Aerospace Engineering Commons^™

Thermal Conductivity Of Interfacial Layers In Nanofluids, Zhi Liang, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Thermal Conductivity of Interfacial Layers is an Essential Parameter for Determining How the Ordered Liquid Layering Around the Particle-Liquid Interface Contributes to the Unusual High Thermal Conductivity of Nanofluids. However, So Far There is No Experimental Data Regarding This Parameter. using Nonequilibrium Molecular Dynamics Simulations of an Inhomogeneous Au-Ar System in Which the Solid-Liquid Interactions Are Assumed to Be Much Stronger Than the Liquid-Liquid Interactions, We Show Explicitly that the Thermal Conductivity of a 1-Nm-Thick Interfacial Layer is 1.6∼2.5 Times Higher Than that of the Base Fluid. the Simulation Results Are Incorporated into a Three-Level Clustering Model to Calculate the …

Deterministic Integrated Tuning Of Multicavity Resonances And Phase For Slow-Light In Coupled Photonic Crystal Cavities, T. Gu, S. Kocaman, Xiaodong Yang, J. F. Mcmillan, M. B. Yu, G.-Q. Lo, D.-L. Kwong, C. W. Wong

Mechanical and Aerospace Engineering Faculty Research & Creative Works

We present the integrated chip-scale tuning of multiple photonic crystal cavities. The optimized implementation allows effective and precise tuning of multiple cavity resonances (up to ~1.60 nm/mW) and intercavity phase (~0.038 π/mW) by direct local temperature tuning on suspended silicon nanomembranes. Through designing the serpentine metal electrodes and careful electron-beam alignment to avoid cavity mode overlap, the coupled photonic crystal L3 cavities preserve their high quality factors. The deterministic resonance and phase control enables switching between the all-optical analog of electromagnetically-induced-transparency to flat-top filter lineshapes, with future applications of trapping photons and optoelectronic modulators.

Fuel Cycle Co2-E Targets Of Renewable Hydrogen As A Realistic Transportation Fuel In Australia, Alberto Boretti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The claim of catastrophic manmade climate change or global warming through anthropogenic CO₂ has presently focused the interest on the tailpipe emissions of CO₂ per km, with recent legislations obsessively targeting these emissions of CO₂ with defectively implemented procedures. with a variety of different propulsion solutions (electric, hybrid electric, hybrid mechanic, conventional) and different fuels (Diesel, Petrol, alternative fossil, alternative renewable) available in the near future, a more comprehensive approach based on the full fuel cycle, and eventually also the full life cycle of the vehicle appear to be necessary. the paper is a contribution to trigger …

Nanostructured Substrate With Nanoparticles Fabricated By Femtosecond Laser For Surface-Enhanced Raman Scattering, Yukun Han, Zhi Liang, Huilai Sun, Hai Xiao, Hai-Lung Tsai

Electrical and Computer Engineering Faculty Research & Creative Works

A Simple and Fast Method to Fabricate Nanostructured Substrates with Silver Nanoparticles over a Large Area for Surface-Enhanced Raman Scattering (SERS) is Reported. the Method Involves Two Steps: (1) Dip the Substrate into a Silver Nitrate Solution for a Few Minutes, Remove the Substrate from the Solution, and Then Air Dry and (2) Process the Silver Nitrate Coated Substrate by Femtosecond (Fs) Laser Pulses in Air. the Second Step Can Create Silver Nanoparticles Distributed on the Nanostructured Surface of the Substrate by the Photoreduction of Fs Multiphoton Effects. This Study Demonstrates that an Enhancement Factor (EF) Greater Than 5x105, Measured …

Study Of Emission Turbulence-Radiation Interaction In Hypersonic Boundary Layers, L. (Lian) Duan, M. P. Martín, I. Sohn, D. A. Levin, M. F. Modest

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Direct numerical simulations are conducted to study the effects of emission turbulence-radiation interaction in hypersonic turbulent boundary layers, representative of the Orion Crew Exploration Vehicle at peak-heating condition during reentry. A nondimensional governing parameter to measure the significance of emission turbulence-radiation interaction is proposed, and the direct numerical simulation fields with and without emission coupling are used to assess emission turbulence-radiation interaction. Both the uncoupled and coupled results show that there is no sizable interaction between turbulence and emission at the hypersonic environment under investigation. An explanation of why the intensity of emission turbulence-radiation interaction in the hypersonic boundary layer …

