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Articles 1 - 30 of 124
Full-Text Articles in Propulsion and Power
Measurements And Scaling Of Ion Propulsion Impulse During Driven Magnetic Reconnection, Fatima Ebrahimi, Nicholas A. O'Gorman, Kush Maheshwari, Jongsoo Yoo, Alexandre Sainterme, Hantao Ji
Measurements And Scaling Of Ion Propulsion Impulse During Driven Magnetic Reconnection, Fatima Ebrahimi, Nicholas A. O'Gorman, Kush Maheshwari, Jongsoo Yoo, Alexandre Sainterme, Hantao Ji
Faculty Publications
Impulse scaling during magnetic reconnection, the magnetic energy conversion to kinetic energy, via direct Mach probe measurements in Magnetic Reconnection Experiment is examined. Ion exhaust velocity and impulse scalings with reconnecting magnetic field during the push phase of driven reconnection are presented. The outflows and impulse measurements are compared with global MHD simulations. Both measurements and simulations reveal a favorable scaling, greater than linear, of impulse with reconnecting field. These scaling results establish that magnetic reconnection could be utilized for plasma propulsion.
Life And Performance Improvement Trenches, Thomas J. Praisner, John R. Farris, Connor Wiese
Life And Performance Improvement Trenches, Thomas J. Praisner, John R. Farris, Connor Wiese
AFIT Patents
A blade outer air seal assembly includes a plurality of seal segments circumferentially disposed about an array of blades rotatable about an axis, each of the plurality of seal segments having a radially inner surface facing a tip of each blade of the array of blades, the radially inner surface having an arrangement of trenches formed therein, and a radially outer surface opposite the radially inner surface. The arrangement of trenches is disposed between 30% and 80% of a chord of a blade of the array of blades as taken at the respective tip, and the arrangement of trenches is …
Seal For A Wave Rotor Disk Engine, Christopher Tait, Pejman Abkari, Brian Sell, Marc D. Polanka
Seal For A Wave Rotor Disk Engine, Christopher Tait, Pejman Abkari, Brian Sell, Marc D. Polanka
AFIT Patents
A unique seal for a wave rotor disk engine is disclosed herein. The seal is operable for sealing a region between a rotor and a rotor casing. The seal is spring loaded and will engage with the tip of the rotor to reduce pressure loss within the wave rotor disk engine.
The Space Rescue Professional: Operationalizing Guardians For The Future, Benjamin Johnis, Robert Bettinger, James Dean
The Space Rescue Professional: Operationalizing Guardians For The Future, Benjamin Johnis, Robert Bettinger, James Dean
Faculty Publications
The escalating competition in space exploration demands a dedicated space rescue capability. This article argues for the establishment of a space rescue professional (SRP) career field within the Department of Defense and the US Space Force. By harnessing existing US Air Force combat rescue expertise and partnering with the National Aeronautics and Space Administration, the Space Force can rapidly develop a robust SRP program with the warrant officer corps as its backbone. This article addresses a critical gap in national space policy to outline a cost-effective dual-service training pipeline and SRP operational roles. Such an investment safeguards astronauts, bolsters US …
The Impact Of Film Cooling On The Heat Release Within A Rotating Detonation Combustor, Shreyas Ramanagar Sridhara, Antonio Andreini, Marc D. Polanka, Myles D. Bohon
The Impact Of Film Cooling On The Heat Release Within A Rotating Detonation Combustor, Shreyas Ramanagar Sridhara, Antonio Andreini, Marc D. Polanka, Myles D. Bohon
Faculty Publications
Rotating detonation combustors establish a detonation wave that continuously circulates inside a small annulus. The presence of the detonation wave and the downstream oblique shock within the small annulus coupled with high mass flow induces a high heat load to the combustor wall. Preliminary analysis shows that for higher thermal power, internal air cooling alone is not sufficient to remove the heat out of the walls to maintain them below the maximum temperature of the metal. A possible solution is to use film cooling to reduce the heat flux to the combustor walls. One issue, though, is that the introduction …
Disk Engine With Circumferential Swirl Radial Combustor, Brian T. Bohan, Marc D. Polanka, Bennett Staton
Disk Engine With Circumferential Swirl Radial Combustor, Brian T. Bohan, Marc D. Polanka, Bennett Staton
AFIT Patents
A disk engine and system configured to provide high power at a reduced axial length is disclosed herein. The disk engine includes a radial compressor, a compressor discharge manifold positioned circumferentially about compressor, a combustion chamber positioned within the discharge manifold and a radial turbine positioned radially inward of the combustion chamber.
