Characterization of nanoscale aluminum and ice solid propellants

Travis R Sippel, Purdue University

Abstract

Solid rocket motors are favored for launch applications because of their simplicity and high thrust to weight ratio. Longer space missions and manned missions will require new, higher performance propellants. Preliminary calculations by others have identified the aluminum and water combustion system as having high potential for propulsion applications. Problems achieving and sustaining combustion experienced by early research have been solved through the development of aluminum nanoparticles. As a result, aluminum and water propellants have received renewed attention. Nearly all recent work on nanoscale aluminum and water propellants has been small in scale. The purpose of this work is to provide fundamental propellant characterization and safety testing, providing a foundation for scale up and development of these propellants. The first part of this work presents a historical overview of research pertinent to the development of aluminum and water propellants. It also discusses aluminum nanoparticles and their characterization. This work also examines the combustion characterization of aluminum and ice propellants experimentally, computationally, and analytically. The safety characterization of propellant formulations in terms of impact, shock, and electrostatic discharge sensitivity are also examined. Procedures for large-scale mixing of the propellant are presented. Results of this work are as follows: Equilibrium combustion calculations predict Al/H2O/H2O2 propellants to have theoretical vacuum specific impulses of over 350 seconds. The linear burning rate pressure dependence of formulations has been experimentally shown to vary between 0.25-0.43 depending on formulation. Hydrogen peroxide was used to enhance the burn rate of aluminum ice mixtures containing larger nanoparticles to replicate burning characteristics of aluminum ice formulations containing smaller aluminum nanoparticles. The surfactant Neodol 91-6 was successfully used to mix hydrophobic palmitic acid coated aluminum. Sensitivity testing reveals that palmitic acid and Viton aluminum particle coatings have the potential to dramatically decrease the electrostatic discharge ignition sensitivity of dry aluminum Nanopowders. Shock sensitivity tests reveal that mixtures of aluminum and water containing 5% hydrogen peroxide in the water are detonable. Stoichiometric aluminum-ice propellants containing 38 nm Technanogy aluminum were determined to be weakly detonable. All mixtures of aluminum and ice containing between 0-10% hydrogen peroxide were insensitive to impact ignition.

Degree

M.S.M.E.

Advisors

Son, Purdue University.

Subject Area

Aerospace engineering|Mechanical engineering

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