Arcuate-to-Annular Diffuser for Rotating Detonation Engines

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Solution Overview

Problem

Traditional diffusers for rotating detonation engines limit design space and are inefficient in transitioning supersonic airflow to subsonic conditions.

Innovation Solution

A diffuser design with radially inner and outer walls that increase in arc angle and decrease in distance as it extends axially, transitioning from an arcuate inlet to an annular outlet, increasing the cross-sectional area, which includes a transition portion between the inlet and the outlet, providing additional design space for fuel, payload, or payload, and enhancing the range and payload capacity, and the diffuser is configured to receive air flow from the inlet and transition supersonic airflow to subsonic airflow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a typical radial duct diffuser is used, then the structure is simple, but the design space is limited and airflow transition efficiency is poor

Engineering Contradiction:
Improvedesign spaceVSAvoiddiffuser structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The diffuser transitions from a simple two-dimensional radial duct to a three-dimensional structure with arcuate walls that wrap around the engine. The radially inner and outer walls extend in the arcwise direction with increasing arc angles, creating additional spatial dimensions for design flexibility while maintaining structural efficiency for airflow transition.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The diffuser is divided into multiple functional sections: an inlet portion, a transition portion with increasing arc angles, and an outlet portion. The radially inner and outer walls are segmented into discrete panels that can be independently configured, allowing optimization of each section for its specific airflow requirements while contributing to overall design space expansion.

Inventive Principle:
Principle #1Segmentation

2Volume of moving object

If the diffuser arc angle increases axially, then design space and fuel capacity increase, but the structural complexity increases

Engineering Contradiction:
Improvefuel capacityVSAvoiddiffuser geometry
Core Design Contradiction:
Volume of moving objectVSDevice complexity

Solution Approach 1:

The diffuser employs arcuate radially inner and outer walls that curve in the arcwise direction, replacing straight linear geometry with curved surfaces. This curvature naturally increases the enclosed volume and design space while the smooth continuous arcs maintain structural simplicity compared to complex angular transitions.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The arc angle is defined as a varying parameter that increases axially from the inlet to the outlet portion. By treating the arc angle as a continuous function rather than a fixed value, the design achieves increased volume and fuel capacity while the systematic parameter variation maintains manufacturing feasibility and structural regularity.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If the diffuser distance between radially inner and outer walls decreases axially, then supersonic to subsonic transition efficiency improves, but the cross-sectional area for airflow reduces

Engineering Contradiction:
Improveairflow transition efficiencyVSAvoidcross-sectional area
Core Design Contradiction:
ProductivityVSArea of moving object

Solution Approach 1:

The diffuser resolves the area reduction problem by expanding in the arcwise dimension. While the radial distance between walls decreases to improve compression and airflow transition, the arc length of the radially inner and outer walls increases, maintaining or increasing the overall cross-sectional area through growth in the third dimension (arcwise direction).

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

Different sections of the diffuser have locally optimized geometries: the radial wall distance decreases in the compression section to improve supersonic-to-subsonic transition efficiency, while the arc length increases simultaneously to maintain adequate cross-sectional area for mass flow. Each local region is optimized for its specific function while contributing to overall performance.

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

The diffuser effectively transitions supersonic airflow to subsonic conditions while providing additional design space within the airframe, allowing for increased fuel capacity and payload.

Implementation Method 1

a diffuser to feed the rotating detonation engine. The diffuser may be configured to reduce a flow from a supersonic inlet to subsonic conditions

Methodology Applied
Scientific EffectDiffusion: Diffusion

Implementation Method 2

the cross-sectional area increases as the diffuser extends axially

Methodology Applied
Scientific EffectPressure gradient: Pressure Gradient

Data Source

PatentEP3851660B1Diffuser for rotating detonation engine
Publication Date: 2025.12.24 RTX CORP
  • EP3851660B1 patent drawingFigure 1
  • EP3851660B1 patent drawingFigure 2
  • EP3851660B1 patent drawingFigure 3

AI summary

A diffuser (300) may comprise an inlet (310) and an outlet (340). The inlet may comprise an arcuate shape. The outlet may comprise an annular shape. The diffuser may transition from the arcuate shape at the inlet to the annular shape at the outlet. The diffuser may comprise a radially inner wall (320) and a radially outer wall (330) disposed opposite the radially inner wall. The radially inner wall and the radially outer wall may partially define a duct.