CMC Stepped Combustor Liner for Thermal Stress Management
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Solution Overview
Problem
Ceramic matrix composite (CMC) combustor liners face high thermal gradient stresses, limiting their component life due to inability to tolerate similar levels of thermal strain and gradient as other materials.
Innovation Solution
A combustor liner design featuring a stepped arrangement with axially longer panels and controlled cooling flow slots, formed as a unitary ceramic component, to manage thermal stresses and enhance cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If CMC materials are used for combustor liners to withstand high thermal loads, then temperature capability is improved, but tolerance to thermal gradient and strain deteriorates
Solution Approach 1:
The combustor liner is divided into multiple segments separated by circumferential slots. This segmentation allows each segment to expand and contract independently in response to thermal gradients, reducing the overall thermal stress on the CMC material while maintaining the ability to withstand high temperatures.
Solution Approach 2:
The liner design incorporates varying wall thicknesses and localized cooling slots at specific positions to create non-uniform thermal management. Thinner sections and strategically placed slots allow for controlled heat dissipation in high-stress areas, while maintaining thicker sections in lower-stress zones, thereby optimizing thermal gradient tolerance throughout the component.
2Device complexity
If traditional combustor liner designs are used, then structural simplicity is maintained, but thermal stress management capability deteriorates
Solution Approach 1:
The liner is segmented into multiple sections with circumferential slots, creating a more complex structure that enables superior thermal stress management through independent segment expansion and contraction, directly addressing the trade-off between structural simplicity and thermal stress management capability.
Solution Approach 2:
The design introduces circumferential slots that create a third dimension of thermal management beyond traditional axial and radial approaches. These slots enable multi-directional heat dissipation and stress distribution, adding dimensional complexity to the structure to achieve enhanced thermal stress management.
3Weight of stationary object
If CMC materials are used to reduce weight, then weight is reduced, but tolerance to thermal cycling deteriorates
Solution Approach 1:
By segmenting the CMC liner into multiple sections separated by slots, the design allows each segment to undergo thermal cycling independently with reduced stress accumulation. This segmentation approach extends the service life of the lightweight CMC material by preventing the propagation of thermal shock through the entire component.
Solution Approach 2:
The circumferential slots act as pre-designed stress relief features that cushion against thermal cycling effects before they can cause damage. These slots are built into the structure beforehand to absorb and distribute thermal shock, protecting the lightweight CMC material from cumulative damage during thermal cycling operations.
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 design reduces thermal stresses and heat load on CMC liners, extending their lifespan and reducing part count and weight, while maintaining high-temperature capabilities.
Implementation Method 1
controlled cooling flow slots
Implementation Method 2
manage thermal stresses
Data Source
AI summary
In one exemplary embodiment, a combustor liner includes a first portion extending in a substantially axial direction and a second portion that extending in the substantially axial direction. A step connects the first portion and the second portion. The step is arranged at an angle to the second portion that is less than 90°. The step has a step height defined as a distance between the first portion and the second portion. The first portion, second portion, and step are formed as a unitary ceramic component. A slot extends through the step, and a ratio of a height of the slot to a height of the step is greater than 0.66.