Gas Turbine Vane Cooling via Segmented Flow Path
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Solution Overview
Problem
Conventional vanes in gas turbine engines experience inefficient cooling due to insufficient pressure drop, leading to uneven thermal expansion and potential overheating, especially when using low-pressure bypass air, as the cooling air flow is insufficient to effectively reach and cool the internal surfaces.
Innovation Solution
A vane design comprising a vane plate, guide plate, and baffle, where the guide plate has a slot aligned with the leading edge to focus cooling air flow and minimize the flow path, and a porous baffle to control cooling air distribution, ensuring even temperature reduction and enhanced cooling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If low-pressure bypass air is used for cooling the vane, then the pressure losses are reduced, but the cooling effectiveness decreases due to insufficient pressure drop
Solution Approach 1:
The internal flow path is segmented into multiple regions using flow directors and baffles. Cooling air is divided into different streams that are directed to specific areas of the vane, allowing effective cooling distribution despite low overall pressure drop. The flow path is divided into a first region for the leading edge and a second region for the body portion.
Solution Approach 2:
Flow directors and baffles act as intermediary elements to redirect and condition the low-pressure cooling air flow. These intermediaries manipulate the flow path to ensure adequate cooling reach without requiring high pressure differential, thus maintaining cooling effectiveness while using low-pressure bypass air.
2Device complexity
If cooling air flow path is not controlled, then the device complexity is reduced, but uneven thermal expansion and overheating occur
Solution Approach 1:
Different regions of the vane are provided with customized cooling flow characteristics. Flow directors and baffles create locally optimized flow patterns that direct cooling air to specific hot spots and areas requiring different cooling intensities. This ensures uniform thermal expansion by addressing the unique thermal conditions of each vane region.
Solution Approach 2:
The flow directors and baffles are pre-positioned within the vane structure to establish controlled flow paths before the cooling air enters. This preliminary flow conditioning ensures that cooling air is properly distributed to all critical areas before contact with hot surfaces, preventing localized overheating and uneven thermal expansion.
3Reliability
If cooling air is directed to reach internal surfaces, then cooling effectiveness is improved, but the flow path length increases causing temperature rise of cooling air
Solution Approach 1:
The cooling flow path utilizes three-dimensional space within the vane structure by incorporating baffles and flow directors that create vertical and lateral flow components. This multi-dimensional flow path allows cooling air to reach internal surfaces more efficiently without excessively increasing path length, as the air can descend and move laterally rather than only traveling horizontally.
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 design achieves more even temperature distribution and improved cooling effectiveness by focusing cooling air at the highest heat input region and controlling air flow to prevent separation zones, reducing thermal stress and overheating risks.
Implementation Method 1
The cooling flow cools the vane plate by convection and thereby limits the transfer of heat energy from the vane plate to the guide plate
Implementation Method 2
The first aperture focuses the cooling flow at the leading edge of the vane where heat input from the hot core flow is greatest
Data Source
AI summary
A vane for an exhaust system duct in a gas turbine engine including a vane plate, a guide plate, and a baffle. The vane plate includes a leading edge, a first leg and a second leg, with the first and second legs respectively extending on opposing sides of the leading edge to form a substantially U-shaped profile. The baffle connects respective distal ends of the first and second legs. The guide plate is accommodated within the vane plate, and includes a first aperture extending along the guide plate and aligned with the leading edge. The vane further includes a fluid inlet arranged, in use, to direct a fluid flow from outside the duct into an interior of the vane.