Dynamic Ergonomic Analysis And Simulation Of Fastening Operation, Akul Joshi

Doctoral Dissertations

"Operator performing fastening operation with powered hand-tools at awkward postures is subjected to external forces that may pose a risk of developing ergonomic injuries. For design of safe workplaces and selection of tools it is necessary to identify the probable causes of discomfort by simulating the work conditions and quantifying the risk factors. An ergonomic simulator is developed to simulate the fastening operation and quantify the effects of posture and force in fastening operation. The effect of dynamic forces is analyzed using two approaches. The first approach analyzes the effect of tool vibration while the second analyzes the hand-arm system …

Inherent And Model-Form Uncertainty Analysis For Cfd Simulation Of Synthetic Jet Actuators, Daoru Frank Han

Masters Theses

"A mixed aleatory (inherent) and epistemic (model-form) uncertainty quantification (UQ) analysis method was applied to a computational fluid dynamics (CFD) modeling problem of synthetic jet actuators. A test case, (Case 3, flow over a hump model with synthetic jet actuator control) from the CFDVAL2004 workshop was selected to apply the Second-Order Probability framework implemented with a stochastic response surface obtained from Quadrature-Based Non-Intrusive Polynomial Chaos (NIPC). Three uncertainty sources were considered: (1) epistemic uncertainty in turbulence model, (2) aleatory uncertainty in free stream velocity and (3) aleatory uncertainty in actuation frequency. Uncertainties in both long-time averaged and phase averaged quantities …

Uncertainty Quantification Integrated To Computational Fluid Dynamic Modeling Of Synthetic Jet Actuators, Srikanth Adya

Masters Theses

"The Point Collocation Non-Intrusive Polynomial Chaos (NIPC) method was applied to a stochastic synthetic jet actuator problem to demonstrate the integration of computationally efficient uncertainty quantification to the high-fidelity CFD modeling of Synthetic Jet Actuators. The uncertainty quantification approach was first implemented in two stochastic model problem cases for the prediction of peak exit plane velocity using a Fluid Dynamic Based analytical model of the Synthetic Jet Actuator, which is computationally less expensive than CFD simulations. The NIPC results were compared with direct Monte Carlo sampling results. To demonstrate the efficient uncertainty quantification in CFD modeling of synthetic jet actuators, …

A Numerical Study Of Novel Drag Reduction Techniques For Blunt Bodies In Hypersonic Flows, Christopher Marley

Masters Theses

"Numerical simulations of a full three-dimensional hemispherical body in hypersonic flow are conducted and innovative techniques involving forward injection of gas from the stagnation point of the sphere are investigated; techniques include annular (ring) and swirled injection both with and without upstream energy deposition. Objectives of the analysis are the assessment of 1) drag reductions achieved on the blunt body (including the detrimental drag effect caused by the forward-facing injection itself) and 2) stability characteristics of the jet. Studies are conducted at free-stream Mach numbers of 10 and 6.5 at standard atmospheric conditions corresponding to 30 km altitude. While centered …

Computational Investigation Of Plasma Actuator As An Active Flow Control Strategy Of Laminar Separation Bubbles, Justin Roger Aholt

Masters Theses

"A parametric computational study designed to examine the plausibility of an external body force generated by active means, such as a plasma actuator, as a means of controlling a Laminar Separation Bubble (LSB) over an airfoil at low Reynolds numbers was conducted. Computational Fluid Dynamics (CFD) was employed to characterize the effect that a body force, localized to a small region tangent to the airfoil surface, might have on an LSB. In this study, the effects of altering the strength and location of the "actuator" on the size and location of the LSB and on the aerodynamic performance of the …

Heat Transfer Augmentation In Rectangular Ducts Due To Passive Flow Destabilization, James Jackson Tinsley

Masters Theses

"The following thesis documents the comparison of surface enhancements in rectangular ducts for heat transfer enhancement of the air-side of off-road heat exchangers. Two sets of experiments were completed, one utilizing air as the working fluid, and the other utilizing water. Five air geometries and four water geometries were studied, including those with crosswise bumps, longitudinal vortex generators, and a unique rifling geometry. A smooth test section was also tested in the water experiments to verify the experimental setup. Such verification had been performed previously for the air experiments by Rucker [2007]. The experiment involved an applied constant heat flux …

Continuous Low Thrust For Small Spacecraft Proximity Operations, James Harris Meub

