Rotating Detonation Combustor Offset Inlet Stability

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Solution Overview

Problem

Maintaining a rotating detonation wave within rotating detonation combustors during low power conditions and selectively controlling operating conditions is challenging, as the detonations may dissipate or be extinguished, particularly at idle conditions.

Innovation Solution

The design includes an annular tube with an annulus inlet and outlet, an annulus forward wall with a backward facing step to reflect pressure waves, and a fluid inlet plenum that is offset from the annulus inlet, allowing pressure waves to be reflected back into the combustor and minimizing energy loss, thereby maintaining the detonation wave and enhancing stability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a rotating detonation combustor operates at idle conditions, then the engine can remain running, but the detonation wave dissipates or is extinguished

Engineering Contradiction:

Improvedetonation wave stabilityVSAvoidengine power output

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The combustor is divided into distinct functional zones: a first portion with a first cross-sectional area and a second portion with a second cross-sectional area. This segmentation allows different regions to serve different purposes - the first portion maintains detonation stability while the second portion manages exhaust flow, enabling stable operation at idle conditions

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the combustor are given different local characteristics - the first portion has specific geometric features (cross-sectional area, length ratios) optimized for detonation wave maintenance, while the second portion is optimized for exhaust management. This local differentiation allows the system to maintain detonation stability at low power conditions

Inventive Principle:

Principle #3Local quality

2Reliability

If the combustor geometry is optimized for detonation stability, then the detonation wave is maintained at low power, but the device complexity increases

Engineering Contradiction:

Improvedetonation wave maintenanceVSAvoidcombustor geometry complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The combustor employs asymmetric geometry where the first portion has a specific cross-sectional area and dimensional relationships (L1/D1 ratios) that differ from the second portion. This asymmetric design creates favorable flow conditions for detonation stability without requiring overly complex configurations

Inventive Principle:

Principle #4Asymmetry

Solution Approach 2:

Instead of attempting to control detonation through complex active control systems or intricate geometric features, the invention uses a relatively simple geometric configuration with specific dimensional relationships. The simplicity of the geometric approach reduces device complexity while maintaining effectiveness

Inventive Principle:

Principle #13The other way round (Inversion)

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 configuration ensures stable operation and improved performance by retaining energy released during rotating detonation, allowing the combustor to maintain a rotating detonation wave even at low power conditions and enhancing overall efficiency.

Implementation Method 1

The backward facing step reflects pressure waves resulting from rotating detonation toward the outlet end

Methodology Applied

Scientific EffectPressure wave reflection: Reflection

Implementation Method 2

A detonation wave travels in a circumferential direction of the annulus and consumes the incoming fuel and air mixture

Methodology Applied

Scientific EffectDetonation: Detonation

Implementation Method 3

The burned fuel and air mixture (e.g., combustion gases) exits the annulus

Methodology Applied

Scientific EffectCombustion: Combustion

Data Source

PatentUS11371711B2Rotating detonation combustor with offset inlet

Publication Date: 2022.06.28 GENERAL ELECTRIC CO

AI summary

A combustion system includes an annular tube disposed between an inner wall and an outer wall, the annular tube extending from an inlet end to an outlet end; at least one annulus inlet disposed in the annular tube proximate the inlet end, the annulus inlet providing a conduit through which fluid flows into the annular tube; at least one outlet disposed in the annular tube proximate the outlet end; at least one inlet fluid plenum disposed upstream of the annulus inlet; and at least one fluid inlet disposed upstream of the inlet fluid plenum. The fluid inlet is linearly offset from the annulus inlet.