Aircraft Boundary Layer Ingestion Multiple Fans

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Solution Overview

Problem

Existing aircraft boundary layer ingestion solutions are bulky, non-retrofitable, and ineffective for asymmetric boundary layer flows, leading to increased fuel consumption due to drag forces.

Innovation Solution

The implementation of multiple fans positioned about the fuselage, forward of the rearward-most end, which accelerate boundary layer air flow from a first to a second average velocity, improving aerodynamic efficiency without interfering with operational parts and being lightweight and retrofittable.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If a single boundary layer ingestion apparatus is used, then boundary layer flow can be accelerated, but the apparatus becomes bulky and heavy, offsetting fuel consumption gains

Engineering Contradiction:

Improvefuel consumptionVSAvoidapparatus weight

Core Design Contradiction:

Use of energy by moving objectVSWeight of moving object

Solution Approach 1:

The single bulky boundary layer ingestion apparatus is divided into multiple smaller fan units distributed around the fuselage. Each fan unit independently accelerates boundary layer flow at its location, achieving the overall boundary layer ingestion effect without the weight penalty of a single large apparatus. This segmentation allows the system to maintain effectiveness while significantly reducing individual component size and total weight.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If a single boundary layer ingestion apparatus is positioned circumferentially about the aircraft, then axisymmetric boundary layer flow can be addressed, but the solution cannot be retrofitted to existing aircraft and interferes with operational parts

Engineering Contradiction:

Improveretrofit capabilityVSAvoidinterference with operational parts

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The circumferential apparatus is segmented into multiple discrete fan units that can be independently positioned at selected locations around the fuselage. This allows installation on existing aircraft without requiring complete circumferential integration, enabling retrofit capability while avoiding interference with operational parts such as the APU by carefully selecting fan locations away from sensitive areas.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of treating the entire circumferential boundary layer uniformly, each fan unit addresses the local boundary layer conditions at its specific location. This allows asymmetric boundary layer flows to be addressed by positioning fans strategically at locations where they are most effective, rather than requiring a complete circumferential arrangement that would interfere with aircraft operations.

Inventive Principle:

Principle #3Local quality

3Reliability

If a single apparatus is positioned circumferentially about the aircraft, then boundary layer ingestion can be achieved, but it assumes axisymmetric boundary layer flow and cannot handle asymmetric flows

Engineering Contradiction:

Improveboundary layer ingestion effectivenessVSAvoidhandling asymmetric boundary layer flow

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The system transitions from a symmetric circumferential apparatus to an asymmetric arrangement of individual fan units. Each fan unit can be positioned at different locations and orientations to match the asymmetric boundary layer flow pattern, allowing the system to effectively address asymmetric flows while maintaining boundary layer ingestion effectiveness through strategic placement of fans at locations of maximum benefit.

Inventive Principle:

Principle #4Asymmetry

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 solution effectively reduces drag forces by accelerating boundary layer air flow, improving fuel efficiency and aerodynamic performance while being adaptable to various aircraft designs and flow asymmetries.

Implementation Method 1

When an aircraft is in flight, air flows over the aircraft and creates a boundary layer of slower moving air near the exterior surface of the aircraft

Methodology Applied

Scientific EffectBoundary layer: Boundary Layer

Implementation Method 2

The velocity of the boundary layer air flow is lower than the free stream velocity of the aircraft. Accordingly, the boundary layer air flow generates a drag force on the aircraft

Methodology Applied

Scientific EffectDrag force: Drag

Data Source

PatentUS12071224B2Aircraft boundary layer ingestion using multiple fans and associated methods

Publication Date: 2024.08.27 THE BOEING CO

AI summary

An aircraft is equipped with multiple fans for boundary layer ingestion. The aircraft comprises a fuselage, having an exterior surface and a rearward-most end. The aircraft also comprises a plurality of fans that are fixed to and positioned about the exterior surface of the fuselage at an axial location forward of the rearward-most end of the fuselage. Each one of the plurality of fans comprises a plurality of fan blades and a fan drive configured to rotate the plurality of fan blades. The plurality of fan blades are positioned at lateral locations relative to the exterior surface of the fuselage such that when rotated by the fan drive the plurality of fans receive and accelerate fuselage boundary layer air flow, along the exterior surface of the fuselage, from a first average velocity to a second average velocity, greater than the first average velocity, when the aircraft is in flight.