Gas Turbine Buffer Cooling System for Bearing Temperature Control
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Solution Overview
Problem
Gas turbine engines face challenges in effectively conditioning components like rotor assemblies and bearing compartments to manage high temperatures, as existing cooling systems may not adequately address temperature-related reliability and durability issues.
Innovation Solution
A buffer cooling system is introduced, featuring a heat exchanger that conditions airflow by exchanging heat with a bleed airflow, which is then communicated through a network of passageways and nozzle assemblies to reach critical components, including a tangential onboard injection (TOBI) nozzle, to provide both cooling and heating as needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional cooling system is used to condition rotor assemblies and bearing compartments, then the system structure is simple, but the temperature control effectiveness is insufficient and reliability is reduced
Solution Approach 1:
The cooling system is divided into multiple independent buffer compartments (first buffer compartment, second buffer compartment, third buffer compartment) that can be separately controlled and conditioned. Each compartment serves specific components (bearing compartment, nozzle assembly, rotor assembly), allowing targeted temperature control without requiring a complex unified system.
Solution Approach 2:
Buffer compartments are introduced as intermediary elements between the hot gas path and the components requiring cooling. These buffer compartments receive hot airflow from the gas path, condition it through heat exchange, and then deliver the conditioned airflow to components like bearings and nozzles, thereby mediating the thermal interaction.
2Temperature
If airflow is directly channeled through the primary gas path, then the system is simple, but high temperature impacts on hardware are not minimized
Solution Approach 1:
The airflow path is segmented into a primary gas path and a separate buffer cooled cooling air path. The cooling air path includes multiple buffer compartments and passageways that are distinct from the primary combustion gas flow, allowing independent temperature control of cooling airflow without interfering with the primary gas path function.
Solution Approach 2:
Airflow is pre-conditioned in buffer compartments before being delivered to components. The first buffer compartment conditions airflow for the bearing compartment, the second buffer compartment conditions airflow for the nozzle assembly, and the third buffer compartment conditions airflow for the rotor assembly, ensuring temperature control is established before the cooling air reaches the components.
3Duration of action of stationary object
If existing cooling systems are used, then the system complexity is low, but temperature-related durability issues are not adequately addressed
Solution Approach 1:
Different buffer compartments provide localized temperature control tailored to specific component requirements. The bearing compartment receives conditioned airflow at temperatures suitable for bearing operation, the nozzle assembly receives airflow conditioned for nozzle temperature control, and the rotor assembly receives airflow appropriate for rotor cooling, with each location having optimized thermal characteristics.
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 buffer cooling system effectively conditions airflow to minimize high temperature impacts on hardware, ensuring reliable performance and durability by providing a separate buffer cooled cooling air path that complements the primary gas path, thereby enhancing the operational stability of gas turbine engine components.
Implementation Method 1
a heat exchanger configured to exchange heat with a bleed airflow to provide a conditioned airflow
Data Source
AI summary
A gas turbine engine according to an exemplary aspect of the present disclosure includes, among other things, a heat exchanger configured to exchange heat with a bleed airflow to provide a conditioned airflow. A bearing compartment is in fluid communication with the heat exchanger, and a first passageway communicates the conditioned airflow to the bearing compartment. The conditioned airflow is communicated radially between a bearing housing of the bearing compartment and a diffuser case and a nozzle assembly in fluid communication with the bearing compartment. A second passageway communicates the conditioned airflow from the bearing compartment and then through a plurality of openings of the nozzle assembly.