Rocket Injector Subscale Testing With Dynamically Tunable Combustion Volume
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Solution Overview
Problem
Existing subscale testing methods for rocket engine injectors fail to accurately assess full-scale performance due to limited understanding of combustion stability and the lack of predictive analytic models, leading to costly and time-consuming full-scale tests.
Innovation Solution
A subscale testing system with a dynamically tunable combustion chamber volume, achieved by a continuously moveable piston, exposes injector elements to a range of acoustic frequencies mimicking full-scale engine conditions, allowing for rapid and accurate stability assessment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional subscale testing is used, then testing cost and time are reduced, but measurement precision of full-scale performance is insufficient
Solution Approach 1:
The combustion chamber volume is made dynamically variable through a moveable piston that can be positioned at multiple locations. This dynamic adjustment allows the subscale chamber to simulate different full-scale engine conditions and acoustic modes, enabling accurate stability assessment across a range of operating conditions without requiring multiple fixed-scale test facilities.
Solution Approach 2:
The system changes the physical parameter of combustion chamber volume to match different full-scale engine conditions. By adjusting the chamber volume through piston positioning, the acoustic modes and flow characteristics in the subscale chamber can be tuned to correspond with full-scale engine operating conditions, thereby improving measurement precision while maintaining subscale testing advantages.
2Measurement precision
If full-scale testing is performed, then measurement precision of stability is improved, but loss of time and cost increase
Solution Approach 1:
The subscale combustion chamber is designed to replicate the essential acoustic modes and flow characteristics of full-scale engine combustion chambers. By carefully scaling the chamber geometry and using variable volume to match acoustic resonance conditions, the system creates an accurate physical copy of full-scale conditions, enabling reliable stability prediction without the time and cost constraints of actual full-scale testing.
3Adaptability or versatility
If fixed combustion chamber volume is used, then device complexity is reduced, but adaptability to different acoustic modes is limited
Solution Approach 1:
Rather than using multiple fixed chamber configurations, the system employs a single dynamic chamber volume adjustment mechanism. The moveable piston allows continuous or discrete adjustment of chamber volume to match different acoustic modes, providing high adaptability while keeping the overall device structure relatively simple compared to having multiple dedicated test chambers.
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 system effectively characterizes injector stability across a range of frequencies, reducing the need for costly full-scale tests, accelerating design iterations, and minimizing risk 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 with telescoping throat that is continuously axially moveable via an actuator. A modular injector plate comprises one or more first rocket engine injector elements configured to inject one or more propellants, such as a fuel and an oxidizer, into the chamber. The injector plate and/or the telescoping throat may be continuously translated, to thereby continuously vary a combustion volume of the chamber and create a dynamically tunable downstream boundary. The injectors 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 injectors with different, second injectors for subsequent testing.