Analysis Of Shock Wave Unsteadiness Using Space And Time Correlations Applied To Shadowgraph Flow Visualization Data,
2019
University of Alabama in Huntsville
Analysis Of Shock Wave Unsteadiness Using Space And Time Correlations Applied To Shadowgraph Flow Visualization Data, Shannon Marko, Phillip M. Ligrani
PRC-Affiliated Research
Unsteady flow characteristics of a normal shock wave, a lambda foot, and a separated turbulent boundary layer are investigated within a unique test section with supersonic inlet flow. The supersonic wind tunnel facility, containing this test section, provides a Mach number of approximately 1.54 at the test section entrance. Digitized shadowgraph flow visualization data are employed to visualize shock wave structure within the test section. These data are analyzed to determine shock wave unsteadiness characteristics, including grayscale spectral energy variations with frequency, as well as time and space correlations, which give coherence and time lag properties associated with perturbations associated …
Analysis Of Shock Wave Unsteadiness Using Space And Time Correlations Applied To Shadowgraph Flow Visualization Data,
2019
University of Alabama in Huntsville
Analysis Of Shock Wave Unsteadiness Using Space And Time Correlations Applied To Shadowgraph Flow Visualization Data, Shannon Marko, Phillip M. Ligrani
PRC-Affiliated Research
Unsteady flow characteristics of a normal shock wave, a lambda foot, and a separated turbulent boundary layer are investigated within a unique test section with supersonic inlet flow. The supersonic wind tunnel facility, containing this test section, provides a Mach number of approximately 1.54 at the test section entrance. Digitized shadowgraph flow visualization data are employed to visualize shock wave structure within the test section. These data are analyzed to determine shock wave unsteadiness characteristics, including grayscale spectral energy variations with frequency, as well as time and space correlations, which give coherence and time lag properties associated with perturbations associated …
Methodology Of Topology Optimization,
2019
Western Michigan University
Methodology Of Topology Optimization, Naziha Khandoker
Honors Theses
The need for lighter products is becoming increasingly essential as it cuts material cost and significant amount of weight, which is a key factor in the automotive and aerospace industries. Topology optimization allows us to achieve that by applying the concept to different structures with the goal of optimal distribution of material within finite volume design domain. Its algorithms selectively remove and relocate elements to achieve the optimum performance. This project performs a study on the effect of each design parameter over mechanical performance using Finite Element Analysis and applies it to set of wing attachment brackets. The optimized brackets …
A Reinforcement Learning Approach To Spacecraft Trajectory Optimization,
2019
Western Michigan University
A Reinforcement Learning Approach To Spacecraft Trajectory Optimization, Daniel S. Kolosa
Dissertations
This dissertation explores a novel method of solving low-thrust spacecraft targeting problems using reinforcement learning. A reinforcement learning algorithm based on Deep Deterministic Policy Gradients was developed to solve low-thrust trajectory optimization problems. The algorithm consists of two neural networks, an actor network and a critic network. The actor approximates a thrust magnitude given the current spacecraft state expressed as a set of orbital elements. The critic network evaluates the action taken by the actor based on the state and action taken. Three different types of trajectory problems were solved, a generalized orbit change maneuver, a semimajor axis change maneuver, …
Dynamic Pressure Sensing For The Flight Test Data System,
2019
California Polytechnic State University - San Luis Obispo
Dynamic Pressure Sensing For The Flight Test Data System, Marc Y. Goupil
Master's Theses
This thesis describes the design, assembly, and test of the FTDS-K, a new device in the Boundary Layer Data System (BLDS) family of flight data acquisition systems. The FTDS-K provides high-frequency, high-gain data acquisition capability for up to two pressure sensors and an additional three low-frequency pressure sensors. Development of the FTDS-K was separated into a core module, specialized analog subsystem, and practical testing of the FTDS-K in a flow measurement mission. The core module combines an nRF52840-based microcontroller module, switching regulator, microSD card, real-time clock, temperature sensor, and trio of pressure sensors to provide the same capabilities as previous-generation …
Wall-Jet Turbulence And Mixing Control By Way Of A Pulsed Inlet Velocity,
2019
Embry-Riddle Aeronautical University
Wall-Jet Turbulence And Mixing Control By Way Of A Pulsed Inlet Velocity, Cristale D. Garnica Vallejo
Doctoral Dissertations and Master's Theses
Understanding wall-jet-induced turbulence and mixing is an important challenge in modern engineering, as drag reduction and mixing enhancement are attainable by modifying the flow development. Simulations are performed to investigate the effect on skin friction and flow mixing due to introducing controlled perturbations, at the initial shear layer of a planar wall-jet using jet inlet cyclic pulsing. The billow production by the Kelvin-Helmholtz instability, the instability that drives turbulence in a wall-jet, is modified by the excitation of the inlet velocity profile by a sine wave perturbation. Two types of wall-jet simulations are carried out, a two-dimensional compressible case at …
Large Eddy Simulation Of Coolant Flow Field And Heat Transfer In Low Aspect Ratio Incremental Impingement Pin-Fin Configurations,
2019
Louisiana State University and Agricultural and Mechanical College
Large Eddy Simulation Of Coolant Flow Field And Heat Transfer In Low Aspect Ratio Incremental Impingement Pin-Fin Configurations, Susheel Kumar Singh
LSU Doctoral Dissertations
To address the issue of variable heat load near the stagnation and the mid-chord region of a modern gas turbine blade, an incremental impingement cooling technique, which is a combination of pin-fin channel and jet impingement, is designed and explored. Large Eddy Simulation (LES), a well-known turbulence model, is used to simulate the coolant flow field and heat transfer. The streamwise (X) and the spanwise spacing (S) of the pin-fin arrangement are 1.074D and 1.625D. The aspect ratio of the pin-fin channel is 0.5D. The diameter (D) of the pin-fin is 2.54 cm. The configuration consists of five rows of …
Wind Tunnel Measurements And Data Analysis Tutorial,
2019
Minnesota State University, Mankato
Wind Tunnel Measurements And Data Analysis Tutorial, Nihad E. Daidzic
Aviation Department Publications
This tutorial gives details on processing of raw aerodynamic data measured directly in the wind tunnel on airfoils and wings. Also procedures and equations from the lab report are given and demonstrated how to compute geometric characteristics of wings/airfoils and air data. All numeric results are typically rounded to five significant digits.
