Aerospace Engineering Commons^™

Characterization Of The Global Hawk Low Pressure Turbine First Rotor, Timothy L. Garmoe

Theses and Dissertations

The Air Force Research Laboratory, Propulsion Directorate at Wright Patterson Air Force Base has studied the performance of turbine blade geometries utilizing a large scale, low speed, drawdown wind tunnel in an effort to better understand gas turbine blade aerodynamics. Currently, the Air Force's Unmanned Aerial Vehicle (UAV) Global Hawk has been operated primarily at flight conditions other than the design point of its Allison AE3007H turbofan engine. This off design condition decreased the Reynolds number at the low pressure turbine causing losses in efficiency and loading. Two different blades were studied to maximize performance of the Global Hawk turbine. …

A Prediction Code For The Thrust Performance Of Two-Dimensional, Non-Axisynnetric, Converging Diverging Nozzles, Angela M. Geatz

Theses and Dissertations

The objective of this research is to develop a prediction code for the Air Force Research Laboratory Propulsion Directorate that can accurately determine the gross thrust coefficient for a user defined nonaxisymmetric two-dimensional converging diverging nozzle. The code includes the effects of friction, angularity, and expansion losses on nozzle efficiency. To demonstrate the prediction method, the generated computational results were compared to experimental data, as well as computational results from other existing nozzle performance codes, for a number of different nozzle geometries. The nozzle internal performance prediction code showed excellent agreement with experimental data in predicting the gross thrust performance …

A Flash Vaporization System For Detonation Of Hydrocarbon Fuels In A Pulse Detonation Engine, Kelly C. Tucker

Theses and Dissertations

Current research by the US Air Force and Navy is concentrating on obtaining detonations in a pulse detonation engine (PDE) with low vapor pressure, kerosene based jet fuels. These fuels have a low vapor pressure and the performance of a liquid hydrocarbon fueled PDE is significantly hindered by the presence of fuel droplets. A high pressure, fuel flash vaporization system (FVS) has been designed and built to reduce and eliminate the time required to evaporate the fuel droplets. Four fuels are tested: n-heptane, isooctane, aviation gasoline, and JP-8. The fuels vary in volatility and octane number and present a clear …

Study Of Magnetogasdynamic Flow Acceleration In A Scramjet Nozzle, Erik K. Ross

Theses and Dissertations

The research project studied the benefits of Magnetogasdynamic (MGD) acceleration on a scramjet nozzle. MGD is a technology that relies on electromagnetic fields to extract and/or add energy to flow fields. The scramjet engine in the "AJAX" concept proposed by D.I. Brichkii et al. (2001) of St. Petersburg, Russia would utilize an MGD power generator in the diffuser user which could potentially provide electrical power for the aircraft support systems and an MGD accelerator in the nozzle of the engine. Using an AFRL/VAAC CFD code that was modified for MGD computations, this project investigated the effect conductivity and load factor …

Design Of A Prototype Model Aircraft Utilizing Propulsive Airfoil Technology, Richard L. Pepe

Renée Crown University Honors Thesis Projects - All

Researchers have considered the concept of a simple, compact aircraft for personal use for many years. To date, no effort has led to the development of a practical and affordable vehicle. The Computational Fluid Dynamics (CFD) Lab atSyracuseUniversity, however, has been researching a distributed propulsion technique, called propulsive airfoil technology, that has significant promise to meet the requirements for personal ownership of a small, hybrid road and air vehicle.

