Aerodynamics and Fluid Mechanics Commons^™

Fuel Flow Reduction Impact Analysis Of Drag Reducing Film Applied To Aircraft Wings, Damon Resnick, Chris Donlan, Nimish Sakalle, Cody Pinkerman

SMU Data Science Review

In this paper, we present an analysis of flight data in order to determine whether the application of the Edge Aerodynamix Conformal Vortex Generator (CVG), applied to the wings of aircraft, reduces fuel flow during cruising conditions of flight. The CVG is a special treatment and film applied to the wings of an aircraft to protect the wings and reduce the non-laminar flow of air around the wings during flight. It is thought that by reducing the non-laminar flow or vortices around and directly behind the wings that an aircraft will move more smoothly through the air and provide a …

Electro-Drop Bouncing In Low-Gravity, Erin Stivers Schmidt

Dissertations and Theses

We investigate the dynamics of spontaneous jumps of water drops from electrically charged superhydrophobic dielectric substrates during a sudden step reduction in gravity level. In the brief free-fall environment of a drop tower, with a non-homogeneous external electric field arising due to dielectric surface charges (with surface potentials 0.4-1.8 kV), body forces acting on the jumped drops are primarily supplied by polarization stress and Coulombic attraction instead of gravity. This electric body force leads to a drop bouncing behavior similar to well-known phenomena in 1-g₀, though occurring for much larger drops (~0.5 mL). We show a simple …

A Microresonator-Based Laser Doppler Velocity Sensor For Interplanetary Atmospheric Re-Entry, Benjamin Wise

Mechanical Engineering Research Theses and Dissertations

In this thesis, a laser velocity sensor concept based on optical microresonators is presented and the application to spacecraft atmospheric entry is explored. The concept is based on the measurement of Doppler shift of back-scattered laser light. Specifically, the Doppler shift is detected by observing the whispering gallery optical modes (WGM) of a dielectric microresonator excited by the back scattered light from particulates and gas molecules. The microresonator replaces the typical Fabry-Perot interferometer and CCD camera system, thereby significantly reducing the size and weight of the overall detection system. This thesis presents proof-of-concept results for this measurement approach. The Doppler …

The Drag Coefficient Of Varying Dimple Patterns, James M. Seeley, Michael S. Crosser

Senior Theses

There are many golf balls on the market today with varying dimple sizes, shapes, and distribution. These proprietary differences are all designed to reduce drag on the balls during flight, allowing golfers to hit the ball farther distances. There are limited published studies comparing how varying the dimples affects the reduction of drag. An experiment was developed in which golf balls were pulled through a water tank to measure the drag force acting on each ball. The water was chosen to allow for testing at slower velocities than the typical necessary speeds to cause turbulence for balls traveling in air. …

Experimental Investigation Of A New Spiral Wingtip, Naseeb Ahmed Siddiqui, Mohammed Aldheeb, Waqar Asrar, Erwin Sulaeman

International Journal of Aviation, Aeronautics, and Aerospace

Experiments on the relative merits and demerits of slotted wingtips mimicking a bird’s primary feathers have been performed. The real emargination length of feather tips, their flexibility and curved shapes during cruise are considered in the present study. The experiments were performed at a Reynolds number of 3.7 x 10⁵ on a symmetric flat plate half wing of aspect ratio 3. Lift, drag and pitching moments were measured using a six component aerodynamic balance. Four different shapes inspired by bird primary feathers have been analysed. The rigid curved tip performed the best increasing the L/D ratio by 20%. This …

Wall-Modeled Large Eddy Simulation Of A Three-Dimensional Shock-Boundary Layer Interaction, Nicholas J. Marco

Theses and Dissertations

The direct simulation of turbulent flows is prohibitive at high Reynolds numbers; thus, methods such as RANS and LES are used. However, these methods still require a large number of cells near a solid boundary. To circumvent this issue, a Wall-Modeled Large Eddy Simulation (WM-LES) can be used. Of interest is how these wall models perform in comparison to a Wall-Resolved Large Eddy Simulation (WR-LES) and experimental results of a shock turbulent boundary layer interactions (STBLI) and specifically, whether equilibrium wall models are sufficient to resolve the oscillatory and hence non-equilibrium nature of these flows or whether a non-equilibrium model …