Masters Theses

"Recently, both DoD and NASA have demonstrated increased interest in the development of close proximity operations for space systems. AFRL's Advanced Sciences and Technology Research Institute for Astrodynamics (ASTRIA) has defined several key research topics relevant to military priorities, with one area of critical importance being the inspection and observation of low Earth orbit resident space objects (RSOs). This study investigates the feasibility of using a low-thrust cold-gas propulsion system to effectively and accurately facilitate resident space object inspection. Specifically, this study focuses on the Missouri S&T Satellite mission (M-SAT) as a means to demonstrate autonomous RSO inspection. This paper …

Shaker Table Vibration Testing Of A Microsatellite, Tonya Michelle Sanders

Masters Theses

"In the satellite development process, structural testing is a means to gain confidence in analytical models and ultimately support qualification of the spacecraft for flight. Vibration testing, in particular, is motivated by the safety considerations of crew or launch personnel, the survivability of delicate hardware and electronics, and the avoidance of large stresses that cause structural fatigue or failure. The subject of this thesis is concerned with the shaker table vibration testing of a microsatellite pair designed and built by students at the Missouri University of Science and Technology in Rolla, Missouri. A finite element model (FEM) used in structural …

Hall-Effect Thruster Surface Properties Investigation, David George Zidar

Masters Theses

"Surface properties of Hall-effect thruster channel walls play an important role in the performance and lifetime of the device. Physical models of near-wall effects are beginning to be incorporated into thruster simulations, and these models must account for evolution of channel surface properties due to thruster operation. Results from this study show differences in boron nitride channel surface properties from beginning-of-life and after 100's of hours of operation. Two worn thruster channels of different boron nitride grades are compared with their corresponding pristine and shadow-shielded samples. Pristine HP grade boron nitride surface roughness is 9000±700 Å, while the worn sample …

Design, Analysis, And Optimization Of Composite Structures For Aerospace Applications, Tyler Jason Keil

Masters Theses

"This thesis contains three papers that focus on composites that pertain to a variety of structures commonly found in the aerospace industry. The first paper presents an investigation of the stowage and deployment strength of a thin carbon fiber-reinforced polymer shell capable of being rolled and stowed in a tight rolled configuration. The intent of this structure is for use as a segment of a larger deployable reflective aperture. This study involved finite element analysis of several laminates, coupon-level and full-scale prototype testing, which provided a much needed insight and benchmark of composite shells used in this manner.

The second …

Magnetometer-Only Attitude Determination With Application To The M-Sat Mission, Jason D. Searcy

Masters Theses

"The topic of this thesis focuses on attitude determination for small satellites. The method described uses only a magnetometer to resolve the three-axis attitude of the satellite. The primary challenge is that magnetometers only instantaneously resolve two axes of a satellite's attitude. Typically, magnetometers are used in conjunction with other sensors to resolve all three axes. However, by using a filter over an adequately long orbit arc, the magnetometer data can yield all the information necessary. The magnetic field data are filtered to obtain the magnetic field derivative vector, which are combined with the magnetic field vector to fully resolve …

Use Of Bio-Ethanol And Bio-Diesel The Key Solution For A More Sustainable Road Transport, Alberto Boretti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Life Cycle Analysis (LCA) of alternative transportation fuels clearly shows the advantages of reducing the use of nonrenewable fossil fuels vs. renewable biologic novel fuels to reduce the emissions of carbon dioxide. Being based on the natural recycle of carbon dioxide through the use of renewable energy sources, use of these renewable fuels does not imply depletion of natural resources and is therefore sustainable in the long term. Renewable fuels and advanced internal combustion engines and powertrains are the technologies that in addition to be the most likely to produce benefits in term of carbon balance and fossil fuel saving, …

Use Of Bio Ethanol The Key Solution For A More Sustainable Road Transport, Alberto A. Boretti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Life Cycle Analysis (LCA) of alternative transportation fuels clearly shows the advantages of reducing the use of nonrenewable fossil fuels vs. renewable synthetic and biologic novel fuels to reduce the emissions of carbon dioxide. Being based on the natural or synthetic recycle of carbon dioxide through the use of renewable energy sources, use of these renewable fuels does not imply depletion of natural resources and is therefore sustainable in the long term. Renewable fuels and advanced internal combustion engines and powertrains are the technologies that in addition to be the most likely to produce benefits in term of carbon balance …

