Hypersonic propulsion has become an increasingly important research field over the past fifty years, and subsequent interest in propulsion systems utilizing supersonic combustion has emerged. Air-breathing engines are desirable for such applications as hypersonic flight vehicles would not need to carry an oxidizer. Therefore, hypersonic air-breathing propulsion systems require an inlet with high mass capture and compressive efficiency. The present work seeks to outline the development and validation of a novel design tool for producing air inlet designs for hypersonic vehicles at variable flight conditions. A Busemann inlet was chosen for its high compressive efficiency, geometric flexibility, and existing experimental validation. The design tool uses the Taylor-Maccoll equation to generate a streamline through a conical flow field. A streamline tracing technique is used to produce three-dimensional inlet surfaces with various capture areas. Additionally, a surface morphing process is implemented to combine inlet profiles for improved engine compatibility. The inlet morphing process allowed for the creation of inlets with offset exit profiles. These offset profiles were evaluated at off-design Mach numbers using Star-CCM+ to quantify efficiency metrics and characterize starting phenomena.

A facility was designed to provide high-enthalpy, hypersonic flow to a detonation chamber. Preliminary investigation identified 1300 K and Mach 5 as the total temperature and Mach number require to stabilize an oblique detonation wave inside the detonation chamber. Vitiated-air heating was the preheating method chosen to meet these capabilities. The vitiator facility heats compressed air while still retaining about 50% of the original oxygen content. Schlieren flow visualization and conventional photography was performed at the exit plane of a choke plate, which simulated the throat of a converging-diverging nozzle. A shock diamond formation was observed within the jet exhausting out of the choke hole. This is a clear indication that the facility is capable of producing hypersonic flow. A stoichiometric propane-air mixture was burned inside the combustion chamber. A thermocouple survey measured an average temperature of 1099 K at the exit plane of the mixing chamber; however, the actual temperature is likely higher than this, because cool, ambient air could be seen mixing with the hot, vitiated air near the exit plane. Because the adiabatic flame temperature of propane-air is lower than that of hydrogen-air, if hydrogen is used to vitiate the air, the facility is capable of meeting the 1300-K objective.

Supersonic retro-propulsion (SRP) is defined as rocket propulsion used to decelerate aerospace vehicles at supersonic speed. SRP is often used as a method of high-speed deceleration on space vehicles. The main method of propulsion used in the application of SRP is rocket propulsion. Rocket engine thrust and performance changes with altitude and expansion ratio. Changing altitudes across the trajectory of a rocket affect how the exhaust plume shock waves expand. Being able to identify how different expansion ratios affect the exhaust plume flow fields would provide useful data on how SRP performance can be predicted. This research projects aims at developing a computational model for existing physical test data on SRP and extrapolating data from the model to assess how SRP would perform with different nozzle expansion ratios.

Three-dimensional, additive printing has emerged as an exciting new technology for the design and manufacture of small spacecraft systems. Using 3-D printed thermoplastic materials, hybrid rocket fuel grains can be printed with nearly any cross-sectional shape, and embedded cavities are easily achieved. Applying this technology to print fuel materials directly into a CubeSat frame results in an efficient, cost-effective alternative to existing CubeSat propulsion systems. Different 3-D printed materials and geometries were evaluated for their performance as propellants and as structural elements. Prototype "thrust columns" with embedded fuel ports were printed from a combination of acrylonitrile utadiene styrene (ABS) and VeroClear, a photopolymer substitute for acrylic. Gaseous oxygen was used as the oxidizer for hot-fire testing of prototype thrusters in ambient and vacuum conditions. Hot-fire testing in ambient and vacuum conditions on nine test articles with a combined total of 25 s burn time demonstrated performance repeatability. Vacuum specific impulse was measured at over 167 s and maximum thrust of individual thrust columns at 9.5 N. The expected ΔV to be provided by the four thrust columns of the consumable structure is approximately 37 m/s. With further development and testing, it is expected that the consumable structure has the potential to provide a much-needed propulsive solution within the CubeSat community with further applications for other small satellites.

Experimental investigations have evaluated the feasibility of using laser-driven plasma microthrusters for small-thrust, high-specific-impulse space maneuvers, particularly for micro- and nanosatellite missions. Recent work made use of the Mach2 hydromagnetics code for the construction of an adequate computational model of the micro-thruster opera- tion. This thesis expounds on this previous work by extending the computational modeling capabilities, allowing for the determination of plasma plume properties and characteristic performance assessment of the microthruster; this allows for further computational investi- gation of the performance improvements achieved by new design considerations. Two par- ticular design changes are implemented and measured: (i) the simulation of microthruster performance intentionally achieving laser-supported detonation of energetic polymer fuels for higher-thrust capabilities, and (ii) the implementation of an axisymmetric nozzle to improve passive solid-fuel performance. The Mach2 hydromagnetics code with the new performance assessment capabilities was used to examine the performance improvement of these new modes of operation; results of the simulations are presented and then evaluated for their use in the overall design of the plasma microthruster. Laser-supported detona- tion shows a tremendous potential increase in the laser momentum coupling coefficient Cm , and demonstrates a much higher thrust; the axisymmetric nozzle varies with nozzle half-angle and length, but still demonstrates expected nozzle trends and improves the laser momentum coupling coefficient, Cm , by up to 230% for some designs considered.

