CMC Heat Shield Fuel Nozzle Assembly With Purge-Air Sealing
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Solution Overview
Problem
Conventional gas turbine engines with metallic heat shields in TAPS fuel nozzle/swirler assemblies face deterioration due to high temperatures, requiring frequent and costly replacements, which are cumbersome and cause engine downtime.
Innovation Solution
Implementing a ceramic matrix composite (CMC) heat shield in the TAPS fuel nozzle/swirler assembly, secured with a seal member and backplate, allowing for axial force and radial expansion, with purge orifices to prevent hot gas ingestion and facilitate easier maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metallic heat shield is used in the TAPS fuel nozzle/swirler assembly, then the assembly can be manufactured with conventional materials and processes, but the heat shield deteriorates due to high temperatures requiring frequent and costly replacements
Solution Approach 1:
The patent replaces the conventional metallic heat shield with a ceramic matrix composite (CMC) heat shield. The CMC material provides superior high-temperature resistance and durability compared to metallic materials, directly addressing the deterioration issue while maintaining compatibility with the existing TAPS fuel nozzle/swirler assembly structure.
2Ease of manufacture
If a metallic heat shield is used, then the assembly structure is simple and easy to manufacture, but replacement is cumbersome and causes engine downtime
Solution Approach 1:
The CMC heat shield is designed as a separate, modular component that can be independently replaced without disassembling the entire TAPS fuel nozzle/swirler assembly. This segmentation enables quick replacement procedures, reducing engine downtime while maintaining the overall structural simplicity of the assembly.
3Reliability
If a CMC heat shield is implemented, then durability is enhanced and maintenance frequency is reduced, but the assembly requires additional components like seal members and purge orifices
Solution Approach 1:
A seal member is introduced as an intermediary component between the CMC heat shield and the surrounding assembly structures. This seal member ensures proper sealing and integration of the CMC heat shield, allowing the durable ceramic composite to be effectively incorporated into the existing assembly without compromising the overall system integrity.
Solution Approach 2:
Purge orifices are integrated into the CMC heat shield structure to extract and remove hot gases from the combustion chamber. This extraction function prevents hot gas ingestion that could affect the fuel nozzle/swirler assembly, thereby protecting the CMC heat shield and other components while adding minimal structural complexity.
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 CMC heat shield provides enhanced durability, reducing maintenance frequency and simplifying replacement, while maintaining engine performance and reducing downtime.
Implementation Method 1
a seal member arranged within the backplate to provide an axial force, when compressed axially, against an upstream side of the CMC heat shield so as to hold the CMC heat shield axially
Implementation Method 2
allowing radial and circumferential expansion between the CMC heat shield, the metallic backplate, and the venturi
Implementation Method 3
a flow of purge air from the purge orifices to pass through the radial gap to purge any hot gases that may be ingested between the CMC heat shield, the venturi, and the backplate
Data Source
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AI summary
A fuel nozzle/swirler assembly (58) includes a venturi (108, 108a) including a heat shield retaining wall (164, 164a). A backplate (146, 146a) is connected to the venturi (108, 108a) and includes a plurality of purge orifices (186, 186a) extending through the backplate (146, 146a). A ceramic matrix composite (CMC) heat shield (148, 148a) includes a heat shield attachment wall (166, 166a) engaged between the heat shield retaining wall (164, 164a) of the venturi (108, 108a) and the backplate (146, 146a), and a seal member (176, 196, 200, 202, 204) is arranged between the backplate (146, 146a) and the CMC heat shield (148, 148a). The plurality of purge orifices (186, 186a) are arranged between the seal member (176, 196, 200, 202, 204) and the venturi (108, 108a) and provide a flow of purge air (82c) therethrough to flow through a radial gap (178). The seal member (176, 196, 200, 202, 204) provides a force against the CMC heat shield (148, 148a) to axially engage the heat shield attachment wall (166, 166a) of the CMC heat shield (148, 148a) against the heat shield retaining wall (164, 164a) of the venturi (108, 108a).