On The Advantages Of E100 Over Gasoline In Down-Sized, Turbo-Charged, Direct-Injected, Variable Valve Actuated, And Stoichiometric S.I. Engines, Alberto A. Boretti

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Current flexi fuel gasoline and ethanol engines have efficiencies generally lower than dedicated gasoline engines. Considering ethanol has a few advantages with reference to gasoline, namely the higher-octane number and the larger heat of vaporization, the paper explores the potentials of dedicated pure ethanol engines using the most advanced techniques available for gasoline engines, specifically direct injection, turbo charging and variable valve actuation. Computations are performed with state-of-the-art, well validated, engine and vehicle performance simulations packages, generally accepted to produce accurate results targeting major trends in engine developments. the higher compression ratio and the higher boost permitted by ethanol allows …

Alternative Crankshaft Mechanisms And Kinetic Energy Recovery Systems For Improved Fuel Economy Of Passenger Cars, Alberto A. Boretti, Joseph Scalzo, Houshang Masudi

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The paper presents a novel design of a variable compression ratio advanced spark ignition engine that also permits an expansion ratio that may differ from the compression ratio therefore generating an Atkinson cycle effect. the stroke ratio and the ratio of maximum to minimum in-cylinder volumes may change with load and speed to provide the best fuel conversion efficiency. the variable ratio of maximum to minimum in-cylinder volumes also improves the full load power output of the engine. Brake specific fuel consumption maps are computed for a gasoline engine 2 Liters, in-line four, turbocharged and direct injection showings significant fuel …

Ultra-Abrupt Tapered Fiber Mach-Zehnder Interferometer Sensors, B. Li, J. Lan, W. Sumei, L. Zhou, Hai Xiao, Hai-Lung Tsai

Electrical and Computer Engineering Faculty Research & Creative Works

A fiber inline Mach-Zehnder interferometer (MZI) consisting of ultra-abrupt fiber tapers was fabricated through a new fusion-splicing method. By fusion-splicing, the taper diameter-length ratio is around 1:1, which is much greater than those (1:10) made by stretching. The proposed fabrication method is very low cost, 1/20-1/50 of those of LPFG pair MZI sensors. The fabricated MZIs are applied to measure refractive index, temperature and rotation angle changes. The temperature sensitivity of the MZI at a length of 30 mm is 0.061 nm/°C from 30-350 °C. The proposed MZI is also used to measure rotation angles ranging from 0° to 0.55°; …

Assessment Of Turbulence-Chemistry Interaction In Hypersonic Turbulent Boundary Layers, L. (Lian) Duan, M. P. Martín

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Studies of the turbulence-chemistry interaction are performed in hypersonic turbulent boundary layers using direct numerical simulation flow fields under typical hypersonic conditions representative of blunt-body and slender body hypersonic vehicles, with super catalytic and noncatalytic wall conditions in pure air. Nondimensional governing parameters, the interaction Damköhler number and the interaction relative heat release, are proposed to measure the influence of turbulence-chemistry interaction on flow composition and temperature. Both a priori and posteriori studies are performed to assess the effect of turbulence-chemistry interaction on chemical production rates and mean and turbulent flow characteristics. It is found that the governing parameters provide …

Quantifying Model Uncertainty Using Measurement Uncertainty Standards, Harsheel Rajesh Shah

Masters Theses

"Model uncertainty quantification is mainly concerned with the problem of determining whether the observed data is consistent with the model prediction. In real world, there is always a disagreement between a simulation model prediction and the reality that the model intends to represent. Our increased dependence on computer models emphasizes on model uncertainty which is present due to uncertainties in model parameters, lack of appropriate knowledge, assumptions and simplification of processes. In addition, when models predict multi-variate data, the experimental observation and model predictions are highly correlated. Thus, quantifying the uncertainty has a basic requirement of comparison between observation and …

Study Of Turbulence-Radiation Interaction In Hypersonic Turbulent Boundary Layers, L. (Lian) Duan, A. M. Feldick, M. P. Martín, M. F. Modest, D. A. Levin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

In the paper, we conduct direct numerical simulations (DNS) to investigate the effect of turbulence-radiation interaction (TRI) in hypersonic turbulent boundary layers, representative of the Orion crew exploration vehicle (CEV) at peak heating condition during reentry. The radiative transfer equation (RTE) is solved using the tangent slab approximation. 1 The RTE solver is line-by-line (LBL) accurate, making use of a developed efficient spectral database 2 for spectral modeling. A multi-group full-spectrum correlated-k-distribution (FSCK) method 3 is used to reduce the number of RTE evaluations while preserving LBL accuracy. A nondimensional governing parameter to measure the significance of TRI is proposed, …

