Open Access. Powered by Scholars. Published by Universities.®

Aerodynamics and Fluid Mechanics Commons

Open Access. Powered by Scholars. Published by Universities.®

424 Full-Text Articles 581 Authors 268584 Downloads 33 Institutions

All Articles in Aerodynamics and Fluid Mechanics

Faceted Search

424 full-text articles. Page 1 of 19.

Multiple Pure Tone Noise Prediction, Fei Han, Anupam Sharma, Umesh Paliath, Chingwei Shieh 2017 General Electric Global Research Center

Multiple Pure Tone Noise Prediction, Fei Han, Anupam Sharma, Umesh Paliath, Chingwei Shieh

Anupam Sharma

This paper presents a fully numerical method for predicting multiple pure tones, also known as “Buzzsaw” noise. It consists of three steps that account for noise source generation, nonlinear acoustic propagation with hard as well as lined walls inside the nacelle, and linear acoustic propagation outside the engine. Noise generation is modeled by steady, part-annulus computational fluid dynamics (CFD) simulations. A linear superposition algorithm is used to construct full-annulus shock/pressure pattern just upstream of the fan from part-annulus CFD results. Nonlinear wave propagation is carried out inside the duct using a pseudo-two-dimensional solution of Burgers׳ equation. Scattering from nacelle ...


Multiple Pure Tone Noise Prediction, Fei Han, Anupam Sharma, Umesh Paliath, Chingwei Shieh 2017 General Electric Global Research Center

Multiple Pure Tone Noise Prediction, Fei Han, Anupam Sharma, Umesh Paliath, Chingwei Shieh

Anupam Sharma

This paper presents a fully numerical method for predicting multiple pure tones, also known as “Buzzsaw” noise. It consists of three steps that account for noise source generation, nonlinear acoustic propagation with hard as well as lined walls inside the nacelle, and linear acoustic propagation outside the engine. Noise generation is modeled by steady, part-annulus computational fluid dynamics (CFD) simulations. A linear superposition algorithm is used to construct full-annulus shock/pressure pattern just upstream of the fan from part-annulus CFD results. Nonlinear wave propagation is carried out inside the duct using a pseudo-two-dimensional solution of Burgers׳ equation. Scattering from nacelle ...


In-House Fabrication Of Temperature Sensitive Paint For Turbine Cooling Research, Mayur D. Patel, Mark A. Ricklick 2017 Embry-Riddle Aeronautical University

In-House Fabrication Of Temperature Sensitive Paint For Turbine Cooling Research, Mayur D. Patel, Mark A. Ricklick

Beyond: Undergraduate Research Journal

The Temperature Sensitive Paint (TSP) is a widely used method in measuring and visualizing flow separation and heat transfer. Compared to the cost and time consumption needed for methods such as pitot tubes, temperature sensitive paint is a cheaper alternative. Due to high usage in College of Engineering research projects, it was determined that in house fabrication of temperature sensitive paint would reduce time and cost limitations. For initial stages, literature research was performed to determine the recipe of intensity based TSP with luminophore and polymer binder that operated optimum at temperatures from 0-100°C. Europium III thenoyltrifluoroacetonate was determined ...


A General Algorithm For The Numerical Solution Of Hypersingular Boundary Integral Equations, Massimo Guiggiani, Geeta Krishnasamy, Thomas J. Rudolphi, F. J. Rizzo 2017 Università di Pisa

A General Algorithm For The Numerical Solution Of Hypersingular Boundary Integral Equations, Massimo Guiggiani, Geeta Krishnasamy, Thomas J. Rudolphi, F. J. Rizzo

Thomas Rudolphi

The limiting process that leads to the formulation of hypersingular boundary integral equations is first discussed in detail. It is shown that boundary integral equations with hypersingular kernels are perfectly meaningful even at non-smooth boundary points, and that special interpretations of the integrals involved are not necessary. Careful analysis of the limiting process has also strong relevance for the development of an appropriate numerical algorithm. In the second part, a new general method for the evaluation of hypersingular surface integrals in the boundary element method (BEM) is presented. The proposed method can be systematically applied in any BEM analysis, either ...


Boundary Element Solutions To Wave Scattering By Surface Irregularities On A Fluid-Solid Interface, S. Shenoy, Thomas J. Rudolphi, F. J. Rizzo 2017 Iowa State University

Boundary Element Solutions To Wave Scattering By Surface Irregularities On A Fluid-Solid Interface, S. Shenoy, Thomas J. Rudolphi, F. J. Rizzo

Thomas Rudolphi

The boundary element method is used to solve fluid-solid half-space problems with fluid-filled dimples and air bubbles on the solid surface. The problems, formulated in the Fourier (frequency) domain, are described by the fullspace three-dimensional acoustic and elastodynamic boundary integral equations (BIE), with pressure and displacement serving as primary variables. The techniques developed are general and may be with any kind of incident wave, however, plane waves are used in all numerical experiments. The equations governing the acoustic region are first converted mathematically to equations like those of an elastic region. The two regions are coupled and solved for the ...


