Gas Turbine Ring Segment Cooling System
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Solution Overview
Problem
Conventional ring segment cooling systems in gas turbines face issues with thermal damage due to high temperature combustion gas and inefficiencies in cooling air distribution, leading to reduced thermal efficiency and increased cooling air usage.
Innovation Solution
A ring segment cooling system with a first cavity at the upstream end and a second cooling passage that communicates from the first cavity to the combustion gas space, enhancing convection cooling and minimizing cooling air loss, while maintaining a compact design with elongated cooling passages and optimized passage arrangements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is discharged from the upstream end portion of the ring segment to the combustion gas space, then the upstream end portion is cooled, but the cooling air is lost and thermal efficiency decreases
Solution Approach 1:
Instead of discharging cooling air from the upstream end portion to the combustion gas space, the invention discharges the cooling air from the downstream end portion. This inversion of the discharge location prevents the loss of cooling air to the combustion gas space while still achieving effective cooling of the upstream end portion through the elongated cooling passage that extends along the inner circumferential surface.
2Reliability
If cooling passages are extended to cool the upstream end portion, then thermal damage is prevented, but the amount of cooling air required increases
Solution Approach 1:
The cooling passage is extended in the axial direction along the inner circumferential surface of the ring segment, utilizing the third dimension (axial length) to achieve effective cooling of the upstream end portion. This dimensional extension allows the cooling air to travel further and cool previously unprotected areas without requiring a proportional increase in cooling air quantity, as the elongated passage efficiently utilizes the cooling air flow path.
3Productivity
If multiple cooling passages are arranged to enhance cooling coverage, then cooling efficiency improves, but device complexity increases
Solution Approach 1:
The cooling passage is divided into two distinct segments: a first cooling passage that extends from the cooling space to the downstream end portion, and a second cooling passage that extends from the cooling space along the inner circumferential surface to the upstream end portion. This segmentation allows each passage to be optimized for its specific cooling zone, improving overall cooling efficiency while maintaining manageable structural complexity through functional division.
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 effectively prevents thermal damage and improves cooling efficiency, reducing the amount of cooling air required, thereby enhancing the reliability and operational efficiency of the gas turbine.
Implementation Method 1
The cooling air CA jets into the space enclosed by the collision plate 64 and the segment body 61, through the small holes 65 opened in the collision plate 64, and carries out impingement cooling of the outer circumferential surface of the segment body 61
Implementation Method 2
when the cooling air CA after the impingement cooling jets into the combustion gas space from the downstream end of the segment body 61 in the flow direction of the combustion gas via the cooling passage 63, convection cooling of the segment body 61 is carried out by the cooling air CA that flows through the cooling passage 63
Data Source
Figure 1
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AI summary
A ring segment (10;40;50;60) with a cooling system that is formed from a plurality of segment bodies (11;41;51;61) that are to be arranged in a casing of a gas turbine in the circumferential direction of a rotating shaft (5) of the gas turbine (1) to form a ring shape, the ring segment (10;40;50;60) comprising a cooling space which is formed in each of the plurality of segment bodies (11;41;51;61), that is in contact with an outer circumferential surface of a main body (12;42) of the segment body (11;41;51;61), a first cavity (20;43) that is arranged at an upstream end portion (16) of the segment body (11;41;51;61) in the axial direction of a rotating shaft (5) so as to be perpendicular to the axial direction of the rotating shaft (5), a plurality of first cooling passages (21;44) that communicate from the cooling space (29) to the first cavity (20;43), and a plurality of second cooling passages (22;45) that are provided along the inner circumferential surface (11a) of the segment body (11;41;51;61) and communicate from the first cavity (20;43) to a combustion gas space (W) at a downstream end portion (17) of the segment body (11;41;51;61) in the axial direction of the rotating shaft (5).