Gas Turbine Combustor Dual-Wall Casing Cooling Film Barrier
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In gas turbine engines, the combustor casing walls face extreme temperatures due to the combustion process, leading to potential damage and reduced operational life, especially where obstacles like fasteners or dilution holes interrupt the cooling air flow, limiting the effectiveness of traditional dual-wall cooling structures.
Innovation Solution
A dual-wall component design with a primary inlet and array of effusion holes is implemented, where the primary inlet has a larger flow area than the combined inlet areas of the effusion holes, and secondary inlet holes are used to create a pressure drop, preventing flow reversal and ensuring a continuous cooling film barrier across the inner and outer walls, even in regions with obstacles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional dual-wall cooling structures are used with standard effusion hole arrays, then cooling protection is provided in most regions, but cooling effectiveness is reduced in regions with obstacles like fasteners or dilution holes that interrupt the effusion hole array
Solution Approach 1:
The invention introduces a primary inlet positioned upstream of obstacle regions to pre-establish cooling airflow before the obstacles interrupt the effusion hole array. This preliminary action ensures that cooling air is already present and properly directed in regions where obstacles would otherwise create gaps in the cooling protection, maintaining continuous thermal barrier coverage throughout the combustor casing.
2Quantity of substance
If effusion holes are arranged in standard arrays, then cooling coverage is achieved in open regions, but flow reversal can occur in regions with obstacles that block or interrupt the cooling air flow path
Solution Approach 1:
The invention introduces secondary inlet holes positioned downstream of obstacle regions to act as intermediary flow regulators. These secondary inlets provide additional cooling air supply that compensates for flow disruptions caused by obstacles, preventing flow reversal by maintaining positive pressure gradient and ensuring unidirectional cooling airflow through the effusion hole arrays even in regions with fasteners or dilution holes.
3Quantity of substance
If the inlet area is made larger to provide sufficient cooling air, then cooling airflow is improved, but the pressure drop across the inlet increases
Solution Approach 1:
The invention divides the cooling air supply system into multiple segments: a primary inlet for the main cooling air supply and multiple secondary inlet holes distributed downstream. This segmentation allows the total cooling air flow requirement to be distributed across multiple smaller inlets rather than requiring one large inlet, thereby reducing the pressure drop associated with each individual inlet while maintaining adequate cooling air flow rate through the effusion holes.
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 effectively protects the combustor casing from high thermal profiles by maintaining a continuous cooling film, enhancing the mechanical properties and operational life of the component by ensuring efficient coolant distribution and preventing flow reversal.
Implementation Method 1
provide a substantially continuous boundary layer of cooling air along the inner wall surface, protecting the component from the extremely hot combustion product generated in the combustion chamber
Implementation Method 2
cooling air is directed through holes in the outer wall into a channel defined between them
Implementation Method 3
secondary inlet holes are used to create a pressure drop, preventing flow reversal
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
In an embodiment of the invention, a dual-wall casing (50) for a combustor comprises an outer wall (50a) and an inner wall (50b) defining a channel (56) therebetween. The walls (50a, 50b) are fastened together by a bolt (52) which extends from the inner wall (50b) and across the channel (56). In use, the inner wall (50b) is exposed to combustion products. Cooling is provided by a primary inlet hole (54) extending through the outer wall (50a) and arranged upstream (with respect to the direction of flow of coolant in the channel) of the bolt (52) and an array of effusion holes (55) extending through the inner wall (50b) and positioned with their inlet in line of sight of the primary inlet hole (54). The primary inlet hole (54) is sized with respect to the array of effusion holes (55) such that it has a flow area which causes locally negligible flow restriction.