Aerodynamics and Fluid Mechanics Commons^™

Numerical Investigation On Charring Ablator Geometric Effects: Study Of Stardust Sample Return Capsule Heat Shield, Haoyue Weng, Alexandre Martin

Mechanical Engineering Faculty Publications

Sample geometry is very influential in small charring ablative articles where 1D assumption might not be accurate. In heat shield design, 1D is often assumed since the nose radius is much larger than the thickness of charring. Whether the 1D assumption is valid for the heat shield is unknown. Therefore, the geometric effects of Stardust sample return capsule heat shield are numerically studied using a material response program. The developed computer program models material charring, conductive heat transfer, surface energy balance, pyrolysis gas transport and orthotropic material properties in 3D Cartesian coordinates. Simulation results show that the centerline temperatures predicted …

Evaporative Vapor Deposition For Depositing 2d Materials, Kevin Gleason

Electronic Theses and Dissertations

The development of a new deposition technique called evaporative vapor deposition (EVD) is reported, allowing deposition and formation of atomically-thin, large area materials on arbitrary substrates. This work focuses on the highly popular monolayer material – graphene oxide (GO). A droplet of a GO solution is formed on a heated polymer substrate, and maintained at steady-state evaporation (all droplet parameters are held constant over time). The polymer substrate is laser patterned to control the droplet's contact line dynamics and the droplet's contact angle is maintained using a computer controlled syringe pump. A room temperature silicon wafer is translated through the …

Magnus Effect In Duct Flow, Jesse S. Batko, Cameron W. Clarke, Kenneth W. Smith Jr.

Williams Honors College, Honors Research Projects

The following research paper details the preliminary research carried out by this team. The project was originally conceived to determine if Magnus Lift could be utilized in an unconventional way to assist rockets during takeoff. Several conceptual designs were proposed, but the idea was scrapped when it became apparent that the team would not be able to generate the desired lift without inducing significant amounts of drag and additional weight on a rocket. Instead, the team focused on researching an interesting topic that hasn’t been previously explored: Magnus lift on a cylinder within a duct.

An experimental procedure that could …

Experimental Investigation Of Wall Shear Stress Modifications Due To Turbulent Flow Over An Ablative Thermal Protection System Analog Surface, Jacob Helvey

Theses and Dissertations--Mechanical and Aerospace Engineering

Modifications were made to the turbulent channel flow facility to allow for fully developed rough quasi-2D Poiseuille flow with flow injection through one surface and flow suction through the opposing surface. The combination of roughness and flow injection is designed to be analogous to the flow field over a thermal protection system which produces ablative pyrolysis gases during ablation. It was found that the additional momentum through the surface acted to reduce skin friction to a point below smooth-wall behavior. This effect was less significant with increasing Reynolds number. It was also found that the momentum injection modified the wake …

Modeling Of Spallation Phenomenon In An Arc-Jet Environment, Raghava Sai Chaitanya Davuluri

Theses and Dissertations--Mechanical and Aerospace Engineering

Space vehicles, while entering the planetary atmosphere, experience high loads of heat. Ablative materials are commonly used for a thermal protection system, which undergo mass removal mechanisms to counter the heat rates. Spallation is one of the ablative processes, which is characterized by the ejection of solid particles from the material into the flow. Numerical codes that are used in designing the heat shields ignore this phenomenon. Hence, to evaluate the effectiveness of spallation phenomenon, a numerical model is developed to compute the dynamics and chemistry of the particles. The code is one-way coupled to a CFD code that models …

High Temperature Flow Solver For Aerothermodynamics Problems, Huaibao Zhang

Theses and Dissertations--Mechanical and Aerospace Engineering

A weakly ionized hypersonic flow solver for the simulation of reentry flow is firstly developed at the University of Kentucky. This code is the fluid dynamics module of known as Kentucky Aerothermodynamics and Thermal Response System (KATS). The solver uses a second-order finite volume approach to solve the laminar Navier– Stokes equations, species mass conservation and energy balance equations for flow in chemical and thermal non-equilibrium state, and a fully implicit first-order backward Euler method for the time integration. The hypersonic flow solver is then extended to account for very low Mach number flow using the preconditioning and switch of …

