Cold gas thrusters are commonly used on spacecraft for in-space attitude control and adjustment. These thrusters use inert gases stored at high pressures to create small amounts of thrust and typically have multiple fixed outlets, each controlled by its own actuated valve, to control the direction the thrust is directed. Having individual outlets with their own actuated valve leads to a great amount of power drawn for the individual actuators, as well as general added complexity by having a large number of parts. To address this issue, this thesis investigates an attempt to minimize the number of actuators required for a cold gas thruster system to operate. This thesis details the design, analysis, electronics integration, manufacturing, and testing of a cold gas thruster system with as few actuators as possible. In addition, a thrust target, a maximum response time, and a long duration test regime were set as requirements to drive the design. From these goals and requirements, a cold gas thruster system that uses a single central selector valve to control the actuation of four outlets while only using two motors was designed. The selector valve design uses a sleeve that rotates and moves vertically to align ports in the valve to allow the propellant gas to flow freely through the valve and to the nozzle where thrust is produced. The sleeve is rotated by a motor connected to a pair of gears, and the vertical motion is controlled by a motor with a lead screw. Along with the mechanical design of the system, a great amount of compressible flow fluids analysis was performed. This analysis was used to determine the geometry of the outlet nozzle and its tolerances. In addition, a model was created using MATLAB and Simulink to predict the pressure drops throughout the system. This model is used to estimate the necessary pressure regulator outlet pressure that produces the nominal thrust. The electronic control panel was developed to control the motors as well as to obtain performance data. Stepper motors were used to control the selector valve and controlled by a Teensy microcontroller board and custom libraries to operate the stepper motors simultaneously. Pressure and thrust data were collected from sensors that report the data to an Arduino microcontroller. The testing performed was highly successful with the thrust requirement and the long duration test regime requirements were achieved, while the maximum response time requirement was missed, but not by a large margin. The targeted thrust was able to be produced, and the required endurance test profile was successfully performed. The response time requirement was met for two out of the three valve actuation motions and was slightly exceeded for the last one.

Future Navy Capabilities indicate the need for a supersonic cruise missile. Thus the need exists for a low cost, light-weight, and efficient means of supersonic propulsion. NPS has been developing the Pulse Detonation Engine, which in theory has a thermodynamic efficiency greater than 50% as compared to 35% for state of the art constant-pressure cycles currently in use in gas turbines/ramjets/scramjets. Nonetheless, there are two major problems in the development of this engine. These are the increase of the propulsive efficiency by removing the oxygen-assisted initiator currently in use, and the reduction of internal total pressure losses caused by the highly constrictive internal flow-path geometry currently required to promote the deflagration to detonation transition (DDT). The aforementioned problems have been addressed and a viable design proposed through the implementation of a novel Transient Plasma Ignition system and a split-flow path engine geometry as described in this work. Future work will concentrate on the development of a performance measurement test rig to experimentally assess the designs presented herein. / US Navy (USN) author.

The use of surface piercing propellers (SPPs) shows promise for high speed operation by virtually eliminating appendage drag, which can be as much as 30 percent of the total drag on a vehicle at high speeds. The scarcity of available systematic test data has made reliable performance prediction difficult. The primary objective of this research is to obtain experimental performance prediction data that can be used in SPP design. In a series of open water tests in a non-pressurized towing tank facility, force transducer measurements were taken at tip immersion ratios from 0.5 to .33, yaw angles from 0° to 30° and inclination angles from 0° to 15° over a range of advance ratios from 0.8 to 1.8. Force transducer measurements were taken for thrust, torque, side forces and moments. These results will help develop a baseline for the verification of SPP performance prediction. / by Justin M. Lorio. / Thesis (M.S.C.S.)--Florida Atlantic University, 2010. / Includes bibliography. / Electronic reproduction. Boca Raton, Fla., 2010. Mode of access: World Wide Web.

A dissertation submitted to the Faculty of Science, University of Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. / In this dissertation a recipe has been outlined on how thrust can be calculated using the conservation of momentum in continuum form. With the aim of modelling a CORION (corona ionization) like thruster in mind it was then argued using a much simpler system and stochastic calculus why a statistical description of the system is necessary. From this the one-particle distribution emerged as a natural tool for the description of a system su cient for the determination of the system's thrust.This was followed by a short investigation into the background of non-equilibrium statistical mechanics, both classical and quantum, necessary to understand how one-particle distributions could be derived formally and in a physically consistent way. Mass ow and current-voltage experiments of the CORION like thrust system, necessary for characterization of part of the system, were conducted. This led to a proposal for a modelling strategy, consisting of merging di erent modelling approaches and descriptions considered throughout the dissertation.