Investigation Of The Effect Of Internal Reynolds Number And Advective Capacity Ratio On Gas Turbine Film Cooling Parameters, John P. Di Lella
Investigation Of The Effect Of Internal Reynolds Number And Advective Capacity Ratio On Gas Turbine Film Cooling Parameters, John P. Di Lella
Theses and Dissertations
The desire for more powerful engines drives higher turbine inlet temperatures and a greater need to cool them. Experimentalists attempt to match cooling effectiveness between two conditions by matching several non-dimensional parameters, one of which is the coolant warming factor. The first investigation of this study examines the effect of the internal Reynolds number and the advective capacity ratio on the coolant warming factor by making use of a computational model and four different gases. It indicates the non-negligible and opposing effects of external convection and solid conduction on the coolant warming factor at matched internal Reynolds number and advective …
Performance Analysis And Recommended Improvements Of A Cubesat Resistojet, Alexander M. Petrocelli
Performance Analysis And Recommended Improvements Of A Cubesat Resistojet, Alexander M. Petrocelli
Theses and Dissertations
A small resistojet design was evaluated for its current performance and assessed for design and operational improvements. This resistojet is designed to operate on AFIT CubeSats with the intent of providing 100-200 mN of thrust at a specific impulse between 66-104 seconds. Using previously collected data and studies conducted on the design, analysis was performed to determine the current performance of this first-generation design. This provided a starting point for performance analysis over a variety of operational temperatures and pressures. This process was conducted for various heat exchanger path lengths of both the current design and two adapted path geometries. …
Gaseous Fuel Combustion In A Small Turbojet, Katherine A. Ashton
Gaseous Fuel Combustion In A Small Turbojet, Katherine A. Ashton
Theses and Dissertations
This project set out to test the suitability of natural gas as an aviation fuel by comparing how a small turbojet performed when run on traditional jet fuel versus methane. A JetCat P400, originally designed for jet fuel, was modified to run on methane. The modifications made did not succeed at getting the engine to run at normal operating speed on methane, but did get the engine to run at normal operating speeds using ethylene and ethane. It was determined a fuel and air mixing problem was hindering the engine performance when run on methane Future studies improving the fuel …
Detonation Confinement In A Second-Generation Radial Rotating Engine, John T. Ursino
Detonation Confinement In A Second-Generation Radial Rotating Engine, John T. Ursino
Theses and Dissertations
In recent years, Rotating Detonation Engines (RDEs) have been coupled with turbomachinery to harness the benefits of detonative combustion. A novel type of RDE, referred to as the disk or Radial RDE (RRDE), has been developed in pursuit of length and weight savings compared to a traditional annular flow RDE. This design includes a disk-shaped device within which reactants flow from the outer radius, detonate, and exit the inner radius. In this paper several modifications have been made to a previously tested RRDE to address issues that arose with the original design. The combustion chamber diameter has been increased to …
Seal For A Wave Rotor Disk Engine, Christopher Tait, Pejman Akbari, Brian Sell, Marc D. Polanka
Seal For A Wave Rotor Disk Engine, Christopher Tait, Pejman Akbari, Brian Sell, Marc D. Polanka
AFIT Patents
A unique seal for a wave rotor disk engine is disclosed herein. The seal is operable for sealing a region between a rotor and a rotor casing. The seal is spring loaded and will engage with the tip of the rotor to reduce pressure loss within the wave rotor disk engine.
Turbine Cooling System With Energy Separation, James L. Rutledge, Matthew Fuqua, Carol M. Bryant
Turbine Cooling System With Energy Separation, James L. Rutledge, Matthew Fuqua, Carol M. Bryant
AFIT Patents
A method and system for cooling an engine and/or vehicle using energy separation is disclosed herein. An energy separation device is operable for separating a compressed gaseous coolant stream into a first relatively cooler coolant flow stream and a second relatively hotter coolant flow stream. The relative cooler coolant flow stream is directed to a first region requiring increased cooling and the relative hotter coolant flow stream is directed to a second region requiring lower cooling than the first region in the engine or vehicle.
Disk Engine With Circumferential Swirl Radial Combustor, Brian Bohan, Marc Polanka, Bennett Staton
Disk Engine With Circumferential Swirl Radial Combustor, Brian Bohan, Marc Polanka, Bennett Staton
AFIT Patents
A disk engine and system configured to provide high power at a reduced axial length is disclosed herein. The disk engine includes a radial compressor, a compressor discharge manifold positioned circumferentially about compressor, a combustion chamber positioned within the discharge manifold and a radial turbine positioned radially inward of the combustion chamber.
