Solid Propellant Grain Molding for Helmholtz Resonator Geometry
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Solution Overview
Problem
Existing methods for manufacturing solid rocket motor propellants struggle with efficiently forming complex grain shapes that require precise control over combustion profiles and thrust profiles, particularly in hybrid rocket motors where liquid flow control is crucial.
Innovation Solution
A method involving the use of a tool with layered materials to mold a second material, which is then used to create a Helmholtz resonator in the rocket propellant grain, utilizing elastic mandrels and laser-cutting techniques to form intricate chamber structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional molding methods are used to form propellant grains, then the manufacturing process is simple, but the ability to create complex grain shapes with precise combustion control is limited
Solution Approach 1:
The molding tool is divided into multiple layers (first layer, second layer, third layer) that can be separately positioned and adjusted. Each layer can be independently moved relative to the others, allowing complex grain shapes to be formed through sequential positioning rather than requiring a single complex monolithic tool.
Solution Approach 2:
The invention introduces a new dimension of control by allowing relative movement between layers in the axial direction. This multi-layer stacking approach with inter-layer movement capability enables the formation of complex three-dimensional grain shapes that cannot be achieved with traditional single-stage molding.
2Manufacturing precision
If complex grain shapes are formed to control combustion profiles, then combustion control is improved, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The layers are pre-positioned and pre-adjusted to their required relative positions before the actual propellant grain formation takes place. This preliminary positioning of layers allows complex grain shapes to be formed in a single molding operation, eliminating the need for multiple sequential molding steps and thereby improving manufacturing efficiency.
Solution Approach 2:
The multi-layer molding tool can form various different complex grain shapes by adjusting the relative positions of layers, making it a universal tool that can produce multiple grain configurations. This eliminates the need for different specialized tools for different grain shapes, thereby improving productivity.
3Reliability
If Helmholtz resonators are incorporated to manage thermoacoustic instabilities, then combustion stability is improved, but the manufacturing process requires additional precision
Solution Approach 1:
The Helmholtz resonator structure is formed by specific positioning and configuration of the layered tool components. The segmentation of the tool into adjustable layers allows precise formation of the resonator's geometric features (cavity volume, neck dimensions) that are critical for combustion stability, while distributing the precision requirements across multiple adjustable components rather than requiring a single ultra-precise tool.
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
Enables the production of propellant grains with tailored combustion and thrust profiles, effectively managing thermoacoustic instabilities and enhancing combustion rates through the use of Helmholtz resonators.
Implementation Method 1
the molded second material molds a Helmholtz resonator in the rocket propellant grain
Implementation Method 2
the forming the layers comprising laser cutting
Data Source
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AI summary
A method for manufacturing a solid propellant (20) includes: forming a tool (200) of layers (250) of a first material wherein cuts in the layers (250) form a first interior chamber in the tool; using the tool (200) to mold a second material in the first interior chamber; removing the molded second material (102) from the tool (200); using the molded second material (102) to mold an interior chamber (30) in a rocket propellant grain (20); and removing the molded second material (102) from the rocket propellant grain (20).