Angled Forward Shaft Turbine Disk Thermal Mismatch
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Solution Overview
Problem
The thermal mismatch between the forward outer seal and the first stage disk in gas turbine engines leads to thermally-induced loads, resulting in low cycle fatigue life predictions due to their differing thermal response rates.
Innovation Solution
The position where the first stage forward shaft intersects the first stage HPT disk is altered to optimize the thermal response rate, and the forward shaft is angled to expose the disk to hotter air, reducing the thermal mismatch between the disk and the forward outer seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the forward outer seal is made thin with low mass to respond quickly to temperature increase, then the thermal response rate of the seal is improved, but the thermal mismatch between the seal and the disk increases
Solution Approach 1:
The patent changes the physical parameters of the forward outer seal by introducing axial slots that reduce its axial thickness in specific regions. This parameter change allows the seal to have reduced mass and improved thermal response rate while maintaining structural integrity through the slot geometry, thereby reducing thermal mismatch with the disk.
2Stability of the object's composition
If the forward outer seal is restrained from growing at a high rate, then the mechanical coupling between seal and disk is maintained, but large thermally-induced loads are generated on both components
Solution Approach 1:
The patent modifies the thermal and mechanical parameters of the forward outer seal by creating axial slots that reduce axial thickness. This allows the seal to expand thermally with reduced constraint, lowering thermally-induced loads while maintaining adequate mechanical coupling through the remaining seal structure and interface design.
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 approach reduces thermal loading on both the forward outer seal and the disk, extending their life by matching their thermal expansion rates and enhancing heat transfer to the disk.
Implementation Method 1
the forward shaft is angled to expose the first stage HPT disk to hotter air, thereby reducing the thermal mismatch between the first stage HPT disk and the forward outer seal
Implementation Method 2
the forward outer seal, which is very thin with a low mass, responds very quickly to an increase in air temperature... the first stage disk, being much more massive, responds very slowly. Thus, the forward outer seal attempts to grow out at a relatively high rate in correlation with the increase in temperature
Data Source
AI summary
A gas turbine section of a gas turbine engine, including a first stage turbine disk, a forward outer seal carried on the turbine disk and a forward shaft cooperating with the first stage turbine disk for transmitting torque generated by the turbine section to a compressor section of the engine. The forward shaft intersects the first stage turbine disk at a non-perpendicular angle in the area of the disk hub for directing sufficient hot air against the disk hub to balance the thermal response rate of the disk hub to the thermal expansion rate of the forward outer seal.