Turbine Ring Sector Cooling via Varying Perforated Sheet Gap
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Solution Overview
Problem
Conventional cooling solutions for turbine ring sectors in turbomachines result in non-uniform cooling, with the central region being better cooled than the periphery, leading to reduced efficiency and shorter lifespan due to uneven thermal stress.
Innovation Solution
A turbine ring sector design featuring a multiply-perforated metal sheet with a varying gap between the sheet and the ring wall, where the gap decreases from a maximum to a minimum and then increases again, ensuring uniform cooling by adjusting the flow of cooling gas and distributing perforations to enhance impact and convective cooling based on hot zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a constant gap is used in the multiply-perforated metal sheet, then the structure is simple, but the cooling is non-uniform with better cooling at the center than at the periphery
Solution Approach 1:
The gap between the multiply-perforated metal sheet and the ring wall is made to vary radially, being smaller at the periphery and larger at the center. This local variation in gap size allows the cooling system to adapt to different thermal conditions across the ring sector, providing adequate cooling at the periphery where heat dissipation is more challenging while maintaining structural simplicity.
2Reliability
If the gap decreases from maximum to minimum and then increases, then uniform cooling is achieved, but the device complexity increases
Solution Approach 1:
The gap parameter is varied radially across the multiply-perforated metal sheet, transitioning from a first maximum value at the periphery to a minimum value at the center and then to a second maximum value. This parameter change optimizes the cooling distribution by controlling the flow of cooling gas through the perforations, ensuring uniform temperature distribution across the ring sector while maintaining manufacturing feasibility.
3Ease of manufacture
If perforations are distributed uniformly, then manufacturing is simple, but cooling efficiency is reduced at the periphery due to shear effects
Solution Approach 1:
The perforations in the multiply-perforated metal sheet are distributed non-uniformly, with a higher density at the periphery and lower density at the center. This local variation in perforation distribution compensates for the shear effects that reduce cooling efficiency at the periphery, ensuring that cooling gas reaches the wall effectively across all radial positions while maintaining manufacturability.
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 design maintains uniform cooling efficiency across the ring sector, concentrating efficient impact cooling on hot zones and utilizing convection in other areas, thereby extending the lifespan and performance of the turbine under high-temperature conditions.
Implementation Method 1
Cooling gas passes through the metal sheet 1 via the perforations 4 in the form of a radial stream of gas, and impacts the wall 5 of the ring sector 6 in order to cool it
Implementation Method 2
The radial stream F1 of gas coming from the perforations 4C1 impacting the wall 5 is sheared by the axial stream of gas resulting from the wall 5 deflecting the radial stream F0
Data Source
AI summary
A turbine ring sector comprising a wall presenting an inside face and an outside face, in which the inside face defines an axially oriented airflow passage through which gas flows; and a multiply-perforated metal sheet situated on the side of the wall that is opposite from the airflow passage is disclosed. The multiply-perforated metal sheet has a bottom, and the space between the outside face of the wall and the bottom of the multiply-perforated metal sheet defines a gap. The variation in the value of the gap over the entire axial extent thereof decreases from a first maximum value towards a minimum value and then increases from the minimum value to a second maximum value.