Valve Timing Control for Liquid Fuel Rocket Thrust Granularity
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Solution Overview
Problem
Liquid fuel rocket engines face challenges in achieving consistent and precise control over fluid flow due to variations in the minimum impulse bit (MIB) of valves, which are influenced by factors like valve wear, environmental conditions, and manufacturing variations.
Innovation Solution
A valve controller system that includes current and voltage sensors, a processor, and memory, which determines the actual minimum impulse bit of a valve based on current and voltage profiles during a single operation, and adjusts valve controls accordingly, while also considering external factors such as engine pressure and battery voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If valve operations are run at slightly longer than the actual minimum impulse bit to compensate for variations, then consistent and predictable control is provided, but the granularity of thrust control is reduced
Solution Approach 1:
The system dynamically changes the valve timing parameters based on real-time monitoring of current and voltage profiles. By adjusting the valve open time to match the actual minimum impulse bit determined from electrical characteristics, the system achieves both consistent control and fine granularity without requiring fixed conservative timing margins
Solution Approach 2:
The controller monitors the electrical characteristics (current and voltage profiles) of the valve actuator and uses this feedback to determine the actual minimum impulse bit. This feedback mechanism allows the system to adapt to valve variations and maintain precise control granularity while ensuring consistent operation
2Ease of operation
If discrete valve operations are run at fixed timing to simplify control, then ease of operation is improved, but the ability to compensate for valve variations is reduced
Solution Approach 1:
The valve control system performs self-characterization by monitoring its own electrical characteristics during operation. The controller automatically determines the actual minimum impulse bit from the current and voltage profiles without requiring external calibration or manual adjustment, enabling the system to adapt to its specific valve characteristics while maintaining simple operation
Solution Approach 2:
The system changes the control parameters based on the determined actual minimum impulse bit. By adjusting the valve timing parameters to match the specific valve's characteristics, the system achieves both operational simplicity and adaptability to individual valve variations
Data Source
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AI summary
A liquid fuel rocket engine according to one example includes a combustor, a liquid fuel repository connected to the combustor via a fuel line and a first valve, an oxidizer repository connected to the combustor via an oxidizer line and a second valve, a valve controller configured to output a valve control current to the first valve, the valve controller storing instructions for determining at least one actual minimum impulse bit of a valve based on a current profile and a voltage profile of a single operation of the first valve, and to adjust valve controls to account for the at least one actual minimum impulse bit.