Concentric Solid Fuel Grain for Hybrid Rocket Propulsion
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Solution Overview
Problem
Hybrid propulsion systems for rockets face limitations due to low regression rates of conventional fuels, leading to complex multi-port designs and inefficiencies, which hinder their practical application despite offering safety and cost advantages over liquid and solid systems.
Innovation Solution
A solid fuel grain with concentric layers and a surface pattern manufactured using freeform-fabrication machines, allowing for increased combustion surface area and smooth burning, enabling higher regression rates without compromising safety or manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solid fuel is used in hybrid propulsion systems, then safety and lower manufacturing costs are achieved, but regression rate is limited to one-tenth or less of solid propellant rates
Solution Approach 1:
The fuel grain is segmented into multiple concentric layers with different fuel types arranged in specific patterns. This segmentation allows different materials to be positioned strategically to optimize combustion characteristics while maintaining the inherent safety advantages of hybrid systems.
Solution Approach 2:
The invention uses composite fuel grain structures combining different solid fuel materials in concentric layers. This composite approach enables the fuel to achieve higher regression rates comparable to solid propellants while retaining the safety benefits of solid fuel in hybrid systems.
2Power
If burning surface area is increased to achieve high thrust in hybrid propulsion, then thrust is improved, but design complexity increases due to multi-port configurations
Solution Approach 1:
The fuel grain is divided into concentric layers that can be manufactured separately and then assembled. This segmentation enables complex multi-layer structures to be created without requiring complex in-situ molding, simplifying the manufacturing process while achieving the desired burning surface area for high thrust.
Solution Approach 2:
The invention transitions from traditional single-port or multi-port radial configurations to a multi-layer concentric structure. This dimensional reorganization allows increased burning surface area through layering rather than through complex port arrangements, reducing design complexity while maintaining high thrust capability.
3Ease of manufacture
If conventional casting or molding methods are used for fuel grain manufacturing, then manufacturing process is simple, but fuel grain geometry is limited
Solution Approach 1:
The fuel grain manufacturing process is segmented into separate casting steps for different concentric layers. Each layer can be manufactured using simple casting or molding techniques, but the layered assembly enables complex overall geometries that would be impossible to achieve with a single casting operation.
Solution Approach 2:
Individual concentric layers are manufactured in advance using simple casting methods, then assembled into the final complex geometry. This preliminary manufacturing of components followed by assembly allows complex fuel grain shapes to be achieved while maintaining the simplicity of conventional manufacturing processes for each component.
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 achieves higher regression rates and thrust impulse while maintaining the safety and cost benefits of hybrid propulsion systems, eliminating the need for complex multi-port designs and ensuring efficient combustion until fuel or oxidizer exhaustion.
Implementation Method 1
combustion occurring along the exposed surface area of the solid fuel grain section adjacent to the center port
Implementation Method 2
Each concentric layer has a surface pattern that serves to increase the surface area for combustion, a surface pattern that persists even as the fuel burns
Implementation Method 3
The solid fuel grain is manufactured using a freeform-fabrication machine
Data Source
AI summary
A solid fuel grain suitable for use in hybrid propulsion systems has a generally cylindrical shape and defines a center port. The solid fuel grain is formed as a series of concentric layers arrayed around the center port. When incorporated into a rocket, an oxidizer is introduced into the solid fuel grain along a pathway defined by the center port, with combustion occurring along the exposed surface area of the solid fuel grain section adjacent to the center port. Each concentric layer has a surface pattern that serves to increase the surface area for combustion, a surface pattern that persists even as the fuel burns. To achieve such a construction, the concentric layers of the solid fuel grain are preferably manufactured using any one of several available freeform-fabrication machines capable of fabricating articles in a polymeric material suitable for a hybrid propulsion system.