Planetary Mixing for Solid Propellant Homogeneity
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Solution Overview
Problem
Conventional methods for mixing solid propellants are inefficient, requiring long times to achieve homogenous mixtures and are limited to linear burn rates below 1.5 inches per second due to the difficulty in handling finely ground oxidizers, which results in viscous mixtures and trapped air bubbles.
Innovation Solution
A method involving a mixing system that rotates a mix vessel about a spin axis while simultaneously revolving it around a planetary axis, generating high shear forces to produce a homogenous propellant mixture with finely ground oxidizers, allowing for higher burn rates by reducing oxidizer particle sizes to 0.3 to 50 microns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If oxidizer is ground to fine particle size (0.3 to 50 microns) to increase burn rate, then linear burn rate increases to above 1.5 inches per second, but mixture viscosity increases making it difficult to mix and handling
Solution Approach 1:
The patent changes the mixing parameters by implementing a dual-axis planetary mixing system with specific rotational speeds and directions. The mix vessel rotates on a spin axis while simultaneously revolving on a planetary axis, creating complex shear flow patterns that enable effective mixing of fine oxidizer particles despite high viscosity. This parameter change resolves the contradiction by finding optimal mixing conditions for fine particle propellants.
Solution Approach 2:
The patent replaces conventional single-axis mechanical mixing systems with a dual-axis planetary mixing system. This substitution creates more effective shear forces and flow patterns that overcome the high viscosity caused by fine oxidizer particles, enabling proper mixing where conventional systems fail.
2Device complexity
If conventional planetary mixers are used to mix propellant ingredients, then mixing can be performed with simple equipment, but mixing time is long (6 to 8 hours) to achieve homogenous mixture
Solution Approach 1:
The patent implements a dynamic dual-axis planetary mixing system where the mix vessel simultaneously rotates on a spin axis and revolves on a planetary axis. This dynamic motion creates varying shear rates and flow patterns throughout the mixture, significantly accelerating homogenization compared to static or single-axis systems, reducing mixing time from 6-8 hours to a fraction of that time.
Solution Approach 2:
The patent adds another dimension of motion by implementing dual-axis rotation instead of single-axis rotation. The mix vessel rotates on one axis while revolving on a second axis, creating three-dimensional flow patterns that dramatically improve mixing efficiency and reduce the time required to achieve homogenous mixtures.
3Device complexity
If paint shaker-type equipment is used to mix propellant, then mixing can be performed with simpler equipment, but mixing time is still substantial (1 to 2 hours) and air bubbles may be trapped
Solution Approach 1:
The patent implements dynamic dual-axis planetary motion that creates continuous varying shear forces and flow patterns, significantly more effective than the oscillating motion of paint shakers. This dynamic approach not only reduces mixing time from 1-2 hours but also prevents air bubble entrapment by maintaining continuous, uniform flow throughout the mixture.
Solution Approach 2:
The patent replaces the oscillating mechanical system of paint shakers with a dual-axis planetary rotational system. This substitution creates more effective shear forces and eliminates dead zones where air bubbles could become trapped, achieving both faster mixing and better degassing in a single process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces mixing time by 50-90% and enables linear burn rates up to 8.5 inches per second, while eliminating air bubbles and handling higher viscosities, resulting in more efficient propellant production.
Implementation Method 1
rotating the mix vessel about a spin axis while revolving the mix vessel about a planetary axis that is offset from the spin axis. Mixing the first and second components together in this manner can cause high shear forces in the mixture
Data Source
AI summary
Methods and systems for mixing propellant formulations are disclosed herein. In one embodiment, a method of mixing a solid propellant formulation includes placing a first component (e.g., a polymer or fuel) and a second component (e.g., an oxidizer of suitable particle size) in a mix vessel. The method further includes mixing the first and second components together by rotating the mix vessel about a first axis and, during at least a portion of the vessel rotation, revolving the vessel about a second axis spaced apart from the first axis. In one embodiment, the first axis can be a vessel spin axis, and the second axis can be spaced apart from the first axis so that the vessel revolves about the second axis in a planetary manner. In another embodiment, the vessel can rotate about the first axis in a first direction while revolving about the second axis in a second direction, opposite to the first direction.