Rocket Engine Injector Assembly Pressure Regulation
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Solution Overview
Problem
Deep throttling maneuvers in rocket engines result in a small pressure differential between propellants and combusted gases, leading to poor combustion stability and instability due to reduced atomization, vaporization, and mixing of propellants, as well as hydraulic stiffness issues in injector assemblies with large internal volumes.
Innovation Solution
An injector assembly with a pressure-actuated valve and swirl cap design, featuring a poppet assembly and spring element, regulates propellant flow by adjusting the pressure in the oxidizer chamber to maintain a sufficient pressure differential, utilizing a plurality of inlets and outlets to control the flow into the combustion chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the flow of liquid propellants is greatly decreased during deep throttling maneuver, then engine thrust is reduced to less than thirty percent of full throttle, but the pressure differential between propellants and combusted gases becomes small causing poor combustion stability
Solution Approach 1:
The injector assembly employs a dynamic pressure regulation mechanism with a movable diaphragm and adjustable orifice that automatically adapts to changing propellant flow conditions during deep throttling maneuvers, maintaining optimal pressure differential across varying thrust levels
Solution Approach 2:
The system changes the pressure differential parameter by using a spring-loaded diaphragm mechanism that adjusts the oxidizer inlet pressure dynamically, ensuring sufficient pressure differential is maintained even when propellant flow is reduced to less than 30% of full throttle
2Stress or pressure
If the pressure differential becomes small during deep throttling, then atomization, vaporization and mixing of propellants is reduced, but this leads to poor combustion performance
Solution Approach 1:
The diaphragm acts as an intermediary pressure regulation element that translates spring force into controlled pressure adjustments at the oxidizer inlet, maintaining the pressure differential needed for effective atomization and mixing during throttled operation
Solution Approach 2:
The invention replaces complex active control systems with a passive spring-loaded mechanical pressure regulation mechanism that automatically maintains pressure differential through elastic force, ensuring consistent propellant mixing without electronic controls
3Stress or pressure
If manifolds with large internal volume are used to maintain pressure differential, then propellant pressure can be maintained within certain range, but purging during low power operation creates combustion instabilities due to lower hydraulic stiffness
Solution Approach 1:
The injector assembly segments the pressure regulation function into a dedicated diaphragm chamber separated from the main manifold, allowing independent optimization of pressure control without requiring large-volume manifolds that compromise hydraulic stiffness
Solution Approach 2:
The compact diaphragm-based pressure regulation mechanism rapidly responds to pressure changes and purging events, maintaining hydraulic stiffness by quickly equalizing pressures during low-power operation without the lag associated with large-volume manifolds
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 solution ensures stable combustion during deep throttling by maintaining a consistent pressure differential, reducing combustion instability and enhancing propellant mixing, even at low power operation, thereby improving engine performance.
Implementation Method 1
a spring element disposed in the oxidizer chamber and configured to exert a spring bias force between the poppet assembly and the end wall
Implementation Method 2
The valve assembly is adapted to selectively regulate flow of a propellant through the one or more inlets in the swirl cap body in response to a pressure differential between the oxidizer chamber and the combustion chamber
Data Source
Figure 1
Figure 2~3C
Figure 3A~3B
AI summary
A cap (66) for a liquid propellant injection assembly of a rocket engine includes a cap body (80) and a valve assembly (82). The cap body (80) extends between first and second ends. The cap body (80) has a bore (96) that fluidly connects one or more inlets (90,92) to an outlet (94). The inlets (90,92) are disposed in a tubular sidewall (88) of the cap body (80). The outlet (94) is disposed in the second end of the cap body (80). The valve assembly (82) includes a valve cap (128) disposed around the first end of the cap body (80). The valve assembly (82) is adapted to selectively regulate flow of a propellant through the inlets (90,92) in the cap body (80) as a function of pressure exerted by the propellant against the valve assembly (82).