Study Of Turbulence-Chemistry Interaction In Hypersonic Turbulent Boundary Layers, Lian Duan, M. Pino Martín

Mechanical and Aerospace Engineering Faculty Research & Creative Works

Studies of the turbulence-chemistry interaction (TCI) are performed in hypersonic turbulent boundary layers using direct numerical simulation (DNS) flow fields under typical hypersonic conditions representative of blunt-body and slender-body hypersonic vehicles, with super catalytic and noncatalytic wall conditions in pure air. Nondimensional governing parameters, 'interaction' Damk̈ohler number and relative heat release, are proposed to measure the influence of TCI on flow composition and temperature. Both a priori and posteriori studies are performed to assess the effect of TCI on chemical production rates and mean and turbulence flow characteristics. In addition, an effective approach (called PDF-TS) to estimate the intensity of …

A High-Quality Mach-Zehnder Interferometer Fiber Sensor By Femtosecond Laser One-Step Processing, Longjiang Zhao, Lan Jiang, Sumei Wang, Hai Xiao, Yongfeng Lu, Hai-Lung Tsai

Mechanical and Aerospace Engineering Faculty Research & Creative Works

During new fiber sensor development experiments, an easy-to-fabricate simple sensing structure with a trench and partially ablated fiber core is fabricated by using an 800 nm 35 fs 1 kHz laser. It is demonstrated that the structure forms a Mach-Zehnder interferometer (MZI) with the interference between the laser light passing through the air in the trench cavity and that in the remained fiber core. The fringe visibilities are all more than 25 dB. The transmission spectra vary with the femtosecond (fs) laser ablation scanning cycle. The free spectral range (FSR) decreases as the trench length increases. The MZI structure is …

A Comparative Verification Of Forecasts From Two Operational Solar Wind Models, Donald C. Norquist, Warner C. Meeks

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The solar wind (SW) and interplanetary magnetic field (IMF) have a significant influence on the near‐Earth space environment. In this study we evaluate and compare forecasts from two models that predict SW and IMF conditions: the Hakamada‐Akasofu‐Fry (HAF) version 2, operational at the Air Force Weather Agency, and Wang‐Sheeley‐Arge (WSA) version 1.6, executed routinely at the Space Weather Prediction Center. SW speed (V_sw) and IMF polarity (Bpol) forecasts at L1 were compared with Wind and Advanced Composition Explorer satellite observations. Verification statistics were computed by study year and forecast day. Results revealed that both models’ mean Vsw are …

Bi-Material Attachment Through A Soft Tissue Interfacial System, Y. X. Liu, S. Thomopoulos, Victor Birman, J. S. Li, G. M. Genin

Mechanical and Aerospace Engineering Faculty Research & Creative Works

No abstract provided.

2-D Path Planning For Direct Laser Deposition Process, Swathi Routhu, Divya Kanakanala, Jianzhong Ruan, Xiaoqing Frank Liu, Frank Liou

Computer Science Faculty Research & Creative Works

The zigzag and offset path have been the two most popular path patterns for tool movement in machining process. Different from the traditional machining processes, the quality of parts produced by the metal deposition process is much more dependent upon the choice of deposition paths. Due to the nature of the metal deposition processes, various tool path patterns not only change the efficiency but also affect the deposition height, a critical quality for metal deposition process. This paper presents the research conducted on calculating zigzag pattern to improve efficiency by minimizing the idle path. the deposition height is highly dependent …

Uncertainty Quantification Integrated To Cfd Modeling Of Synthetic Jet Actuators, Srikanth Adya, Daoru Frank Han, Serhat Hosder

Mechanical and Aerospace Engineering Faculty Research & Creative Works

The Point-Collocation Non-intrusive Polynomial Chaos (NIPC) method has been applied to a stochastic synthetic jet actuator problem used as one of the test cases in the CFDVAL2004 workshop to demonstrate the integration of computationally efficient uncertainty quantification to the high-fidelity CFD modeling of synthetic jet actuators. The test case included the simulation of an actuator generating a synthetic jet issued into quiescent air. The Point-Collocation NIPC method is used to quantify the uncertainty in the long-time averaged u and v-velocities at several locations in the flow field due to the uniformly distributed uncertainty introduced in the amplitude and frequency of …