An aircraft will encounter freezing rain, snow, and ice during ground operation and flight. In cold conditions, ice may form on th einlet and internal stators and rotors of the gas turbine engine. When ice accumulates on blades (and/or stators), the aerodynamic characteristics of the blades change due to the altered size, shape, and roughness. This change causes the blade to no longer operate at its design point and decreases compressor performance. Therefore, characterization of the aerodynamic performance is required to define the associated losses due to the effects of supercooled liquid water ingestion. This characterization can be accomplished through analysis and test. This research developed an analysis method to calculate the aerodynamic changes on a blade due to ice accumulation and the associated degradation in performance.

The use of aluminum as an energetic additive in solid rocket propellants has been around since the 1950’s. Since then, much research has been done both on the aluminum material itself and on chemical techniques to properly prepare aluminum particles for injection into a solid propellant. Although initial interests in additives were centered on space limited applications, performance increases opened the door for higher performance systems without the need to remake current systems. This thesis aims to compare the performance for aluminized solid rocket motors and non-aluminized motors, as well as focuses on design considerations for a thrust stand that can be created easily at low cost for initial testing. A theoretical model is created for predicting propellant performance and the results are compared with experimental data taken from the thrust stand as well as existing data. What is seen at the end of testing is the non-aluminized grains follow the same trends as previously conducted tests and firings. The aluminized grains follow their expected trend but at a lower performance level due to grain degradation. However, the aluminized grains still show a specific impulse increase of 6%-23% over the non-aluminized grains.

Experimental investigations have evaluated the feasibility of using laser-driven plasma microthrusters for small-thrust, high-specific-impulse space maneuvers, particularly for micro- and nanosatellite missions. Recent work made use of the Mach2 hydromagnetics code for the construction of an adequate computational model of the micro-thruster opera- tion. This thesis expounds on this previous work by extending the computational modeling capabilities, allowing for the determination of plasma plume properties and characteristic performance assessment of the microthruster; this allows for further computational investi- gation of the performance improvements achieved by new design considerations. Two par- ticular design changes are implemented and measured: (i) the simulation of microthruster performance intentionally achieving laser-supported detonation of energetic polymer fuels for higher-thrust capabilities, and (ii) the implementation of an axisymmetric nozzle to improve passive solid-fuel performance. The Mach2 hydromagnetics code with the new performance assessment capabilities was used to examine the performance improvement of these new modes of operation; results of the simulations are presented and then evaluated for their use in the overall design of the plasma microthruster. Laser-supported detona- tion shows a tremendous potential increase in the laser momentum coupling coefficient Cm , and demonstrates a much higher thrust; the axisymmetric nozzle varies with nozzle half-angle and length, but still demonstrates expected nozzle trends and improves the laser momentum coupling coefficient, Cm , by up to 230% for some designs considered.

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Nanosatellites, such as Cubesats, are a rapidly growing sector of the space industry. Their popularity stems from their low development cost, short development cycle, and the widespread availability of COTS subsystems. Budget-conscious spacecraft designers are working to expand the range of missions that can be accomplished with nanosatellites, and a key area of development fueling this expansion is the creation of micropropulsion systems. One such system, originally developed at the Australian National University (ANU), is an electrothermal plasma thruster known as Pocket Rocket (PR). This device heats neutral propellant gas by exposing it to a Capacitively Coupled Plasma (CCP), then expels the heated gas to produce thrust. Significant work has gone towards understanding how PR creates and sustains a plasma and how this plasma heats the neutral gas. However, no research has been published on varying in the device's geometry. This thesis aims to observe how the size of the RF electrode affects PR operation, and to determine if it can be adjusted to improve performance. To this end, a thruster has been built which allows the geometry of the RF electrode to be easily varied. Measurements of the plasma density at the exit of this thruster with different sizes of electrode were then used to validate a Computational Fluid Dynamics (CFD) model capable of approximately reproducing experimental measurements from both this study and from the ANU team. From this CFD, the number of argon ions in the thruster was found for each geometry, since collisions between argon ions and neutrals are primarily responsible for the heating observed in the thruster. A geometry using a 10.5 mm electrode was observed to produce a 23% increase in the quantity of ions produced compared to the baseline 5 mm electrode size, and a 3.5 mm electrode appears to produce 88% more ions.