Pulsed Optical Ignition of Solid Fuel Combustion
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Solution Overview
Problem
Solid state solid fuels are difficult to ignite using traditional electric spark or torch-ignition techniques due to their high density, which reduces their thrust potential and specific impulse.
Innovation Solution
An optically initiated method using a pulsed optical signal generated by a laser pump, modulated by an intensity profiler to provide initial high peak power for ignition and subsequent lower peak power for sustaining the combustive reaction, directed to multiple ignition points within a combustion chamber containing a solid fuel and oxidizer mixture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If traditional electric spark or torch-ignition techniques are used, then the ignition process is simple, but the solid fuel cannot be effectively ignited due to high density
Solution Approach 1:
The patent replaces traditional mechanical/electric ignition systems (electric spark, torch) with an optical system (laser). The laser delivers high peak power pulses that can effectively ignite solid fuel by providing sufficient energy density to overcome the high density and activation energy barriers of solid state fuel, while maintaining operational simplicity through automated optical delivery.
Solution Approach 2:
The patent changes the ignition method from continuous or low-power energy delivery to pulsed high-power optical energy. By modulating the laser to deliver high peak power pulses with specific pulse widths and frequencies, the system provides the necessary energy density to ignite solid fuel effectively, transforming the ignition process to match the high energy requirements of solid state fuel.
2Reliability
If high peak power optical signal is used to initiate combustion, then the combustive reaction is effectively initiated, but the system complexity increases
Solution Approach 1:
The patent employs periodic pulsed optical signals rather than continuous high power. The laser is modulated to deliver discrete pulses with high peak power for ignition, followed by lower power sustainment phases. This periodic action reduces average power requirements and system complexity while maintaining effective ignition through the high peak power pulses.
Solution Approach 2:
The patent uses dynamic power modulation where the optical signal transitions from high peak power during ignition to lower power during sustainment. This dynamic adjustment allows the system to provide sufficient energy for ignition without maintaining unnecessarily high power levels throughout, thereby reducing overall system complexity and energy consumption.
3Duration of action of stationary object
If continuous high power optical signal is used to sustain combustion, then the combustive reaction is maintained, but energy consumption increases
Solution Approach 1:
The patent uses periodic pulsed optical signals for sustainment rather than continuous power. After the initial high power ignition pulse, the system switches to lower power pulses that are sufficient to maintain the combustive reaction. This periodic action reduces average energy consumption while maintaining adequate sustainment through the repeated pulse delivery.
Solution Approach 2:
The patent leverages the exothermic energy released by the combustive reaction itself to sustain the process. Once ignition occurs, the heat generated by the combustion reaction provides much of the energy needed to maintain the burn, reducing or eliminating the need for continuous external optical energy input. The optical system only needs to provide initial ignition and occasional sustainment pulses.
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
Effectively initiates and sustains a combustive reaction in solid fuels, overcoming the challenges of high density and energy absorption, leading to self-sustaining exothermic energy release and enhanced propulsion efficiency.
Implementation Method 1
The pulsed optical signal is generated by an optical source, e.g. a laser pump, and modulated using an intensity profiler. The intensity profiler modulates the pulsed optical signal to initially have a first peak power sufficient to initiate a combustive reaction in a solid fuel.
Implementation Method 2
The intensity profiler further modulates the pulsed optical signal to subsequently have a second peak power sufficient to sustain the combustive reaction until sufficient exothermic energy is released by the combustive reaction to make the reaction self-sustaining.
Data Source
AI summary
A method is provided for initiating and sustaining a combustive reaction in a solid fuel. The method includes generating at least one pulsed optical signal and directing the pulsed optical signal to a plurality of ignition points within at least one combustion chamber containing a solid fuel. The pulsed optical signal is generated by an optical source, e.g. a laser pump, and modulated using an intensity profiler. The intensity profiler modulates the pulsed optical signal to initially have a first peak power sufficient to initiate a combustive reaction in a solid fuel. The intensity profiler further modulates the pulsed optical signal to subsequently have a second peak power sufficient to sustain the combustive reaction until sufficient exothermic energy is released by the combustive reaction to make the reaction self-sustaining.