Integrated Fan Case Thrust Reversal Assembly

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Solution Overview

Problem

Conventional jet aircraft propulsion systems with separate thrust reversing assemblies increase the axial span and weight of the pylon, leading to increased stress and reduced efficiency due to the extended pylon length and weight, which affects smooth airflow and fuel efficiency.

Innovation Solution

Incorporating the thrust reversing assembly into the fan case, where the sleeve can translate or hinge to expose a cascade array and deploy blocker doors within the bypass air duct, reducing the axial span of the outer barrel and pylon, thereby reducing structural loads and weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate thrust reversing assembly is used, then thrust reversal function is achieved, but the axial span and weight of the pylon increase

Engineering Contradiction:

Improvethrust reversal functionVSAvoidaxial span of pylon

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The thrust reversing assembly is merged with the fan case to form an integrated structure. The fan case now houses both the fan blades and the thrust reversing mechanism (including the cascade array and blocker doors), eliminating the need for a separate thrust reversing assembly and reducing the overall axial span of the pylon.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If a separate thrust reversing assembly is used, then thrust reversal function is achieved, but the weight of the pylon increases

Engineering Contradiction:

Improvethrust reversal functionVSAvoidweight of pylon

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

3Length of moving object

If the outer barrel is shortened, then structural loads and weight are reduced, but the thrust reversing assembly configuration becomes more complex

Engineering Contradiction:

Improveaxial span of outer barrelVSAvoidthrust reversing assembly configuration

Core Design Contradiction:

Length of moving objectVSDevice complexity

Solution Approach 1:

The thrust reversing assembly components (cascade array, blocker doors, translating sleeve) are nested within the fan case structure. The cascade array is positioned within the fan case, the translating sleeve moves within the fan case to expose the cascade, and the blocker doors are housed within the fan case, creating a compact nested arrangement that shortens the outer barrel while managing complexity through integrated design.

Inventive Principle:

Principle #7Nested doll (Nesting)

Data Source

PatentEP2876288B1Aircraft propulsion system fan case comprising thrust reversing assembly

Publication Date: 2021.01.13 ROHR INC

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AI summary

An aircraft propulsion system (200) includes a generally annular fan case (206) defined by a fan (110) configured to be disposed at a forward end thereof and a stator blade array (215) configured to be disposed at an aft end thereof, a thrust reversing assembly (204) comprising at least a portion of the fan case (206), the fan case (206) comprising a generally annular cascade array (210), and a sleeve (208) situated at least partially about the cascade array (210), the sleeve (210) configured to deploy to expose the cascade array (210). The aircraft propulsion system may further comprise a blocker door (214) coupled to at least one of the cascade array (210) and an inner surface of the fan case (206), the blocker door (214) configured to deploy to redirect airflow through the cascade array (210).