Composite Vane Dovetail Mounting with Bias Preload
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Solution Overview
Problem
Existing mounting systems for composite airfoils in gas turbine engine fan frames lack robustness and longevity, hindering the integration of composite materials for weight reduction and fuel efficiency in aircraft engines.
Innovation Solution
A dovetail mounting system with biasing means, such as jack screws or axially curved flat springs, is used to securely attach composite airfoils to the fan frame, featuring dovetail feet and roots with crush faces that preload against the slot faces, enhancing the structural integrity and durability of the airfoils and fan frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If composite materials are used for outlet guide vanes to reduce weight, then fuel efficiency improves, but mounting robustness and longevity deteriorate
Solution Approach 1:
The mounting system is divided into separate functional components: a mounting bracket attached to the fan frame, and a dovetail foot attached to the composite vane. This segmentation allows each component to be optimized independently - the bracket provides robust mounting while the dovetail foot provides secure attachment to the composite airfoil, resolving the contradiction between weight reduction and mounting robustness.
Solution Approach 2:
The dovetail foot acts as an intermediary element between the composite vane and the mounting bracket. It features a dovetail shape that engages with a corresponding slot in the bracket, creating a robust mechanical connection that transfers loads effectively while maintaining the lightweight composite construction of the vane itself.
2Reliability
If dovetail mounting system with biasing means is implemented, then mounting robustness improves, but device complexity increases
Solution Approach 1:
The biasing means (spring or adjustable mechanism) is pre-configured in the mounting bracket to apply continuous axial load on the dovetail foot. This preliminary action ensures that the dovetail engagement remains tight and robust under operational conditions without requiring complex adjustment mechanisms during operation, thus improving reliability while limiting complexity increase.
Solution Approach 2:
The biasing means allows for adjustment of the axial load parameter applied to the dovetail foot. By changing this mechanical parameter, the system can optimize the engagement force to achieve robust mounting while keeping the overall structure relatively simple, avoiding the need for multiple complex 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
The proposed mounting system securely attaches composite airfoils, enhancing their life and the structural stiffness of the fan frame, thereby contributing to a more fuel-efficient engine by reducing weight and improving durability.
Implementation Method 1
each of the forward and aft dovetail feet includes a shank connecting a dovetail root to the airfoil base... a biasing means for urging the root bottom of the dovetail roots of the forward and aft dovetail feet, respectively away from the slot bottom along the dovetail slot and pressing and preloading the flat dovetail root pressure and suction side crush faces of the dovetail roots against the slot pressure and suction side slot crush faces
Data Source
AI summary
A vane includes a composite airfoil having chordwise spaced apart forward and aft dovetail feet at or near leading and trailing edges of the airfoil. Each foot includes a shank connecting a dovetail root to an airfoil base and each root is slidably received in a dovetail slot in an inner vane mount. The dovetail slot has a triangular slot cross section and a flat slot bottom and flat slot pressure and suction side crush faces corresponding to pressure and suction sides of the airfoil. The dovetail root having a triangular root cross section and a flat root bottom and flat dovetail root pressure and suction side crush faces. A biasing means urges the root bottom of the dovetail roots away from the slot bottom and presses and preloads the dovetail root pressure and suction side crush faces against the slot pressure and suction side slot crush faces.