Concentric Annular Solid Fuel Elements in Hybrid Rocket Motors
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Solution Overview
Problem
Hybrid rocket systems face challenges in achieving efficient and controlled combustion due to the slow burning rate of solid fuel grains, leading to high residual fuel and separation issues when attempting to reinforce the fuel grain with stiffening sheets.
Innovation Solution
A hybrid rocket motor design featuring concentric annular solid fuel grains with a combustion port between them, where a liquid oxidizer is injected to interact with the solid fuel elements, enhancing combustion efficiency and stability by maximizing the length-to-diameter ratio and using a nozzle for thrust generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If stiffening sheets are used to reinforce the fuel grain, then structural strength is improved, but fuel grain separation occurs and combustion efficiency deteriorates
Solution Approach 1:
The fuel grain is divided into multiple separate annular segments rather than using a single continuous grain with stiffening sheets. Each annular segment can burn independently, eliminating the separation problem caused by stiffening sheets while maintaining structural integrity through the annular geometry itself.
Solution Approach 2:
The stiffening sheets are completely removed from the fuel grain structure. Instead of reinforcing the grain with external sheets, the invention uses the annular geometry and positioning of fuel segments to provide structural support, thereby eliminating the source of combustion instability.
2Duration of action of stationary object
If solid fuel grains are used, then combustion continuity is improved, but burning rate is too slow causing high residual fuel
Solution Approach 1:
The fuel is segmented into multiple annular grains positioned at different radii, creating multiple combustion zones that burn simultaneously. This segmentation increases the overall burning rate while maintaining continuous combustion, as multiple segments can burn at different rates without interrupting the overall combustion process.
Solution Approach 2:
The fuel grain configuration transitions from a single radial dimension to multiple radial positions (inner and outer annular grains). This multi-dimensional arrangement increases the effective burning surface area and allows for higher burning rates while maintaining combustion continuity through the coordinated burning of multiple segments.
3Productivity
If concentric annular fuel grains are used, then combustion efficiency is improved, but device complexity increases
Solution Approach 1:
The fuel grain configuration uses nested annular structures where inner annular grains are positioned within the radial space defined by outer annular grains. This nesting arrangement maximizes combustion efficiency by creating multiple burning zones within a compact radial space, while the concentric geometry simplifies manufacturing compared to complex multi-layered structures.
Solution Approach 2:
The annular fuel grain configuration serves multiple functions simultaneously: it provides structural support, creates multiple combustion zones for efficient burning, and allows for flexible positioning of oxidizer injection ports. This multi-functionality reduces the need for additional components, thereby limiting the increase in device complexity.
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 design improves combustion efficiency and reduces residual fuel by maintaining a stable combustion process, preventing fuel grain separation and enhancing thrust production through optimized fuel interaction and combustion product discharge.
Implementation Method 1
The oxidizer interacts with the first and second solid fuel elements within the combustion port to produce a combustion product
Data Source
AI summary
A hybrid rocket motor includes a supply of oxidizer, a first solid fuel element positioned around the supply of oxidizer, a second solid fuel element positioned concentrically around the first solid fuel element, and a combustion port positioned between the first and second solid fuel elements. The oxidizer interacts with the first and second solid fuel elements within the combustion port to produce a combustion product. A nozzle is in communication with the combustion port for combustion discharge of the combustion product.