Aerodynamics and Fluid Mechanics Commons^™

Study Of Biomimetic Micro And Macro Structures For Drag Reduction, Justin S. Schrout

Graduate Theses, Dissertations, and Problem Reports (ETD)

The ever increasing demand for global travel coupled with increasing costs of fuels have prompted many researchers to study new methods to save fuel to make travel more efficient. One of the proverbial low-hanging fruits for fuel efficiency is aerodynamic drag reduction. Simple changes in the shape or placement of structures on the surface of different types of vehicles have been shown to increase fuel efficiency by reducing drag (e.g., add-on lower and aft wake fairings on tractor trailers which have seen a tremendous rise in popularity on US highways in recent years). Areas of interest in drag reduction have …

Guardian Condor, Jake Stefanick, Matt Wallace, Dan Bologna, Kevin Bayonnet

Williams Honors College, Honors Research Projects

The group was tasked with designing a 3D printed glider. The scope of this assignment is to someday use the developed glider design and equip it with electronics and controls to deliver medical materials to remote areas in drone-like fashion. The glider was to be designed so that it could be printed using a lower-end, compact, and relatively portable 3D printer for optimal field efficiency. For this reason, the makerbot 3D printer was selected. The compact base plate of the makerbot printer left the team with strict size limitations, so the glider was printed in a series of nine parts …

Design Of Shape-Conforming Nosecone For Optimal Fluid Flow From Transonic To Supersonic Range, Anna Tombazzi

Williams Honors College, Honors Research Projects

Modern flight vehicles, such as rockets, missiles, and airplanes, experience a force caused by forebody wave drag during the flight. This drag force is induced when the frontal point of each vehicle breaks the pressure wave during flight. Efforts to reduce this wave drag force to improve flight efficiency include modifying the nosecone profile of the flight vehicles to lower the drag force.

This project revolved around creating a design to make the transformation of nosecone shapes from a ¾ Parabolic profile to a ½ Power Series profile possible, mid-flight. Using a novel nosecone assembly, shape memory alloys (SMAs) and …

Characterization Of Acoustic Modes In Aeroengines, Michelle Otero

Electronic Theses and Dissertations

Acoustic instabilities remain a key design concern faced in the development of liquid rocket engines. The interaction between the acoustic modes and the occurring combustion reactions can be detrimental to the engine. The fluctuating pressure waves resulting from the flame oscillations in the system can potentially lead to engine failure. For this reason, research in acoustic instabilities and methods to minimize the influences on the engine, has maintain interest in the aerospace community. The scope of this study was to design, optimize and characterize acoustic behaviors of a scaled rocket combustion chamber simulating acoustic pressure waves. Tangential and longitudinal acoustic …

The Separation Of Shear-Driven Liquid Films From A Sharp Corner, Zahra Sadeghizadeh

Doctoral Dissertations

"The separation of shear-driven liquid films occurs in many engineering applications such as port fuel injected engines, demisters, and gas transfer lines. Despite the importance of this problem, the details of the interaction between operating parameters such as liquid flow rate, gas velocities and liquid film properties on the forces at the expanding corner are still not clear. To enhance the insight on the complicated interaction between the gas and liquid phases, the shear-driven liquid flow around a corner has been studied both experimentally and analytically in this work. The effect of the complex liquid film structure on liquid mass …

A Comparison Of The Aerodynamic Centers For Panel Code Compressible Corrections And Openfoam 5 For Mach 0.1 To 0.8, Dustin Weaver

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

It is known that the aerodynamic center changes from quarter chord to half chord from incompressible to compressible flows on airfoils. Compressible corrections are derived and implemented in a vortex panel code. These results will be used to find the aerodynamic centers for the specified Mach range of 0.1 to 0.8 in 0.1 increments within - 6 to 6 degrees angle of attack. OpenFOAM 5 cases will be created with specific meshes and settings. The results calculated from OpenFOAM 5 will be compared to the results obtained from the compressible corrections.