Mechanisms And Identification Of Unsteady Separation Development And Remediation, Matthew Scott Melius

Dissertations and Theses

Unsteady flow separation represents a highly complex and important area of study within fluid mechanics. The extent of separation and specific time scales over which it occurs are not fully understood and has significant consequences in numerous industrial applications such as helicopters, jet engines, hydroelectric turbines and wind turbines. A direct consequence of unsteady separation is the erratic movement of the separation point which causes highly dynamic and unpredictable loads on an airfoil. Current computational models underestimate the aerodynamic loads due to the inaccurate prediction of the emergence and severity of unsteady flow separation especially in response to a sudden …

Dust Control Examination Using Computational Fluid Dynamics Modeling And Laboratory Testing Of Vortecone And Impingement Screen Filters, Ashish R. Kumar

Theses and Dissertations--Mining Engineering

Heavy industries, such as mining, generate dust in quantities that present an occupational health hazard. Prolonged exposure to the respirable dust has been found to result in many irreversible occupational ailments in thousands of miners. In underground mining applications, a variety of scrubbing systems are used to remove dust near the zones of generation. However, the wire-mesh type fibrous screens in the flooded-bed dust scrubbers used on continuous miners, are prone to clogging due to the accumulation of dust particles. This clogging results in a reduced capture efficiency and a higher exposure to the personnel. This research establishes the Vortecone, …

Literature Review: Biomimetic And Conventional Aircraft Wing Tips, Naseeb Ahmed Siddiqui, Waqar Asrar, Erwin Sulaeman

International Journal of Aviation, Aeronautics, and Aerospace

This paper is an attempt to summarize the effect of wing tip devices employed by birds, as well as aeronautical engineers in the past to improve the performance characteristics of aircraft. The focus is on reduction of the induced drag or drag due to lift also known as inviscid drag. This paper will provide an insight on both biomimetic and conventional wing tip approaches to reduce the induced drag. Prior analysis and experiments on the aerodynamics of airplane performance due to both these separate studies have been discussed. The needs of the industry and their past inventions have been described …

Multi-Stage Axial Compressor With Counter-Rotation, Vinod Gehlot, Magdy S. Attia, Divyam Garg

Publications

A multi-stage axial compressor incorporating a counter-rotational movement is provided with a series of rotors mounted along and driven by a driveshaft, and a geared counter-rotating outer casing. A planetary gear system is assembled along a static casing, which can be assembled as a forward or aft casing for the compressor. The bearings of the planetary gear system typically will be aligned concentrically with a center rotor drum assembly mounted along the single driveshaft. The counter-rotating drum assembly will be assembled over the rotor drum assembly and will be engaged by the forward and aft casings so as to provide …

Computational Fluid Dynamics Is Key To Better Flying Aircraft, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

Applying Newton’S Law Of Cooling When The Target Keeps Changing Temperature, Such As In Stratospheric Ballooning Missions, James Flaten, Kaye Smith, Erick Agrimson

2017 Academic High Altitude Conference

Newton’s Law of Cooling describes how a “small” system, such as a thermometer, comes to thermal equilibrium with a “large” system, such as its environment, as a function of time. It is typically applied when the environment is in thermal equilibrium and the conditions are such that the thermal decay time for the thermometer is a constant. Neither of these conditions are met when measuring environmental (i.e. atmospheric) temperature using a thermometer mounted in a payload lofted into the stratosphere under weather balloons. In this situation the thermometer is in motion so it encounters layer after layer of atmosphere which …

Estimation Of Performance Airspeeds For High-Bypass Turbofans Equipped Transport-Category Airplanes, Nihad E. Daidzic

Journal of Aviation Technology and Engineering

Conventional Mach-independent subsonic drag polar does not replicate the real airplane drag characteristics exactly and especially not in the drag-divergence region due to shock-induced transonic wave drag. High-bypass turbofan thrust is a complicated function of many parameters that eludes accurate predictions for the entire operating envelope and must be experimentally verified. Fuel laws are also complicated functions of many parameters which make optimization and economic analysis difficult and uncertain in the conceptual design phase. Nevertheless, mathematical models and predictions have its important place in aircraft development, design, and optimization. In this work, airspeed-dependent turbofan thrust and the new fuel-law model …