Inkjet Printing: Facing Challenges And Its New Applications In Coating Industry, Sadegh Poozesh

Theses and Dissertations--Mechanical and Aerospace Engineering

This study is devoted to some of the most important issues for advancing inkjet printing for possible application in the coating industry with a focus on piezoelectric droplet on demand (DOD) inkjet technology. Current problems, as embodied in liquid filament breakup along with satellite droplet formation and reduction in droplet sizes, are discussed and then potential solutions identified. For satellite droplets, it is shown that liquid filament break-up behavior can be predicted by using a combination of two pi-numbers, including the Weber number, We and the Ohnesorge number, Oh, or the Reynolds number, Re, and the Weber number, …

Magnus Effect In Duct Flow, Cameron W. Clarke, Jesse S. Batko, Kenneth W. Smith Jr.

Williams Honors College, Honors Research Projects

The following research paper details the preliminary research carried out by this team. The project was originally conceived to determine if Magnus Lift could be utilized in an unconventional way to assist rockets during takeoff. Several conceptual designs were proposed, but the idea was scrapped when it became apparent that the team would not be able to generate the desired lift without inducing significant amounts of drag and additional weight on a rocket. Instead, the team focused on researching an interesting topic that hasn’t been previously explored: Magnus lift on a cylinder within a duct. An experimental procedure that could …

Planar Laser Induced Fluorescence Experiments And Modeling Study Of Jets In Crossflow At Various Injection Angles, Luke Thompson

Electronic Theses and Dissertations

Planar Laser Induced Fluorescence (PLIF) with acetone seeding was applied to measure the scalar fields of an axisymmetric freejet and an inclined jet-in-crossflow as applicable to film cooling. From the scalar fields, jet-mixing and trajectory characteristics were obtained. In order to validate the technique, the canonical example of a nonreacting freejet of Reynolds Numbers 900-9000 was investigated. Desired structural characteristics were observed and showed strong agreement with computational modeling. After validating the technique with the axisymmetric jet, the jet-in-crossflow was tested with various velocity ratios and jet injection angles. Results indicated the degree of wall separation for different injection angles …

Use Of Single Stage Model Rockets To Teach Some Engineering Principles And Practices To First Year Engineering And Engineering Technology Students, Hüseyin Sarper, Linda Vahala

Electrical & Computer Engineering Faculty Publications

Model rocketry has been called miniature astronautics; a technology in miniature, a hobby, a sport, a technological recreation, an educational tool, and it is all of these things. This paper will describe student projects using model rockets and engines to learn engineering principles for launching rockets and determining the apogee. Model rocketry is a powerful tool for instructors who wish to incorporate science, technology, engineering, and mathematics into a fun, engaging, and challenging activity for first year engineering students. The apogee can be determined using four distinct methods: trigonometry using hand held angle measuring tools, onboard altimeter devices, analytical calculations …

Identification Of Hydrodynamic Forces Developed By Flapping Fins In A Watercraft Propulsion Flow Field, Erdem Aktosun

LSU New Orleans Theses and Dissertations

In this work, the data analysis of oscillating flapping fins is conducted for mathematical model. Data points of heave and surge force obtained by the CFD (Computational Fluid Dynamics) for different geometrical kinds of flapping fins. The fin undergoes a combination of vertical and angular oscillatory motion, while travelling at constant forward speed. The surge thrust and heave lift are generated by the combined motion of the flapping fins, especially due to the carrier vehicle’s heave and pitch motion will be investigated to acquire system identification with CFD data available while the fin pitching motion is selected as a function …

Design And Dynamic Analysis Of A Variable-Sweep, Variable-Span Morphing Uav, Nirmit Prabhakar

Doctoral Dissertations and Master's Theses

Morphing wings have the potential to optimize UAV performance for a variety of flight conditions and maneuvers. The ability to vary both the wing sweep and span can enable maximum performance for a diverse range of flight regimes. For example, low-speed missions can be optimized using a wing with high aspect ratio and no wing sweep whereas high-speed missions are optimized with low aspect ratio wings and large wing sweep. Different static morphing wing configurations clearly result in varying aerodynamics and, as a result, varying dynamic modes. Another important consideration, however, is the transient dynamics that occur when transitioning between …

