Aft Engine Boundary Layer Ingestion Fan

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional aircraft propulsion systems face inefficiencies due to drag, which is not adequately addressed by existing boundary layer ingestion systems that often result in non-uniform airflow and efficiency losses in turbofan jet engines.

Innovation Solution

The implementation of an aft-mounted boundary layer ingestion fan with a nacelle and structural members that extend between the fan and fuselage, incorporating a fan shaft and tail cone, to ingest and reenergize the boundary layer airflow, reducing drag and improving engine efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If boundary layer ingestion systems are used to route slow moving air into turbofan jet engines, then drag on the aircraft is reduced, but the relatively slow moving flow with non-uniform velocity profile causes efficiency loss in the engines

Engineering Contradiction:

ImprovedragVSAvoidengine efficiency

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

A flow conditioning system with guide vanes and straightening elements is introduced as an intermediary between the boundary layer ingestion and the turbofan engine. This intermediary device conditions the non-uniform boundary layer airflow, straightening it and creating a more uniform velocity profile before the air enters the engine, thereby preserving engine efficiency while maintaining drag reduction benefits

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system changes the velocity profile parameter of the boundary layer air from non-uniform to uniform through flow conditioning. By adjusting the flow parameters (velocity distribution, direction) using guide vanes and straightening elements, the air is prepared to match engine inlet requirements, resolving the contradiction between drag reduction and engine efficiency

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If turbofan jet engines are mounted separately from the fuselage to interact with freestream airflows, then turbulence in the inlet airflow is reduced, but drag on the aircraft increases

Engineering Contradiction:

Improveairflow uniformityVSAvoiddrag

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The invention merges the boundary layer ingestion system with the turbofan engine inlet, combining two previously separate functions into one integrated system. The boundary layer air is ingested and conditioned to join the freestream airflow entering the engine, allowing the engine to be positioned closer to the fuselage while maintaining acceptable airflow quality and reducing drag

Inventive Principle:

Principle #5Merging (Combining)

3Object-affected harmful factors

If an aft-mounted fan is used to ingest boundary layer airflow, then drag is reduced, but the structural complexity of mounting the fan increases

Engineering Contradiction:

ImprovedragVSAvoidmounting structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The nacelle structure is designed to serve multiple functions: it houses the fan, provides structural support for mounting, conditions the airflow, and integrates with the fuselage. This multi-functionality reduces the need for separate structural components, thereby reducing overall structural complexity while enabling aft-mounted boundary layer ingestion

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 effectively reduces aircraft drag while maintaining engine efficiency by uniformly ingesting and reenergizing the boundary layer airflow, enhancing the net propulsive thrust of the aircraft.

Implementation Method 1

Methodology Applied

Scientific EffectBoundary layer ingestion: Boundary Layer

Implementation Method 2

The fan rotatable about the central axis, the fan having a plurality of fan blades

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP3144226B1Aft engine for an aircraft

Publication Date: 2018.11.21 GENERAL ELECTRIC CO

Figure 1~2
Figure 3
Figure 4

AI summary

A propulsion system for an aircraft (10) is provided having an aft engine configured to be mounted to the aircraft (10) at an aft end of the aircraft (10). The aft engine includes a fan (304) rotatable about a central axis of the aft engine having a plurality of fan blades (310). The aft engine also includes a nacelle (306) encircling the plurality of fan blades (310) with one or more structural members (308) extending between the nacelle (306) and the mean line (15) of the aircraft (10) at a location forward of the plurality of fan blades (310) when the aft engine is mounted to the aircraft (10). The aft engine may increase a net thrust of the aircraft (10) when mounted to the aircraft (10).