Film Cooling Hole Diffuser Taper to Mitigate Flow Separation
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Solution Overview
Problem
The existing manufacturing methods for film cooling holes in gas turbine engines often result in inefficiencies due to intentional or unintentional offsets between the metering section and the diffuser, leading to sharp edges and flow separation, which detract from the effectiveness of the film cooling process.
Innovation Solution
The implementation of a tapered surface oriented between twenty degrees and seventy degrees with respect to the centerline axis of the metering section, and at an obtuse angle with respect to the adjacent surface of the diffuser, helps mitigate flow separation and ensures a smoother transition between the metering section and the diffuser, preventing sharp edges and enhancing cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional manufacturing methods are used for film cooling holes, then manufacturing simplicity is maintained, but flow separation occurs due to sharp edges between metering section and diffuser
Solution Approach 1:
The invention applies curvature by replacing the traditional sharp edge transition between the metering section and diffuser with a tapered surface that has a continuous curved profile. This tapered surface eliminates the abrupt angular transition that causes flow separation, instead providing a smooth gradual transition that maintains attached flow and improves film cooling effectiveness.
Solution Approach 2:
The invention changes the geometric parameters of the film cooling hole by introducing a tapered surface with specific angular characteristics (obtuse angle open towards the centerline axis). This parameter change transforms the geometry from a sharp-edged configuration to a tapered configuration, fundamentally altering the flow characteristics and eliminating flow separation.
2Reliability
If a tapered surface is introduced to mitigate flow separation, then film cooling effectiveness is improved, but manufacturing complexity increases
Solution Approach 1:
The tapered surface with its curved profile is designed to be manufacturable through specialized drilling or machining processes. The curvature is implemented as a controlled geometric feature that can be achieved through single-pass drilling with a tapered bit or through multi-pass machining, balancing the need for flow optimization with manufacturing capability.
Solution Approach 2:
The tapered surface geometry is defined by specific angular parameters (obtuse angle relative to the diffuser surface, oriented between 20-70 degrees with respect to the metering section centerline). These parameter specifications provide clear manufacturing guidelines while achieving the desired flow control, making the complex geometry manufacturable through precision drilling or machining operations.
3Reliability
If the tapered surface orientation is optimized for flow control, then flow separation is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The tapered surface is designed with an optimized angular range (obtuse angle open towards the centerline axis, oriented between 20-70 degrees with respect to the metering section centerline). This parameter specification provides a tolerance window that balances flow control performance with manufacturability, allowing sufficient precision to achieve flow attachment while remaining achievable through standard precision drilling or machining processes.
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 improves the film cooling effectiveness by reducing flow separation and maintaining a consistent cooling film layer, thereby enhancing the cooling performance of gas path components in gas turbine engines.
Implementation Method 1
the tapered surface is configured to mitigate flow separation in the diffuser
Data Source
AI summary
A gas path component for a gas turbine engine includes a film cooling hole disposed in the gas path component. The film cooling hole includes a metering section, a diffuser, and a tapered surface extending between the metering section and the diffuser. The tapered surface is oriented between twenty degrees and seventy degrees with respect to a centerline axis of the metering section. The tapered surface is oriented at an obtuse angle with respect to an immediately adjacent surface of the diffuser, the obtuse angle is open towards the centerline axis. The tapered surface is configured to mitigate flow separation in the diffuser.