Telescoping-Piston Rocket Injector Testing for Acoustic Stability
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Solution Overview
Problem
Conventional subscale testing of rocket engine injectors fails to accurately predict full-scale performance due to limited stability assessment capabilities, leading to costly and time-consuming iterations during full-scale tests and risks to other engine components.
Innovation Solution
A subscale testing system with a continuously variable combustion chamber volume, modular injector plates, and telescoping throats that expose injectors to a range of acoustic modes, allowing for rapid and accurate stability assessment without full-scale testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional subscale testing is used, then testing cost and time are reduced, but stability assessment accuracy deteriorates
Solution Approach 1:
The combustion chamber volume is made dynamically variable through a telescoping piston that can be continuously adjusted along the axial direction. This dynamic adjustment allows the subscale chamber to simulate different combustion chamber volumes corresponding to various acoustic modes, enabling accurate stability assessment across the full range of acoustic modes without requiring full-scale testing.
Solution Approach 2:
The system changes the physical parameter of combustion chamber volume continuously by moving the piston. By varying the chamber volume parameter, the system can reproduce different acoustic mode frequencies and wavelengths, allowing subscale injectors to be tested under conditions that accurately predict full-scale performance while maintaining reduced test time and cost.
2Measurement precision
If full-scale testing is performed, then stability assessment accuracy is improved, but testing cost and risk increase
Solution Approach 1:
The invention creates a scaled-down copy of the combustion chamber with a telescoping piston that can replicate the acoustic modes of full-scale engines. This subscale model accurately copies the essential physics and acoustic characteristics, allowing stability assessment to be performed on smaller, less expensive test rigs while maintaining full-scale predictive accuracy and reducing resource consumption.
Solution Approach 2:
By making the chamber volume dynamically adjustable through piston movement, the subscale system can adapt to match the acoustic modes of full-scale engines. This dynamic capability allows accurate stability assessment without requiring actual full-scale testing, thereby reducing testing resource consumption while maintaining measurement precision.
3Device complexity
If fixed combustion chamber volume is used, then device complexity is reduced, but adaptability to different acoustic modes deteriorates
Solution Approach 1:
The combustion chamber incorporates a telescoping piston that can be continuously moved along the axial direction to vary the chamber volume. This dynamic structure allows the same subscale chamber to adapt to and simulate a wide range of acoustic modes by adjusting its volume, greatly enhancing versatility without requiring multiple fixed-chamber configurations.
Solution Approach 2:
The telescoping piston mechanism enables the subscale combustion chamber to serve multiple functions by accommodating different acoustic mode frequencies and wavelengths. A single chamber design can test injectors across the full range of acoustic modes expected in full-scale engines, providing universal applicability without requiring separate test configurations for different modes.
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
Enables efficient, cost-effective, and risk-reduced evaluation of injector stability by simulating full-scale acoustic modes, reducing design iteration time and minimizing risks to other engine components.
Implementation Method 1
The injector elements are thus exposed to acoustic modes of varying frequency, covering the range of acoustic modes expected in a full scale rocket engine
Implementation Method 2
The injector plate comprises one or more first rocket engine injector elements configured to inject one or more propellants into the chamber
Data Source
AI summary
Systems and methods for subscale testing of rocket engine injector stability. The system includes a combustion chamber and a piston within the chamber that is continuously axially moveable via an actuator. An annular gap between the piston and a chamber sidewall provides a minimal cross-sectional flow area. A modular injector plate comprises one or more injector elements configured to inject a fuel and an oxidizer into the chamber. The piston is continuously translated, to thereby continuously vary a combustion volume of the chamber and to create a dynamically tunable downstream boundary. The injector elements are thus exposed to acoustic modes of varying frequency, covering the range of acoustic modes expected in a full scale rocket engine. The injector plate is removably attached to an upstream end of the chamber for replacement of the first injector elements with different, second injector elements for subsequent testing.