Combustor Pilot Ignition for Thermoacoustic Instability Mitigation

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Solution Overview

Problem

Acoustically-coupled combustion instabilities, or thermoacoustic instabilities, are difficult to avoid in gas turbine engines, leading to potential damage from high noise levels, and existing solutions do not effectively mitigate these instabilities across a wide range of operating conditions.

Innovation Solution

A heat engine with a combustor and a controller that selectively energizes a pilot to ignite fuel from a fuel injection port, using a plurality of pilots distributed radially and angularly to create a flame that is blown-off across a significant portion of the engine's operating map, thereby mitigating thermoacoustic instabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional combustion systems are used, then the engine can operate across a wide range of conditions, but thermoacoustic instabilities develop leading to high noise levels and potential component damage

Engineering Contradiction:

Improveoperating rangeVSAvoidthermoacoustic instability damage

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The combustor is divided into multiple zones with different pilot configurations. Some pilots are configured to create stable flames while others create blown-off flames, allowing the system to segment the combustion process into stability-providing and instability-mitigating regions simultaneously

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different pilots within the same combustor are given different local qualities - some are designed to produce stable attached flames for combustion stability, while others are positioned and sized to produce blown-off flames for acoustic instability mitigation, allowing each local region to serve a specific function

Inventive Principle:

Principle #3Local quality

2Stability of the object's composition

If a stable flame is maintained across the operating map, then combustion stability is improved, but thermoacoustic instabilities may be excited due to flame-structure coupling

Engineering Contradiction:

Improvecombustion stabilityVSAvoidthermoacoustic noise

Core Design Contradiction:

Stability of the object's compositionVSObject-generated harmful factors

Solution Approach 1:

The invention converts the potentially harmful blown-off flame, which would normally be considered a combustion failure, into a beneficial element for acoustic instability mitigation. The periodic attachment and detachment of the blown-off flame creates a stabilizing effect on pressure oscillations while maintaining overall combustion stability through the attached flame region

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 effectively reduces thermoacoustic instabilities by ensuring a stable flame distribution, minimizing noise-related damage and enhancing engine performance across various operating conditions.

Implementation Method 1

selectively energising the pilot to ignite fuel discharged from the fuel injection port

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS12601493B2Combustors and methods of mitigating thermoacoustic instabilities in a gas flow

Publication Date: 2026.04.14 ROLLS ROYCE PLC

AI summary

There is provided a heat engine 10 comprising a combustor 120 and a controller 290. The combustor 120 includes a fuel injection port 128 and a pilot 130. The controller 290 is configured to mitigate thermoacoustic instabilities in a gas flow A, B within the heat engine 10 by selectively energising 320 the pilot 130 to ignite fuel discharged from the fuel injection port 128. There is also provided a method 300 of mitigating thermoacoustic instabilities in a gas flow A, B within a heat engine 10 comprising a combustor 120 including a fuel injection port 128 and a pilot 130. The method 300 comprises selectively energising 320 the pilot 130 to ignite fuel discharged by the fuel injection port 128.