)This dissertation explores a fluid instability known as buffet, which occurs in the subsonic, transonic, and supersonic regimes. Buffet has been observed in experiments and various computational studies, and its underlying ... -
Convolution and Volterra Series Approach to Reduced Order Modelling of Unsteady Aerodynamic Loads and Improving Piezoelectric Energy Harvesting of an Aeroelastic System
(2020)A combined approach of linear convolution and higher order Volterra series to reduced order modelling of unsteady transonic aerodynamic loads is presented. The new approach offers a simple method to determine the memory ... -
Design for Coupled-Mode Flutter and Non-Synchronous Vibration in Turbomachinery
(2013)This research presents the detailed investigation of coupled-mode flutter and non-synchronous vibration in turbomachinery. Coupled-mode flutter and non-synchronous vibration are two aeromechanical challenges in designing ... -
Further Reduction of the Fundamental Mistuning Model Using Mistuned Aeroelastic Modes
(2018)Despite decades of research and attention to the problem of mistuning in bladed disks, both industry and academic efforts have yet to yield a comprehensive design solution for the phenomenon. Regardless, reduced order models ... -
Linear Aeroelastic Stability of Beams and Plates in Three-Dimensional Flow
(2012)The aeroelastic stability of beams and plates in three-dimensional flows is explored as the elastic and aerodynamic parameters are varied. First principal energy methods are used to derive the structural equations of motion. ... -
Minimum Power Requirements and Optimal Rotor Design for Conventional, Compound, and Coaxial Helicopters Using Higher Harmonic Control
(2013)This thesis presents a method for computing the optimal aerodynamic performance of conventional, compound, and coaxial helicopters in trimmed forward flight with a limited set of design variables, including the blade's radial ... -
Multi-Row Aerodynamic Interactions and Mistuned Forced Response of an Embedded Compressor Rotor
(2016)This research investigates the forced response of mistuned rotor blades that can lead to excessive vibration, noise, and high cycle fatigue failure in a turbomachine. In particular, an embedded rotor in the Purdue Three-Stage ... -
Multi-row Aeromechanical and Aeroelastic Aspects of Embedded Gas Turbine Compressor Rotors
(2021)This research helps address one of the grand challenges of turbomachinery i.e., the accurate prediction of the forced response in multi-row compressors subjected to various crossings and operating points. Specifically, this ... -
Optimal Aerodynamic Design of Conventional and Coaxial Helicopter Rotors in Hover and Forward Flight
(2015)This dissertation investigates the optimal aerodynamic performance and design of conventional and coaxial helicopters in hover and forward flight using conventional and higher harmonic blade pitch control. First, we describe ... -
Physical Insights, Steady Aerodynamic Effects, and a Design Tool for Low-Pressure Turbine Flutter
(2016)The successful, efficient, and safe turbine design requires a thorough understanding of the underlying physical phenomena. This research investigates the physical understanding and parameters highly correlated to flutter, ... -
Rotor Vibration Reduction Using Multi-Element Multi-Path Design
(2013)Multi-Element Multi-Path (MEMP) structural design is a new concept for rotor vibration reduction. This thesis explores the possibility of applying MEMP design to helicopter rotor blades. A conceptual design is developed ...