Performance Study Of Post-Processed Additively Manufactured Low Thrust Nozzles, Tyler W. Gerhold
Performance Study Of Post-Processed Additively Manufactured Low Thrust Nozzles, Tyler W. Gerhold
Theses and Dissertations
This research explores metal post-processing techniques to effectively reduce the large anomalous protrusions found in small additively manufactured low thrust rocket nozzles. Research has found that nozzles of this kind can experience losses in thrust of over 40%. Analytic theory of adiabatic nozzle flow with viscous losses for additively manufactured nozzles does not align with what has been found when tested experimentally. Compressible flow losses, such as shock wave formation inside the nozzle diverging cone, are likely the leading causes of such loss. Reduction in nozzle irregularities can likely yield results seen in analytic theory with similar performance to traditional …
Manufacturing Of A Ceramic Turbine Rotor For A Compact Jet Engine, Bryan T. Leicht
Manufacturing Of A Ceramic Turbine Rotor For A Compact Jet Engine, Bryan T. Leicht
Theses and Dissertations
The primary goal of this study was to develop a low-cost, timely, scalable manufacturing method that produced a ceramic turbine that can be tested as a drop-in replacement on a JetCat P400 small scale gas turbine engine. This research compared two processes for manufacturing a ceramic turbine utilizing a pour casting method and 3D printing using stereolithography ceramic manufacturing (SLCM). The pour casting method used Silicon Nitride to create a cast turbine using a sacrificial 3D printed mold. The SLCM method evaluated producing an alumina turbine using an ADMATEC Admaflex 300 SLCM printer to directly print a ceramic turbine. This …
Design And Application Of Compact Combustors In Small-Scale Jetcat Engines, Nathan A. Clark
Design And Application Of Compact Combustors In Small-Scale Jetcat Engines, Nathan A. Clark
Theses and Dissertations
Ultra-compact combustors (UCC) are an innovative approach to improving overall engine efficiency and thrust-to-weight ratio by reducing the axial length and weight of the engine. Previous efforts looked at integrating a UCC into a small-scale JetCat P90 engine utilizing gaseous propane fuel. The current investigation aimed to utilize the previous compact combustor design and switch fuels to liquid kerosene. Based on the results from testing, a new combustor was designed equipped with a different flame holding mechanism at the larger P400-scale while maintaining a length savings of 20%. Testing of the P400 compact combustors was performed within a newly designed …
Design Of An Electro-Thermal Nanosatellite Propulsion System, James H. Founds
Design Of An Electro-Thermal Nanosatellite Propulsion System, James H. Founds
Theses and Dissertations
This research focused on designing an arcjet system with water as the propellant. Previous research developed a compact, reliable, and safe propellant storage and feed system. The goal is to combine the arcjet with the previous tank to achieve thrust and specific impulse characteristics greater than cold gas or resistojet system. This platform features a 1 U, non-hazardous, and sub-kilowatt powered propulsion system for nanosatellites. A simplified analysis of the design predicts thrust and specific impulse greater than can be achieved by cold gas or resistojet thrusters. Testing resulted in oxidation of the electrodes raising concerns about the longevity of …
Injection Studies On A Small-Scale Rotating Detonation Engine With Improved Flow Control, Jonathan J. Wyatt
Injection Studies On A Small-Scale Rotating Detonation Engine With Improved Flow Control, Jonathan J. Wyatt
Theses and Dissertations
The Rotating Detonation Engine (RDE) has gained increasing attention in recent years for its potential advantages over typical deflagration combustion. A Micro-RDE design with an outer diameter of 28mm operating on Nitrous Oxide and Ethylene was recently developed, which stretched the limits of small-scale detonation engines. The testing on this rig has shown a stable one wave mode detonation with frequencies reaching 16.8 kHz. Key parameters that influence the detonation wave mode are cell size, fill height, and wave speed, which are heavily influence d by injection schemes. Previous testing utilized a partially premixed jets in crossflow (JIC) injection scheme, …
One Dimensional Study Of Magnetoplasmadynamic Thrusters For A Potential New Class Of Heavy Ion Drivers For Plasma Jet Driven Magnetoinertial Fusion, Patrick M. Brown
One Dimensional Study Of Magnetoplasmadynamic Thrusters For A Potential New Class Of Heavy Ion Drivers For Plasma Jet Driven Magnetoinertial Fusion, Patrick M. Brown
Theses and Dissertations
