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Aerodynamics and Fluid Mechanics Commons

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Nanoindentation Study Of Corrosion-Induced Grain Boundary Degradation In A Pipeline Steel, Denizhan Yavas, Pratyush Mishra, Abdullah Alshehri, Pranav Shrotriya, Kurt R. Hebert, Ashraf F. Bastawros 2018 Iowa State University

Nanoindentation Study Of Corrosion-Induced Grain Boundary Degradation In A Pipeline Steel, Denizhan Yavas, Pratyush Mishra, Abdullah Alshehri, Pranav Shrotriya, Kurt R. Hebert, Ashraf F. Bastawros

Aerospace Engineering Publications

High-strength low-alloy steels used for oil and gas pipelines are vulnerable to intergranular stress corrosion cracking in moderately alkaline soils. The mechanism of corrosion-induced embrittlement under such conditions is not yet understood. Nanoindentation was used to detect localized degradation of mechanical properties near internal grain boundaries of X-70 steel undergoing intergranular corrosion at active dissolution potentials at pH 8.2. The measurements identified a one-micron thick mechanically-degraded layer with 25% reduced hardness near corroded grain boundaries. It is suggested that the corrosion process may introduce an active softening agent, possibly non-equilibrium lattice vacancies generated by oxidation.


Low Reynolds Number Numerical Simulation Of The Aerodynamic Coefficients Of A 3d Wing, Khurshid Malik, Waqar Asrar, Erwin Sulaeman 2018 International Islamic University - Malaysia

Low Reynolds Number Numerical Simulation Of The Aerodynamic Coefficients Of A 3d Wing, Khurshid Malik, Waqar Asrar, Erwin Sulaeman

International Journal of Aviation, Aeronautics, and Aerospace

A low Reynolds number, three-dimensional CFD analysis is carried out for a finite flat plate wing using the commercial CFD code STAR CCM+. The six-aerodynamic force and moment components CL, CD, CM, CN, Cl, CY and their derivatives are computed at a Reynolds numbers of 3x105 by varying the pitch, roll and yaw angles about the quarter chord point. The computed results have been validated with experimental aerodynamic balance data when possible. The results indicate that roll and yaw angle affect the aerodynamic coefficients of the flat plate wing along with the pitch ...


Base Pressure Control Using Micro-Jets In Supersonic Flow Regimes, Vigneshvaran Sethuraman, Sher Afghan Khan 2018 Monash University Malaysia

Base Pressure Control Using Micro-Jets In Supersonic Flow Regimes, Vigneshvaran Sethuraman, Sher Afghan Khan

International Journal of Aviation, Aeronautics, and Aerospace

Base pressure plays a vital role in aerospace-related applications and its control is essential in reduction of drag and improving fuel consumption. Low pressure at the base of Rockets, Missiles, bombs and shells are a very common problem happening at transonic and supersonic speeds. In most of the cases there is a significant dip in pressure at the base region which will have implications on the design of aerospace vehicles. This paper presents an experimental investigation carried out for flow control at supersonic regimes. Experiments were conducted to measure the base pressure in the base region and wall pressure distribution ...


Numerical Analysis Of Aerodynamic Noise Mitigation Via Leading Edge Serrations For A Rod–Airfoil Configuration, Bharat Raj Agrawal, Anupam Sharma 2018 Iowa State University

Numerical Analysis Of Aerodynamic Noise Mitigation Via Leading Edge Serrations For A Rod–Airfoil Configuration, Bharat Raj Agrawal, Anupam Sharma

Anupam Sharma

Noise produced by aerodynamic interaction between a circular cylinder (rod) and an airfoil in a tandem arrangement is investigated numerically using incompressible large eddy simulations. Quasi-periodic shedding from the rod and the resulting wake impinges on the airfoil to produce unsteady loads on the two geometries. These unsteady loads act as sources of aerodynamic sound and the sound radiates to the far-field with a dipole directivity. The airfoil is set at zero angle of attack for the simulations and the Reynolds number based on the rod diameter is Red = 48 K. Comparisons with experimental measurements are made for (a) mean ...


Optimization Of Turbulent Prandtl Number In Turbulent, Wall Bounded Flows, Donald Edward Bernard 2018 University of Vermont

Optimization Of Turbulent Prandtl Number In Turbulent, Wall Bounded Flows, Donald Edward Bernard

Graduate College Dissertations and Theses

After nearly 50 years of development, Computational Fluid Dynamics (CFD) has become an indispensable component of research, forecasting, design, prototyping and testing for a very broad spectrum of fields including geophysics, and most engineering fields (mechanical, aerospace, biomedical, chemical and civil engineering). The fastest and most affordable CFD approach, called Reynolds-Average-Navier-Stokes (RANS) can predict the drag around a car in just a few minutes of simulation. This feat is possible thanks to simplifying assumptions, semi-empirical models and empirical models that render the flow governing equations solvable at low computational costs. The fidelity of RANS model is good to excellent for ...