Multiphase Flow Modeling For Design And Optimization Of A Novel Down-Flow Bubble Column, Mutharasu Lalitha Chockalingam

LSU Doctoral Dissertations

The application of the Euler-Euler framework based Computational Fluid Dynamics (CFD) models for simulating the two-phase gas-liquid bubbly flow in down-flow bubble columns is discussed in detail. Emphasis is given towards the modelling and design optimization of a novel down-flow bubble column. The design features of this novel down-flow bubble column and its advantages over a conventional Plunging Jet down-flow bubble column are discussed briefly. Then, some of the present challenges in simulating a conventional Plunging Jet down-flow bubble column in the Euler-Euler framework is highlighted, and a sigmoid function based drag modification function is implemented to overcome those challenges. …

Flight Dynamics: Flying Qualities Of Handling Factors Are Engineered Into The Aircraft Design, Nihad E. Daidzic

Aviation Department Publications

Flight dynamics is an aerospace engineering discupline that addresses aircraft stability and controllability. It is also mathematically very intensive and is traditionally the most difficult in the pilot training curriculum. Ultimately, it does not matter how good steady-state performance of an aircraft design is if its flying (handling) qualities are deficient. Paradoxically, the first airplane Wright Flyer, was statically and dynamically unstable, had large control authority, and was difficult to fly. We've come a long way since those early days, but stability is still vitally important in aircraft design and flight ops. The focus of this article will be airplane …

Aerodynamic And Performance Analysis Of A Morphing Helicopter Rotor System, Vinay Gopal Krishnan

Doctoral Dissertations and Master's Theses

The purpose of this study was to investigate the effect of rotor morphing, specifically variable rotor speed and variable blade twist, on various parameters such as the distribution of angle of attack, lift, power, thrust and/or other metrics describing the performance of a helicopter rotor. A MATLAB based blade element theory model was developed and executed for different flight conditions. The model was validated against the flight test data of a UH-60. Effects on power, lift to drag ratio and rotor drag from variations in blade twist, rotor speed, rotor radius and blade chord was analyzed. Morphing cases were applied …

Manufacturing And Instrumentation Of An Open End Compressed Air Shock Tube, Josue O. Ruiz

Master's Theses

Shock tubes have been used extensively to study shock wave structures and high speed flow features. The purpose of constructing this open end shock tube was to have the ability to produce shock waves in a laboratory setting but also understand the exit flow coming out which can be applied to future studies that are beyond the scope of this work. This undertaking would require that an open end shock tube be built and instrumented with PCB Integrated Circuit Piezoelectric (ICP) Pressure Sensor Model 113B24 that would then be connected to a PCB Model 482C05 Signal Conditioner with the purpose …

Implementation And Verification Of A Synthetic Eddy Method (Sem) In The Eagle3d Compressible Flow Solver, Patrick Kopper

Doctoral Dissertations and Master's Theses

The objective of this thesis is to implement and evaluate a Synthetic Eddy Method (SEM) into the Eagle3D compressible flow solver. Both the ability of Eagle3D to resolve unsteady turbulent ow field and capability of the SEM to reproduce given Reynolds stress profiles to start realistic turbulent behavior are verified using common academic cases. Eagle3D is a Computational Fluid Dynamics (CFD) solver using a novel combination of a Bounded Central Differencing (BCD) scheme with Weighted Essentially Non-Oscillatory (WENO) approximation to reduce numerical dissipation. SEM is a modern synthetic turbulence method able to reproduce an arbitrary Reynolds stresses specification on discretionary …

Numerical Characterization Of The Flow Field And Heat Transfer Inside The Receiver Of A Parabolic Trough Solar Collector Carrying Supercritical Co2, Samad Gharehdaghimollahajloo

UNLV Theses, Dissertations, Professional Papers, and Capstones

The aim of this research is to provide a detailed numerical analysis of flow field and heat transfer inside the heat collecting element of a parabolic trough collector. The parabolic trough collector is used as the boiler in a direct Super Critical Carbon Dioxide (S-CO2) Brayton cycle.

A single collector is modeled and analyzed with different inlet conditions. The working fluid is supercritical since its pressure is increased to above critical pressure in the compressor while its temperature reaches 300 °C after passing through the recuperators and before entering the solar field. For the first time, this research considers both …

Blended Wing Body Propulsion System Design, Parth Kumar, Adeel Khalid

International Journal of Aviation, Aeronautics, and Aerospace

This research paper focuses on the optimization of the propulsion system of a blended wing body design. Two different aspects of the design, the engine placement and count, and the engine itself, are investigated. The preliminary wing of the BWB is created through aerodynamic analysis, and is kept as a constant over the different propulsion system configurations. The engine parameters are first investigated. Equations are derived to express takeoff distance and climb rate as a function of engine sea level thrust, cruise thrust, and the number of engines. Nearly 150 different engine models, in BWB configurations of 2, 3, 4, …

