Aerodynamics and Fluid Mechanics Commons^™

Local Field Effects On Magnetic Suppression Of The Converging Richtmyer-Meshkov Instability, Vincent Wheatley, Wouter Mostert, D. M. Bond, Ravi Samtaney

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We examine how the suppression of the converging shockdriven Richtmyer-Meshkov instability by an applied magnetic field is dependent on the local magnetic field strength and orientation. In particular, we examine whether the extent of suppression can be reasonably predicted by a linear model for the planar case. This is done for cylindrically converging cases with a high perturbation wavenumber and two different initial magnetic field configurations.

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

Aviation Department Publications

No abstract provided.

Effect Of Slot Span On Wing Performance, Juan F. Granizo

Doctoral Dissertations and Master's Theses

This report presents new numerically-derived correlations to estimate the aerodynamic properties of a three-dimensional wing that features a partial to full span fixed slot. Fixed slots have been thoroughly studied in the past with regards to their operation and the relation between slot geometry and wing performance. There have also been many studies on the advantages and disadvantages of tip-slotted wings and the comparison between these and full-slotted wings. Up to this point however, a study on the effects of slot span on wing performance has not been performed. Effect of slot span on wing performance is evaluated in an …

Effect Of Flow-Acoustic Resonant Interactions On Aerodynamic Response Of Transitional Airfoils, Joseph Hayden

Doctoral Dissertations and Master's Theses

A high-accuracy numerical study is conducted to examine the impact of flow-acoustic resonant interactions on the aerodynamic response of symmetric and cambered airfoils in the realistic transitional flow regimes with Rec=140,000 and M=0.0465 as well as the low Reynolds number flow regime with Rec=10,000 and M=0.2. The symmetric NACA-0012 and the cambered SD7003 airfoils are investigated at various angles of attack that have been found previously to include both the tone and no-tone producing regimes, with specific focus on the aerodynamic lift response. Additional simulations are conducted with a low-intensity synthetic turbulence introduced upstream of the airfoils in order to …

Turbulence Control In Wall Jets, Jonathan Latim

Doctoral Dissertations and Master's Theses

The turbulent boundary layer has been the focus of many studies over the last century or so due to its engineering significance. Recent studies have shown that the turbulent boundary layer encapsulates extremely energetic large-scale structures which play a much more significant role in its dynamics than has been previously thought. Further, these large scales amplitude and frequency modulate the finer scales of turbulence. This offers a path to control wall turbulence by controlling the large-scales of the flow. The focus of this thesis is to establish ways to manipulate the energy of the large-scale structures in a model turbulent …

Assessment Of Asymmetric Flight On Solar Uas, Eric Belfield

Master's Theses

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

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

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 …

Brakes, Thrust Reversers, Beta Props, Spoilers And Life Dumps All Help In Deceleration Of Jets And Turboprops, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

A Computer Program For The Coupled Implementation Of Meanline And Throughflow Methods To Simplify The Aerodynamic Design Of Multistage Axial Compressors, Alexander V. Rozendaal

Doctoral Dissertations and Master's Theses

A computer program capable of simplifying the preliminary aerodynamic design process of multistage axial compressors has been developed. This interactive design tool, named C-STAAC, combines the Meanline and Throughflow analysis capabilities of two independent compressor design codes to form one standalone system. The program greatly improves the efficiency of the Preliminary-to-Throughflow stages of compressor design by providing fully coupled interaction between the two platforms. The result enables the user to produce stacked airfoil geometry from only a handful of initial input parameters.

The program additionally offers a wide selection of pre- and post-processing capabilities that were not previously available with …

Climb Performance Of Business Jets, Nihad E. Daidzic

Aviation Department Publications

No abstract provided.

Heat Transfer Analysis Of An Oblique Jet Impingement Cooling On Cmc Rough Surface, Karthik Krishna

Doctoral Dissertations and Master's Theses

A Ceramic Matrix Composite is high strength and high temperature capability composite, utilized in components like heat shield of space vehicles, flame holders and disc brakes. To be used in both static and dynamic components of a future gas turbine engine and even with high temperature capabilities of these CMC components, convection cooling will still likely be required. The surface of the CMC varies significantly from traditional super-alloy used in a modern engine, with large level of roughness and significant three-dimensional waviness. These complex features will impact the behavior of the near wall flows, and affect the heat transfer rates …

Cavity Geometric Features And Entrainment Characterization Resulting From A Ballistically Induced Hydrodynamic Ram Event, Andrew J. Lingenfelter

