Spacecraft Enclosure Evacuation Pipe with Two-Stage Expansion
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Solution Overview
Problem
Current methods for emptying spacecraft enclosures with high-pressure gaseous compositions at the end of a mission are costly, complex, and uncontrolled, leading to potential phase changes and disruptive thrusts, which can cause attitude changes in satellites, making it difficult to ensure efficient and safe passivation and deorbiting.
Innovation Solution
A method involving a two-stage expansion process within the evacuation pipe, where the initial expansion is isenthalpic and the final expansion is isentropic, using a capillary pipe and sonic outlets to control pressure and temperature, ensuring minimal thrust and controlled emptying, with a filtration device and a controlled valve for precise operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a simple pipe or nozzle is used for emptying, then the device complexity is reduced, but the temperature control becomes uncontrolled leading to potential phase changes
Solution Approach 1:
The emptying device is segmented into multiple functional sections: a controlled valve for pressure regulation, an expansion chamber for temperature management, and a nozzle for directed flow. This segmentation allows each component to perform its specific function optimally while maintaining overall system reliability without excessive complexity.
Solution Approach 2:
The expansion chamber performs preliminary action by pre-cooling and pressurizing the gas before it reaches the nozzle. This preliminary treatment ensures that the gas enters the nozzle at controlled conditions, preventing uncontrolled phase changes during the emptying process.
2Object-affected harmful factors
If the emptying rate is reduced to minimize attitude changes, then the harmful factors are reduced, but the emptying duration increases
Solution Approach 1:
The controlled valve provides dynamic adjustment of the emptying rate, allowing the system to adapt the flow rate in real-time. This enables minimal attitude changes during emptying while maintaining a reasonable duration by optimizing the valve opening degree and response characteristics.
Solution Approach 2:
The system changes physical parameters (pressure, temperature, flow rate) through the expansion chamber and controlled valve to achieve optimal emptying conditions. By adjusting these parameters dynamically, the system minimizes attitude changes while maintaining efficient emptying duration.
3Reliability
If a controlled valve is added to regulate emptying, then the temperature and pressure control is improved, but the device complexity increases
Solution Approach 1:
The controlled valve and expansion chamber form a self-regulating system that uses the inherent properties of gas expansion and compression to maintain control. The system leverages the thermodynamic processes themselves to regulate temperature and pressure, reducing the need for additional active control mechanisms and minimizing overall device complexity.
4Productivity
If the nozzle is designed for high flow rate, then the productivity is improved, but the thrust generated increases causing attitude disturbances
Solution Approach 1:
The expansion chamber acts as a counterbalancing element that absorbs and distributes the thrust forces generated by high-speed gas flow. By providing a large-volume expansion space, the system converts linear thrust into distributed pressure forces, maintaining high emptying rates while minimizing net attitude-disturbing forces.
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
This approach allows for a controlled, efficient, and rapid emptying process that prevents phase changes and minimizes thrust, ensuring safe and precise passivation of spacecraft without excessive attitude changes, compatible with various gaseous compositions and pressures.
Implementation Method 1
The initial expansion inside a vent line is mostly isenthalpic
Implementation Method 2
the expansion at the outlet of the evacuation pipe, via each outlet end with a section constriction of the evacuation pipe opening into said external environment. The initial expansion inside a vent line is mostly isenthalpic, while the expansion at the outlet of the evacuation pipe is mostly isentropic
Data Source
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AI summary
The invention relates to a method and device for draining a spacecraft enclosure containing a gaseous composition at a pressure P1 higher than that P2 prevailing in an environment external to the spacecraft in space, the enclosure being connected to this external environment in space by at least one discharge pipe (14). The gaseous composition flowing in each discharge pipe (14) passes through at least one initial pressure relief device (20, 21) having at least one constriction at the outlet of which the pressure of the gaseous composition is at a third value Pi intermediate between the first pressure P1 in the enclosure and the second pressure P2 of the external environment.