Staged Heat Exchangers for Multi-Bypass Gas Turbine Cooling
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Solution Overview
Problem
In high-speed military gas turbine engines with multiple bypass flows, the limited 'face' area of bypass ducts restricts the effectiveness of heat exchangers in cooling both electrical components and providing air for propulsion, as well as cooling engine components efficiently.
Innovation Solution
A staged heat exchanger arrangement is implemented within the bypass ducts, where a first heat exchanger is positioned upstream in the outer bypass duct, a second heat exchanger is placed upstream in the inner bypass duct, and a downstream heat exchanger directs air from the inner bypass duct into the outer bypass duct, increasing the cooled area and facilitating airflow across heat exchangers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple bypass ducts are used to provide propulsion, then propulsion capability is improved, but the face area available for heat exchanger cooling is limited
Solution Approach 1:
The patent implements nested heat exchangers where one heat exchanger is positioned within another heat exchanger's flow path. Specifically, a first heat exchanger is placed in the outer bypass duct, and a second heat exchanger is placed in the inner bypass duct such that cooled air from the second heat exchanger flows through the first heat exchanger. This nesting arrangement allows both heat exchangers to utilize the same bypass duct space efficiently, maximizing cooling capacity without requiring additional face area.
Solution Approach 2:
The patent utilizes the third dimension (depth/length of the duct) to accommodate multiple heat exchangers. By positioning heat exchangers at different longitudinal locations within the bypass duct and creating staged cooling zones, the system effectively increases the total heat exchange surface area available within the constrained face area of the bypass duct.
2Temperature
If heat exchangers are added to cool electrical components and engine components, then cooling capacity is improved, but device complexity increases
Solution Approach 1:
The patent designs the heat exchanger system to serve multiple functions simultaneously. The staged heat exchangers provide cooling for both electrical components (via the first heat exchanger in the outer bypass duct) and engine components (via the second heat exchanger in the inner bypass duct). The interconnected flow paths allow a single system to address multiple cooling requirements without requiring separate, independent cooling systems for each component type.
Solution Approach 2:
The patent merges the cooling functions for electrical components and engine components into a unified heat exchanger system. By combining the cooling pathways and utilizing shared bypass duct space, the system reduces the overall complexity that would result from having completely separate cooling systems. The integration is achieved through strategic positioning and interconnection of the heat exchangers within the existing bypass duct infrastructure.
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 configuration enhances the cooling capacity of heat exchangers, allowing for efficient cooling of both electrical components and engine components, while optimizing the use of bypass duct area for air flow and propulsion purposes.
Implementation Method 1
heat exchangers for various functions. The bypass ducts in military applications generally are not unduly large and, thus, there is limited 'face' area for air to pass through the heat exchangers
Data Source
AI summary
A gas turbine bypass flow arrangement comprises an outer housing and an inner housing, an outer bypass duct defined between the outer housing and the inner housing and an inner bypass duct defined inwardly of the inner housing. A first heat exchanger is positioned at an upstream location within the outer bypass duct and a second heat exchanger is positioned within the inner bypass duct at an upstream location. A downstream heat exchanger is positioned to be in the path of air downstream of the second heat exchanger in the inner bypass duct. Air flowing across the downstream heat exchanger passes from the inner bypass duct into the outer bypass duct. A gas turbine engine is also disclosed.