Engineering Commons^™

Clustering Of Rapidly Settling, Low-Inertia Particle Pairs In Isotropic Turbulence. Part 1. Drift And Diffusion Flux Closures, Sarma L. Rani, Vijay K. Gupta, Donald L. Koch

PRC-Affiliated Research

In this two-part study, we present the development and analysis of a stochastic theory for characterizing the relative positions of monodisperse, low-inertia particle pairs that are settling rapidly in homogeneous isotropic turbulence. In the limits of small Stokes number and Froude number such that , closures are developed for the drift and diffusion fluxes in the probability density function (p.d.f.) equation for the pair relative positions. The theory focuses on the relative motion of particle pairs in the dissipation regime of turbulence, i.e. for pair separations smaller than the Kolmogorov length scale. In this regime, the theory approximates the fluid …

Clustering Of Rapidly Settling, Low-Inertia Particle Pairs In Isotropic Turbulence. Part 1. Drift And Diffusion Flux Closures, Sarma L. Rani, Vijay K. Gupta, Donald L. Koch

PRC-Affiliated Research

In this two-part study, we present the development and analysis of a stochastic theory for characterizing the relative positions of monodisperse, low-inertia particle pairs that are settling rapidly in homogeneous isotropic turbulence. In the limits of small Stokes number and Froude number such that , closures are developed for the drift and diffusion fluxes in the probability density function (p.d.f.) equation for the pair relative positions. The theory focuses on the relative motion of particle pairs in the dissipation regime of turbulence, i.e. for pair separations smaller than the Kolmogorov length scale. In this regime, the theory approximates the fluid …

Clustering Of Rapidly Settling, Low-Inertia Particle Pairs In Isotropic Turbulence. Part 2. Comparison Of Theory And Dns, Sarma L. Rani, Rohit Dhariwal, Donald L. Koch

PRC-Affiliated Research

Part 1 (Rani et al. J. Fluid Mech. , vol. 871, 2019, pp. 450–476) of this study presented a stochastic theory for the clustering of monodisperse, rapidly settling, low-Stokes-number particle pairs in homogeneous isotropic turbulence. The theory involved the development of closure approximations for the drift and diffusion fluxes in the probability density function (p.d.f.) equation for the pair relative positions $\boldsymbol{r}$ . In this part 2 paper, the theory is quantitatively analysed by comparing its predictions of particle clustering with data from direct numerical simulations (DNS) of isotropic turbulence containing particles settling under gravity. The simulations were performed at …

Clustering Of Rapidly Settling, Low-Inertia Particle Pairs In Isotropic Turbulence. Part 1. Drift And Diffusion Flux Closures, Sarma L. Rani, Vijay K. Gupta, Donald L. Koch

PRC-Affiliated Research

In this two-part study, we present the development and analysis of a stochastic theory for characterizing the relative positions of monodisperse, low-inertia particle pairs that are settling rapidly in homogeneous isotropic turbulence. In the limits of small Stokes number and Froude number such that , closures are developed for the drift and diffusion fluxes in the probability density function (p.d.f.) equation for the pair relative positions. The theory focuses on the relative motion of particle pairs in the dissipation regime of turbulence, i.e. for pair separations smaller than the Kolmogorov length scale. In this regime, the theory approximates the fluid …

Clustering Of Rapidly Settling, Low-Inertia Particle Pairs In Isotropic Turbulence. Part 2. Comparison Of Theory And Dns, Sarma L. Rani, Rohit Dhariwal, Donald L. Koch

PRC-Affiliated Research

Part 1 (Rani et al. J. Fluid Mech. , vol. 871, 2019, pp. 450–476) of this study presented a stochastic theory for the clustering of monodisperse, rapidly settling, low-Stokes-number particle pairs in homogeneous isotropic turbulence. The theory involved the development of closure approximations for the drift and diffusion fluxes in the probability density function (p.d.f.) equation for the pair relative positions $\boldsymbol{r}$ . In this part 2 paper, the theory is quantitatively analysed by comparing its predictions of particle clustering with data from direct numerical simulations (DNS) of isotropic turbulence containing particles settling under gravity. The simulations were performed at …

Keeping Your Library Relevant For Your Users- Engine Parts Petting Zoo, Gabriele Hysong

Midwest Business Librarian Summit (MBLS)

As corporate libraries are downsized or even closed how do information professionals keep their libraries relevant?