Plasma Jet Driven Magnetoinertial Fusion (PJMIF) requires high velocity heavy ion drivers in order to compress a magnetized target to fusion conditions. Previous work with heavy ion drivers has revealed sub-par accelerations due to plasma instabilities; thus, it is necessary to investigate new methods of heavy ion plasma acceleration. One such method is Magnetoplasmadynamic (MPD) thrusters. Past studies of these thrusters have been conducted at an initial temperature at or below the energy of full ionization. Here MPD thrusters are investigated using a Godunov type MHD solver with a Harten-Lax van Leer-D (HLLD) flux solving scheme assuming the plasma is …
Improving The Stability And Operability Of A Small-Scale Rotating Detonation Engine, Nathan T. Fiorino
Improving The Stability And Operability Of A Small-Scale Rotating Detonation Engine, Nathan T. Fiorino
Theses and Dissertations
A small scale RDE was designed with a channel diameter of 28 mm and channel gap of 2 mm and operated on nitrous oxide (N2O) and ethylene (C2H4) as the oxidizer and fuel respectively. Changes to the original Jets in Crossflow (JIC) injection scheme and spark plug ignition method were implemented to counteract previously observed wave instabilities. Successful detonation was observed over a range of mass flows (0.035-0.068 kg/s) and equivalence ratios (ɸ = 0.6-1.4) and a stable single wave mode with frequency up to 16.8 kHz was observed for the first time. Injection …
Density Measurements Of Neutral Xenon Using Multiphoton Ionization And Microwave Spectroscopy In A Hall Effect Thruster, Taylor J. Foy
Density Measurements Of Neutral Xenon Using Multiphoton Ionization And Microwave Spectroscopy In A Hall Effect Thruster, Taylor J. Foy
Theses and Dissertations
A new dye laser and microwave scattering system for measuring low speed xenon particles was installed to characterize a commercially sourced 600 W Hall effect thruster. The new system uses multiphoton ionization and microwave spectroscopy to determine number density and velocity measurements of neutral xenon atoms in the plume of a Hall thruster. A study was conducted to ensure the new system will be able to accurately measure these neutrals in future work. The ultimate goal of this new system is to isolate and characterize the extra thrust produced in Hall Effect Thrusters due to finite volume vacuum chambers.
Analysis For Hybrid Rocket Fuel Regression Using Stereolithographic Geometry, Michael P. King
Analysis For Hybrid Rocket Fuel Regression Using Stereolithographic Geometry, Michael P. King
Theses and Dissertations
Hybrid Rocket Engines (HRE) have characteristically low fuel regression that limits their performance. Additive manufacturing and rapid prototyping can possibly solve some of the problems with Hybrid propulsion regression by creating geometry not possible with conventional manufacturing. This work is attempting to make geometric regression simulation of HRE easier by using STereoLithography (STL files) as the geometry. This analysis sets flow conditions, boundary conditions, propellant selection, and allows for fuel geometry to be altered to simulate geometry’s effects on regression rate and propellant performance. This model can be used for more advanced geometric analysis to improve and predict performance.
Detonation Confinement In A Radial Rotating Detonation Engine, Kavi Muraleetharan
Detonation Confinement In A Radial Rotating Detonation Engine, Kavi Muraleetharan
Theses and Dissertations
Radial Rotating Detonation Engines (RRDE) have provided an opportunity for use of a pressure-gain combustor in a more compact form compared to an axial RDE. A successfully tested RRDE has operated over a wide range of test conditions and produced detonation modes with one, two, and three waves. The presence of multiple waves located the detonation waves to the outer radius, while one wave modes operated closer to the inner radius. Locating the detonation wave closer to the inner diameter resulted in less time for combustion prior to the radial turbine. Subsequently, this tended to decrease efficiency. To attempt to …
Microturbine Turbojets: Experimental Evaluation Of Commercially Available Engines, Richard A. Depaola Iii
Microturbine Turbojets: Experimental Evaluation Of Commercially Available Engines, Richard A. Depaola Iii
Theses and Dissertations
This research assessed the performance of commercial microturbine turbojets and was the first industry-wide investigation into this class of engine by AFRL's SERL. Four commercial engines of the same thrust class were evaluated for overall and component-level performance. In addition to providing an evaluation of existing systems, the maximum performance for a commercial turbojet was predicted based on component evaluations. This analysis indicated that a commercial turbojet could have comparable thrust performance to a similarly sized military-grade engine, but it is unlikely that commercial engines can achieve the SFC of military engines without upgrading the compressors found in commercial microturbines.