The propulsive airfoil concept is rooted in HVAC technology, utilizing a cross-flow fan (CFF) embedded into the trailing edge of a thick airfoil section, drawing in air from the top surface …

Robust Control Techniques For State Tracking In The Presence Of Variable Time Delays, Jarrett Goodell, Marc Compere, Miguel Simon, Wilford Smith, Ronnie Wright, Mark Brudnak

Publications

In this paper, a distributed driver-in-the-Ioop and hardware-in-the-Ioop simulator is described with a driver on a motion simulator at the U.S. Army TARDEC Ground Vehicle Simulation Laboratory (GVSL). Realistic power system response is achieved by linking the driver in the GVSL with a full-sized hybrid electric power system located 2,450 miles away at the TARDEC Power and Energy Systems Integration Laboratory (P&E SIL), which is developed and maintained by Science Applications International Corporation (SAIC). The goal is to close the loop between the GVSL and P&E SIL over the Internet to provide a realistic driving experience in addition to realistic …

An Existing Global Heptane Mechanism Augmented With Diffusive Transport, Michael R. Foster, Howard Pearlman

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

The couplings between diffusive transport and the temperature and species concentration distributions associated with low and intermediate temperature heptane oxidation are explored using an existing four-step heptane mechanism, tuned for elevated pressures. The energy and species concentration equations are augmented with diffusive fluxes for heat and species and solved numerically in a one-dimensional domain. The ignition delay times are also tabulated and compared with the zero-dimensional data reported in the literature.

Detonation Branching In A Pde With Liquid Hydrocarbon Fuel, Kristin L. Panzenhagen

Theses and Dissertations

A pulse detonation engine (PDE) capitalizes on the large mass flux and pressure rise associated with detonations to create thrust, which is proportional to PDE cycle frequency. This research showed that using a branched detonation as an ignition source, as opposed to standard spark ignition, deposits more energy into the thrust tube head. The increase in energy decreases ignition delay and detonation to deflagration transition (DDT) time. This allows a theoretical 85% cycle frequency increase that is accompanied by an 85% increase in thrust. The increase in energy also reduces the need for a DDT enhancement device, thereby increasing thrust …

Ion Based Pressure Sensor For Pulse Detonation Engines, Jeffrey S. Zdenek

Theses and Dissertations

A high speed, durable, ion probe based pressure sensor is being investigated for use in pulse detonation engines. Traditional pressure sensors are ill suited for the high temperature and vibratory environment encountered in such engines. An alternative transient pressure sensing method is investigated for pressures behind a hydrocarbon flame. These flames generate ions that are quenched by collisions as a function of pressure. An experiment was devised to correlate the ion decay rate with the pressure using an ion probe well suited for the flow. A correlation has been established showing the ion decay rate is a function of pressure. …

Isomer Energy Source For Space Propulsion Systems, Benjamin L. Johnson

Theses and Dissertations

Presented in this work are the results of an investigation of alternative means for powering spacecraft and launch vehicles with energy sources other than chemical combustion. Nuclear thermal propulsion and the energy release of a nuclear spin isomer present potential for increased rocket performance with compact, high-energy fuel sources replacing the combustion engines of the Delta IV-H 1st and 2nd stage vehicles. Analysis of historical fission designs along with the isomer hafnium-178-m2 in a particle bed configuration was conducted. Energy storage levels of 1.3 GJ/g are possible with this material, though the successful triggering and maintenance of a chain reaction …

Experimental Results For A High Swirl, Ultra Compact Combustor For Gas Turbine Engines, Ryan J. Quaale

Theses and Dissertations

Laser Doppler Velocimeter (LDV) experiments have been conducted within the cavity of an atmospheric pressure, small scale, Ultra Compact Combustor (UCC). The UCC uses highly swirled flow in a cavity around the outside periphery of the combustor to generate high centripetal acceleration in the fluid. This enhances mixing and leads to a very short axial flame length. Additionally, due to the circumferential velocity, much of the residence time required by the flame is provided by the circumference of the engine rather than axial length as in conventional combustors.

Cool Flames In Propane-Oxygen Premixtures At Low And Intermediate Temperatures At Reduced-Gravity, Howard Pearlman, Michael R. Foster, Devrez Karabacak

Faculty Publications - Biomedical, Mechanical, and Civil Engineering

No abstract provided.