Cold Flow Performance Of A Ramjet Engine, Harrison G. Sykes

Master's Theses

The design process and construction of the initial modular ramjet attachment to the Cal Poly supersonic wind tunnel is presented. The design of a modular inlet, combustor, and nozzle are studied in depth with the intentions of testing in the modular ramjet. The efforts undertaken to characterize the Cal Poly supersonic wind tunnel and the individual component testing of this attachment are also discussed. The data gathered will be used as a base model for future expansion of the ramjet facility and eventual hot fire testing of the initial components. Modularity of the inlet, combustion chamber, and nozzle will allow …

Mitigation Of Moving Shocks In An Expanding Duct, Veraun Chipman

UNLV Theses, Dissertations, Professional Papers, and Capstones

Inviscid flow theory governs the bulk motion of a gas at some distance away from the walls (i.e. outside the boundary layer). That is to say, there are no viscous forces in the bulk flow, which is modeled using the Euler equations. The Euler equations are simply the Navier-Stokes equations with zero viscosity terms. An ideal inviscid fluid, when brought into contact with a surface or wall, would naturally slip right past it since the fluid has no viscosity. In real life, however, a thin boundary layer forms between the wall or surface and the bulk flow. Shock wave boundary …

Achieving Global Range In Future Subsonic And Supersonic Airplanes, Nihad E. Daidzic Ph.D., Sc.D.

International Journal of Aviation, Aeronautics, and Aerospace

No commercial airplane in service today is able to fly half great-circle distances over the globe and achieve the non-stop or the global range to any antipodal location on Earth. A subsonic jetliner has the optimum cruising speed at Mach numbers approaching the drag divergence Mach number while still preserving relatively high aerodynamic efficiency. Various fuel-flow laws were used to investigate the cruise performance of subsonic and supersonic aircraft. The effect of wind and aircraft weight and how it affects the optimal cruising airspeed was investigated. Of all different operational cruising techniques, the cruise-climb at high Mach numbers is the …

Aerodynamic Optimization Of Box Wing – A Case Study, Adeel Khalid, Parth Kumar

International Journal of Aviation, Aeronautics, and Aerospace

The optimization of a possible medium range box wing commercial airliner is presented in three stages. Preliminary research is used to determine various parameters for a potential box wing model, and a baseline model is designed in Autodesk Inventor, based upon the cantilever Airbus A330-200, an aircraft of a similar role. The Computational Fluid Dynamics (CFD) software used in this project is Dassault Systèmes SolidWorks, which is validated through comparing the NACA 0009 airfoil lift and drag polars with published results. The first stage of optimization is performed on the airfoil shape, with 8 different designs being tested against the …

A Cfd Investigation Of The Hydrodynamic Characteristics Of Fluid Flow Through An Impeller And Multi-Objective Design Optimization Of A Centrifugal Pump, Mohammed Khammat Sagban

Doctoral Dissertations and Master's Theses

In this thesis, the first part is conducting an investigation of the hydrodynamic characteristics (pressure and velocity) of fluid flow (water) through an impeller of a centrifugal pump. To illustrate a one-dimensional model is used to identify an impeller of a GDM 10 x 12 HD centrifugal pump using Vista CPD design and BladeGen tool. A three-dimensional model is then built with a commercial software package ANSYS Blade Modeler. The structured mesh of the impeller blade is obtained by using TurboGrid system. The volute of the centrifugal pump is built in ANSYS geometry, and an unstructured mesh is accomplished by …

Exploration Of A Computational Fluid Dynamics Integrated Design Methodology For Potential Application To A Wind Turbine Blade, Gaurav Kapoor

Doctoral Dissertations and Master's Theses

The main purpose of this thesis is to conduct a parametric sensitivity study on the blade design of AOC 15/50 wind turbine based on a CFD approach and optimize the blade design for maximizing the power output. The ANSYS® Fluent® flow solver using the k-ω SST turbulence model was validated by simulating the flow over two dimensional airfoils comprising the AOC 15/50 wind turbine blade. The CFD results have shown a considerable agreement with the experimental data for the airfoils. Parametric correlation study and sensitivity analysis were conducted by performing actual flow simulations over the turbine blade using ANSYS® Fluent®. …

Investigation Of Conjugate Heat Transfer In Fluid-Structure Interaction Modeling Using Openfoam, Andrew Brown

Aerospace Engineering

No abstract provided.

