Flexible Force Transmitting Devices for Aircraft Engine Deformation Control
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Solution Overview
Problem
Ultra-high bypass ratio engines experience increased flexibility due to larger fan diameters, leading to flexural deformation that results in turbine blade tip wear and reduced engine performance, as existing attachment systems fail to effectively limit deformation.
Innovation Solution
Incorporation of flexible force transmitting devices between the thrust reversal cowls and the engine case, which are elastically deformable to apply prestress and absorb forces, reducing flexural deformation and improving engine efficiency by distributing preload stress thermomechanically.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the fan diameter is increased to improve fuel consumption performance, then the bypass ratio is improved, but the engine flexibility increases causing flexural deformation and turbine blade tip wear
Solution Approach 1:
The patent applies preliminary anti-action by installing elastic force transmitting devices that pre-load the engine case in the opposite direction of expected flexural deformation. These devices create a counteracting force before deformation occurs, preventing the engine case from flexing excessively during operation, thereby reducing turbine blade tip wear while maintaining the large fan diameter for improved fuel consumption
2Stability of the object's composition
If rigid attachment structures are used to limit engine deformation, then engine stability is improved, but the system complexity and weight increase
Solution Approach 1:
The patent changes the mechanical parameters of the force transmitting devices by making them elastic rather than rigid. This allows the devices to provide deformation control through controlled elasticity and pre-loading, achieving engine stability without requiring complex rigid structures. The elastic devices can be adjusted by modifying material properties, geometry, or pre-load forces rather than adding structural complexity
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 flexible devices reduce turbine blade tip wear and enhance overall engine efficiency by controlling flexural deformation, maintaining engine stability and performance through partial elastic deformation and thermomechanical preload.
Implementation Method 1
each flexible device (50) comprising an elastically deformable structure or device (52) configured so that in the closed position of the thrust reversal cowl, with the engine at a standstill, it adopts a partial elastic deformation state allowing the force transmitting device to apply a prestress force to the case portion (40a)
Implementation Method 2
maintaining engine stability and performance through partial elastic deformation and thermomechanical preload
Data Source
AI summary
To reduce flexural deformations of an engine, an engine assembly comprises a device for attaching the engine onto a structure of an aircraft, the attachment device including a primary structure, an attachment device for attaching the engine onto the primary structure of the attachment pylon, and a nacelle including thrust reversal cowls, each equipped with an inner structure arranged around a case portion of the engine. The assembly includes flexible devices for transmitting forces, arranged between the case portion and the inner structures of the cowls, each device including an elastically deformable device configured so that in the closed position of the cowl, with the engine at a standstill, it adopts a partial elastic deformation state allowing the device to apply a prestress force on the case portion.