Strongly Coupled Fluid-Particle Flows In Vertical Channels. Ii. Turbulence Modeling, Jesse Capecelatro, Olivier Desjardins, Rodney O. Fox 2017 University of Illinois at Urbana-Champaign

Strongly Coupled Fluid-Particle Flows In Vertical Channels. Ii. Turbulence Modeling, Jesse Capecelatro, Olivier Desjardins, Rodney O. Fox

Rodney O. Fox

In Part I, simulations of strongly coupled fluid-particle flow in a vertical channel were performed with the purpose of understanding, in general, the fundamental physics of wall-bounded multiphase turbulence and, in particular, the roles of the spatially correlated and uncorrelated components of the particle velocity.The exact Reynolds-averaged (RA) equations for high-mass-loading suspensions were presented, and the unclosed terms that are retained in the context of fully developed channel flow were evaluated in an Eulerian–Lagrangian (EL) framework. Here, data from the EL simulations are used to validate a multiphase Reynolds-stress model (RSM) that predicts the wall-normal distribution of the ...


Strongly Coupled Fluid-Particle Flows In Vertical Channels. I. Reynolds-Averaged Two-Phase Turbulence Statistics, Jesse Capecelatro, Olivier Desjardins, Rodney O. Fox 2017 University of Illinois at Urbana-Champaign

Strongly Coupled Fluid-Particle Flows In Vertical Channels. I. Reynolds-Averaged Two-Phase Turbulence Statistics, Jesse Capecelatro, Olivier Desjardins, Rodney O. Fox

Rodney O. Fox

Simulations of strongly coupled (i.e., high-mass-loading) fluid-particle flows in vertical channels are performed with the purpose of understanding the fundamental physics of wall-bounded multiphase turbulence. The exact Reynolds-averaged (RA) equations for high-mass-loading suspensions are presented, and the unclosed terms that are retained in the context of fully developed channel flow are evaluated in an Eulerian–Lagrangian (EL) framework for the first time. A key distinction between the RA formulation presented in the current work and previous derivations of multiphase turbulence models is the partitioning of the particle velocity fluctuations into spatially correlated and uncorrelated components, used to define the ...


A Comparison Of The Aerodynamic Centers For Panel Code Compressible Corrections And Openfoam 5 For Mach 0.1 To 0.8, Dustin Weaver 2017 Utah State University

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

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.


Evaluation Of A Frost Accumulation Model, D. S. Knollhoff, Eugene Takle, William A. Gallus Jr., D. Burkheimer, D. McCauley 2017 Texas Commission on Environmental Quality

Evaluation Of A Frost Accumulation Model, D. S. Knollhoff, Eugene Takle, William A. Gallus Jr., D. Burkheimer, D. Mccauley

William A. Gallus Jr.

Formation of frost on paved surfaces presents a potential hazard to the motoring public in cold climates. Temperatures of the paved surface are not measured routinely by the National Weather Service and are not part of public forecasts of winter conditions, yet highway maintenance personnel must make frost suppression and anti-icing decisions based on expectations of future paved-surface temperatures. The Road Weather Information System measures road surface, air and dew-point temperatures, road surface conditions, and wind data at numerous locations in the state of Iowa and reports the data in real-time to maintenance offices. A model based on simple concepts ...


Blended Wing Body Propulsion System Design, Parth Kumar, Adeel Khalid 2017 Georgia Institute of Technology

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 2017 New York Institute of Technology

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, Rec = 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 ...


Estimation Of Turbulence Effects On Wind-Induced Suctions On The Roof Of A Low-Rise Building, Chieh-Hsun Wu 2017 The University of Western Ontario

Estimation Of Turbulence Effects On Wind-Induced Suctions On The Roof Of A Low-Rise Building, Chieh-Hsun Wu

Electronic Thesis and Dissertation Repository

The effects of turbulence in the atmospheric boundary layer (ABL) on surface pressures of a typical low-rise building roof are investigated in this thesis. A 1/50 geometrically-scaled model of the Texas Tech University Wind Engineering Field Research Lab (WERFL) building model is used for pressure measurements in wind tunnel experiments. ABL wind turbulence intensities ranging from about 10% to 30%, and length scales ranging from 6 to 12 times of the building height (H) are generated. The effects of ABL turbulence on the mean roof pressures within the separated flow are explained from the time-averaged Navier-Stokes equations. The pressure ...


Design And Validation Of Pressure Based Flow Rate Soft Sensor For Freeze-Drying, Pasita Pibulchinda, Tong Zhu, Vaibhav Kshirsagar, Alina A. Alexeenko 2017 Purdue University

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 ...


Wind Farm Power Prediction In Complex Terrain, Micah Sandusky 2017 Boise State University

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 ...