Investigation Of The Under-Body Flow Field Of A Prototype Long-Range Electric Vehicle,
2019
California Polytechnic State University, San Luis Obispo
Investigation Of The Under-Body Flow Field Of A Prototype Long-Range Electric Vehicle, Matthew P. Nguyen
Master's Theses
This thesis presents changes to the design of the Prototype Vehicles Laboratory (PROVE Lab) Endurance Car, an electric car intended to break the Guinness World Record for the single-charge range of an electric vehicle. The design range is 1609.34 km, however at the design velocity of 104.6 kph, the drag is 196 N; which requires more battery capacity than the 100 kWh maximum of the baseline model. With a fixed frontal area, drag reduction can come from lowered velocity or reduced CD. CD reduction is attempted in four ways: side skirts between the fenders, a raised ride height, an elongated …
Experimental Investigation Into Utilizing Synthetic Jet Actuators To Suppress Bi-Modal Wake Behavior Behind An Ahmed Body,
2019
California Polytechnic State University, San Luis Obispo
Experimental Investigation Into Utilizing Synthetic Jet Actuators To Suppress Bi-Modal Wake Behavior Behind An Ahmed Body, Daniel Jacob Baratta
Master's Theses
Testing done on the flat-back Ahmed Body and other bluff bodies has shown the existence of a bi-stable reflectional symmetry-breaking wake at Reynolds numbers ranging from 340 to 2.41 x 106. Several methods of flow control, both active and passive, have been used to improve the efficiency of the Ahmed body but their effect on the bi-stable nature of the wake has not been investigated. This work details the experimental investigation done to determine if piezoelectrically driven synthetic jet actuators are capable of suppressing the bi-stable wake effects observed behind the Ahmed Body. The synthetic jets were designed …
A Volume-Force Synthetic Disturbance Approach For High-Fidelity Of Unsteady Fluid Structure Interactions,
2019
Embry-Riddle Aeronautical University
A Volume-Force Synthetic Disturbance Approach For High-Fidelity Of Unsteady Fluid Structure Interactions, Marina Kazarina
Doctoral Dissertations and Master's Theses
The purpose of this dissertation is to analyze the momentum source model, for generating synthetic vortical disturbance field in numerical simulations of unsteady fluid-structure interactions, access limitations of this approach, to find requirements for the computational domain, space and time resolution, and apply this model to investigate selected physical problems. For this reason a comprehensive parametric study of volume-force based method of generating spectral synthetic turbulence inside the computational domain is conducted first. The method is then extended to synthesize turbulence with arbitrary energy spectrum. The synthetic turbulence is generated through momentum source terms in Navier-Stokes equations, and the developed …
Computational Fluid Dynamics Analysis Of Inverted, Multi-Element Airfoils In Ground Effect,
2019
Washington University in St. Louis
Computational Fluid Dynamics Analysis Of Inverted, Multi-Element Airfoils In Ground Effect, Michael Grabis, Ramesh K. Agarwal
McKelvey School of Engineering Graduate Student Theses & Dissertations
Formula SAE cars are formula-styled race cars designed to race on an autocross circuit. The autocross circuit is mostly comprised of turning sections as well as a limited amount of straight sections for passing other cars. Highly competitive cars in the competition implement aerodynamic devices to generate negative lift for the race car. This negative lift, or downforce, increases the amount of traction between the race car’s tires and the ground ultimately allowing the drivers to turn at faster speeds. Commonly used aerodynamic devices are a front and rear wing; the wing cross sections are defined by configurations of multiple …
Clustering Of Rapidly Settling, Low-Inertia Particle Pairs In Isotropic Turbulence. Part 2. Comparison Of Theory And Dns,
2019
University of Alabama in Huntsville
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,
2019
University of Alabama in Huntsville
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,
2019
University of Alabama in Huntsville
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,
2019
University of Alabama in Huntsville
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,
2019
University of Alabama in Huntsville
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,
2019
University of Alabama in Huntsville
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 …
First Approach To Coupling Of Numerical Lifting-Line Theory And Linear Covariance Analysis For Uav State Uncertainty Propagation,
2019
Utah State University
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 …
A Homegrown Dsmc-Pic Model For Electric Propulsion,
2019
California Polytechnic State University, San Luis Obispo
A Homegrown Dsmc-Pic Model For Electric Propulsion, Dominic Charles Lunde
Master's Theses
Powering spacecraft with electric propulsion is becoming more common, especially in CubeSat-class satellites. On account of the risk of spacecraft interactions, it is important to have robust analysis and modeling tools of electric propulsion engines, particularly of the plasma plume. The Navier-Stokes equations used in classic continuum computational fluid dynamics do not apply to the rarefied plasma, and therefore another method must be used to model the flow. A good solution is to use the DSMC method, which uses a combination of particle modeling and statistical methods for modeling the simulated molecules. A DSMC simulation known as SINATRA has been …