Propagation Of Detonation Waves In Tubes Split From A Pde Thrust Tube, August J. Rolling, Paul I. King, Fred R. Schauer

Faculty Publications

A Pulse Detonation Engine (PDE) combusts a fuel air mixture through detonation. Existing designs require spark plugs in each separate thrust tube to ignite premixed reactants. A single thrust tube could require the spark plug to fire hundreds of times per second for long durations. This paper reports on the use of a continuously propagating detonation wave as both a thrust producer and a single ignition source for a multi-tube system. The goal was to minimize ignition complexity and increase reliability by limiting the number of ignition sources. The work includes a systematic investigation of single tube geometric effects on …

Design Study Of Triggered Isomer Heat Exchanger-Combustion Hybrid Jet Engine For High Altitude Flight, Christopher E. Hamilton

Theses and Dissertations

This study investigated the possibility of utilizing a Triggered Isomer Heat Exchanger (TIHE) within a conventional jet engine in order to increase the endurance of a High Altitude Long Endurance (HALE) Intelligence, Surveillance, and Reconnaissance (ISR) aircraft. Optimizations of the conventional and TIHE engines along with selection of a switchover flight condition, where the aircraft switches from combustion to TIHE operations, were made utilizing engine design and mission analysis software. Radiation shield weights were determined utilizing point source gamma ray shielding methods. The jet engine best suited for the hybrid use, where both combustion and TIHE components located in a …

Alternative Pulse Detonation Engine Ignition System Investigation Through Detonation Splitting, August J. Rolling

Theses and Dissertations

A Pulse Detonation Engine (PDE) combusts fuel air mixtures through a form of combustion: detonation. Recent PDE research has focused on designing working subsystems. This investigation continued this trend by examining ignition system alternatives. Existing designs required spark plugs in each separate thrust tube to ignite premixed reactants. A single thrust tube could require the spark plug to fire hundreds of times per second for long durations. The goal was to minimize hardware and increase reliability by limiting the number of ignition sources. This research used a continuously propagating detonation wave as both a thrust mechanism and an ignition system …

Analysis Of The Application Of A Triggered Isomer Heat Exchanger As A Replacement For The Combustion Chamber In An Off-The-Shelf Turbojet, Carl R. Hartsfield

Theses and Dissertations

The objective of this research was to evaluate the feasibility of using the triggered decay of a radioactive isomer in a solid-state heat exchanger to power a gas turbine engine. Primary performance measures were stagnation temperature increase and stagnation pressure drop across the heat exchanger. Analysis was performed using commercial software, and explored three types of heat exchanger: concentric tubes, radial fins with constant spacing, and radial fins with constant thickness. All met or exceeded performance of the baseline J-57 turbojet engine at static sea level conditions. A single configuration of heat exchanger, using concentric tubes, was evaluated at typical …

The Static Thrust Characterization Of The Quatra Aerrow Q100xl Engine For Flight Performance Prediction Of The 1/3-Scaled Cessna 172p Model, Joon Fui Ho

Master's Theses - Daytona Beach

The purpose of this research is to predict the thrust as a function of forward flight velocity required for the one-third-scaled Cessna 172P. This model was designed to verify scaling laws. Therefore, it is important that it be aerodynamically scaled and that it have similar thrust characteristic as that of the full scale Cessna 172P. Several propellers and two Quatra Aerrow Q100XL two-cycle engines were acquired for this research project. Three propellers were selected to undergo a series of static thrust testing. The measured static thrust was then used to predict the flight performance of each tested propellers with the …

Investigation Into The Adaptation Of A Steam Injector For Use On A Liquid Rocket Engine, Charles B. Mcfarland

Theses and Dissertations

This thesis investigated the properties of a steam injector to see if the concept might be suitable for use on a liquid rocket engine. A steam injector is a device developed in the 1850's to inject feedwater into the boiler on a steam locomotive without any moving parts. The injectors uses a small portion of the steam generated in the boiler to increase the pressure of the feedwater to a level high than the pressure in the boiler. Previous experiments claim that condensation of steam to water was necessary for an injector to work. This experiment tested injection without condensation …

