Turbine Vane Support Heat Shield for Flange Thermal Gradient Reduction
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Solution Overview
Problem
Gas turbine engines face low cycle fatigue due to significant temperature gradients across flanges, particularly where fasteners are located, leading to reduced lifetime of diffuser and turbine cases.
Innovation Solution
A turbine vane support with a heat shield and radially outward projecting tab provides thermal protection by forming a radial interference fit with the turbine case, redirecting combustion airflow and increasing radial clearance, while anti-rotation features prevent excessive vane rotation and enhance coupling with a combustor lock.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a flange is used to couple the diffuser case and turbine case, then the structural connection is achieved, but a temperature gradient is created leading to low cycle fatigue
Solution Approach 1:
A thermal barrier material is introduced as an intermediary layer between the hot turbine case and the cooler diffuser case flange. This mediator reduces direct thermal conduction across the flange, thereby minimizing the temperature gradient and associated thermal stresses that cause low cycle fatigue, while still allowing mechanical coupling to occur.
Solution Approach 2:
The thermal barrier is applied locally at the flange region where the temperature gradient is most severe, rather than throughout the entire engine structure. This localized approach addresses the specific problem area (the flange connection) without requiring modification of the entire diffuser or turbine case, reducing the temperature differential precisely where it causes the most damage.
2Volume of moving object
If the turbine vane support is positioned close to the flange, then space is optimized, but thermal protection of the flange is reduced
Solution Approach 1:
The thermal barrier material serves as a mediating layer between the turbine vane support and the flange, allowing the vane support to remain in its space-optimized position while still protecting the flange from excessive thermal exposure. The intermediary absorbs and redirects heat away from the flange region.
Solution Approach 2:
The harmful thermal effect is extracted or isolated from the flange region by introducing the thermal barrier, which captures and contains the heat near the turbine vane support while preventing its transmission to the flange. This allows space optimization to be maintained without compromising thermal protection.
3Manufacturing precision
If radial interference fit is used to couple components, then assembly precision is improved, but thermal stress concentration increases
Solution Approach 1:
The thermal barrier acts as an intermediary layer at the radial interference fit interface, allowing precise mechanical coupling to be maintained while interrupting the path of thermal stress. The barrier material accommodates thermal expansion differences between components, preventing stress concentration despite the tight interference fit.
Solution Approach 2:
The interference fit interface becomes a composite structure combining the metallic components with the thermal barrier material. This composite approach maintains the mechanical precision of the interference fit while the dissimilar material properties of the thermal barrier reduce thermal stress transmission across the interface.
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 solution extends the lifetime of engine cases by reducing thermal gradients and providing enhanced thermal protection through airflow redirection and increased radial clearance, thereby mitigating thermally driven stress.
Implementation Method 1
the turbine vane support includes a radially outward projecting tab that couples to the turbine case via a radial interference fit
Implementation Method 2
the diffuser case includes a curved ramp to encourage a combustion airflow to flow over the turbine vane support and away from the extension portion
Implementation Method 3
a portion of the turbine vane support serves as a heat shield for the flange
Data Source
AI summary
Aspects of the disclosure are directed to a system for an engine having an axial centerline, comprising: a diffuser case, a turbine case, and a turbine vane support, where the diffuser case and the turbine case are coupled to one another via a substantially radially oriented flange, where the turbine vane support includes a heat shield for the flange, and where the turbine vane support includes a radially outward projecting tab that couples to the turbine case via a radial interference fit.