Windage Shield Annular Cavity Cooling Fluid Temperature
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Solution Overview
Problem
In turbofan engines, the heat generated by rotating components reduces the cooling efficiency of air channeled through the rotor cavity, as it increases the temperature of the compressor discharge air used for cooling purposes.
Innovation Solution
The implementation of a windage shield system that directs a flow of cooling fluid through an annular cavity, bounded by stationary and rotating components, where the windage shield divides the cavity into separate flow paths to restrict heat transfer and maintain a lower temperature in the cooling fluid channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If cooling air is channeled through the rotor cavity, then cooling is provided to downstream components, but the temperature of the cooling air increases due to windage heat from rotating members
Solution Approach 1:
The rotor cavity is divided into multiple separate flow paths using windage shields. The cooling air is segmented into a first flow path that passes through the rotor cavity and a second flow path that bypasses the hot zone. This segmentation allows the system to maintain cooler air temperature by directing only portion of the air through the heated region, thereby preserving cooling efficiency.
Solution Approach 2:
The harmful windage heat effect is extracted or isolated from the main cooling air flow by creating a separate first flow path between the rotating member and windage shield. The second flow path is taken out from the hot zone entirely, allowing the cooling system to utilize cooler air from this separate path for downstream component cooling.
2Loss of energy
If windage shields are added to divide the annular cavity, then heat transfer is restricted and cooling efficiency improves, but device complexity increases
Solution Approach 1:
Windage shields are introduced as intermediary components between the rotating member and stationary housing. These shields act as mediators that create the flow path divisions without requiring complex external control systems. The shields passively direct the cooling air through different paths based on the pressure differentials created by rotation, simplifying the overall control architecture while achieving the desired thermal management.
Solution Approach 2:
The windage shields and flow paths are designed to automatically self-regulate based on operational conditions. The rotation of the turbine member naturally creates pressure differentials that direct air through the appropriate flow paths without requiring external control mechanisms. The system serves itself by using its own operational dynamics to achieve the flow separation and heat management objectives.
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 solution effectively reduces the temperature of the cooling fluid, thereby enhancing its cooling efficiency and preventing heat from the rotating components from increasing the temperature of the air used for downstream cooling purposes.
Implementation Method 1
the rotating component introduces heat into the annular cavity by windage effects
Implementation Method 2
the first windage shield divides the annular cavity into at least two flow paths... such that a temperature of the second flow path is less than a temperature of the first flow path due to windage effects
Data Source
AI summary
A windage shield system is provided. The system includes an annular cavity having an inlet end and an outlet end. The annular cavity is configured to direct a flow of cooling fluid from the inlet end to the outlet end. The system also includes a source of a flow of cooling fluid coupled in flow communication with the annular cavity. The annular cavity is bounded by a stationary component and a rotating component, and the rotating component introduces heat into the annular cavity by windage effects. The system also includes a cooling channel coupled in flow communication with the outlet end, and a first windage shield extending from the outlet end towards the inlet end within the annular cavity.