Aircraft Engine Attachment Assembly Aerodynamic Integration
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Solution Overview
Problem
Large aircraft engines, such as ultra-high by-pass turbofans, face challenges in integration with aircraft wings due to aerodynamic interference and maintenance access, requiring heavy and complex pylon structures that increase weight and reduce airflow efficiency.
Innovation Solution
An aircraft propulsion system with an attachment assembly that blends aerodynamically with the wing shape, featuring a composite upper support section and movable thrust reversers, allowing for reduced pylon weight and improved engine placement, while maintaining structural integrity and access for maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the engine is positioned vertically closer to the wings to avoid increasing landing gear height, then the landing gear height is reduced, but aerodynamic interference between the engine and wing increases
Solution Approach 1:
The pylon is divided into multiple sections (upper pylon section, lower pylon section, intermediate section) with different functions. The upper section provides engine support while the lower section integrates with the wing structure, allowing optimized positioning that reduces aerodynamic interference while maintaining acceptable landing gear height
Solution Approach 2:
The engine is repositioned in the longitudinal dimension (forward spacing) to resolve the vertical proximity issue. By spacing the engine forward from the wing leading edge, the design maintains vertical closeness to the wing while eliminating aerodynamic interference in the vertical flow field
2Object-affected harmful factors
If the engine is spaced forward from the wings to lessen aerodynamic interference, then aerodynamic performance is improved, but the pylon structure becomes heavier and more complex
Solution Approach 1:
The pylon structure is designed to perform multiple functions: structural support for the engine, aerodynamic fairing to blend with wing flow, and integration with wing spars. This multi-functionality reduces the need for separate components, simplifying the overall structure while maintaining forward spacing for aerodynamic performance
Solution Approach 2:
The pylon is merged with the wing structure through integration with wing spars and blending of external surfaces. This merging eliminates the need for heavy, complex standalone pylons by making the pylon an integral part of the wing-engine assembly
3Object-affected harmful factors
If the engine is spaced forward from the wings, then aerodynamic interference is reduced, but fan duct airflow is reduced
Solution Approach 1:
The pylon surface geometry is optimized in different local regions: the upper surface blends with the wing upper surface to maintain smooth airflow over the wing, while the lower surface is shaped to minimize interference with the fan duct inlet. This local optimization allows forward spacing for aerodynamic performance while preserving fan duct airflow
4Ease of repair
If nacelle components are positioned higher to facilitate engine maintenance access, then maintenance access is improved, but the components interfere with the wing when the engine is placed closer to the wing
Solution Approach 1:
The nacelle components (thrust reversers, fan cowls) are designed with dynamic movement capability, allowing them to be positioned higher for maintenance access but repositioned or retracted during flight to clear the wing. The lower pivot axis enables the cowls to swing downward for maintenance while maintaining clearance during operation
Data Source
AI summary
An aircraft propulsion system configured to be supported from an aircraft wing having a leading edge and opposing upper and lower surfaces. The aircraft propulsion system broadly comprises an engine having a core, a fan case, and a nacelle including a plurality of access panels, and an attachment assembly for securing the engine to the aircraft wing. The attachment assembly broadly comprises an upper support section including a number of spars and a number of ribs connected between the spars, a lower support section, and an aft section. The attachment assembly aerodynamically melds the nacelle and the aircraft wing together via the upper support section so that air flowing over the engine flows over the aircraft wing along the upper surface and air flowing laterally alongside the nacelle flows under the aircraft wing along the lower surface.