Resonant Acoustic Mixing of Solid Rocket Motor Propellant to Minimize Property Variations

ABSTRACT: Current mixing and casting procedures result in unwanted gradients in solid rocket motor (SRM) material properties with subsequent ballistic property variations. Resodyn Corporations ResonantAcoustic mixing (RAM) technology is poised to revolutionize the design, development and production of SRMs. RAM technology has the unique capability of rapidly mixing high solids propellant without using the high levels of shear that contribute to non-uniform material properties of the SRMs that are currently produced. Additionally RAM enables a method to reduces the number steps needed to fabricate an SRM. Uniform mixing of an inert propellant was successfully demonstrated in Phase I resulting in tensile modulus variations in the propellant less than, or equal to, 5%. The mix-in-case concept was demonstrated for both an end-burner and a center perforation grain configuration. A first principles model was introduced and its applicability was demonstrated. This Phase II proposal extends the Phase I effort with more detailed evaluations of propellant formulation and grain configuration relative to ResonantAcoustic Mixing focusing upon scaling up the process and mixing in case. Safety concerns and facility requirements are also addressed. A method for dissemination and exchange of RAM best practices throughout the energetics community is also proposed. BENEFIT: RAM technologies will have significant impact at all levels of the SRM industry from laboratory development work, to engineering prototype motors, and into qualified production programs. This technology dramatically reduces production cycle times and reduces the significance of the uncured propellant viscosity, which is currently a limiting factor that dominates current mixing procedures. When the RAM technology is integrated into all levels of the SRM industry, the inherent benefits of using RAM technology will allow for improvements in mix quality, safety, production time and quality.