Dual Stage Catalytic Thruster Thermal Standoff Cup
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Solution Overview
Problem
Catalytic thrusters in space vehicles face issues with catalyst granule migration and thermal stress over thousands of firing cycles, leading to potential blockages and reduced durability.
Innovation Solution
A catalytic thruster design featuring a thermal standoff cup, a removable flow restrictor made of environmentally-non-resistant material, and an environmentally-resistant feed tube, which blocks catalyst granules from entering injection ports and manages heat to prevent thermal decomposition, with the flow restrictor consuming under controlled conditions to unblock ports and allow lower velocity, higher momentum propellant flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a feed tube extends directly into the reaction chamber without protection, then propellant delivery is simple, but catalyst granules migrate into the injection port causing blockages
Solution Approach 1:
A sacrificial screen is introduced as an intermediary component between the feed tube and catalyst bed. This screen acts as a mediator that blocks catalyst granules from migrating into the injection port while allowing propellant to pass through. The screen is deliberately designed to be consumable, sacrificing itself to protect the injection port throughout the thruster's operational life.
Solution Approach 2:
The sacrificial screen is designed as a disposable, consumable component that degrades over time under controlled conditions. By using a relatively inexpensive, short-living protective element, the expensive injection port is protected from blockages throughout the thruster's operational life, after which the screen naturally degrades and is replaced.
2Use of energy by moving object
If the feed tube is exposed to high temperature in the reaction chamber, then propellant heating occurs, but thermal decomposition and nitrogen embrittlement reduce durability
Solution Approach 1:
The feed tube is extracted from the high-temperature reaction zone by extending it through a thermal standoff cup. This positioning removes the feed tube from direct exposure to the catalyst bed and reaction chamber walls, isolating it thermally while still allowing efficient propellant heating through the injection ports into the reaction chamber.
Solution Approach 2:
The thermal standoff cup is constructed from materials with low thermal conductivity to provide thermal isolation. This composite structure allows the feed tube to remain in the reaction chamber for efficient propellant delivery while the low-conductivity cup material protects it from thermal decomposition and nitrogen embrittlement.
3Power
If propellant flows at high velocity through the injection port, then thrust generation is effective, but catalyst granules are more likely to be entrained and migrate
Solution Approach 1:
The sacrificial screen is installed in advance at the injection port to establish a physical barrier before operation begins. This preliminary protective measure prevents catalyst granule migration during high-velocity propellant flow, allowing effective thrust generation without the risk of granule entrainment.
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
Enhances thruster durability by preventing catalyst granule migration and reducing thermal stress, leading to longer life and reduced performance degradation by allowing lower velocity, higher momentum propellant flow.
Implementation Method 1
The propellant reacts in the presence of the catalyst to generate a gas that is expelled through a nozzle to generate thrust
Implementation Method 2
a thermal standoff cup... the feed tube extends into the reaction chamber through the thermal standoff cup
Data Source
AI summary
A catalytic thruster includes a reaction chamber that extends between first and second opposed chamber ends. The first chamber end includes a thermal standoff cup. There is a catalyst bed in the reaction chamber, and a feed tube extends into the reaction chamber through the thermal standoff cup.