The Design And Computational Validation Of A Mach 3 Wind Tunnel Nozzle Contour, Sarah Elizabeth Adams 2016 University of Tennessee, Knoxville

The Design And Computational Validation Of A Mach 3 Wind Tunnel Nozzle Contour, Sarah Elizabeth Adams

Masters Theses

The objective of this effort was to design and validate a Mach 3 wind tunnel nozzle contour. The nozzle will be used for an existing facility, replacing a Mach 2.3 nozzle. The nozzle contour was design using the widely-distributed CONTUR code developed by Sivells. The program uses a combination of analytical solutions and the method of characteristics in order to calculate a nozzle contour. A nozzle contour adhering to the existing geometry requirements was achieved through an iterative process. The flowfield of the finalized nozzle contour was solved using ANSYS fluent. The solution results were analyzed for flow uniformity.


Dji S-1000 Spreading Wings Octocopter: Determination Of Rotor Downwash Slipstream Size, Jonathan Lemieux 2016 University of Tennessee, Knoxville

Dji S-1000 Spreading Wings Octocopter: Determination Of Rotor Downwash Slipstream Size, Jonathan Lemieux

Masters Theses

The DJI S-1000 Spreading Wings octocopter rotor downwash slipstream area of influence was measured in axial climb conditions and in straight level flight. These data were gathered using a simple apparatus of distributed anemometers and a custom made boom affixed to the drone. Straight level flight tests incurred autopilot oscillations that rendered the data gathering and analysis challenging. The best quality data was acquired during the axial climb flight tests. The axial climbs were conducted in calm winds. It was determined that the axial climbs under these conditions displaced the rotor slipstream 9 ± 2.5 cm to the rear of ...


Assessment Of Asymmetric Flight On Solar Uas, Eric Belfield 2016 California Polytechnic State University, San Luis Obispo

Assessment Of Asymmetric Flight On Solar Uas, Eric Belfield

Master's Theses and Project Reports

An investigation was conducted into the feasibility of using an unconventional flight technique, asymmetric flight, to improve overall efficiency of solar aircraft. In this study, asymmetric flight is defined as steady level flight in a non-wings-level state in- tended to improve solar incidence angle. By manipulating aircraft orientation through roll angle, solar energy collection is improved but aerodynamic efficiency is worsened due to the introduction of additional trim drag. A point performance model was devel- oped to investigate the trade-off between improvement in solar energy collection and additional drag associated with asymmetric flight. A mission model with a focus on ...


Determination Of Aqueous Surfactant Solution Surface Tensions With A Surface Tensiometer, Remelisa Esteves, Birce Dikici Ph.D, Matthew Lehman, Qayyum Mazumder, Nonso Onukwuba 2016 Embry-Riddle Aeronautical University

Determination Of Aqueous Surfactant Solution Surface Tensions With A Surface Tensiometer, Remelisa Esteves, Birce Dikici Ph.D, Matthew Lehman, Qayyum Mazumder, Nonso Onukwuba

Beyond: Undergraduate Research Journal

Surfactant solutions are applicable to engineering systems for cooling equipment for electronics. Surfactants can be added to water to improve heat transfer. An application of using aqueous surfactant solutions can be through microchannel heat sink. Although it is ideal to redesign these systems to reduce heat, it is a costly method. Surfactant solutions at optimal solution concentration can be able to transfer heat quickly and effectively with minimum expense. The surface tension of surfactant solutions is an important parameter for boiling heat transfer and must be taken into consideration. The purpose of this research is to measure surface tension of ...


Determination Of Surfactant Solution Viscosities With A Rotational Viscometer, Remelisa Esteves, Nonso Onukwuba, Birce Dikici Ph.D 2016 Embry-Riddle Aeronautical University

Determination Of Surfactant Solution Viscosities With A Rotational Viscometer, Remelisa Esteves, Nonso Onukwuba, Birce Dikici Ph.D

Beyond: Undergraduate Research Journal

Aqueous surfactant solutions are used in engineering systems for improving boiling heat transfer. The purpose of this research is to determine the viscosities of surfactant solutions and to investigate the effect of composition on viscosity. The results obtained can possibly be used as reference for further study in the effects of surfactant solution viscosities on nucleate boiling. A rotational viscometer was used to determine the viscosities of three surfactant solutions – SLS, EH-14, and SA-9 – of various compositions at room temperature. It was discovered that the viscosities of SLS, EH-14, and SA-9 had a nearly consistent pattern as their compositions increased ...


