Feasibility Study and Demonstration of an Aluminum and Ice Solid Propellant

Abstract

Aluminum-water reactions have been proposed and studied for several decades for underwater propulsion systems and applications requiring hydrogen generation. Aluminum and water have also been proposed as a frozen propellant, and there have been proposals for other refrigerated propellants that could be mixed, frozen in situ, and used as solid propellants. However, little work has been done to determine the feasibility of these concepts. With the recent availability of nanoscale aluminum, a simple binary formulation with water is now feasible. Nanosized aluminum has a lower ignition temperature than micronsized aluminum particles, partly due to its high surface area, and burning times are much faster than micron aluminum. Frozen nanoscale aluminum and water mixtures are stable, as well as insensitive to electrostatic discharge, impact, and shock. Here we report a study of the feasibility of an nAl-ice propellant in small-scale rocket experiments. The focus here is not to develop an optimized propellant; however improved formulations are possible. Several static motor experiments have been conducted, including using a flight-weight casing. The flight weight casing was used in the first sounding rocket test of an aluminum-ice propellant, establishing a proof of concept for simple propellant mixtures making use of nanoscale particles.

Novel Energetic Materials for Space Propulsion

“…In the current investigation, the performance and viability of nAl and ice (ALICE), and various ALICE based propellant formulations were examined. Safety tests such as ESD, mechanical tensile tests, and impact tests have been performed [25]. Both fundamental steady-state strand-burner experiments and applied lab-scale hot-fire motor experiments were employed to ascertain ballistic data.…”

The effects of additives on the combustion characteristics of aluminum powder in steam

“…17,18 However, most of studies had focused on the investigation of the reaction of aluminum and water at low temperature, [19][20][21] and the combustion behaviors of aluminum/ice solid propellant. [22][23][24] Only a few experimental studies were carried out on the combustion characteristics of aluminum in heated steam atmosphere. 25,26 Based on thermogravimetric analysis, Schoenitz et al 27 found that the oxidation process of aluminum powder in steam atmosphere was similar to that in oxygen atmosphere.…”

Combustion of Nanoaluminum and Water Propellants: Effect of Equivalence Ratio and Safety/Aging Characterization

“…Frozen nano-aluminum and water (ALICE) has been researched recently as a propellant [2,3,[11][12][13][14][15]. Burning rate and combustion efficiency experiments on aluminum and water propellants containing 38 nm aluminum powder have been reported [2,3,16].…”

“…Likewise, nAl/H 2 O mixtures are insensitive to impact ignition, having an ignition threshold in excess of 2.2 m. Propellants containing 80 nm or larger average particle size aluminum were also found to be insensitive to shock initiation. [3,12,13]. In exploring the effects of particle size variation, Risha et al [3] found that the burning rate is predominantly a function of aluminum particle diameter.…”