Effect Of Spalled Particles Thermal Degradation On A Hypersonic Flow Field Environment, Raghava S. C. Davuluri, Huaibao Zhang, Alexandre Martin

Mechanical Engineering Faculty Publications

Two-way coupling is performed between a spallation code and a hypersonic aerothermodynamics CFD solver to evaluate the effect of spalled particles on the flow field. Time accurate solutions are computed in argon and air flow fields. A single particle simulations and multiple particles simulations are performed and studied. The results show that the carbon vapor released by spalled particles tend to change the composition of the flow field, particularly the upstream region of the shock.

Flame-Turbulence Interaction For Deflagration To Detonation, Jessica Chambers

Honors Undergraduate Theses

Detonation is a high energetic mode of pressure gain combustion that exploits total pressure rise to augment high flow momentum and thermodynamic cycle efficiencies. Detonation is initiated through the Deflagration-to-Detonation Transition (DDT). This process occurs when a deflagrated flame is accelerated through turbulence induction, producing shock-flame interactions that generate violent explosions and a supersonic detonation wave. There is a broad desire to unravel the physical mechanisms of turbulence induced DDT. For the implementation of efficient detonation methods in propulsion and energy applications, it is crucial to understand optimum turbulence conditions for detonation initiation. The study examines the role of turbulence-flame …

Quantitative Assessment Of Secondary Flows Of Single-Phase Fluid Through Pipe Bends, Z. Kaldy, O. Ayala

Engineering Technology Faculty Publications

Single-phase fluid flow was simulated passing through various three dimensional pipe elbows. The simulations varied by Reynolds number, curvature ratios, and sweep angles and were all conducted using the k-e model available in COMSOL Multiphysics 5.1. The intent of this research was to qualitatively assess the flow characteristics under several different conditions. Many similarities were seen especially when comparing curvature ratios, the vorticity location for the turbulent cases show near identical behavior at the elbow midsection. One of the variables quantified in this paper is the maximum secondary velocity module which shows increasing values until the midsection of the elbow.

Secondary Flow Of Liquid-Liquid Two-Phase Fluids In A Pipe Bend, M. Ayala, P. Santos, G. Hamester, O. Ayala

Engineering Technology Faculty Publications

A simulated study of oil and water in 90 degree bend was carried on COMSOL 5.1 to characterize flow pattern and analyze the secondary flow. The Euler-Euler k-e Reynolds Averaged Navier-Stokes model was used to represent the fluid motion. Changes in the Reynolds number, curvature ratio and direction of gravity were made to evaluate the effects in the intensity of the secondary flow. In the end, it was possible to see that the bend direction does not affect the formation of secondary flow for Reynolds above 100,000. It appears that the fluid behavior on the pipe bend is strongly related …

Thrust Prediction For A Rotor Operating In A Ship Airwake, Mathew Thomas

Mechanical & Aerospace Engineering Theses & Dissertations

This report details work performed at Old Dominion University focused on developing a thrust prediction capability for a rotor operating in a ship airwake. The study has built upon previous experimental work utilizing particle image velocimetry-based velocity field measurements to quantify the degree of coupling in a simplified rotor/ship airwake experiment. Using the velocity field data of the previous study, a database was built representing the volume over the landing deck. Rotor thrust was computed using blade element methods and compared to direct load cell measurements and to a superposed velocity field. Results show that the blade element method has …

Dsmc Simulation Of Microstructure Actuation By Knudsen Thermal Force, Aaron Pikus, Israel Sebastiao, Andrew Strongrich, Alina Alexeenko

The Summer Undergraduate Research Fellowship (SURF) Symposium

In many industrial and research applications there is a need for vacuum sensors with higher accuracy and spatial resolution than what is currently available. Examples of target applications include high-altitude platforms, satellites and in-vacuum manufacturing processes such as freeze-drying of food and pharmaceuticals. In this connection, a novel pressure sensor, named Microelectromechanical In-plane Knudsen Radiometric Actuator (MIKRA), has been developed by at Purdue University. MIKRA is based on Knudsen thermal forces generated by rarefied flow driven by thermal gradients within the microstructure Thus, the goal of this work is to model the rarefied gas flow in the MIKRA sensor under …

Book Review: High G Flight - Physiological Effects And Countermeasures, Stefan Kleinke

International Journal of Aviation, Aeronautics, and Aerospace

This review provides insight on the content and a review of the quality of the recent release of High G Flight - Physiological Effects and Countermeasures from Ashgate Publications.

