Turbine Upstream Tangential Onboard Injector Flow Control
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Solution Overview
Problem
In gas turbine engines, the mixing of leakage flow and primary flow due to forward-facing tangential onboard injectors (TOBIs) located aft of the rotor disc results in unidirectional mixing losses, as the leakage flow is swirled in the same direction as the rotor, while the primary flow is swirled in the opposite direction, leading to turbulent mixing and increased energy losses.
Innovation Solution
The implementation of a secondary tangential onboard injector positioned between the stator and rotating sections to reorient the leakage flow, aligning it with the primary flow direction, and the use of restrictive seals to minimize leakage and regulate flow, thereby controlling the mixing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a forward-facing TOBI is used to direct cooling air toward the rotating disc, then cooling effectiveness is improved, but mixing losses increase due to unidirectional swirl in opposite directions
Solution Approach 1:
The patent introduces a secondary TOBI that inverts the swirl direction of the leakage flow. Instead of allowing the leakage flow to swirl in the same direction as the rotor (causing opposite-direction mixing with the primary flow), the secondary TOBI swirles it in the opposite direction, making it align with the primary flow direction and eliminating the harmful mixing losses.
Solution Approach 2:
The secondary TOBI acts as an intermediary device between the leakage flow and the primary gaspath flow. It modifies the leakage flow's tangential velocity vector to mediate the interaction between the two flows, transforming the harmful opposite-direction mixing into beneficial aligned-flow mixing.
2Productivity
If the TOBI is positioned forward of the rotating disc, then cooling air delivery is improved, but flow direction control becomes challenging
Solution Approach 1:
The patent divides the TOBI function into two separate devices: a primary TOBI for delivering cooling air to the rotating disc, and a secondary TOBI for controlling the flow direction of leakage air. This segmentation allows each device to be optimized for its specific function, simplifying the overall flow direction control while maintaining effective cooling air delivery.
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 reduces airflow losses by ensuring that both flows are swirling in the same direction at the inner diameter of the gaspath, minimizing turbulent mixing and enhancing the overall efficiency of the turbine section.
Implementation Method 1
The second wall may be fixed to the first wall by a fixed airfoil meant to turn the leakage air in the flow direction of the gaspath flow.
Implementation Method 2
a rotating seal positioned between the stator section and the rotating section along the flow path of the leakage flow
Implementation Method 3
a restrictive flow seal positioned downstream from the secondary TOBI along the flow path of the leakage flow
Implementation Method 4
The TOBI is configured to swirl secondary flow cooling air in a direction that is parallel to or along a direction of rotation of the rotating disc.
Data Source
Figure 1A
Figure 1B
Figure 2A~2B
AI summary
Gas turbine engines and turbines thereof including a stator section (301; 401; 501) having a plurality of vanes (302a; 402a; 502a), a rotating section (303; 403; 503) having a plurality of blades (302b; 402b; 502b), the rotating section (303; 403; 503) being axially adjacent the stator section (301; 401; 501) along an axis of the turbine, the stator section being aftward of the rotating section (303; 403; 503) along the axis of the turbine, and a primary tangential onboard injector (328; 428; 528) located radially inward from the stator section (301; 401; 501) and configured to direct an airflow (310; 410; 510) from the stator section (301; 401; 501) in a forward direction toward the rotating section (303; 403; 503), the primary tangential onboard injector (328; 428; 528) turning the airflow in a direction of rotation (DR) of the rotating section (303; 403; 503).