Variable Area Inlet Axial Translation for Mass Flow Control

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Solution Overview

Problem

Existing aircraft propulsion systems with variable airflow inlet areas face challenges in adapting to changing mass flow requirements during different flight conditions, such as supersonic and subsonic speeds, necessitating an improved inlet assembly that can dynamically adjust airflow.

Innovation Solution

The aircraft propulsion system incorporates a variable area inlet with a center body, aft fixed structure, and forward moveable structure, which form an annular inner airflow passage and secondary outer airflow passages, allowing for axial translation to adjust airflow and regulate mass flow, thereby accommodating varying operational conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a fixed inlet structure is used, then the structure is simple and reliable, but the mass flow cannot be adjusted for different flight conditions

Engineering Contradiction:
Improvemass flow adjustment capabilityVSAvoidinlet structure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The inlet structure incorporates a moveable forward section that can translate axially between different positions to dynamically adjust the inlet area. This allows the mass flow to be adapted for different flight conditions (supersonic and subsonic) while maintaining a relatively simple overall structure based on a fixed center body and aft section.

Inventive Principle:
Principle #15Dynamics

2Quantity of substance

If the inlet area is increased for supersonic flight, then more mass flow is available, but the inlet area must be reduced for subsonic flight to optimize performance

Engineering Contradiction:
Improvemass flowVSAvoidinlet area adaptability
Core Design Contradiction:
Quantity of substanceVSAdaptability or versatility

Solution Approach 1:

The forward moveable structure translates axially to increase the inlet area when supersonic flight is detected, allowing greater mass flow. When subsonic flight conditions are detected, the structure retracts to reduce the inlet area, optimizing performance for different flight regimes.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes the physical parameter of inlet area by translating the forward moveable structure to different axial positions, thereby adapting the mass flow capacity to match the detected flight conditions (supersonic or subsonic).

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4148246B1Aircraft propulsion system with variable area inlet
Publication Date: 2024.10.02 ROHR INC
  • EP4148246B1 patent drawingFigure 1
  • EP4148246B1 patent drawingFigure 2
  • EP4148246B1 patent drawingFigure 3~4

AI summary

An assembly is provided for an aircraft propulsion system (20). This assembly includes a variable area inlet (66). The variable area inlet (66) includes a moveable structure (72) configured to move axially along an axial centerline (30, 78) between a first position and a second position. The variable area inlet (66) is configured to open an airflow inlet passage (74) into the aircraft propulsion system (20) when the movable structure (72) is in the first position. The variable area inlet (66) is configured to close the airflow inlet passage (74) when the movable structure (72) is in the second position. The airflow inlet passage (74) includes an inlet. The inlet extends axially along the axial centerline (30, 78) from a first end to a second end. A distance from the first end to the second end changes as the inlet extends laterally between a first side (138) and a second side (140).