Crossflow Instability And Transition On A Circular Cone At Angle Of Attack In A Mach-6 Quiet Tunnel, Christopher A. C Ward

Open Access Dissertations

To investigate the effect of roughness on the stationary crossflow vortices, roughness elements 2 inches from the nosetip were created in a Torlon insert section of a 7-deg half-angle cone at 6-deg angle of attack in the Boeing/AFOSR Mach-6 Quiet Tunnel. Roughness elements with depths and diameters on the order of 500 microns were found to have a significant effect on the generation of the stationary vortices and the location of crossflow-induced transition under quiet flow. Crossflow-induced transition was measured under fully quiet flow. The controlled roughness elements also appeared to dominate the generation of the vortices, overwhelming the effect …

Characterization And Low-Dimensional Modeling Of Urban Fluid Flow, Dietmar Rempfer, Candace Wark, Bruno Monnier, Sriharsha Kandala

Publications

This report describes work that was done under AFOSR Contract Number FA9550-11-1-0056, studying the structure of a model urban boundary layer flow. The model geometry consisted of a set of plexiglass blocks, and the flow around this geometry was studied both experimentally as well as computationally. For the experiment, a Stereoscopic Particle Image Velocimetry (SPIV) method was developed that allows for a three-dimensional description of this urban flow, and helps gain insight into the characteristic flow structures in the streets and canyons of our model urban geometry. On the computational side, a new spectral-element code was developed that was demonstrated …

Laminar Deflagrated Flame Interaction With A Fluidic Jet Flow For Deflagration-To-Detonation Flame Acceleration, Joseph P. Mcgarry

Mechanical & Aerospace Engineering Theses & Dissertations

The concept of the Pulse Detonation Engine (PDE) has been of interest for centuries. The issue was originally studied to understand flame propagation in mine shafts after explosions due to methane buildup. The flames would travel down the shafts, transitioning to turbulent flames due to the roughness of the shaft walls, and accelerate to detonation, delivering powerful, destructive forces. The potential for efficient energy production was noticed, and the theory behind flame propagation was later applied to developing propulsion systems. Recently, researchers have begun to understand the full potential of PDEs to efficiently produce an immense amount of thrust due …

An Experimental Study Of The Implementation Of A Fluid Diode Inside A Sano Shunt, Patrick Austin Lane

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Fluid diodes are fluidic devices that enhance fluid flow in a particular direction while inhibiting it in the opposite direction without the use of moving parts. This is accomplished through the use of nozzle shaped geometry on one side of the diode, and cusp shaped geometry on the opposing side. Fluid meets very little resistance as is travels though the nozzle side of the diode. The cusps on the other side of the diode reduce the effective flow area, thereby inhibiting flow. The objective of this study is to determine the effectiveness of a fluid diode installed in a reconstructed …

Noise Source Analysis For Simulated Turbulent Jets, Robert W. Skidmore, Nitin S Dhamankar, Kurt M. Aikens, Gregory Blaisdell

The Summer Undergraduate Research Fellowship (SURF) Symposium

Large Eddy Simulation (LES) is an efficient computational approach to study turbulent flows and has seen increasing application to the study of jet noise. The main challenge of LES has been the realistic simulation of experiments at reasonable cost. Recent LES studies have been realistic enough to gain important insight into jet noise from the large amount of data generated. This study attempts to characterize the sources of noise from a turbulent jet via analysis of the LES results. Three different analysis tools are implemented. The first two are comparable to analyses used on experimental data: two-point cross-correlations between far-field …

Microthruster Fabrication And Characterization: In Search Of The Optimal Nozzle Geometry For Microscale Rocket Engines, Katherine L. Fowee, Alina Alexeenko

