Ceramic Vane Airfoil Load Transfer via Bias Member
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Solution Overview
Problem
The challenge in designing airfoil assemblies for gas turbine engines lies in transferring loads from ceramic matrix composite vanes to metallic support spars, which face difficulties due to differences in thermal expansion coefficients and structural strength, making it hard to maintain engagement and prevent damage from hot gases.
Innovation Solution
The airfoil assembly incorporates a ceramic matrix composite vane with a metallic support spar and a bias member that urges the vane and spar toward each other, using load-transfer tabs and clips to ensure engagement and secure the bias member in place, allowing for effective load transfer and maintaining orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If ceramic matrix composite materials are used for vanes to withstand high temperatures, then temperature resistance is improved, but load transfer to metallic support spars becomes difficult due to differences in thermal expansion coefficients and structural strength
Solution Approach 1:
The patent introduces a bias member as an intermediary element between the ceramic matrix composite vane and the metallic support spar. This bias member mediates the load transfer by applying a biasing force that maintains engagement between the vane and spar, compensating for the mismatch in thermal expansion coefficients and structural properties between the ceramic and metallic materials.
Solution Approach 2:
The patent changes the physical state and engagement parameters of the vane-spar interface by introducing a biasing force. The bias member modifies the contact pressure and engagement conditions between the ceramic vane and metallic spar, allowing reliable load transfer despite the fundamentally different material properties of ceramics and metals.
2Temperature
If ceramic matrix composite materials are used for vanes, then high-temperature capability is improved, but maintaining engagement with metallic support spars at cold conditions becomes difficult
Solution Approach 1:
The bias member applies a preliminary biasing force that pre-loads the engagement interface between the ceramic vane and metallic spar. This preliminary action ensures that the components remain engaged at cold conditions before thermal expansion occurs, preventing separation or misalignment when the engine reaches operating temperature.
Solution Approach 2:
The biasing force changes the engagement parameters by maintaining constant contact pressure between the vane and spar across the temperature range. This parameter modification ensures stable engagement at cold conditions while accommodating thermal expansion at high temperatures.
3Strength
If load-transfer features are designed to transfer loads from ceramic vanes to metallic spars, then load transfer capability is improved, but the complexity of the assembly increases
Solution Approach 1:
The bias member serves as a simple intermediary element that enables load transfer without requiring complex mechanical interfaces. Instead of designing complex load-transfer features directly between the ceramic vane and metallic spar, the bias member mediates the interaction, simplifying the overall assembly while maintaining load transfer capability.
Solution Approach 2:
The patent changes the approach to load transfer by using a biasing force to maintain engagement, rather than relying solely on complex mechanical load-transfer features. This parameter change from mechanical interlocking to force-based engagement reduces assembly complexity while preserving load transfer capability.
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 configuration ensures reliable load transfer from the ceramic matrix composite vane to the metallic support spar, maintaining engagement even at cold conditions and preventing damage from hot gases, thereby enhancing the structural integrity and efficiency of the airfoil assembly.
Implementation Method 1
a bias member that urges the vane and spar toward each other
Data Source
AI summary
An airfoil assembly includes a vane that includes an outer platform, an inner platform, and an airfoil. The outer platform defines an outer boundary of a gas path. The inner platform is spaced apart axially from the outer platform relative to an axis and defines an inner boundary of the gas path. The airfoil extends axially between and interconnects the outer platform and the inner platform.