Comparative Analysis Of Small Unmanned Aircraft Systems Operations Manuals, Stephen M. Cigal

Student Works

With over 100,000 remote pilots in the United States, individuals and companies are rapidly incorporating unmanned aircraft system technologies into their everyday life and businesses models. The companies that use these technologies must comply with federal and state regulations in order to maintain a safe environment to operate. These operations must also be accepted by the general public. Since the FAA regulations for small unmanned aircraft systems (sUAS) went into effect in 2016, supplemented by additional state and/or local requirements, some companies have generated operations manuals (OM) to ensure consistent, safe flight that meets these requirements. By analyzing the OM’s …

How Vision Governs The Collective Behaviour Of Dense Cycling Pelotons, J. Belden, Mohammad M. Mansoor, A. Hellum, S. R. Rahman, A. Meyer, C. Pease, J. Pacheco, S. Koziol, Tadd T. Truscott

Mechanical and Aerospace Engineering Faculty Publications

In densely packed groups demonstrating collective behaviour, such as bird flocks, fish schools or packs of bicycle racers (cycling pelotons), information propagates over a network, with individuals sensing and reacting to stimuli over relatively short space and time scales. What remains elusive is a robust, mechanistic understanding of how sensory system properties affect interactions, information propagation and emergent behaviour. Here, we show through direct observation how the spatio-temporal limits of the human visual sensory system govern local interactions and set the network structure in large, dense collections of cyclists. We found that cyclists align in patterns within a ± 30° …

Computational Analysis Of 3d Lattice Structures For Skin In Real-Scale Camber Morphing Aircraft, Bashir Alsaidi, Woong Yeol Joe, Muhammad Akbar

Mechanical and Manufacturing Engineering Faculty Research

Conventional or fixed wings require a certain thickness of skin material selection that guarantees structurally reliable strength under expected aerodynamic loadings. However, skin structures of morphing wings need to be flexible as well as stiff enough to deal with multi-axial structural stresses from changed geometry and the coupled aerodynamic loadings. Many works in the design of skin structures for morphing wings take the approach either of only geometric compliance or a simplified model that does not fully represent 3D real-scale wing models. Thus, the main theme of this study is (1) to numerically identify the multi-axial stress, strain, and deformation …

Range Of Motion Evaluation Of A Final Frontier Design Iva Spacesuit Using Motion Capture, Ryan L. Kobrick, Nicholas Lopac, Chase Covello, Benjamin Banner, Theodore Southern, Nikolay Moiseev

Publications

Embry-Riddle Aeronautical University’s Spacesuit Utilization of Innovative Technology Laboratory (S.U.I.T. Lab) is focused on improving human performance in spaceflight by concentrating on spacesuit research for intravehicular activities (IVA) and extravehicular activities (EVA). The design and execution of range of motion (ROM) protocols in an experimental setting will provide insight on the functions and restrictions of spacesuits, aiding in current and future designs or modification. The S.U.I.T. Lab worked with Final Frontier Design (FFD) to provide a quantitative analysis protocol for seated arm mobility of their NASA Flight Opportunities Program (FOP) IVA spacesuit. The lab used reflective tracking markers on three …

Keeping Your Distance: The Science Of Turns-Around-A-Point And Ground Reference Maneuvers, Nihad E. Daidzic

Aviation Department Publications

Ground reference maneuvers are more important than you may think. Frequently regarded as unimportant or boring, ground reference maneuver training is often limited to a few minutes of flight instructor demonstration and brief student practice.

Manipulating Fiber Orientation For The Reduction Of Warpage In Carbon Fiber Composite Sandwich Panels, Landon Burnley, Gabrielle Correia

Materials Engineering

Safran Cabin (Santa Maria, CA), previously known as Zodiac Aerospace, designs and manufactures interior cabin components for private and commercial aircraft. Carbon fiber face sheets have recently been incorporated in their overhead luggage bin assemblies which utilize a composite sandwich panel design, in order to provide additional stiffness to the previous glass fiber sandwich panels. Since the introduction of carbon fiber in these luggage bin panels, Safran has experienced an increase in warpage during manufacturing. When inspected by quality control, the panels are tested mimicking how they are installed in aircraft. If the panels do not meet specifications, the warped …

