Rotating Detonation Combustor Pilot for Hypersonic Engine Unstart

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Solution Overview

Problem

Conventional supersonic aircraft engines, particularly scramjet engines, face challenges with unstart conditions at lower Mach numbers, where the supersonic airflow breaks down, leading to inefficiencies and operational limitations.

Innovation Solution

A combined cycle propulsion system incorporating a compressor-fed combustion engine with a rotating detonation combustor (RDC) as a pilot for a supersonic combustion type combustor, allowing for seamless transition between ramjet and scramjet modes, reducing the likelihood of unstart conditions by utilizing combustion products to initiate and stabilize scramjet operation at higher Mach numbers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a scramjet engine is used to achieve hypersonic flight speeds, then the aircraft can operate at higher Mach numbers, but unstart conditions occur at lower Mach numbers causing airflow breakdown and operational limitations

Engineering Contradiction:

ImproveMach numberVSAvoidoperational stability

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The engine system dynamically transitions between different operational modes (ramjet mode at lower Mach numbers, scramjet mode at higher Mach numbers) to adapt to varying flight conditions. This dynamic operation allows the engine to maintain reliable combustion across the entire Mach number range by switching combustion mechanisms appropriately.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the combustion parameter from subsonic combustion (ramjet) to supersonic combustion (scramjet) based on flight Mach number. By adjusting the combustion mode parameter, the engine achieves both high-speed capability and operational reliability across different flight regimes.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a ramjet engine is used for supersonic flight, then combustion occurs at subsonic speeds providing stable operation, but the engine cannot achieve hypersonic flight speeds efficiently

Engineering Contradiction:

Improvecombustion stabilityVSAvoidflight speed capability

Core Design Contradiction:

ReliabilityVSSpeed

Solution Approach 1:

The engine is designed with multi-functionality to perform both subsonic combustion (ramjet mode for stable operation) and supersonic combustion (scramjet mode for hypersonic capability) within the same engine system, allowing it to serve multiple flight regimes effectively.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The engine dynamically switches between ramjet and scramjet operational modes depending on the flight Mach number, enabling it to achieve both combustion stability at lower speeds and hypersonic speed capability at higher Mach numbers.

Inventive Principle:

Principle #15Dynamics

3Reliability

If the isolator reduces airflow speed to subsonic before combustion, then stable combustion occurs, but the engine cannot maintain supersonic combustion required for hypersonic efficiency

Engineering Contradiction:

Improvecombustion stabilityVSAvoidpropulsion efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The combustion process is segmented into two distinct modes: subsonic combustion in ramjet mode for stability, and supersonic combustion in scramjet mode for efficiency. The engine can select the appropriate combustion segment based on flight conditions, achieving both stability and efficiency in their respective operational ranges.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The combustion parameter (subsonic vs. supersonic) is changed based on flight Mach number to optimize both stability and efficiency. At lower Mach numbers, subsonic combustion provides stability; at higher Mach numbers, supersonic combustion maintains efficiency.

Inventive Principle:

Principle #35Parameter changes

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 enables efficient operation across a wider range of flight speeds, from subsonic to hypersonic, by using the RDC to initiate and sustain scramjet combustion, thereby reducing the risk of unstart conditions and enhancing propulsion efficiency.

Implementation Method 1

a first combustion portion (62) having at least one rotating detonation combustor (82)

Methodology Applied

Scientific EffectRotating detonation: Detonation

Implementation Method 2

the inlet duct compresses the supersonic airflow using shock waves

Methodology Applied

Scientific EffectShock waves: Shock Wave

Implementation Method 3

combustion in a combustion chamber of the ramjet engine occurs at sub-sonic speeds

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS12253050B2Combined cycle propulsion system for hypersonic flight

Publication Date: 2025.03.18 GENERAL ELECTRIC CO

AI summary

A combined cycle propulsion system for a flight vehicle includes a compressor-fed combustion engine, and a multi-mode supersonic engine. The multi-mode supersonic engine includes an adjustable inlet section, a combustion section arranged downstream of the adjustable inlet section and including a first combustor portion having at least one rotating detonation combustor and a second combustor portion having a supersonic combustion type combustor, and an adjustable exhaust nozzle section arranged downstream of the combustion section. The at least one rotating detonation combustor functions as a pilot for the supersonic combustion type combustor.