Rocket Engine Combustor Inertance Design for Vibration Suppression

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Solution Overview

Problem

Existing combustors for reusable rocket engines fail to effectively suppress vibration across a wide range of thrusts, unlike disposable engines, which are limited to a narrow thrust range.

Innovation Solution

The combustor design includes an inertance increasing portion with branching fuel and oxidant passages that lengthen the passage length without changing the cross-sectional area, providing a cooling mechanism and increasing equivalent inertance in the vibration equivalent circuit to suppress vibrations across multiple thrusts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the shape of the injection orifice is changed to suppress vibration, then vibration is suppressed in a single thrust, but vibration cannot be suppressed in a plurality of thrusts

Engineering Contradiction:

Improvevibration suppressionVSAvoidthrust range

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The inertance increasing portion allows the equivalent inertance to vary dynamically with thrust conditions. At different thrust levels, the inertance automatically adjusts to appropriate values, enabling vibration suppression across multiple thrusts without requiring manual intervention or complex control systems.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the physical parameter of equivalent inertance by modifying the passage length in the inertance increasing portion. This parameter change enables the system to adapt to different thrust conditions and suppress vibrations across a wide thrust range.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If the passage length is lengthened to increase equivalent inertance, then vibration suppression is improved, but the device complexity increases

Engineering Contradiction:

Improvevibration suppressionVSAvoidpassage structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The inertance increasing portion is merged with the existing fuel passage or oxidant passage, rather than being a separate component. This integration increases equivalent inertance while minimizing additional device complexity, as the inertance function is combined with the propellant delivery function.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The inertance increasing portion serves multiple functions: it increases equivalent inertance for vibration suppression, maintains propellant flow delivery, and can be integrated with cooling passages. This multi-functionality reduces the need for separate components, thereby limiting complexity increase.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If the passage cross-sectional area is changed to increase equivalent inertance, then vibration suppression is improved, but the injection differential pressure is affected

Engineering Contradiction:

Improvevibration suppressionVSAvoidinjection differential pressure

Core Design Contradiction:

ReliabilityVSStress or pressure

Solution Approach 1:

The inertance increasing portion is designed with specific local characteristics (lengthened passage) in a particular location of the fuel or oxidant passage. This localized modification increases equivalent inertance without changing the overall passage cross-sectional area, thereby maintaining injection differential pressure while achieving vibration suppression.

Inventive Principle:

Principle #3Local quality

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 design effectively suppresses vibrations in reusable rocket engines by increasing equivalent inertance, ensuring stability even at reduced thrust levels, thereby maintaining performance across a wide thrust range.

Implementation Method 1

an inertance increasing portion configured to increase an equivalent inertance in a vibration equivalent circuit of the combustor for the rocket engine

Methodology Applied

Scientific EffectInertance: Inertia

Implementation Method 2

the fuel passage or/and the oxidant passage may include a cooling passage configured to cool the nozzle skirt

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS12129815B2Combustor for rocket engine

Publication Date: 2024.10.29 IHI CORP

AI summary

The combustor for a rocket engine includes a combustion room configured to cause a combustion reaction between a fuel and an oxidant, an injector configured to inject the fuel and the oxidant into the combustion room, and a nozzle skirt configured to inject combustion gas generated by the combustion reaction to an outside, and an inertance increasing portion configured to increase an equivalent inertance in a vibration equivalent circuit of the combustor for the rocket engine.