Foundation Effects Of Trees Under Wind Loads, Padmavathi Venkata Sagi 2016 The University of Western Ontario

Foundation Effects Of Trees Under Wind Loads, Padmavathi Venkata Sagi

Electronic Thesis and Dissertation Repository

Winching tests were conducted on a mature 24-year-old Norway spruce tree. The tree was instrumented with strain gauges along the root structure and tilt sensors along the tree stem and was winched to failure. Tracked tree-root system response to failure load and the material properties of the tree-root-soil system were used to examine the applicability of simple engineering principles to tree stability analysis. Tree stability was studied using the principles of Winkler foundation model for the first time. In order to study the very complex windthrow phenomenon, a novel experimental technique was used. Tree saplings with complete structural root systems ...


Industrial Solid-State Energy Harvesting: Mechanisms And Examples, Matthew Kocoloski, Carl Eger, Robin McCarty, Kevin P. Hallinan, J. Kelly Kissock 2016 Carnegie Mellon University

Industrial Solid-State Energy Harvesting: Mechanisms And Examples, Matthew Kocoloski, Carl Eger, Robin Mccarty, Kevin P. Hallinan, J. Kelly Kissock

J. Kissock

This paper explores the potential for solid-state energy harvesting in industrial applications. In contrast to traditional heat recovery, the output of solid-state devices is electricity, which can be readily used in virtually any plant. The progress in harvesting waste heat via thermoelectric and thermionic generators is described. With second law efficiencies now approaching 50% and 80% respectively, we show that these technologies are on the cusp of practical use. Finally, we present an example of energy harvesting using thermionic devices in an industrial application. The example considers energy harvesting from a furnace at a glass manufacturing facility where exhaust gases ...


The Key Ideas Of Mdw Viii: A Summary, Aaron Altman, Clive L. Dym, Ray Hurwitz, John W. Wesner 2016 University of Dayton

The Key Ideas Of Mdw Viii: A Summary, Aaron Altman, Clive L. Dym, Ray Hurwitz, John W. Wesner

Aaron Altman

This paper summarizes and highlights the presentations and discussions that took place during Mudd Design Workshop VIII, ‘Design Education: Innovation and Entrepreneurship,’ at Harvey Mudd College. This paper also describes both the key ideas that emerged from the presentations and discussions of the participating engineering design educators, practitioners and researchers, and the methodology used to capture and retain those ideas. Additionally, this paper proposes a framework of design competencies that were created and evolved by the workshop’s participants as a response to a question posed at one of the workshop sessions: ‘What are the minimum design competencies students should ...


Design Methodology For Low Speed High Altitude Long Endurance Unmanned Aerial Vehicles, Aaron Altman 2016 University of Dayton

Design Methodology For Low Speed High Altitude Long Endurance Unmanned Aerial Vehicles, Aaron Altman

Aaron Altman

High Altitude Long Endurance (HALE) Unmanned Aerial Vehicles (UAV's) are increasingly being considered to perform a wide range of tasks. Recent years have seen greater value of UAV's in the military reconnaissance arena, first in the Persian Gulf war, with the use of small UAV's, and more recently over Bosnia with medium sized UAV's.

The NASA ERAST program uses HALE UAV's for environmental sensing and monitoring. The military has investigated using HALE UAV's for Theater Ballistic Missile defense, as well as general battlefield reconnaissance. Proposals have been made to use HALE UAV's for ...


Wing Tip Vortices From An Exergy-Based Perspective, Muhammad Omar Memon, Kevin Wabick, Aaron Altman, Rainer M. Buffo 2016 University of Dayton

Wing Tip Vortices From An Exergy-Based Perspective, Muhammad Omar Memon, Kevin Wabick, Aaron Altman, Rainer M. Buffo

Aaron Altman

The lens of exergy is used to investigate a wingtip vortex in the near wake over a range of angles of attack. Exergy is the measure of thermodynamically “available” energy as determined through the more discriminating second law of thermodynamics. Experiments were conducted in a water tunnel at Institute of Aerospace Systems at Aachen.

The data were taken three chord lengths downstream in the Trefftz plane of an aspect ratio 5 Clark-Y wing with a square-edged wing tip using particle image velocimetry. Intuitively, the minimum available energy state is expected to correspond to the maximum lift-to-drag ratio angle of attack ...


