Gas Turbine Airfoil Rib Communication for Cooling Efficiency
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Solution Overview
Problem
Gas turbine engines face inefficiencies in cooling airflow, which can reduce overall engine performance and thermal efficiencies due to the need for increased airflow to maintain temperature limits within the turbine section.
Innovation Solution
The design of an airfoil with a rib separating two cavities and baffles that direct cooling airflow through specific channels and communication openings, including flow disruptors and impingement holes, to enhance heat transfer and reduce cooling airflow requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If increased airflow is provided for cooling purposes, then temperature limits within the turbine section are maintained, but overall engine operating efficiencies are reduced
Solution Approach 1:
The cooling airflow is segmented into multiple pathways: primary cooling airflow through the first cavity, secondary cooling airflow through the second cavity, and tertiary cooling airflow through the rib. This segmentation allows optimized heat transfer from different thermal zones without requiring excessive total airflow, thereby maintaining temperature limits while minimizing energy loss.
Solution Approach 2:
Different regions of the airfoil receive differentiated cooling strategies: the first cavity receives high-pressure cooling air for the hottest regions, the rib provides intermediate cooling, and the second cavity receives lower-pressure cooling air. This local quality approach optimizes cooling efficiency in each zone, reducing the total airflow required to maintain temperature limits.
2Reliability
If cooling air is provided at pressures above those generated by the gas flow, then ingestion into interior cavities is prevented, but overall engine efficiencies are reduced
Solution Approach 1:
The system dynamically balances pressure distributions across different cavities and flow paths. By providing cooling air at elevated pressures selectively in the first cavity and through the rib while using lower pressures in the second cavity, the system maintains pressure differentials that prevent hot gas ingestion without excessively increasing total cooling airflow and associated energy losses.
Solution Approach 2:
The rib structure acts as an intermediary element that receives cooling air at intermediate pressures and distributes it to the second cavity. This intermediary approach allows the system to maintain adequate pressure differentials to prevent ingestion while using lower-pressure cooling air in the second cavity, thereby reducing the overall energy penalty compared to pressurizing all cooling paths equally.
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 design improves heat transfer coefficients while minimizing cooling airflow, maintaining temperature limits and preventing gas flow ingestion, thus enhancing engine efficiency and operational life.
Implementation Method 1
Air for cooling is provided at pressures above those generated by the gas flow through a core flow path
Implementation Method 2
Components within a turbine section include features for communicating cooling air onto surfaces exposed to the gas flow and maintain temperatures within acceptable limits
Data Source
AI summary
An airfoil for a gas turbine engine according to an example of the present disclosure includes a first cavity, a second cavity, and a rib extending from a suction sidewall to a pressure sidewall and separating the first cavity from the second cavity. The rib includes a central portion, a first edge portion extending from the pressure sidewall to the central portion, and a second edge portion extending from the suction sidewall to the central portion. The rib defines one or more communication openings from the first cavity to the second cavity in the first or second edge portion.