Development Of A Small Scale Rotating Detonation Engine, Joseph R. Dechert
Development Of A Small Scale Rotating Detonation Engine, Joseph R. Dechert
Theses and Dissertations
The Rotating Detonation Engine (RDE) has been researched extensively in recent years, but the minimum size limits of an RDE have not been well investigated. The goal of this research was to build an RDE small enough to produce a detonation frequency above 20 kHz with a single detonation wave while also reducing the engine's mass ow rate. An engine with these design characteristics would reduce hazards associated with previous RDE testing. This research objective resulted in the design of an RDE with an outer diameter sized at 28 mm using ethylene and nitrous oxide as a fuel and oxidizer. …
Design And Analysis Of A Compact Combustor For Integration With A Jetcat P90 Rxi, Daniel Holobeny
Design And Analysis Of A Compact Combustor For Integration With A Jetcat P90 Rxi, Daniel Holobeny
Theses and Dissertations
Ultra Compact Combustors are a novel approach to modern gas turbine combustor designs that look to reduce the overall combustor length and weight. A previous study integrated an Ultra Compact Combustor into a JetCat P90 RXi turbine engine and achieved self-sustained operation with a length savings of 33% relative to the stock combustor. However, that combustor could not operate across the full stock engine performance range due to flameout at increased mass ow rates as reactions were pushed out of the primary zone. To ensure reactions stayed in the primary zone, a new design with a larger combustor volume was …
Investigation Of Endwall Vortex Manipulation In High Lift Turbines Caused By Active Endwall Forcing, Horatio J. Babcock
Investigation Of Endwall Vortex Manipulation In High Lift Turbines Caused By Active Endwall Forcing, Horatio J. Babcock
Theses and Dissertations
With the increased demand for lighter, more fuel efficient and smaller gas turbine engines, the impetus to reduce the weight and size of the turbine has become apparent. One approach to reduce this weight is to reduce the number of blades in the turbine. However, to maintain power output, each blade must be capable of supporting a greater amount of lift. While several high-lift turbine profiles have been detailed in literature, most of these profiles have increased endwall losses, despite their desirable mid-span characteristics. To mitigate this endwall loss, a number of active and passive flow approaches have been studied …
Characterization And Anomalous Diffusion Analysis Of A 100w Low Power Annular Hall Effect Thruster, Megan N. Maikell
Characterization And Anomalous Diffusion Analysis Of A 100w Low Power Annular Hall Effect Thruster, Megan N. Maikell
Theses and Dissertations
A Busek 100W low-power annular Hall effect thruster was characterized to determine the thruster’s best operating parameter range and to study plasma oscillations within the thruster. These experiments were conducted using xenon gas in the Space Propulsion Analysis and System Simulator chamber at the Air Force Institute of Technology on Wright-Patterson Air Force Base. The thruster’s performance characteristics were evaluated at nominal discharge voltages and constant total mass flow rate, solenoid current, and keeper current to determine the operating conditions optimizing divergence angle, beam efficiency, and discharge loss. This was accomplished using a Faraday probe to determine the plume’s current …
Flow Behavior In Radial Rotating Detonation Engines, Scott A. Boller
Flow Behavior In Radial Rotating Detonation Engines, Scott A. Boller
Theses and Dissertations
Recent progress has been made in demonstrating Radial Rotating Detonation Engine (RRDE) technology for use in a compact Auxiliary Power Unit with a rapid response time. Investigation of RRDEs also suggests an increase in stable operating range, which is hypothesized to be due to the additional degree of freedom in the radial direction which the detonation wave can propagate. This investigation seeks to determine if the detonation wave is in fact changing its radial location. High speed photography was used to capture chemiluminescence of the detonation wave within the channel to examine its radial location, which was found to vary …
Sheet Velocity Measurements Using Laser Absorption Spectroscopy In A Xenon Hall Effect Thruster Plume, Avery W. Leonard
Sheet Velocity Measurements Using Laser Absorption Spectroscopy In A Xenon Hall Effect Thruster Plume, Avery W. Leonard
Theses and Dissertations
A new laser absorption spectroscopy (LAS) velocimetry system, designed to obtain 2D planar velocity fields for ionized Xenon in the plume of a Hall effect thruster by probing the transition of Xe II at 834.72 nm, was implemented at the Air Force Institute of Technology (AFIT) Space Propulsion Analysis and System Simulator (SPASS) Lab vacuum chamber. A single horizontal laser sheet was used to probe singly-ionized Xenon in the plume of a Busek BHT-600 Hall thruster and obtain a histogram of estimated axial velocity, to validate the system. Similar velocities to those obtained by an earlier intrusive characterization of the …