abstract: In recent years, a new type of ionic salt based solid propellant, considered inert until the application of an electric current induces an electro-chemical reaction, has been under investigation due to its broad range of possible uses. However, while many electric propellant formulations and applications have been explored over the years, a fundamental understanding of the operational mechanisms of this propellant is necessary in order to move forward with development and implementation of this technology. It has been suggested that the metallic additive included in the formulation studied during this investigation may be playing an additional, currently unknown role in the operation and performance of the propellant. This study was designed to examine variations of an electric propellant formulation with the purpose of investigating propellant bulk volume electrical resistivity in order to attempt to determine information regarding the fundamental science behind the operation of this material. Within a set of fractional factorial experiments, variations of the propellant material made with tungsten, copper, carbon black, and no additive were manufactured using three different particle size ranges and three different volume percentage particle loadings. Each of these formulations (a total of 21 samples and 189 specimens) were tested for quantitative electrical resistivity values at three different pulse generator input voltage values. The data gathered from these experiments suggests that this electric propellant formulation’s resistivity value does change based upon the included additive. The resulting data has also revealed a parabolic response behavior noticeable in the 2D and 3D additive loading percentage versus additive particle size visualizations, the lowest point of which, occurring at an approximately 2.3% additive loading percentage value, could be indicative of the effects of the percolation phenomena on this material. Finally, the investigation results have been loosely correlated to power consumption testing results from previous work that may indicate that it is possible to relate propellant electrical resistivity and operating requirements. Throughout this study, however, it is obvious based on the data gathered that more information is required to be certain of these conclusions and in order to fully understand how this technology can be controlled for future use. / Dissertation/Thesis / Masters Thesis Mechanical Engineering 2019

Non-conventional bio-derived fuels have been evaluated for use in hybrid rocket motors. Tests were conducted at combustion pressures in the range of 100 – 220 psig and thrust levels of 40 – 170 newtons. Beeswax was tested with oxygen as the oxidizer and showed a regression rate at least three times as high as traditional hybrid propellant combinations such as hydroxyl-terminated polybutadiene (HTPB) and liquid oxygen (LOX). This provides the promise of a high thrust hybrid rocket motor using a simple, single port geometry and overcomes the main weakness of traditional hybrid rocket motor propellants, which are low regression rates. Beeswax was also tested with nitrous oxide as an oxidizer, but further testing is needed to attain high enough combustion chamber pressures to achieve stable combustion. Experimental evaluation of the specific impulse for beeswax and oxygen was moderately successful for lab scale testing, but needs further refinement. Analytical studies were performed to evaluate the theoretical performance of non-conventional hybrid rocket motors. This analysis indicates beeswax, lard, a mixture of paraffin and lard, and combinations of beeswax and aluminum should all perform better than traditional hybrid rocket propellants considered when burned with oxygen. For a combustion chamber pressure of 500.38 psig, beeswax and oxygen yielded a maximum specific impulse of 327 s. The high specific impulse combined with a high regression rate combine to make beeswax and oxygen a potentially high performing hybrid rocket motor propellant for launch vehicles, suborbital rockets, or orbital kick motors.

Thesis (M.Eng.)--Memorial University of Newfoundland, 2001. / Bibliography: leaves 77-79.

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (p. 165-170).

Atmospheric carbon dioxide and pollution due to the burning of fossil fuels is increasing. Many scientists attribute global warming to the rising levels of carbon dioxide and other pollutants, some of which also pose risks to health. These can be reduced by the more efficient use of conventional fuels and the development of non-polluting energy resources. Fuel cells offer a highly efficient and low polluting method of generating electricity, and are under development for both the power generation and transport sectors. There is a need to assess (a) emissions from fuel cells using various fuels and (b) ways of introducing such technology to transportation in the near future. Fuel consumption, energy and emissions from the production and use of fuels (hydrogen, methane, propane, petrol, diesel, alcohols and rape methyl ester) are calculated per kilowatt hour of fuel cell output over a range of efficiency. These are compared with those for internal combustion engines with advanced exhaust control and for the recharging of battery driven vehicles. The results, which are applicable to both transport and power generation, enable the best low pollution fuels to be selected and are used to calculate through life emissions for public transport buses. Fuel cells are an ideal solution to reduce pollution from transport, but their commercial development in this field is further away than that for stationary applications. Thus, a transition stage is recommended where fuel cell electrical power stations, based on existing demonstrators, are used to recharge fleets of battery driven vehicles during the development of mobile fuel cell systems. These fleets include public transport and commercial vehicles. Also, fuel cell power stations could provide energy for electric trains. A combined system is proposed where electric trains recharge battery driven commercial vehicles during long journeys. The above proposals would enhance fuel cell development, introducing them alongside current transport systems, possibly using the same fuel.

Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: Teflon ablation; pulsed plasma thrusters; numerical analysis; PPT; depolymerization. Includes bibliographical references (p.102-105).