Turbofan Mounting Pylons Reducing Structural Complexity
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Solution Overview
Problem
The existing mounting pylons for turbofans under aircraft wings are complex to design and embody due to the need to absorb various directional forces, leading to high bending moments and torsional loads, which complicates the structure.
Innovation Solution
A simplified propulsion assembly design featuring a mounting pylon with a rigid structure that includes forward and aft engine attachments and a thrust force absorption device with hinged links, allowing for the absorption of vertical and transverse forces, reducing the complexity of the rigid structure by eliminating the need for combined bending moment absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the forward engine attachment absorbs forces in multiple directions (Y and Z), then the turbofan can be securely mounted, but the rigid structure becomes complex with high bending moments and torsional loads
Solution Approach 1:
The patent divides the force absorption function into separate components: the forward engine attachment handles only vertical forces (Z direction), while transverse forces (Y direction) and thrust forces are handled by dedicated absorption devices with links and struts. This segmentation allows each component to be optimized for its specific function, reducing the complexity of the rigid structure.
Solution Approach 2:
The patent extracts the force absorption functions from the forward engine attachment and places them in separate dedicated devices. The forward engine attachment is left with only the essential suspension function, while transverse force absorption and thrust force absorption are performed by separate mechanisms with links, struts, and absorption devices positioned at the aft part of the rigid structure.
2Stability of the object's composition
If the forward engine attachment absorbs transverse forces, then the turbofan is stable, but high bending moments and torsional moments require a complex closed box structure
Solution Approach 1:
The patent extracts the transverse force absorption function from the forward engine attachment and implements it through a separate absorption device with links and struts at the aft part of the rigid structure. This allows the forward engine attachment to use a simpler structure without requiring the complex closed box design with transverse ribs.
Solution Approach 2:
The patent introduces intermediate components (links and struts forming absorption devices) between the turbofan and the rigid structure to handle transverse forces. These intermediary elements absorb transverse forces and thrust forces before they reach the rigid structure, allowing the rigid structure to be simpler while maintaining stability.
3Strength
If multiple force absorption functions are integrated into the forward engine attachment, then the mounting is robust, but the structure becomes difficult to design and embody
Solution Approach 1:
The patent segments the mounting system into functionally distinct components: the forward engine attachment for suspension, transverse force absorption devices with links for lateral stability, and thrust force absorption devices with struts for longitudinal forces. Each segment is designed and manufactured independently, reducing overall complexity while maintaining robustness.
Solution Approach 2:
The patent extracts specific force absorption functions from the forward engine attachment and implements them in separate dedicated devices positioned at the aft part of the rigid structure. This separation simplifies the forward engine attachment while maintaining robust mounting through the combined action of all components.
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 design simplifies the structure of the mounting pylon by allowing only vertical suspension forces to be applied at the forward engine attachment, reducing the complexity of the rigid structure and enabling a more straightforward stress transfer to the wing, thereby simplifying the overall design.
Implementation Method 1
two links placed either side of a median plane and hinged, on one hand, forward, on a forward part of the central casing, and on the other, aft, directly on the rigid structure, enabling absorption of bending moments (Mz) around a vertical direction Z
Data Source
AI summary
A propulsion assembly includes a turbojet incorporating a fan casing and a central casing around a longitudinal axis, a mounting pylon having a rigid structure, a forward engine attachment interposed between a forward extremity of the rigid structure and an upper part of the fan casing, the upper part being in a vertical median plane (P) passing through the longitudinal axis, an aft engine attachment interposed between a median zone of the rigid structure and an upper aft part of the central casing, and a device for absorbing the thrust forces generated by the turbojet, including two links placed either side of the median plane (P) and hinged, on one hand, forward, on a forward part of the central casing, and on the other, aft, directly on the rigid structure. Such an arrangement enables a reduction of the stresses, and the possibility of designing a simplified rigid structure.