Theses and Dissertations

Hydrodynamic Ram can cause damage to industrial and aircraft systems. The resulting transient spray increases the probability of fire. To better understand the driving mechanisms behind transient spray, internal, and external measurements of the cavity geometry, and entrained flow field were accomplished. Research determined cavity contraction and separation are pre-cursors to the initiation of the transient spray phases. The entrained flow measurement required development of a new and novel technique using a continuous wave laser and atomized water particles. The peak mass flow correlated well with cavity geometric features, such as cavity contraction. Using the mass flow, cavity diameter at …

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

McKelvey School of Engineering Graduate Student 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 …

Evaluation Of Various Turbulence Models For Shock-Wave Boundary Layer Interaction Flows, Francis K. Acquaye

McKelvey School of Engineering Graduate Student Theses & Dissertations

Despite the modeling capabilities of current computational fluid dynamics (CFD), there still exist problems and inconsistencies in simulating fluid flow in certain flow regimes. Most difficult are the high-speed transonic, supersonic and hypersonic wall-bounded turbulent flows with small or massive regions of separation. To address the problem of the lack of computational accuracy in turbulence modeling, NASA has established the Turbulence Modeling Resource (TMR) website and has issued the NASA 40% Challenge. The aim of this challenge is to identify and improve/develop turbulence and transition models as well as numerical techniques to achieve a 40% reduction in the predictive error …

Impact Of A Reverse Delta Type Add-On Device On The Flap-Tip Vortex Of A Wing, Afaq Altaf, Tan Boon Thong, Ashraf Ali Omar, Waqar Asrar

International Journal of Aviation, Aeronautics, and Aerospace

The effect of interactions of vortices produced by an outboard flap-tip of a half-span wing (NACA 23012 in landing configuration) and a slender reverse delta type add-on device, placed in the proximity of the outboard flap-tip, on the upper surface of the half-span wing is investigated using Particle Image Velocimetry in a closed loop low speed wind tunnel. Specifically the characteristics of the vortex interactions generated downstream in planes perpendicular to the free stream direction and their dependence on angles of attack at a chord-based Reynolds number of Re_c=2.75×10⁵ have been determined. It was found that the …

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 …

Flow Meter Test Rig, Cory Davis, Emily Guss, Michael Swartz

Mechanical Engineering

As part of a fluid mechanics laboratory, there should be an experiment that demonstrates the proper use of flow meters, devices that are necessary and relevant in many fluids-related industries. In order to provide students with exposure to these types of devices and how they work, a test rig was developed with the ability to interchange a variety of flow meters in order to broaden the students’ knowledge of the different types of measuring devices. This report was also written to outline the steps taken to ensure the test rig would match a laboratory and industry setting. Additionally, it was …

Three-Dimensional Simulation For Fast Forward Flight Of A Calliope Hummingbird, Jialei Song, Bret W. Tobalske, Don Powers, Tyson Hedrick, Haoxiang Luo

Faculty Publications - Department of Biological & Molecular Science

We present a computational study of flapping-wing aerodynamics of a calliope hummingbird (Selasphorus calliope) during fast forward flight. Three-dimensional wing kinematics were incorporated into the model by extracting time-dependent wing position from high-speed videos of the bird flying in a wind tunnel at 8.3 m s⁻¹. The advance ratio, i.e. the ratio between flight speed and average wingtip speed, is around one. An immersed-boundary method was used to simulate flow around the wings and bird body. The result shows that both downstroke and upstroke in a wingbeat cycle produce significant thrust for the bird to overcome …

Time-Of-Flight Based Sonic Speed Measurements For Cold Gas Thruster Development, Brandon W. Kempf

Mechanical Engineering Undergraduate Honors Theses

The purpose of this thesis is to explore an experiment developed for validating the usage of a gaseous solution of water and propylene glycol for cold gas propulsion. The experiment involves a “Time of Flight” method of calculating the speed of sound in the gas and the corresponding specific heat ratio using a copper tube, two MEMS microphones, a piezoelectric speaker, and data-acquisition hardware. The experiment was calibrated using the known thermodynamic properties of air. The accuracy of the experiment was found to be within 0.6% for calculations of the speed of sound in air and within 1.0% of the …

Computational Investigation Of Impingement Cooling For Regeneratively Cooled Rocket Nozzles, Bianca A. De Angelo

Doctoral Dissertations and Master's Theses

Jet impingement cooling is an internal cooling configuration used in the thermal management of temperature sensitive systems. With rocket engine combustion temperatures rising as high as 3600 K, it is essential for a cooling method to be applied to ensure that the nozzle integrity can be maintained. Therefore, a novel heat transfer study is conducted to investigate if jet impingement cooling is feasible for a regenerative cooling rocket nozzle application. Regenerative cooling for liquid propellant rockets has been widely studied. However, to the best of the author’s knowledge, there is currently no literature describing this method in conjunction with impingement …