This review does not reflect the views of IJAAA or ERAU. This work was not peer reviewed.

High G Flight - Physiological Effects and Countermeasures

On The Selection Of A Good Shape Parameter For Rbf Approximation And Its Application For Solving Pdes, Lei-Hsin Kuo

Dissertations

Meshless methods utilizing Radial Basis Functions~(RBFs) are a numerical method that require no mesh connections within the computational domain. They are useful for solving numerous real-world engineering problems. Over the past decades, after the 1970s, several RBFs have been developed and successfully applied to recover unknown functions and to solve Partial Differential Equations (PDEs).
However, some RBFs, such as Multiquadratic (MQ), Gaussian (GA), and Matern functions, contain a free variable, the shape parameter, c. Because c exerts a strong influence on the accuracy of numerical solutions, much effort has been devoted to developing methods for determining shape parameters which provide …

Efficient General Computational Method For Estimation Of Standard Atmosphere Parameters, Nihad E. Daidzic Ph.D., Sc.D.

International Journal of Aviation, Aeronautics, and Aerospace

Knowledge of standard air temperature, pressure, density, speed of sound, and viscosity as a function of altitude is essential information in aircraft design, performance testing, pressure altimeter calibration, and several other aeronautical engineering and aviation science applications. A new efficient computational method for rapid calculations of standard atmospheric parameters up to 86 orthometric km is presented. Additionally, mass and weight of each standard atmospheric layer were calculated using a numerical integration method. The sum of all fractional masses and weights represents the total mass and weight of Earth’s atmosphere. The results obtained here agree well with measurements and models of …

A Contribution Toward Better Understanding Of Overbanking Tendency In Fixed-Wing Aircraft, Nihad E. Daidzic

Journal of Aviation Technology and Engineering

The phenomenon of overbanking tendency for a rigid-body, fixed-wing aircraft is investigated. Overbanking tendency is defined as a spontaneous, unbalanced rolling moment that keeps increasing an airplane’s bank angle in steep turns and must be arrested by opposite aileron action. As stated by the Federal Aviation Administration, the overbanking tendency may lead to a loss of control, especially in instrument meteorological conditions. It was found in this study that the speed differential over wing halves in horizontal turns indeed creates a rolling moment that achieves maximum values for bank angles between 45 and 55 degrees. However, this induced rolling moment …

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 …

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 …

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 …

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 …

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.

Numerical Study Of Spallation Phenomenon In An Arc-Jet Environment, Raghava Davuluri, Alexandre Martin

Mechanical Engineering Faculty Publications

The spallation phenomenon might affect the aerodynamic heating rates of re-entry vehicles. To investigate spallation effects, a code is developed to compute the dynamics of spalled particles. The code uses a finite-rate chemistry model to study the chemical interactions of the particles with the flow field. The spallation code is one-way coupled to a CFD solver that models the hypersonic flow field around an ablative sample. Spalled particles behavior is numerically studied for argon and air flow field. The chemistry model is compared with that of Park's model which complies with oxidation and sublimation and shows disagreement for nitridation.

On The Growth Rate Of Turbulent Mixing Layers: A New Parametric Model, Jeffrey L. Freeman

Master's Theses

A new parametric model for the growth rate of turbulent mixing layers is proposed. A database of experimental and numerical mixing layer studies was extracted from the literature to support this effort. The domain of the model was limited to planar, spatial, nonreacting, free shear layers that were not affected by artificial mixing enhancement techniques. The model is split into two parts which were each tuned to optimally fit the database; equations for an incompressible growth rate were derived from the error function velocity profile, and a function for a compressibility factor was generalized from existing theory on the convective …