Pellet-Loaded Rocket Motor Combustion Surface Optimization
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Solution Overview
Problem
Existing solid fuel rocket motors for attitude control thrusters face challenges in achieving rapid and efficient thrust due to limitations in propellant surface area, burn rate, and density, which affect the impulse and thrust duration.
Innovation Solution
The design incorporates a solid fuel rocket motor with a center-perforated grain and pellet-loaded configurations, featuring a longitudinal cavity for increased burnable surface area, convex pellets for minimized contact and enhanced burning, and a perforated pellet retainer to manage combustion gases and maintain structural integrity, allowing for controlled ignition and thrust optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a conventional solid fuel propellant grain is used, then the motor structure is simple, but the burnable surface area is limited which restricts thrust and impulse
Solution Approach 1:
The propellant is divided into multiple convex pellets rather than using a single continuous grain. Each pellet has a center perforation, creating multiple burning surfaces that simultaneously contribute to thrust. This segmentation dramatically increases the total burnable surface area while maintaining a relatively simple overall motor structure.
Solution Approach 2:
The invention introduces a center perforation through the pellets, adding a dimensional feature that creates internal burning surfaces. This transforms the propellant from a simple external-burning configuration to one with both external and internal burning surfaces, effectively multiplying the burnable area without significantly increasing the propellant volume.
2Speed
If the propellant burn rate is increased to achieve rapid thrust, then thrust duration is reduced which limits impulse
Solution Approach 1:
The segmented pellet structure provides multiple burning surfaces that burn simultaneously at high rates. The convex shape and center perforation create controlled burning patterns that maintain high surface area throughout combustion, allowing rapid burn rates to be sustained for longer durations compared to conventional grains.
Solution Approach 2:
The invention changes the physical parameters of the propellant configuration - using convex pellets with center perforations instead of conventional grains. This geometric parameter change optimizes the surface-area-to-volume ratio, enabling both high burn rates and extended thrust duration by maintaining effective burning surface area throughout the combustion process.
3Quantity of substance
If propellant density is increased to reduce motor volume, then manufacturing and loading complexity increases
Solution Approach 1:
The propellant is manufactured as discrete convex pellets with center perforations that can be individually produced and then loaded into the motor. This segmentation allows for standardized manufacturing processes and simplifies loading compared to forming and curing large monolithic grains, as pellets can be simply poured or fed into the motor housing.
Solution Approach 2:
The center perforation in each pellet is self-formed during manufacturing, creating the burning surface geometry inherently within the propellant structure itself. This self-service feature eliminates the need for complex post-manufacturing modifications or assembly steps to create burning surfaces, simplifying both manufacturing and loading processes while maintaining high propellant density.
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 configuration enables rapid ignition and sustained thrust by increasing the burnable surface area and managing combustion pressures, resulting in improved impulse and thrust control for attitude control thrusters.
Implementation Method 1
pellets of a chemical composition which undergoes self-sustaining combustion to generate a combustion gas
Implementation Method 2
an initiator attached to the housing to ignite the pellets
Data Source
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AI summary
There is disclosed a solid fuel rocket motor (500) which may include a case (510) and a nozzle (540) coupled to the case. A plurality of fuel pellets (525) may be disposed within the case. An igniter (550) may be disposed to ignite at least a portion of the fuel pellets. A pellet retainer (535) may be positioned within the case to retain the plurality of fuel pellets within the case. The pellet retainer may be perforated to allow exhaust gases to flow from the ignited fuel pellets to the nozzle while preventing unburned fuel pellets from being expelled through the nozzle.