Gas Turbine Stator Blade Clocking for Axial Cavity Cooling
Solution Overview
Problem
Existing gas turbine designs face challenges in ensuring the durability of axial cavity sections and effective cooling of blades using sealing air, as the existing methods either prioritize main flow performance or component durability over axial cavity considerations, leading to inefficiencies and reduced cooling effectiveness.
Innovation Solution
The gas turbine design involves adjusting the relative positions of stator and rotor blades in the circumferential direction to guide wake flows from upstream blades to specific regions of downstream blades, ensuring effective cooling of the hub and tip regions while maintaining a smaller amount of sealing air, thereby enhancing durability and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the amount of sealing air in axial cavities is increased to prevent entry of high-temperature main-flow gas, then the reliability of axial cavity sections is improved, but the performance of the gas turbine is reduced
Solution Approach 1:
The patent applies local quality by directing sealing air specifically to the axial cavity regions where it is needed for cooling and protection, rather than uniformly distributing it throughout the system. The wake flow from upstream blades is strategically positioned to target specific downstream blade regions, providing localized cooling where thermal stress is highest while minimizing overall sealing air consumption and maintaining turbine performance.
2Temperature
If sealing air is allowed to leak into the main flow from axial cavities to cool blade surfaces, then the cooling ability of blade surfaces is improved, but the effectiveness of cooling is reduced due to dominant main-flow patterns
Solution Approach 1:
The patent introduces asymmetry in the blade arrangement by setting specific blade count differences between stator and rotor blades (1-4 blades). This asymmetric configuration creates non-uniform wake flow patterns that strategically direct cooler sealing air toward specific high-temperature regions on blade surfaces, overcoming the dominant main-flow patterns and improving cooling effectiveness in critical areas.
3Stability of the object's composition
If the blade-count difference between stator and rotor blades is small (1-4 blades), then the pressure and temperature distribution uniformity is improved, but the risk of main-flow gas entering axial cavities is increased
Solution Approach 1:
The patent utilizes periodic action by creating pressure and temperature distributions that vary in a predictable periodic pattern around the circumference, with blade-count differences of 1-4 blades. This periodic variation, when combined with proper clocking arrangement, creates regions where low pressure on the axial-cavity side and high pressure on the main-flow side are aligned, preventing main-flow gas entry while maintaining overall distribution uniformity.
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 effectively cools the hub and tip regions of downstream blades, improving durability and reducing pressure and temperature variations, thus enhancing the overall performance and reliability of the gas turbine without compromising efficiency.
Implementation Method 1
a relative position between the n-th stage stator blade and the (n+1)-th stage stator blade is set such that a wake flow produced by the stator-blade segments of the n-th stage stator blade is guided to a ±1/4 pitch region in the circumferential direction with respect to a leading edge of each stator-blade segment of the (n+1)-th stage stator blade
Data Source
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AI summary
A gas turbine that can effectively cool an axial cavity between a stator blade and a rotor blade and a blade-end surface is provided. In a gas turbine in which a blade-count difference between stator-blade segments (17) of a second-stage stator blade and a third-stage stator blade is set to zero, a relative position between the second-stage stator blade and the third-stage stator blade in the circumferential direction is set by clocking so that a wake flow produced by the stator-blade segments of the second-stage stator blade is guided to the leading edges of the stator-blade segments (17) of the third-stage stator blade within a range of 0% to 15% of the length in a span direction from a hub side of the stator-blade segments (17) of the third-stage stator blade.