Turbine Vane Cooling Segmentation for Hot Gas Ingestion
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Solution Overview
Problem
High temperatures in gas turbine engines cause unbalanced stagnation points on variable turbine vanes, leading to decreased engine efficiencies due to shifting heat loads and potential ingestion of hot gases through cooling openings, which affects cooling airflow and vane operation.
Innovation Solution
A turbine vane assembly with radial separators between impingement baffles and the airfoil surface, directing cooling airflow through specific cavities to maintain consistent cooling and prevent hot gas ingestion, featuring cooling holes along the airfoil surface and impingement openings to manage temperature extremes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If variable turbine vanes are used to improve fuel efficiency through flow variation, then engine efficiency is improved, but unbalanced temperatures occur as the stagnation point shifts during operation
Solution Approach 1:
The cooling chamber is divided into multiple separate cavities (leading edge cavity, pressure side cavity, suction side cavity) using separators. This segmentation allows independent cooling airflow management for each cavity, enabling the stagnation point to shift without causing unbalanced temperatures across the vane surface.
2Temperature
If cooling airflow is increased to maintain temperature control, then temperature stability is improved, but cooling system complexity increases
Solution Approach 1:
The cooling system is segmented into multiple cavities with dedicated impingement baffles and cooling openings for each cavity. This allows targeted cooling airflow delivery to specific regions, maintaining temperature stability without requiring a single complex high-flow cooling system.
Solution Approach 2:
Impingement baffles are introduced as intermediary components that direct cooling airflow onto the inner surface of the forward chamber. These baffles with their impingement openings create a controlled cooling mechanism that stabilizes temperatures without requiring excessive cooling airflow.
3Adaptability or versatility
If the stagnation point shifts during vane operation, then variable flow capability is improved, but hot gas ingestion through cooling openings occurs
Solution Approach 1:
The cooling chamber is segmented into separate cavities with dedicated cooling openings for each cavity. This ensures that cooling airflow is delivered to the correct region regardless of stagnation point position, preventing hot gas ingestion even when the stagnation point shifts during variable flow operation.
Solution Approach 2:
Cooling airflow is pre-directed through impingement baffles and cooling openings to specific cavities before hot gas ingestion can occur. This preliminary cooling action ensures that the vane surface is protected regardless of the current stagnation point position.
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 solution maintains consistent cooling airflow and prevents hot gas ingestion, enhancing engine efficiency by stabilizing temperature distribution across the vane surface, even at varying rotational positions, thus improving thermal and propulsive efficiencies.
Implementation Method 1
The forward impingement baffle includes a plurality of impingement openings for directing cooling airflow against the inner surface of the forward chamber
Implementation Method 2
includes cooling holes for communicating cooling airflow along an outer surface of the airfoil
Data Source
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AI summary
A disclosed turbine vane assembly for a gas turbine engine includes an airfoil including a pressure side and a suction side that extends from a leading edge toward a trailing edge. The airfoil is rotatable about an axis transverse to an engine longitudinal axis and includes a forward chamber within the airfoil and in communication with a cooling air source, a forward impingement baffle defining a pre-impingement cavity within the forward chamber. The pre-impingement cavity is split into a leading edge cavity, pressure side cavity and a suction side cavity defined between an inner surface of the forward chamber and an outer surface of the forward impingement baffle.