Wingtip Vortex Alleviation Using A Reverse Delta Type Add-On Device, Afaq Altaf

International Journal of Aviation, Aeronautics, and Aerospace

The result of interactions of a wingtip vortex of a half-span wing and vortices generated by a slender reverse delta type add-on device were studied using Particle Image Velocimetry in a closed-loop low-speed wind tunnel. Characteristics of the vortex interactions produced downstream in planes perpendicular to the free stream direction at a mean chord-based Reynolds number, Re_c = 2.75×10⁵, are explored in this work. The study reveals that the reverse delta type add-on device considerably reduces the tangential velocity, vorticity and circulation magnitude of the resultant vortex by up to 79.6%, 85.6% and 48.7%, respectively. It was …

Design And Validation Of Pressure Based Flow Rate Soft Sensor For Freeze-Drying, Pasita Pibulchinda, Tong Zhu, Vaibhav Kshirsagar, Alina A. Alexeenko

The Summer Undergraduate Research Fellowship (SURF) Symposium

Lyophilization or freeze drying is a process of removing water by sublimation. It is commonly used to extend the shelf life of drugs in the pharmaceutical industry. Because the process is costly and time consuming, precise and efficient pressure, temperature control and drying time estimation are required. It is the goal of freeze-drying to run at maximum capacity while staying within the safe zone by carefully controlling the sublimation rate. Currently, real time estimation of sublimation rate is still challenging. The technique available called Tunable diode laser absorption spectroscopy (TDLAS) is invasive, and requires major modifications. The current study focuses …

Effect Of Boundary-Layer Tripping On Turbulence Generation And Trailing-Edge Noise In Transitional Airfoils, James Benjamin Lewis

Doctoral Dissertations and Master's Theses

The need arises for developing quiet aircraft and silent Unmanned Aerial Vehicles (UAVs) to minimize the environmental effects as well as for stealth missions. We focus here on attempting to directly predict the noise associated with airframe by considering a single isolated airfoil. Developing an ability to directly predict the radiated noise and how it is generated is a first step for passive or active control of the generated noise. We choose herein a NACA0012 airfoil and specific flow condition to test whether we can directly predict the sound in accordance with the corresponding experimental data identified in the Benchmark …

Wind Farm Power Prediction In Complex Terrain, Micah Sandusky

Boise State University Theses and Dissertations

There has been increasing interest in predicting the velocity field within wind farms in complex terrain for resource assessment, turbine siting, and power forecasting. These capabilities are made possible by advancements in computational speed from a new generation of computing hardware and numerical methods. The current thesis research focuses on two technical components to advance the current state in wind power forecasting. The first component is improved prediction of wind flow over complex terrain using the versatile immersed boundary method to represent surface boundary conditions on a fixed Cartesian mesh. The proposed approach embodies the law-of-the-wall for rough surfaces and …

Singularity Formation In The Geometry Of Perturbed Shocks Of General Mach Number, Wouter Mostert, Dale I. Pullin, Ravi Samtaney, Vincent Wheatley

Mechanical and Aerospace Engineering Faculty Research & Creative Works

While planar shock waves are known to be stable to small perturbations in the sense that the perturbation amplitude decays over time, it has also been suggested that plane propagating shocks can develop singularities in some derivative of their geometry (Whitham (1974) Linear and nonlinear waves. Wiley, New York) in a nonlinear, wave reinforcement process. We present a spectral-based analysis of the equations of geometrical shock dynamics that predicts the time to singularity formation in the profile of an initially perturbed planar shock for general shock Mach number. We find that following an initially sinusoidal perturbation, the shock shape remains …

Wing Deflection Analysis Of 3d Printed Wind Tunnel Models, Matthew G. Paul

Master's Theses

This work investigates the feasibility of producing small scale, low aerodynamic loading wind tunnel models, using FDM 3D printing methods, that are both structurally and aerodynamically representative in the wind tunnel. To verify the applicability of this approach, a 2.07% scale model of the NASA CRM was produced, whose wings were manufacturing using a Finite Deposition Modeling 3D printer. Experimental data was compared to numerical simulations to determine percent difference in wake distribution and wingtip deflection for multiple configurations.

Numerical simulation data taken in the form of CFD and FEA was used to validate data taken in the wind tunnel …

Leading Edge Boundary Layer Suction Device For The Cal Poly Rolling Road Wind Tunnel, Daniel C. Glover, Liam M. Madden, Robert J. Cabri

Mechanical Engineering

Over the course of three quarters from Fall of 2016 to Spring of 2017, our team designed and built a boundary layer suction device. The boundary layer suction device has three main functions: a scoop that redirects most of the boundary layer air out of the wind tunnel, fans that suck the remaining boundary layer air through a porous plate and ducting and out of the wind tunnel, and a transition bridge that transitions the remaining air smoothly onto the rolling road. The wind tunnel is owned by Cal Poly and the rolling road is a new addition to it. …