Rocket Injector Subscale Stability Testing With Telescoping Throat

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Solution Overview

Problem

Conventional subscale testing of rocket engine injectors fails to accurately assess full-scale performance due to limited stability assessment capabilities, leading to costly and time-consuming iterations during full-scale tests, with risks to other engine components.

Innovation Solution

A subscale testing system with a continuously variable combustion chamber volume, featuring a modular injector plate and piston or telescoping throat, allowing exposure to a range of acoustic modes, and sensors to detect acoustic responses, enabling rapid and accurate stability assessment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If conventional subscale testing is used, then testing cost and time are reduced, but stability assessment accuracy deteriorates

Engineering Contradiction:

Improvetesting timeVSAvoidstability assessment accuracy

Core Design Contradiction:

Loss of timeVSMeasurement precision

Solution Approach 1:

The combustion chamber volume is made dynamically variable through piston movement, allowing the subscale chamber to simulate different full-scale chamber volumes and acoustic modes. This dynamic adjustment enables accurate stability assessment across multiple operating conditions without requiring multiple fixed subscale chambers, resolving the contradiction between testing efficiency and assessment accuracy.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the physical parameter of combustion chamber volume to match different full-scale engine conditions. By varying the chamber volume through piston displacement, the acoustic modes and combustion characteristics are adjusted to represent full-scale performance, enabling accurate stability prediction while maintaining subscale testing benefits.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If full-scale testing is used, then stability assessment accuracy is improved, but testing cost and risk to other components increase

Engineering Contradiction:

Improvestability assessment accuracyVSAvoidrisk to other engine components

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

A subscale combustion chamber is used as a simplified copy of the full-scale chamber, retaining the essential acoustic modes and combustion characteristics. This scaled-down model allows stability testing without exposing other engine components to full-scale testing risks, while still providing accurate stability assessment through proper scaling laws and acoustic mode matching.

Inventive Principle:

Principle #26Copying

3Device complexity

If fixed combustion chamber volume is used, then device complexity is reduced, but adaptability to different acoustic modes deteriorates

Engineering Contradiction:

Improvechamber configuration complexityVSAvoidacoustic mode coverage

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

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 allows for efficient, cost-effective, and rapid screening of injector designs, reducing the risk to other engine components and shortening design cycles by decoupling from full-scale testing, thereby enabling more ambitious design iterations.

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

Methodology Applied

Scientific EffectAcoustic modes: Sound

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

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 3

Sensors in the chamber detect the acoustic responses

Methodology Applied

Scientific EffectAcoustic response detection: Sound

Data Source

PatentUS12435683B2Rocket injector subscale stability assessment with telescoping throat or moveable injector plate

Publication Date: 2025.10.07 BLUE ORIGIN MANUFACTURING LLC

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.