Coaxial Ignition Assembly for Rocket Engines
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Solution Overview
Problem
Large rocket engine ignition systems are bulky, inefficient, and complex due to the need for dedicated propellant mixtures for pilot lights, and direct spark ignition systems face challenges with component degradation and off-optimum mixture ratios, making them unsuitable for smaller engines.
Innovation Solution
A bi-propellant injector system with a spark exciter assembly that generates an electrical arc between conductive and nonconductive components to initiate combustion in a combustion chamber, using non-hypergolic propellants and operating at optimal mixture ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large ignition assembly with dedicated propellant mixture is used, then reliable ignition is achieved, but the system becomes bulky in size and mass
Solution Approach 1:
The patent combines the ignition function with the injector element by integrating a spark gap directly into the injector structure. The injector element serves dual purposes: delivering propellant and generating the ignition spark, eliminating the need for separate large ignition assemblies with dedicated propellant supplies.
Solution Approach 2:
The injector element is designed to perform multiple functions simultaneously: it acts as both a propellant delivery device and an ignition source. The conductive layer on the injector element serves as one electrode of the spark gap, while the propellant mixture itself serves as the medium for both combustion and spark transmission, eliminating the need for separate ignition propellants.
2Reliability
If dedicated propellant mixtures are used for pilot light, then ignition is maintained, but design complexity increases
Solution Approach 1:
The same propellant supply system serves both ignition and thrust generation functions. The injector delivers the primary engine propellant mixture directly to the combustion chamber, and this same mixture is used as the medium for spark ignition, eliminating the need for separate dedicated ignition propellant storage and delivery systems.
Solution Approach 2:
The patent merges the ignition propellant supply with the main engine propellant supply into a single unified system. The injector element receives propellant from the main supply and simultaneously uses it for both combustion and as the spark gap medium, simplifying the overall propellant delivery architecture.
3Reliability
If off-optimum mixture ratios are used for ignition, then electrode thermal damage is prevented, but combustion performance decreases
Solution Approach 1:
The patent replaces the traditional mechanical/electrical spark ignition system with a plasma-based ignition mechanism. The high-voltage pulse creates a plasma channel through the propellant mixture at the injector face, which then ignites the combustion chamber contents. This plasma mechanism eliminates the need for exposed electrodes that would suffer from thermal damage.
Solution Approach 2:
The invention changes the ignition mechanism from electrode-based electrical discharge to plasma-based discharge through the propellant medium. By using the propellant itself as the spark medium and applying high-voltage pulses, the system achieves ignition at optimal mixture ratios without the thermal damage problems of traditional electrodes.
4Ease of operation
If special injection orifices and manifolds are used for spark ignition, then easy ignition is achieved, but manufacturing difficulty increases
Solution Approach 1:
The patent combines the spark gap electrodes with the existing injector structure. The conductive layer on the injector element serves as one electrode, and the injector face or adjacent structure serves as the other electrode. This integration eliminates the need for separate special-purpose ignition orifices and manifolds, simplifying manufacturing while maintaining easy ignition.
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 system is compact, efficient, and easy to fabricate, maintaining high combustion performance without the need for dedicated ignition propellants, reducing weight and design complexity, and avoiding component degradation issues.
Implementation Method 1
The exciter can generate an electrical arc between the conductive layer of the first injector element and the second injector element
Data Source
AI summary
A bi-propellant injector includes first and second injector elements and a spark exciter assembly. The first injector element has a conductive layer electrically connected to the spark exciter assembly and a nonconductive layer disposed on an exterior portion of the conductive layer. The second injector element comprises a conductive material and has an opening therethrough in fluid communication with a combustion chamber. An end of the first injector element is positioned at or near the opening in the second injector element. The spark exciter assembly can generate an electrical arc between the conductive layer of the first injector element and the second injector element.