Spatially Continuous Strain Monitoring Using Distributed Fiber Optic Sensors Embedded In Carbon Fiber Composites, Sasi Jothibasu, Yang Du, Sudharshan Anandan, Gurjot S. Dhaliwal, Rex E. Gerald Ii, Steve Eugene Watkins, K. Chandrashekhara, Jie Huang

Electrical and Computer Engineering Faculty Research & Creative Works

A distributed fiber optic strain sensor based on Rayleigh backscattering, embedded in a fiber-reinforced polymer composite, has been demonstrated. The optical frequency domain reflectometry technique is used to analyze the backscattered signal. The shift in the Rayleigh backscattered spectrum is observed to be linearly related to the change in strain of the composite material. The sensor (standard single-mode fiber) is embedded between the layers of the composite laminate. A series of tensile loads is applied to the laminate using an Instron testing machine, and the corresponding strain distribution of the laminate is measured. The results show a linear response indicating …

The Effects Of Atomic Oxygen On Patch Antenna Performance And Lifetime, Max J. Barta

Master's Theses

The space environment is a volatile and challenging place for satellites to survive in. For Low Earth Orbiting (LEO) satellites, atomic oxygen (AO) is a constant corrosive effect that degrades the outer surface of satellites over long durations. Atomic oxygen exists in the atmosphere between 180 and 675 km and has a relatively high energy at 4.5 eV, which allows AO to break molecular bonds in materials on the surfaces of spacecraft. As the number and complexity of CubeSat missions increase, there is an increased risk that AO degradation on commercial off the shelf parts (COTS), such as antenna, could …

Investigation Of Fundamental Principles Of Rigid Body Impact Mechanics, Khalid Alluhydan

Mechanical Engineering Research Theses and Dissertations

In impact mechanics, the collision between two or more bodies is a common, yet a very challenging problem. Producing analytical solutions that can predict the post-collision motion of the colliding bodies require consistent modeling of the dynamics of the colliding bodies. This dissertation presents a new method for solving the two and multibody impact problems that can be used to predict the post-collision motion of the colliding bodies. Also, we solve the rigid body collision problem of planar kinematic chains with multiple contacts with external surfaces.

In the first part of this dissertation, we study planar collisions of Balls and …

First Approach To Coupling Of Numerical Lifting-Line Theory And Linear Covariance Analysis For Uav State Uncertainty Propagation, Cory D. Goates, Randall S. Christensen, Robert C. Leishman

Faculty Publications

Numerical lifting-line is a computationally efficient method for calculating aerodynamic forces and moments on aircraft. However, its potential has yet to be tapped for use in guidance, navigation, and control (GN&C). Linear covariance analysis is becoming a popular GN&C design tool and shows promise for pairing with numerical lifting-line. Pairing numerical lifting-line with linear covariance analysis allows for forward propagation of state uncertainty for real-time decision making. We demonstrate this for select state variables in a drone aerial recapture situation. Linear covariance analysis uses finite difference derivatives obtained from numerical lifting-line to calculate force and moment variances. These show agreement …

Distributed State Estimation By Using Active-Passive Sensor Networks, Akhilesh Raj, S. Jagannathan, Tansel Yucelen

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes a novel adaptive observer for heterogeneous sensor networks (HSNs) to estimate state vector of an unknown target or process by using the sensed output when the input to the target/process is also not known. In an HSN, nodes are considered either active or passive depending upon their ability to sense the target output. The local information exchange among the nodes is dictated by a connected graph. By using the criterion of collective observability, a novel distributed adaptive estimation is introduced where the nodes are allowed to have different sensor modalities. Stability analysis shows uniform ultimate boundedness of …

The Potentiality Of Space Enterprise Force Reconstitution: Nationalizing Civilian Satellites During Kinetic Conflicts, Robert A. Bettinger, Sara Schmitt

Faculty Publications

This article will discuss the possibility of employing a policy of civilian satellite nationalization during a space war as a means of US Space Enterprise force re- constitution to ensure continued access to space capabilities necessary for the execution of the national strategy, as well as deterring potential adversaries from initiating counterspace hostilities. In terms of structure, the authors will examine the thesis by answering these questions. First, what historical precedent exists for the rapid military acquisition of civilian assets via nationalization? Second (given the unique nature of space as an operational environment), can that historical precedent be applied to …

