Rocket Motor Ignition Device with Thermal Barrier Membrane
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Solution Overview
Problem
Existing two-pulse rocket motor ignition devices face challenges in ensuring reliable barrier membrane rupturing and structural strength against vibrations and heat without increasing weight, particularly in long motors, and there is a need for a simpler structure that can be installed on the rear end of the second propellant.
Innovation Solution
An ignition device with an energy supply unit, energy transfer unit, and ignition unit is fixed to the aft barrier membrane, utilizing a boron potassium nitrate based pelletized explosive and a flexible, non-scattering sheet-like molded material to ensure reliable membrane rupture and structural integrity, while being lightweight and compact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the second ignition device is placed close to the weak portion of the barrier membrane to enhance rupturing reliability, then the reliability of barrier membrane rupturing is improved, but the ignition device requires a new installation structure on the rear end of the second propellant rather than on structural members
Solution Approach 1:
The patent employs the thin film principle by using the barrier membrane itself as the mounting substrate for the ignition device. The ignition device is installed directly on the rear end surface of the second propellant, utilizing the flexible barrier membrane structure rather than rigid structural members, enabling close placement near the weak portion while maintaining structural integrity.
2Strength
If the ignition device structure is strengthened to ensure strength against vibrations and environmental loads, then the strength and reliability are improved, but the structural weight increases which decreases acceleration performance
Solution Approach 1:
The patent applies preliminary action by providing thermal protection to the ignition device before it is exposed to harsh environmental conditions. The barrier membrane serves as a protective barrier that shields the ignition device from heat generated during first propellant combustion, allowing the use of lighter materials without compromising strength during operation.
Solution Approach 2:
The patent changes the operational parameters of the ignition device by isolating it thermally from the combustion environment. The barrier membrane maintains a lower temperature environment for the ignition device during first pulse combustion, allowing the device to be designed with lighter materials that would not withstand direct exposure to combustion temperatures.
3Reliability
If a duplex structure with annular chamber is used for the second ignition device as in Patent Document 1, then the ignition function is achieved, but the structure becomes large in both dimensions and weight
Solution Approach 1:
The patent extracts the essential ignition function from the complex annular chamber duplex structure. By placing the ignition device directly on the rear end surface of the second propellant near the weak portion of the barrier membrane, the design eliminates unnecessary structural elements while retaining the core ignition capability, resulting in a more compact and lighter configuration.
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 enables a simple, reliable ignition device installation on the rear end of the second propellant, enhancing barrier membrane rupturing reliability and withstanding environmental loads without increasing structural weight, ensuring proper thrust generation in two-pulse rocket motors.
Implementation Method 1
utilizing a boron potassium nitrate based pelletized explosive
Implementation Method 2
the second propellant is protected from heat of first propellant burning by the barrier membrane
Data Source
AI summary
In a two-pulse rocket motor provided with a pressure vessel, a first propellant placed within the pressure vessel that burns during a first pulse stage, a second propellant placed within the pressure vessel that burns during a second pulse stage following the first pulse stage, and a barrier membrane placed so as to cover the entire initial burning surface of the second propellant, wherein the barrier membrane is provided with an inner barrier membrane that covers the inner peripheral surface of the second propellant and an aft barrier membrane that covers the rear surface of the second propellant, and an end portion where the aft barrier membrane and the inner barrier membrane meet is joined over the entire circumference thereof. The ignition device includes an energy supply unit, an energy transfer unit connected at one end to the energy supply unit, and an ignition unit.