Propellant Grain Conductive Membrane Thrust
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Solution Overview
Problem
End-burning solid rocket motors face limitations in achieving high thrust levels and mass flow rates due to low initial surface area and low loading density, with previous attempts to enhance thrust through embedded thermally conductive wires being restricted by limited wire patterns and potential displacement during propellant casting.
Innovation Solution
A flexible polymer membrane with a thermally conductive coating, featuring a patterned metallic foil, is embedded within the propellant grain to maintain the position of thermally conductive pathways, allowing for controlled heat transfer and increased combustion rates without reducing the propellant mass.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If internal passageways are added to increase burning surface area, then thrust profile can be controlled, but loading density decreases and range is reduced
Solution Approach 1:
A flexible membrane with thermally conductive coating is embedded in the propellant grain. The membrane maintains its shape during casting to define wire positions, then flexes to accommodate propellant expansion without disrupting the thermal conduction pathways, enabling both high loading density and controlled thrust profile.
Solution Approach 2:
The flexible membrane acts as an intermediary structure that facilitates heat transfer from the combustion zone to the propellant interior through its thermally conductive coating. This mediator enables controlled burning patterns without requiring internal passageways that would reduce loading density.
2Power
If straight thermally conductive wires are embedded to increase mass flow rate, then thrust increases, but wire position stability decreases during casting
Solution Approach 1:
The flexible membrane with pre-formed thermally conductive pattern is positioned in the mold before propellant casting. This preliminary action establishes the exact wire positions and patterns beforehand, preventing displacement during casting and ensuring manufacturing precision.
Solution Approach 2:
The flexible membrane accommodates propellant expansion and contraction during casting and curing without disrupting the embedded thermally conductive wires. The membrane's flexibility maintains wire position stability while allowing the propellant to be properly formed.
3Quantity of substance
If end-burning grain configuration is used to maximize loading density, then propellant mass is maximized, but initial surface area and thrust level are reduced
Solution Approach 1:
The thermally conductive coating is applied locally on the flexible membrane at specific positions within the propellant grain. This creates localized heating zones that generate additional combustion surfaces in strategic locations, increasing thrust without compromising the overall end-burning configuration and loading density.
Solution Approach 2:
The flexible membrane with thermally conductive coating serves as an intermediary that introduces controlled heat transfer pathways into the end-burning grain. This mediator creates localized conical combustion surfaces that increase mass flow rate and thrust while maintaining the high loading density of the end-burning configuration.
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
The solution enhances mass flow rate and thrust while maintaining high loading density, allowing for greater propulsion without additional propellant mass, and enables flexible design of thermally conductive patterns for optimized performance.
Implementation Method 1
the heat from the combustion zone is thermally conducted by the wires into the rocket propellant
Implementation Method 2
a membrane comprising of a flexible polymer will have a thermally conductive coating
Implementation Method 3
The solid propellant is ignited and creates a combustion zone on the propellant grain surface
Data Source
AI summary
A solid rocket propellant grain having rocket propellant and a membrane in contact with the rocket propellant. The membrane includes a highly heat conductive pattern which affects the propellant burning rate through localized conductive heat transfer from the combustion zone and into the uncombusted propellant. Different geometries for the thermally conductive pattern produce different combustion results.