Active-Passive Dynamic Consensus Filters For Linear Time-Invariant Multiagent Systems, J. Daniel Peterson, Tansel Yucelen, S. Jagannathan

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Active-passive dynamic consensus filters consist of a group of agents, where a subset of these agents is able to observe a quantity of interest (i.e. active agents) and the rest are subject to no observations (i.e. passive agents). Specifically, the objective of these filters is that the states of all agents are required to converge to the weighted average of the set of observations sensed by the active agents. Existing active-passive dynamic consensus filters in the classical sense assume that all agents can be modeled as having single integrator dynamics, which may not always hold in practice. Motivating from this …

Stabilization Of Homoclinic Orbits Of Two Degree-Of-Freedom Underactuated Systems, Nilay Kant, Ranjan Mukherjee, Hassan K. Khalil

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A hybrid controller for stabilization of homoclinic orbits of two degree-of-freedom (DOF) underactuated systems is proposed. The controller is comprised of continuous-time inputs, impulsive brakings, and virtual impulsive inputs for resetting of the passive coordinate. Impulsive brakings of the active coordinate result in instantaneous negative changes in the mechanical energy of the system. An impulsive dynamical system framework is adopted for modeling the hybrid dynamics and a Lyapunov function is defined for stabilization of the orbit. Sufficient conditions for stabilization are presented such that the Lyapunov function decreases monotonically under the action of the continuous inputs and undergoes negative jumps …

Prediction Of Noise Associated With An Isolated Uav Propeller, Samuel O. Afari

Doctoral Dissertations and Master's Theses

The emergent field of interest in the Urban Air Mobility community is geared towards a world where aerial vehicles are commonplace. This poses the problem of the effects of the radiated noise. The present research presents an in-depth analysis of the noise generation mechanism of a propeller as a mode of propulsion of the said aerial vehicles. Numerical simulation utilizing a Hybrid Large-Eddy Simulation (LES) coupled with Unsteady Reynolds-Averaged Navier-Stokes (RANS) solver, is adopted on an isolated propeller modeled from the commercial DJI Phantom II 9450 propeller. The Spalart-Allmaras one equation turbulence model with rotation/curvature correction is used. The Farassat’s …

Periodic Orbit Analytic Construction In The Circular Restricted Three-Body Problem, Jay Shriram Suryawanshi

Mechanical & Aerospace Engineering Theses & Dissertations

This thesis investigates an approximate analytic construction of halo-type periodic orbits about the collinear equilibrium points in the circular restricted three-body problem. The research follows a parallel approach to the one used by Ghazy and Newman, but the initial assumptions and utilized functions are unique to this thesis. A suppositional base solution constructed using Jacobi elliptic functions and satisfying Jacobi's integral equation is at the core of the analytic construction framework. The locus of this solution is a circle lying in the plane perpendicular to the line joining the primaries. The base solution elicits a closed-form expression for the period …

Reducing The Noise Impact Of Unmanned Aerial Vehicles By Flight Control System Augmentation, Matthew B. Galles

Mechanical & Aerospace Engineering Theses & Dissertations

The aim of this thesis is to explore methods to reduce the noise impact of unmanned aerial vehicles operating within acoustically sensitive environments by flight control system augmentation. Two methods are investigated and include: (i) reduction of sound generated by vehicle speed control while flying along a nominal path and (ii) reduction of acoustic exposure by vehicle path control while flying at a nominal speed. Both methods require incorporation of an acoustic model into the flight control system as an additional control objective and an acoustic metric to characterize primary noise sources dependent on vehicle state. An acoustic model was …

A Set-Theoretic Model Reference Adaptive Control Architecture With Dead-Zone Effect, Ehsan Arabi, Tansel Yucelen

Mechanical and Aerospace Engineering Faculty Research & Creative Works

By introducing a system error dependent learning rate, the recently proposed set-theoretic model reference adaptive control architecture provides user-defined worst-case performance guarantees on the system error between an uncertain dynamical system of interest and a given reference model. In this architecture, the adaptation process is always active. However, it is of practical interest to stop the adaptation process when it is not needed (i.e., in the presence of small system errors). Motivated from this standpoint, we present a new set-theoretic model reference adaptive control architecture with dead-zone effect. The key feature of our framework utilizes a modified and continuous generalized …