The Summer Undergraduate Research Fellowship (SURF) Symposium

A major consideration in microsatellite design is the engineering of micropropulsion systems that can deliver the required thrust efficiently with tight restrictions on space, weight, and power. Cold gas thrusters are one solution to the demand for smaller propulsion systems to accommodate the advancements in technology that have allowed for a reduction in the size and thus the cost of satellites. While much research has been done in understanding the flow regimes within these microthrusters, there is a need to understand how different nozzle designs affect microthruster performance. This requires that experimental data be collected on varying nozzles shapes (orifices, …

Particle Image Velocimetry Of Transverse Jets In Crossflow, Jesse K. Tsai, Kayla Kuzmich, David Forliti, Kriss Vanderhyde, Nils Sedano

STAR Program Research Presentations

The jet in crossflow (JICF) has been an ongoing study for the past several decades with applications in the field of fluid mechanics. This particular flow field produces vortical structures tied to the entrainment and mixing of two separate fluids. Research of the JICF seeks to determine a model and trajectory scaling law for future designs. This will help future designers to optimize the mixing and homogeneity of the two fluids to decrease emissions from pollutants, make ignition easier, and improve combustion efficiency of rockets.

Our experiment will employ Particle Image Velocimetry (PIV) to determine the fluid motion of the …

Effect Of Adaptive Tabs On Drag Of A Square-Base Bluff Body, Brian W. Barker

Master's Theses

This thesis involves the experimental wind tunnel testing of a 0.127m by 0.127m square-base bluff body to test the effectiveness of trailing edge tabulations to reduce drag in the Cal Poly 0.912m by 1.219 m low-speed wind tunnel. To accomplish this, the boundary layer was first measured on the trailing edge of the model for the three speeds at 10, 20, and 30 m/s, with Re = 8.3e4, 1.6e5 and 2.5e5 respectively, without the tabs. Three different tests were performed to determine the effectiveness of the tabs. These tests included base pressure measurements, total drag force measurements and hotwire velocity …

Experimental Investigation Of Active Wingtip Vortex Control Using Synthetic Jet Actuators, Peter J. Sudak

Master's Theses

An experiment was performed in the Cal Poly Mechanical Engineering 2x2 ft wind tunnel to quantify the effect of spanwise synthetic jet actuation (SJA) on the drag of a NACA 0015 semispan wing. The wing, which was designed and manufactured for this experiment, has an aspect ratio of 4.20, a span of 0.427 m (16.813”), and is built around an internal array of piezoelectric actuators, which work in series to create a synthetic jet that emanates from the wingtip in the spanwise direction. Direct lift and drag measurements were taken at a Reynolds Number of 100,000 and 200,000 using a …

Unsteady Viscous Cavity Flow Using Computational Fluid Dynamics, Chandramouli Vadlamudi

Doctoral Dissertations and Master's Theses

The problem of unsteady viscous incompressible flow in a two-dimensional cavity is treated using the unsteady incompressible Navier-Stokes equations with various initial and boundary conditions. First the case of a square cavity with one inlet and one outlet is treated in steady and unsteady flows. The software package ANSYS FLUENT was used in the CFD simulations. This approach captures the appearance of separation bubbles and vortex formation inside the cavity. Steady state flows are also obtained from the unsteady simulations after convergence of the time dependent solutions. Then the case of a cavity with a synthetic jet and two outlets …

Numerical Investigation Of Pyrolysis Gas Blowing Pattern And Thermal Response Using Orthotropic Charring Ablative Material, Haoyue Weng, Alexandre Martin

Mechanical Engineering Faculty Publications

An orthotropic material model is implemented in a three-dimensional material response code, and numerically studied for charring ablative material. Model comparison is performed using an iso-Q sample geometry. The comparison is presented using pyrolysis gas streamlines and time series of temperature at selected virtual thermocouples. Results show that orthotropic permeability affects both pyrolysis gas flow and thermal response, but orthotropic thermal conductivity essentially changes the thermal performance of the material. The effect of orthotropic properties may have practical use such that the material performance can be manipulated by altering the angle of orthotropic orientation.