Heat Shield Element Ribs for Cooling Air Distribution
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Solution Overview
Problem
The existing heat shields in gas turbines face inefficiencies in cooling air distribution due to varying gap widths and large cross-sections of fastening grooves, leading to inadequate cooling of all areas and potential damage to the supporting structure or reduced turbine efficiency.
Innovation Solution
The introduction of web-like ribs on the cold side of heat shield elements that protrude into fastening grooves, reducing the free cross-section and improving cooling air distribution, with the ribs being designed to match thermal expansion and operating temperatures, and arranged symmetrically to ensure even cooling air distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If cooling air is increased to ensure sufficient flushing of all gaps, then cooling effectiveness is improved, but gas turbine efficiency decreases
Solution Approach 1:
The patent applies local quality by varying the rib structure across different regions of the heat shield element. Ribs are positioned at specific locations (e.g., at gaps between heat shield elements) to locally enhance cooling air distribution where it is most needed, rather than uniformly increasing cooling air across the entire structure. This targeted approach improves cooling effectiveness at problem areas without requiring a proportional increase in overall cooling air consumption.
Solution Approach 2:
The patent changes geometric parameters of the heat shield element by introducing ribs with specific dimensions, positions, and configurations. These parameter changes (rib height, width, spacing, and location) modify the flow characteristics of cooling air through the fastening grooves, optimizing air distribution to achieve better cooling effectiveness while maintaining or reducing total cooling air requirements.
2Ease of manufacture
If fastening grooves are made larger to accommodate fastening means, then ease of assembly is improved, but cooling air distribution becomes insufficient
Solution Approach 1:
The patent segments the fastening groove structure by introducing ribs that divide the groove into multiple sub-channels or flow paths. This segmentation allows the groove to maintain its overall size for easy assembly while creating smaller, more numerous flow paths that improve cooling air distribution. The ribs act as internal partitions that guide and distribute cooling air more effectively throughout the groove structure.
Solution Approach 2:
The patent adds a third dimension to the fastening groove structure by introducing vertical ribs that extend into the groove depth. This dimensional addition transforms the simple groove geometry into a multi-level structure with ribs creating elevated surfaces and channels, thereby improving cooling air flow paths without increasing the horizontal footprint or compromising assembly ease.
3Stability of the object's composition
If heat shield elements are spaced apart to allow thermal expansion, then thermal stress is reduced, but gaps allow hot gas entry
Solution Approach 1:
The patent introduces ribs as intermediary structures within the gaps between heat shield elements. These ribs act as mediators that physically block hot gas flow paths while still allowing the heat shield elements to expand and contract. The ribs create tortuous flow paths that impede hot gas penetration into critical areas, thereby protecting against harmful hot gas entry while maintaining the expansion gaps necessary for thermal stress management.
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 enhances cooling effectiveness and reduces cooling air consumption by ensuring uniform air distribution across all gaps, preventing premature damage and maintaining turbine efficiency.
Implementation Method 1
cooling air is introduced via cooling air ducts in the supporting structure 26, which blocks the expansion gaps. The cooling air can be introduced, for example, below a heat shield element 28, so that the cooling air is first distributed under the heat shield element 28 and cools the supporting structure and the fastening means 40
Implementation Method 2
Because of the thermal expansion and because of the large dimensions, the heat shield must be composed of a large number of individual, generally ceramic, heat shield bricks which are spaced apart from one another and are fastened to a supporting structure by means of holding elements with a sufficient gap. This expansion gap offers the heat shield bricks, which can also be referred to as heat shield elements, sufficient space for thermal expansion
Implementation Method 3
the heat shield elements have a hot side that can be acted upon by hot gas
Implementation Method 4
heat shields are used, which have to withstand hot gases from 1000 to 1600 degrees Celsius
Data Source
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AI summary
The invention relates to a heat shield element (50) for a heat shield (24) of a combustion chamber (10), comprising a hot side (32) which can be exposed to hot gas, an opposite cold side (34), and peripheral sides (36a, 36b); the heat shield element (50) can be fastened to a support structure (26) of the heat shield (24). In order to optimize the distribution of cooling air, two bridge-shaped ribs (54) are disposed on the cold side (34) of the heat shield element (50) and are designed in such a way as to protrude into fastening grooves (44) in the support structure (26).