Axial Movable Fan Variable Area Nozzle for Turbofan Engines

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Solution Overview

Problem

Conventional gas turbine engines with fixed geometry fan nozzles compromise performance across different flight conditions, and existing fan variable area nozzles increase engine weight, negating fuel efficiency gains.

Innovation Solution

A fan variable area nozzle (VAFN) with a movable second fan nacelle section that axially slides relative to a fixed first fan nacelle section, allowing for adjustment of the fan nozzle exit area and bypass flow path geometry in response to flight conditions, controlled by a controller to optimize thrust and fuel economy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If existing fan variable area nozzles are implemented, then fan exit nozzle diameter can be varied for different flight conditions, but engine weight increases to the extent that fuel efficiency gains are negated

Engineering Contradiction:

Improvefan exit nozzle diameter adjustmentVSAvoidengine weight

Core Design Contradiction:

Adaptability or versatilityVSWeight of moving object

Solution Approach 1:

The patent implements a movable fan nozzle section that can dynamically adjust the fan exit nozzle diameter along the axial direction. The second fan nozzle section is configured to move relative to the first fan nozzle section, enabling the nozzle area to be varied in response to different flight conditions such as takeoff, landing, and cruise, thereby achieving adaptability without requiring complex mechanisms that would significantly increase weight

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The fan nozzle is divided into at least two separate sections: a first fan nozzle section and a second fan nozzle section. The second section is movable relative to the first section, allowing independent adjustment of the nozzle exit area. This segmentation enables the variable area function while maintaining a relatively simple and lightweight structure compared to conventional variable area nozzle designs

Inventive Principle:

Principle #1Segmentation

2Device complexity

If fixed geometry fan nozzles are used, then engine structure is simple, but performance is compromised across different flight conditions

Engineering Contradiction:

Improvenozzle structure simplicityVSAvoidperformance across flight conditions

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent transitions from a fixed geometry fan nozzle to a dynamic configuration where the second fan nozzle section can move axially relative to the first section. This movement allows the fan exit nozzle diameter to be adjusted according to different flight conditions (takeoff, landing, cruise), enabling the engine to optimize performance across various operating regimes while maintaining a relatively simple structure

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS11454193B2Gas turbine engine with axial movable fan variable area nozzle

Publication Date: 2022.09.27 RTX CORP

AI summary

A turbofan engine includes fan section including a plurality of fan blades, a gear train, a low spool including a low pressure turbine and a low pressure compressor, the low pressure turbine driving the plurality of fan blades through the gear train, and a high spool including a high pressure turbine driving a high pressure compressor. A fan nacelle at least partially surrounds a core nacelle to define a fan bypass flow path. A fan variable area nozzle is in communication with the fan bypass flow path and defines a fan nozzle exit area between the fan nacelle and the core nacelle. The fan variable area nozzle varies the fan nozzle exit area.