Tip Vortex And Crenulation Effects In A Compressor Cascade With Moving Endwall, Barry W. St Germain

Theses and Dissertations

The effects of changing Reynolds number and flow coefficients on the velocity and pressure flow fields within a linear cascade with moving endwall were investigated in this experimental thesis. All flow field measurements were taken at a constant compressor blade tip gap clearance of 1.0 % chord and endwall speed of 318.6 ft/s (97.1 m/s), with flow coefficients of 0.40, 0.52, 0.62 and 0.72. All data acquisition occurred in a plane 23 % chord downstream of the trailing edge plane of the linear cascade. Hotwire probes determined the complete passage, three-dimensional fowled behind both crenulated and regular blade geometries. Vector …

Effects Of Liquid Transpiration Cooling On Heat Transfer To The Diverging Region Of A Porous-Walled Nozzle, Daniel J. Schieb

Theses and Dissertations

This research effort investigated the effects of evaporation of water on the heat transferred to the wall of the diverging portion of a porous walled nozzle The AFIT High Pressure Shock Tube was used with a two-dimensional Mach 3 nozzle. One flat surface of the nozzle was fitted with a layer of porous stainless steel from the nozzle throat to the exit. This porous material was saturated with water to simulate liquid transpiration cooling. Surface temperature data was taken in this region using fast response coaxial thermocouple. Heat transfer was determined from the surface temperature history. Data was taken for …

Testing Of Solid Rocket Propellants With An Ultrasonic Transducer, Bryan Rasmussen

Honors Capstone Projects and Theses

No abstract provided.

Influence Of Tip Clearance On The Flowfield In A Compressor Cascade With A Moving Endwall, Richard J. Mcmullan

Theses and Dissertations

The effects of changing the blade tip clearances on the velocity and pressure flowfields within a compressor cascade were investigated in this experimental thesis. All moving endwall measurements were taken at a constant flow coefficient of 0.5 and tip clearances of 0.5, 1.0 and 2.0 percent chord. Hot-wire/film probes were used to determine the three-dimensional velocity vector components in various transverse planes - one upstream of the leading edges of the blades, three within the blade cascade and one downstream of the trailing edges of the blades. The transverse velocity vector plots showed a scraping of the tip leakage vortex …

Multidisciplinary And Multiobjective Optimization In Conceptual Design For Mixed-Stream Turbofan Engines, Luc J. J. P. Nadon

Theses and Dissertations

Despite major advances in design tools such as engine cycle analysis software and computer aided design, conceptual gas turbine engine design is essentially a trial-and-error process based on the experience of engineers. Modern optimization concepts, such as multidisciplinary optimization (MDO), and multiobjective optimization (MOO), linked with sequential quadratic programming (SQP) methods and genetic algorithms (GA), were applied to the conceptual engine design process to automate the conceptual design phase. Robust integrated computer codes were created to find the optimal values of eight engine parameters in order to minimize fuel usage, aircraft cost and engine annulus area over a given mission. …

The Design, Fabrication, And Evaluation Of A Low-Speed, Low-Turbulence, Anechoic Wind Tunnel, Brian J. Kaplan

Master's Theses - Daytona Beach

In order to provide a means for testing noise reduction techniques in propellers and fans, a low-speed, low-turbulence, anechoic wind tunnel was designed, fabricated and evaluated at Embry-Riddle Aeronautical University.

This open circuit wind tunnel was designed using several other existing wind tunnels as a guide and incorporated an open jet test section. The tunnel, which was built almost entirely out of wood and fiberglass, is powered by a 15 hp centrifugal fan.

