Aircraft Distributed Propulsion with Auxiliary Fan

Solution Overview

Problem

Conventional aircraft propulsion systems are oversized to overcome the boundary layer drag, leading to inefficiencies due to the resistance created by the fuselage, which results in increased fuel consumption and engine stress.

Innovation Solution

A distributed propulsion system incorporating at least two gas turbine engines and an auxiliary propulsion fan, where the auxiliary fan is selectively driven by a combination of mechanical and electric power sources through a shared drive shaft, allowing for adjustable thrust and reduced engine size by ingesting drag and providing supplemental power during various flight phases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If conventional aircraft use oversized gas turbine engines to overcome boundary layer drag, then thrust requirement is met, but fuel consumption increases and engine stress increases

Engineering Contradiction:

ImprovethrustVSAvoidfuel consumption

Core Design Contradiction:

ForceVSUse of energy by moving object

Solution Approach 1:

The propulsion system is segmented into multiple independent thrust sources: wing-mounted gas turbine engines and a fuselage-mounted auxiliary propulsion fan. This segmentation allows the auxiliary fan to specifically address boundary layer drag while the main engines provide primary thrust, enabling more efficient overall system performance and reduced fuel consumption.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The auxiliary propulsion fan acts as an intermediary element between the main engines and the boundary layer drag. By positioning the fan within the fuselage boundary layer and driving it with exhaust gases from the main engines, the system creates an intermediate thrust source that directly counteracts boundary layer resistance without requiring oversized main engines.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Force

If conventional aircraft use oversized gas turbine engines to overcome boundary layer drag, then thrust requirement is met, but engine stress increases

Engineering Contradiction:

ImprovethrustVSAvoidengine stress

Core Design Contradiction:

ForceVSStress or pressure

Solution Approach 1:

The propulsion system is segmented into multiple independent thrust sources: wing-mounted gas turbine engines and a fuselage-mounted auxiliary propulsion fan. This segmentation allows the auxiliary fan to specifically address boundary layer drag while the main engines provide primary thrust, enabling more efficient overall system performance and reduced fuel consumption.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The auxiliary propulsion fan acts as an intermediary element between the main engines and the boundary layer drag. By positioning the fan within the fuselage boundary layer and driving it with exhaust gases from the main engines, the system creates an intermediate thrust source that directly counteracts boundary layer resistance without requiring oversized main engines.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If auxiliary propulsion fan is added to provide supplemental thrust, then fuel burn is reduced, but device complexity increases

Engineering Contradiction:

Improvefuel burnVSAvoidpropulsion system complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The auxiliary propulsion fan serves multiple functions: it provides supplemental thrust during takeoff and climb to reduce fuel burn, acts as a thrust reverser during landing, and can be driven by multiple power sources (gas turbine engines or electric motors). This multi-functionality justifies the added complexity by delivering diverse operational benefits from a single integrated system.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The auxiliary propulsion fan's operation is dynamic and adaptive, with variable speed control based on flight phase and power source availability. The system can switch between different drive sources (gas turbine exhaust, electric motors, or combinations) and adjust fan speed to optimize performance for different operational requirements, making the complexity manageable through intelligent control.

Inventive Principle:

Principle #15Dynamics

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 system achieves up to 33% of the required thrust, enabling downsizing of the gas turbine engines, reducing fuel burn, and providing flexible power distribution during takeoff and other phases, while maintaining operational efficiency and safety.

Implementation Method 1

The auxiliary propulsion fan generates thrust by moving air through mechanical rotation

Methodology Applied

Scientific EffectThrust generation through fan rotation: Fan

Implementation Method 2

at least two gas turbine engines

Methodology Applied

Scientific EffectCombustion: Combustion

Implementation Method 3

The engines generate thrust, propelling the aircraft forward

Methodology Applied

Scientific EffectThrust generation: Jet

Data Source

PatentUS10906657B2Aircraft system with distributed propulsion

Publication Date: 2021.02.02 RTX CORP

AI summary

A propulsion system for an aircraft includes at least two gas turbine engines and at least one auxiliary propulsion fan. The at least one auxiliary propulsion fan is configured to selectively receive a motive force from either or both of the at least two gas turbine engines through at least one shaft operatively coupled to the at least one auxiliary propulsion fan.