2.5 Bleed Duct Core Case Section for Gas Turbine Engine
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Solution Overview
Problem
Existing gas turbine engines face complexity in directing bleed flow into a secondary air flow, making it more challenging than dumping the bleed flow overboard, particularly during off-design conditions.
Innovation Solution
Integration of a 2.5 bleed duct structure into the structural wall of the core case section, which allows for the selective exit of compressed airflow into the bypass flow stream through a bleed valve, facilitating easier maintenance and optimal positioning between fan blades and exit guide vanes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bleed valves are incorporated in the engine casing to rematch compressor stages during off-design conditions, then compressor stage matching is improved, but the complexity of directing bleed flow into secondary air flow increases
Solution Approach 1:
The patent merges the bleed flow path with the existing secondary air flow path by directing bleed flow from the compressor stages directly into the secondary air flow that is already being extracted from the compressor. This integration eliminates the need for separate complex flow management systems while achieving the required compressor stage matching during off-design conditions.
Solution Approach 2:
The secondary air flow system is designed to serve multiple functions: it provides both the secondary air required for combustion and serves as the receptacle for bleed flow during off-design conditions. This multi-functionality reduces the need for separate dedicated bleed flow management systems, thereby reducing overall device complexity while maintaining reliable compressor stage matching.
2Ease of repair
If bleed ducts are integrated into the core case section structural wall, then maintenance accessibility is improved, but the structural design complexity increases
Solution Approach 1:
The core case section structural wall is segmented to incorporate the bleed duct as a distinct integrated component rather than a separate attachment. This segmentation allows the duct to be built into the structural wall during manufacturing while maintaining access points for maintenance, balancing structural integrity with ease of repair.
Solution Approach 2:
The bleed duct is nested within the core case section structural wall, with the duct path integrated through the structural thickness. This nesting approach allows the duct to be contained within the existing structural envelope while providing access points on the outer surface for maintenance operations, reducing the need for additional external structures.
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
Simplifies the bleed flow handling process by enabling efficient direction of airflow into the bypass stream, improving engine performance and maintenance accessibility during off-design conditions.
Implementation Method 1
air is directed through multiple stage compressors. As the air passes through each successive compressor stage, the pressure of the air is increased
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A core case section (48C) for a gas turbine engine (10) comprises a multitude of discreet radial extending 2.5 bleed ducts (66) defined in part by a structural wall (64) of the case section (48C).