Hybrid Rocket Fuel Grain Casting with Removable Port Cores
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Solution Overview
Problem
Hybrid rocket motors face challenges in maintaining a consistent fuel to oxidizer ratio and suffer from low regression rates, leading to inefficient burning and potential catastrophic failures due to complex fuel grain shapes and oxidizer-rich combustion.
Innovation Solution
A method and system for casting hybrid rocket motor fuel grains using rapid prototyping techniques to create complex port shapes within the fuel grains, allowing for improved fuel and oxidizer mixing, increased surface area, and controlled regression rates, which involves forming a positive image of the port shape using a material that can be removed to create a negative image in the fuel material, enabling the use of various materials and shapes such as helical or three-dimensional geometric designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If complex fuel grain shapes are used to increase surface area, then burning efficiency is improved, but the risk of unsupported fuel sections breaking off and plugging the nozzle increases
Solution Approach 1:
The patent applies preliminary action by pre-forming support structures (such as struts or internal frameworks) within the fuel grain during the manufacturing process before combustion occurs. These support structures are strategically positioned to prevent unsupported fuel sections from breaking off during combustion, thereby maintaining reliability while allowing complex high-surface-area geometries to improve burning efficiency.
2Length of moving object
If the fuel grain is designed with an elongated center flow channel, then the motor length is reduced, but the oxidizer to fuel ratio becomes oxidizer rich leading to wasted oxidizer
Solution Approach 1:
The patent applies local quality by varying the cross-sectional geometry of the flow channel along its length. The channel may be narrower at the oxidizer injection end and gradually widen toward the exhaust end, or include expansion sections that increase the fuel surface area locally. This ensures that the oxidizer-to-fuel ratio remains balanced throughout combustion, preventing oxidizer waste while maintaining a compact motor length.
3Ease of manufacture
If hybrid motors are used instead of composite solid propellants, then safety and simplicity are improved, but regression rate decreases to one third of composite propellants
Solution Approach 1:
The patent applies parameter changes by modifying the physical and chemical parameters of the hybrid fuel material itself. This may include using fuel formulations with higher regression rate characteristics, adjusting fuel density, or incorporating additives that enhance the fuel's combustion properties. By changing these material parameters, the regression rate of hybrid motors is increased while maintaining the safety and simplicity advantages over composite 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 approach enhances fuel efficiency, increases thrust, and minimizes disruptions in fuel flow by maintaining a consistent oxidizer to fuel ratio, improving propellant mass fraction and regression rates, thus addressing the limitations of traditional hybrid rocket motors.
Implementation Method 1
a rapid prototyping device is used to provide at least a portion of the positive image
Implementation Method 2
disposing at least one fuel material around at least a portion of the positive image of the port
Implementation Method 3
removing the at least one material, wherein a negative image of the port is formed in the at least one fuel material
Data Source
AI summary
Embodiments of the invention relate to systems and methods for casting hybrid rocket motor fuel grains. In one embodiment, a method for casting a rocket motor fuel grain can be provided. The method can include providing a positive image of a port made from at least one material. The method can further include disposing at least one fuel material around at least a portion of the positive image of the port. Further, the method can include removing the at least one material, wherein a negative image of the port is formed in the at least one fuel material.