Tufts of yarn, a pitot-static tube, and a hot film anemoter were used to determine the flow characteristics in the test section of this wind tunnel. From …

Numerical Study Of A Transpiration Cooled Rocket Nozzle, Jay A. Landis

Theses and Dissertations

This study proved that transpiration cooling provides a better cooling scheme than regenerative cooling for long operating duration, liquid-fueled rocket engine nozzles. This proof was made on the basis of maximum wall temperature. This study compared transpiration cooling to regenerative cooling in the throat region of the Space Shuttle Main Engine Main Combustion Chamber. The study also analyzed the effects of porosity, solid thermal conductivity, and porous sphere size on a porous wall made of packed spheres. The transpiration cooled nozzle operated 35% cooler than a regeneratively cooled nozzle, but the temperature gradient at the hot gas surface was 72 …

Effects Of Blowing Ratios On Heat Transfer To The Throat Region Of A Porous-Walled Nozzle, Fu-Jung Chen

Theses and Dissertations

The effects of transpiration cooling on heat transfer in the throat region of a porous-walled nozzle were investigated. The experiments were performed in the AFIT low speed shock tube fitted with a Mach 2 nozzle. A blowing region was limited to the area from 1.3 cm prior to the throat to 1.2 cm downstream of the throat. The blowing ratios from -0.0002 (suction) to 0.0117 (blowing) of the main stream flow were studied. Heat flux data were taken from both sides of the nozzle. One side was transpiration cooled by secondary air injection through a porous wall, while the other …

Effects Of Blowing Ratio On Heat Transfer To The Throat Region Of A Porous-Walled Nozzle, Joseph L. Lenertz

Theses and Dissertations

This experiment analyzed the effects of blowing ratio on heat transfer to the throat region of a porous-walled nozzle, using the AFIT low speed shock tube. Heat flux data were taken from both sides of a two-dimensional Mach 2.0 Re-m=5.2x10⁷ nozzle using thin film resistance thermometers. One side was transpiration-cooled by secondary air injection through a sintered wall, while the other side served as a control. Control results were validated using empirical relations, and cooled side results showed up to a 14% reduction in heat transfer coefficient at blowing ratios of only 0.51%. The linear nature of cooling effectiveness …

The Effects Of Channel Curvature And Protusion Height On Nucleate Boiling And The Critical Heat Flux Of A Simulated Electronic Chip, John E. Leland

Office for Research Publications and Presentations

The quest for higher power yet smaller electronics has given rise to the need for very effective cooling of these electronics. Because one of the foremost problems in electronics cooling is achieving high heat flux cooling within small packages while expending minimal pumping power, one focus of this study was to investigate the effects of channel curvature on the CHF. Experimental data were obtained for flow rates of 1-7 m/s, subcoolings of 5-35"C, and radii of curvature of 25.4 and 50.8 mm. A correlation was obtained for these data which provided an excellent fit.

One condition that has been ignored …

Development And Implementation Of A Scramjet Cycle Analysis Code With A Finite-Rate-Chemistry Combustion Model For Use On A Personal Computer, Clarence F. Chenault

Theses and Dissertations

This study compared the performance of an equilibrium combustion model to a finite-rate-chemistry combustion model for a fixed geometry Scramjet flying at the flight conditions of Mach 12, 15, and 18 with a constant dynamic pressure of 50,000 Pa. An integrated PC-based code, developed specifically for this study, models the combustor as an equilibrium combustion process or as finite-rate-chemistry combustion process. This integrated program is based on two existing programs, Ramjet Performance Analysis (RJPA) and 3 STREAM. The effects of mixing schedule, combustor length, and combustor exit area were investigated. The results of this study indicate that inefficient mixing is …

Shielded Coil Electrodynamic Propulsion (Scep). A Feasibility Study, Richard J. R. Ladouceur

Theses and Dissertations

This study investigated Shielded Coil Electrodynamic Propulsion SCEP. The use of the earths magnetic field as a propulsion source has been previously investigated. It was found that a significant amount of power and long conductors were required. A more compact propulsion concept which requires significantly less power is proposed. This concept relies on the feasibility of significantly reducing the magnetic force induced by the earths magnetic field on selected segments of a coil. An experiment design to support the theoretical findings was conducted. The experiment results support the theoretical model.