Browsing by Subject "composite propellant"
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Item Laboratory-Scale Burning and Characterizing of Composite Solid Propellant for Studying Novel Nanoparticle Synthesis Methods(2013-04-29) Allen, Tyler WinstonThis thesis examines the effects of nanoparticle, metal-oxide additives on the burning rate of composite solid propellants. Recent advancements in chemical synthesis techniques have allowed for the production of improved solid rocket propellant nano-scale additives. These additives show larger burning rate increases in composite propellants compared to previous additive generations. In addition to improving additive effectiveness, novel synthesis methods can improve manufacturability, reduce safety risks, and maximize energy efficiency of nano-scale burning rate enhancers. Several different nano-sized additives, each titania-based, were tested and compared for the same baseline AP/HTPB formulas and AP size distributions. The various methods demonstrate the evolution in our methods from spray-dried powders to pre-mixing the additive in the HTPB binder, and finally to a method of producing the additive directly in the binder as a nano-assembly. Burning rate increases as high as 80% at additive mass loadings of less than 0.5% were seen in non-aluminized, ammonium perchlorate-based propellants over the pressure spectrum of 500 psi (3.5 MPa) to 2250 psi (15.5 MPa). Increases in burning rate up to 73% were seen in similarly formulated aluminized propellants. During the past several years, the research team has refined laboratory-scale techniques for quickly and reliably assessing the mixing and performance of composite propellants with catalytic nanoparticle additives. This thesis also documents some of the details related to repeatability, accuracy, and realism of the methods used in the team?s recent nano-additive research; it also introduces the latest techniques for producing propellants with nano-sized additives and provides new burning rate results for the entire scope of additives and mixing methods. Details on the propellant characterization methods with regard to physical and combustion properties are provided. Snapshots from atmospheric propellant combustion videos taken with a Photron FASTCAM SA3 high-speed camera are included along with existing pressure and light-emission responses.Item TAILORING THE PLATEAU BURNING RATES OF COMPOSITE PROPELLANTS BY THE USE OF NANOSCALE ADDITIVES(2010-07-14) Stephens, MatthewComposite propellants are composed of a solid oxidizer that is mixed into a hydrocarbon binder that when polymerized results in a solid mass capable of selfsustained combustion after ignition. Plateau propellants exhibit burning rate curves that do not follow the typical linear relationship between burning rate and pressure when plotted on a log-log scale, and because of this deviation their burning behavior is classified as anomalous burning. It is not unusual for solid-particle additives to be added to propellants in order to enhance burning rate or other properties. However, the effect of nano-size solid additives in these propellants is not fully understood or agreed upon within the research community. The current project set out to explore what possible variables were creating this result and to explore new additives. This thesis contains a literature review chronicling the last half-century of research to better understand the mechanisms that govern anomalous burning and to shed light on current research into plateau and related propellants. In addition to the review, a series of experiments investigating the use of nanoscale TiO2-based additives in AP-HTPB composite propellants was performed. The baseline propellant consisted of either 70% or 80% monomodal AP (223 ?m) and 30% or 20% binder composed of IPDI-cured HTPB with Tepanol. Propellants? burning rates were tested using a strand bomb between 500 and 2500 psi (34.0-170.1 atm). Analysis of the burning rate data shows that the crystal phase and synthesis method of the TiO2 additive are influential to plateau tailoring and to the apparent effectiveness of the additive in altering the burning rate of the composite propellant. Some of the discrepancy in the literature regarding the effectiveness of TiO2 as a tailoring additive may be due to differences in how the additive was produced. Doping the TiO2 with small amounts of metallic elements (Al, Fe, or Gd) showed additional effects on the burning rate that depend on the doping material and the amount of the dopant.