Self-Extinguishing Propellant Grain for Solid Rocket Motors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Solid propellant rocket motors lack a non-destructive method to extinguish the propellant, leading to structural damage and uncontrolled burn-off, as existing shut-off processes require rapid depressurization, which is complex and risky.
Innovation Solution
A self-extinguishing solid propellant grain is developed, comprising a fuel, oxidizer, binder, and surfactant, with a burning rate that decreases with increasing pressure, allowing the propellant to extinguish naturally at a cutoff pressure without the need for depressurization, using additives like sodium dioctyl sulfosuccinate and catalysts to modify the burning rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If rapid depressurization is used to shut off the propellant, then the propellant can be stopped from burning, but the motor suffers severe structural damage and uncontrolled burn-off
Solution Approach 1:
The patent modifies the propellant's burning rate characteristics by adding surfactants and catalysts, changing the pressure-dependence parameter from positive to negative. This allows the propellant to automatically extinguish at operational pressures without requiring destructive depressurization, thus resolving the contradiction between achieving shut-off and preserving structural integrity
Solution Approach 2:
The patent converts the harmful effect of high pressure (which normally increases burning rate) into a beneficial extinguishing mechanism. By formulating the propellant with negative pressure dependence, the high pressure that would normally intensify combustion instead becomes the condition that extinguishes the burn, eliminating the need for destructive shut-off methods
2Reliability
If rapid depressurization is used to extinguish the propellant, then burning can be stopped, but the process is complex and risky
Solution Approach 1:
The patent enables the propellant to extinguish itself automatically when combustion chamber pressure reaches certain levels, eliminating the need for external depressurization systems. The propellant's inherent burning rate characteristics, modified by surfactants and catalysts, provide self-regulating extinguishment, thereby reducing system complexity and eliminating associated risks
3Ease of manufacture
If conventional propellant is used, then the motor is simple to manufacture, but it cannot be extinguished and relit for multiple firings
Solution Approach 1:
The patent modifies the propellant's pressure-dependent burning rate parameter through the addition of surfactants and catalysts. This parameter change enables the propellant to be extinguished at operational pressures and relit for multiple firings, while maintaining the simplicity of solid propellant manufacturing processes
Solution Approach 2:
The patent creates a composite propellant material combining traditional fuel and oxidizer components with surfactants and catalysts. This composite formulation provides the unique property of extinguishability at operational pressures, enabling multiple firings while preserving the manufacturing simplicity of solid propellants
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 solution enables safe, non-destructive shut-off of the propellant, preventing catastrophic failures and allowing for re-ignition, enhancing the reliability and safety of solid rocket motors, particularly in applications requiring multiple firings and trajectory adjustments.
Implementation Method 1
The propellant grain is a self-extinguishing propellant grain that exhibits a burning rate as a function of pressure that includes a negative pressure dependence portion, wherein the burning rate in the negative pressure dependence portion decreases with increasing pressure until a cutoff pressure is reached which results in extinguishment of the propellant grain
Implementation Method 2
using additives like sodium dioctyl sulfosuccinate and catalysts to modify the burning rate
Data Source
AI summary
A solid rocket motor includes a combustion chamber bounded by an outer casing, a propellant grain within the combustion chamber, and an igniter within the outer casing for igniting the propellant grain. A nozzle is coupled to the combustion chamber for releasing hot gasses evolved from burning the propellant grain to provide thrust for propelling the solid rocket motor. The propellant grain is a self-extinguishing propellant grain that includes at least one fuel, at least one oxidizing agent, at least one binder, and at least one surfactant that imparts the self-extinguishing property. The propellant grain provides a burning rate as a function of pressure that includes a negative pressure dependence portion, wherein the burning rate in the negative pressure dependence portion decreases with increasing pressure until a cutoff pressure is reached which results in extinguishment of the propellant grain.