Layered Propellant Grain Burn-Rate Gradients for Pressure Control
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Solution Overview
Problem
Conventional propellant charge manufacturing methods limit the manipulation of variables for achieving a specified performance, particularly in controlling the burn rate and pressure profile, leading to suboptimal projectile acceleration.
Innovation Solution
A propellant charge is manufactured using additive manufacturing techniques, incorporating a gradient of energetic materials with different linear burn rates and perforations, allowing for controlled burn rate distribution and prolonged maximum pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional propellant charge manufacturing methods are used, then production is simpler and more established, but the manipulation of variables for controlling burn rate and pressure profile is limited
Solution Approach 1:
The patent applies local quality by creating spatial variations in propellant composition within the charge. Different regions of the propellant charge contain different concentrations of energetic materials, allowing localized control of burn rate. This enables the pressure profile to be optimized in different zones of the charge, resolving the contradiction by providing variable control without requiring entirely new manufacturing approaches.
Solution Approach 2:
The patent introduces compositional gradients as an additional dimension of control beyond traditional geometric variations. By varying the concentration of energetic materials in three-dimensional space within the propellant charge, the invention adds a new degree of freedom for controlling burn rate and pressure profile, thereby increasing adaptability without proportionally increasing manufacturing complexity.
2Speed
If the burn rate is increased to achieve higher projectile velocity, then acceleration improves, but the period of maximum pressure decreases
Solution Approach 1:
The patent applies dynamics by creating a time-varying burn rate through spatial compositional gradients. As the propellant burns from the exterior inward, the changing composition exposes different concentrations of energetic materials sequentially, causing the burn rate to evolve dynamically over time. This allows the system to maintain high projectile velocity while extending the duration of maximum pressure through controlled temporal variation in burn characteristics.
Solution Approach 2:
The patent uses preliminary action by pre-positioning regions of different energetic material concentrations in specific locations within the propellant charge before ignition. This predetermined compositional arrangement ensures that as burning progresses, the desired sequence of burn rates is automatically achieved, allowing optimization of both projectile velocity and pressure duration without real-time control.
3Manufacturing precision
If uniform distribution of energetic materials is used, then manufacturing is simpler, but control over burn rate distribution is reduced
Solution Approach 1:
The patent applies segmentation by dividing the propellant charge into regions with different energetic material concentrations. Rather than using a uniform composition, the charge is segmented into zones that will burn at different rates, enabling precise control over the overall burn rate distribution. This segmentation approach balances manufacturing complexity with the ability to achieve desired performance characteristics.
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 method enables better regulation of the propellant burn, extending the period of maximum pressure for enhanced projectile velocity and chamber stability.
Implementation Method 1
Gases produced by combustion of the propellant charge cause a rapid build-up of pressure
Implementation Method 2
A propellant charge is an amount of relatively insensitive but powerful energetic material that propels the projectile out of the gun barrel
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
The invention is directed to a method for the preparation of a propellant charge or grain, and to uses of the propellant charge or grain. The method of the invention comprises additive manufacturing of multiple distinctively identifiable print layers to produce a layered propellant charge or grain, wherein two or more of said layers each comprise at least one energetic material and a liquid curable binder, wherein the linear burn rate of an energetic material in a first layer is different from the linear burn rate of an energetic material in a second layer, and wherein each of said layers has a layer thickness in the range of 1-2000 µm, wherein said additive manufacturing comprises layer by layer curing of liquid curable binder material by radiation.