Fluidic Jet Turbulence Generators For Deflagration To Detonation Transition In Pulsed Detonation Combustors, Jarrett E. Lowe

Doctoral Dissertations and Master's Theses

The goal of this study is to establish the dominant flow structure required to effectively accelerate the turbulent deflagration flame front to detonation velocity in the shortest possible distance while using a single Jet in Cross Flow (JICF). Jets in crossflow, depending on orientation and momentum ratio, can induce two types of flow structures that propagate downstream; vortex filaments and turbulent eddies. Vortex flow structures are coherent rotating columns that can persist for a considerable distance before diffusing. Turbulent eddies are characterized as random fluctuations in flow velocity or small pockets of rotation. The test rig used for this study …

Study Of Hybrid Magneto-Active Propellant Management Device For Slosh Damping, Leander Paul

Doctoral Dissertations and Master's Theses

Sloshing of liquid upon the application of an external force is a natural phenomenon as the free surface is allowed to move without any constraints. Study of slosh is an ongoing research for many decades and many novel inventions in Propellant Management Devices (PMDs) such as the rigid baffles and elastomeric membranes have been implemented to counteract the free surface effect in both passive and active membrane known as Magneto-Active Propellant Management Device (MAPMD) to actively control the free surface effect and reduce fuel slosh is explored in this research. Being a hybrid membrane, it would initially offer passive resistance …

2d Aeroacoustic Analysis Of Flow In The Flame Trench, Meghan Pokorski

Doctoral Dissertations and Master's Theses

We present here a methodology for using the commercial software ANSYSFLUENT to predict the acoustic field associated with Space-Launch System (SLS). We consider a two-dimensional model of flame deflector, and flame trench. The ANSYS code is then used to simulate the internal flow. Both the steady state case is considered along with other cases where the inflow has a harmonic component. A Ffowcs-Williams Hawking (FWH) surface is then constructed within the computational domain to use the computed flow fluctuations to obtain the acoustic field. The acoustic data was then compared to the experimental data.

When using the ANSYS code for …

Force And Moment Measurements Applicable To A Flexible Weapons System, James B. Sellers

Theses and Dissertations

Continuing the development of the 6-DOF Motion Test Apparatus (MTA) for performing dynamic wind tunnel tests revealed the importance of a capable data acquisition (DAQ) system for collecting and analyzing data. Assembling and testing the DAQ system in conjunction with the MTA, AFIT Low-Speed Wind Tunnel, and a selection of high-performance sensors was the primary focus of this research. Specifically, acquiring time-accurate aerodynamic force and moment measurements on a variety of test models was of high importance. With the established real-time DAQ system hardware, a National Instruments (NI) LabVIEW program was created to acquire data from an ATI Nano25-E force …

Design And Flight Test Of A Weapons-Cavity Acoustics And Separation Test Bed, Zachary Probst

Theses and Dissertations

Two very important, and often detrimental, phenomena can occur when an open weapons bay, or more generally-a cavity, is exposed to high-velocity flow. First, a shear layer develops over the cavity, leading to large regions of difficult-to-predict flow. Second, dynamic pressure oscillations are generated within the cavity itself. These two issues can combine to have multiple harmful effects on weapons carriage and employment. This provided motivation for flight tests which quantify forces and moments on a store, mounted at various positions in the cavity, for a variety of flight conditions. Specifically, a low-cost, easily reconfigurable test bed for weapons-cavity research …

Investigation Into Reynolds Number Effects On A Biomimetic Flapping Wing, Daniel K. Hope

Theses and Dissertations

This research investigated how the nature of the wing changed as a function of Reynolds number by measuring the forces produced by wings with varying characteristic lengths, tested at varying air densities. Increasing the wing span increased the overall weight of the wing, which reduced the 1st natural frequency; and did not result in an increase in vertical force over the baseline 50 mm wing. However; if the decrease in natural frequency was counteracted by increasing the thickness of the joint material in the linkage mechanism, vertical force production did increase over the baseline wing planform. Negligible forces and moments …

Lift & Drag Reductions On Iced Wings During Take Off And Landing With Unmanned Aerial Vehicles, Ian R. Mcandrew

Publications

This research paper addresses an novel problem that has not been addressed in detail for many decades. Ice formation on aircraft has procedures and protocols to deal with expected and actual problems. Complex modern aircraft are equipped with a variety of techniques to remove Ice formation on an aircraft, especially the wings. The introduction of Unmanned Aerial Vehicles has added an old problem, that of low speed and the lack of power to overcome losses in lift through ice formation. In this research the different types of Ice formation, how they combine and affect Lift and Drag are also addresses …

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.