Sheet Metal Combustor Heat Shield with Brazed Cold Side Details
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Solution Overview
Problem
The high manufacturing costs of combustor heat shields due to expensive casting processes and the need for pack coating, as well as the complexity of drilling effusion holes without damaging studs and rails in one-piece castings, necessitate an alternative construction method.
Innovation Solution
A sheet metal-based combustor heat shield assembly is fabricated by forming a base sheet with opposed hot and cold facing sides, where cold side details such as rails and studs are separately formed and joined to the base sheet, allowing for different gauges and materials to be used, and brazing or welding to create a cost-effective and efficient assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a one-piece casting process is used for the heat shield, then the structural integrity and thermal resistance are improved, but the manufacturing cost increases and the drilling process becomes more complex
Solution Approach 1:
The heat shield is divided into multiple separate components: a base sheet and cold side details (rails, studs). These components are manufactured separately and then joined together through brazing or welding, eliminating the need for expensive one-piece casting while maintaining structural integrity.
Solution Approach 2:
Separately manufactured components (base sheet, rails, studs) are joined together through brazing or welding processes to create an integrated assembly that functions as a unified heat shield structure, achieving both cost efficiency and structural reliability.
2Reliability
If pack coating is applied to casting materials for oxidation resistance, then the corrosion resistance is improved, but the manufacturing cost increases
Solution Approach 1:
The material selection parameters are changed from expensive casting materials requiring pack coating to cost-effective sheet metal materials that inherently provide sufficient oxidation resistance for the application, eliminating the need for additional protective coatings.
3Productivity
If effusion holes are drilled into one-piece heat shields with rails and studs, then the cooling function is achieved, but the risk of damaging rails and studs increases
Solution Approach 1:
By separating the heat shield into a base sheet and cold side details, the drilling operation can be performed on the base sheet alone without the presence of rails and studs, eliminating the risk of damaging these components during drilling while still achieving the required cooling function through 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 method reduces manufacturing costs and simplifies the drilling process by allowing for separate formation and mounting of components, enhancing the assembly's thermal and structural integrity while maintaining high temperature resistance.
Implementation Method 1
separate sheet metal rails brazed or welded to the cold facing side of the sheet metal base
Implementation Method 2
separate sheet metal rails brazed or welded to the cold facing side of the sheet metal base
Data Source
AI summary
A multi-pieces gas turbine engine combustor heat shield is fabricated from sheet metal. The fabrication involves: sheet metal forming a base sheet having opposed hot and cold facing sides, providing cold side details separately from the base sheet, and mounting the cold side details to the cold facing side of the base sheet. The cold side details may be brazed to the base sheet.