A Multi-Directional Treadmill Training Program For Improving Gait, Balance, And Mobility In Individuals With Parkinson’S Disease: A Case Series, Kimberly Smith, Kurt Jackson, Kimberly Edginton Bigelow, Lloyd L. Laubach 2016 University of Dayton

A Multi-Directional Treadmill Training Program For Improving Gait, Balance, And Mobility In Individuals With Parkinson’S Disease: A Case Series, Kimberly Smith, Kurt Jackson, Kimberly Edginton Bigelow, Lloyd L. Laubach

Kimberly Edginton Bigelow

Treadmill training is a commonly used intervention for improving gait in people with Parkinson’s disease (PD). However, little is known about how treadmill training may also influence balance and other aspects of mobility.

The purpose of this case series was to explore the feasibility and possible benefits of multi-directional treadmill training for individuals with PD. Four participants (62.3 ± 6.5 yrs, Hoehn & Yahr 2-4) performed 8 weeks of treadmill training 3 times per week. Weeks 1-4 included forward walking only, while weeks 5-8 included forward and multi-directional walking. Participants were tested every 4 weeks on 4 separate occasions ...


Leveraging Students’ Passion And Creativity: Ethos At The University Of Dayton, Margaret Pinnell, Malcolm Daniels, Kevin P. Hallinan, Gretchen Berkemeier 2016 University of Dayton

Leveraging Students’ Passion And Creativity: Ethos At The University Of Dayton, Margaret Pinnell, Malcolm Daniels, Kevin P. Hallinan, Gretchen Berkemeier

Margaret Pinnell

The Engineers in Technical Humanitarian Opportunities of Service-learning (ETHOS) program was developed in the spring of 2001 by an interdisciplinary group (electrical, chemical, civil and mechanical) of undergraduate engineering students at the University of Dayton (UD). ETHOS was founded on the belief that engineers are more apt and capable to appropriately serve our world if they have an understanding of technology’s global linkage with values, culture, society, politics, and the economy. Since 2001, the ETHOS program at UD has grown and changed.

From conceptualization, to implementation, to maturation and national recognition, the program has addressed challenges of academic acceptance ...


Shape Optimization Of Supersonic Bodies To Reduce Sonic Boom Signature, Junhui Li 2016 Washington University in St Louis

Shape Optimization Of Supersonic Bodies To Reduce Sonic Boom Signature, Junhui Li

Engineering and Applied Science Theses & Dissertations

In recent years there has been resurgence of interest by aerospace industry and NASA in supersonic transport aircraft. In recent studies, the emphasis has been on shape optimization of supersonic plane to reduce the acoustic signature of sonic boom resulting from the supersonic aircraft at high altitude in cruise flight. Because of the limitations of in-flight testing and cost of laboratory scale testing, CFD technology provides an attractive alternative to aid in the design and optimization of supersonic vehicles. In last decade, the predictive capability of CFD technology has significantly improved because of substantial increase in computational power, which allows ...


Lattice Boltzmann Methods For Wind Energy Analysis, Stephen Lloyd Wood 2016 University of Tennessee, Knoxville

Lattice Boltzmann Methods For Wind Energy Analysis, Stephen Lloyd Wood

Doctoral Dissertations

An estimate of the United States wind potential conducted in 2011 found that the energy available at an altitude of 80 meters is approximately triple the wind energy available 50 meters above ground. In 2012, 43% of all new electricity generation installed in the U.S. (13.1 GW) came from wind power. The majority of this power, 79%, comes from large utility scale turbines that are being manufactured at unprecedented sizes. Existing wind plants operate with a capacity factor of only approximately 30%. Measurements have shown that the turbulent wake of a turbine persists for many rotor diameters, inducing ...


Numerical Investigations Of A High Frequency Pulsed Gaseous Fuel Jet Injection Into A Supersonic Crossflow, Nehemiah Joel Williams 2016 University of Tennessee, Knoxville

Numerical Investigations Of A High Frequency Pulsed Gaseous Fuel Jet Injection Into A Supersonic Crossflow, Nehemiah Joel Williams

Doctoral Dissertations

The investigation of fuel delivery mechanisms is a critical design point in the development of supersonic combustion ramjet (scramjet) technology. Primary challenges include proper penetration of the jet in the supersonic cross-flow while keeping total pressure losses and wall drag to a minimum. To reduce drag and heat loads especially at high burner entry Mach numbers it is desirable to use a minimally intrusive means of fuel delivery.

Pulsation of gaseous jets has been shown to increase penetration and mixing in subsonic flows. A limited number of experimental studies and even fewer numerical studies have suggested that when applied to ...


Digital Commons powered by bepress