Event-Triggered Adaptive Distributed State Estimation By Using Active-Passive Sensor Networks, Akhilesh Raj, S. Jagannathan, Tansel Yucelen

Electrical and Computer Engineering Faculty Research & Creative Works

This paper proposes a novel event-triggered adaptive observer for each node in the heterogeneous sensor networks (HSNs) in order to estimate state vector of an unknown target or process by using the sensed output when the input to the target/ process is unknown. A subset of nodes in the HSN referred to as active nodes, can sense the target periodically, estimate the target state vector by using their adaptive observer and can communicate the estimated state vector of the target with the neighboring nodes including passive nodes only at event triggered instants. The adaptive observer parameters of active nodes are …

Design Principles And Preliminary Testing Of A Micropropulsion Electrospray Thruster Research Platform, Will Alan Mcgehee

Master's Theses

The need for micropropulsion solutions for spacecraft has been steadily increasing as scientific payloads require higher accuracy maneuvers and as the use of small form-factor spacecraft such as CubeSats becomes more common. Of the technologies used for this purpose, electrospray thrusters offer performance that make them an ideal choice. Electrosprays offer high accuracy impulse bits at low power and high efficiency, and have low volume requirements. Design choice reasoning and preliminary testing results are presented for two electrospray thruster designs. The first thruster, named the Demonstration thruster, is operated in atmospheric conditions and serves as a highly visible example of …

Experimental Analysis Of The Automated Fiber Placement Manufacturing Parameters For High And Low Tack Prepreg Material, Anis Baz Radwan

Theses and Dissertations

Automated Fiber Placement (AFP) is a flexible but complex manufacturing technique which is used to layup carbon fiber tows into flat or curved structures. That could be achieved through linear and steered paths of fibers. The quality of AFP layup is highly dependent on the manufacturing process parameters such as layup temperature, tow feedrate, compaction force, and tow tension. Understanding how those parameters affect the process is crucial for achieving the desirable quality and productivity. For this work, an experimental investigation is carried out to determine the processing window that yields optimal quality for two types of material: High tack …

Development Of An Automated Fiber Placement Process For The Fabrication Of Thermoplastic Composite Laminates, Anthony M. Sabido

Theses and Dissertations

An automated fiber placement process is desired for manufacturing variable-stiffness thermoplastic composite laminates. By developing such a composite laminate, it is possible to take advantage of the tunable performance increases that are achievable by spatially steering individual tows. In addition, using a thermoplastic polymer as the matrix material has many advantages: a high toughness, ability to employ thermoplastic joining processes that do not require adhesives, long storage life, and lacks the need to be refrigerated. This process was experimentally developed, where the effect of various process parameters on the quality of the laminate were evaluated. An experimental AFP head was …

Spacecraft Trajectory Planning For Optimal Observability Using Angles-Only Navigation, Francisco José Franquiz

Doctoral Dissertations and Master's Theses

This work leverages existing techniques in angles-only navigation to develop optimal range observability maneuvers and trajectory planning methods for spacecraft under constrained relative motion. The resulting contribution is a guidance method for impulsive rendezvous and proximity operations valid for elliptic orbits of arbitrary eccentricity.

The system dynamics describe the relative motion of an arbitrary number of maneuvering (chaser) spacecraft about a single non-cooperative resident-space-object (RSO). The chaser spacecraft motion is constrained in terms of the 1) collision bounds of the RSO, 2) maximum fuel usage, 3) eclipse avoidance, and 4) optical sensor field of view restrictions. When more than one …

Machine Learning Methods For Rapid Inspection Of Automated Fiber Placement Manufactured Composite Structures, Christopher Sacco

Theses and Dissertations

The advanced manufacturing capabilities provided through the automated fiber placement (AFP) system has allowed for faster layup time and more consistent production across a number of different geometries. This contributes to the modern production of large composite structures and the widespread adaptation of composites in industry in general and aerospace in particular. However, the automation introduced in this process increases the difficulty of quality assurance efforts and inspection. The AFP process can induce a number of manufacturing defects including wrinkles, twists, gaps, and overlaps. The manual identification of these defects is often laborious and requires a measure of expert knowledge. …