Experimental Data Analysis Of The Vortex Structures In The Wakes Of Flapping Wings, Kai Wang, Umesh Vaidya, Baskar Ganapathysubramanian, Hui Hu 2017 Iowa State University

Experimental Data Analysis Of The Vortex Structures In The Wakes Of Flapping Wings, Kai Wang, Umesh Vaidya, Baskar Ganapathysubramanian, Hui Hu

Umesh Vaidya

The objective of this paper is to compare the existing methods and develop novel approaches for the experimental data analysis of the unsteady aerodynamics of the flapping wing microaerial-vehicle. These methods are developed for the purpose of identification of the beneficial dynamics and for the development of reduced order models for control design. We first employ Proper Orthogonal Decomposition (POD) method for the data analysis of the PIV measurements in the wakes of piezoelectric flapping wings. The basic idea behind POD based data analysis method is to decompose the time series snapshots of PIV measurements into high energy, POD, modes ...


Experimental Data Analysis Of The Vortex Structures In The Wakes Of Flapping Wings, Kai Wang, Umesh Vaidya, Baskar Ganapathysubramanian, Hui Hu 2017 Iowa State University

Experimental Data Analysis Of The Vortex Structures In The Wakes Of Flapping Wings, Kai Wang, Umesh Vaidya, Baskar Ganapathysubramanian, Hui Hu

Baskar Ganapathysubramanian

The objective of this paper is to compare the existing methods and develop novel approaches for the experimental data analysis of the unsteady aerodynamics of the flapping wing microaerial-vehicle. These methods are developed for the purpose of identification of the beneficial dynamics and for the development of reduced order models for control design. We first employ Proper Orthogonal Decomposition (POD) method for the data analysis of the PIV measurements in the wakes of piezoelectric flapping wings. The basic idea behind POD based data analysis method is to decompose the time series snapshots of PIV measurements into high energy, POD, modes ...


Turbulent Combustion Of Polydisperse Evaporating Sprays With Droplet Crossing: Eulerian Modeling And Validation In The Infinite Knudsen Limit, S. de Chaisemartin, L. Freret, D. Kah, F. Laurent, Rodney O. Fox, J. Reveillon, M. Massot 2017 Ecole Centrale Paris

Turbulent Combustion Of Polydisperse Evaporating Sprays With Droplet Crossing: Eulerian Modeling And Validation In The Infinite Knudsen Limit, S. De Chaisemartin, L. Freret, D. Kah, F. Laurent, Rodney O. Fox, J. Reveillon, M. Massot

Rodney O. Fox

The accurate simulation of the dynamics of polydisperse evaporating sprays in unsteady gaseous flows with large-scale vortical structures is both a crucial issue for industrial applications and a challenge for modeling and scientific computing. The difficulties encountered by the usual Lagrangian approaches make the use of Eulerian models attractive, aiming at a lower cost and an easier coupling with the carrier gaseous phase. Among these models, the multi-fluid model allows for a detailed description of the polydispersity and size-velocity correlations for droplets of various sizes. The purpose of the present study is twofold. First, we extend the multi-fluid model in ...


A Quadrature-Based Moment Closure For The Williams Spray Equation, O. Desjardins, Rodney O. Fox, P. Villedieu 2017 Iowa State University

A Quadrature-Based Moment Closure For The Williams Spray Equation, O. Desjardins, Rodney O. Fox, P. Villedieu

Rodney O. Fox

Sprays and other dispersed-phase systems can be described by a kinetic equation containing terms for spatial transport, acceleration, and particle processes (such as evaporation or collisions). In principle, the kinetic description is valid from the dilute (non-collisional) to the dense limit. However, its numerical solution in multi-dimensional systems is intractable due to the large number of independent variables. As an alternative, Lagrangian methods "discretize" the density function into "parcels" that are simulated using Monte-Carlo methods. While quite accurate, as in any statistical approach, Lagrangian methods require a relatively large number of parcels to control statistical noise, and thus are computationally ...


Numerical Description Of Dilute Particle-Laden Flows By A Quadrature-Based Moment Method, N. Le Lostec, Rodney O. Fox, O. Simonin, P. Villedieu 2017 Office National d'Etudes et de Recherches Aerospatiales, France

Numerical Description Of Dilute Particle-Laden Flows By A Quadrature-Based Moment Method, N. Le Lostec, Rodney O. Fox, O. Simonin, P. Villedieu

Rodney O. Fox

The numerical simulation of gas-particle flows is divided into two families of methods. In Euler-Lagrange methods individual particle trajectories are computed, whereas in Euler-Euler methods particles are characterized by statistical descriptors. Lagrangian methods are very precise but their computational cost increases with instationarity and particle volume fraction. In Eulerian methods (also called moment methods) the particle-phase computational cost is comparable to that of the fluid phase but requires strong simplificaions. Existing Eulerian models consider unimodal or close-to-equilibrium particle velocity distributions and then fail when the actual distribution is far from equilibrium. Quadrature-based Eulerian methods introduce a new reconstruction of the ...


Leading Edge Boundary Layer Suction Device For The Cal Poly Rolling Road Wind Tunnel, Daniel C. Glover, Liam M. Madden, Robert J. Cabri 2017 California Polytechnic State University, San Luis Obispo

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

No abstract provided.


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