Compressor Strut Cooling Nozzles for Bowed Rotor Start Reduction
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Solution Overview
Problem
Gas turbine engines experience bowed rotor conditions due to thermal expansion during on-ground idle operations, leading to engine wear and operational inefficiencies, which are addressed by existing methods that either require prolonged waiting or active techniques causing delays.
Innovation Solution
Incorporating cooling airflow nozzles and passages in compressor struts to inject cooling airflow into the core flowpath, particularly targeting the high and low pressure compressors, to reduce thermal distortion and prevent bowed rotor conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If active cooling techniques are employed to reduce thermal distortion, then thermal distortion is reduced, but significant delays occur at airport gate or alleyway
Solution Approach 1:
The cooling nozzles are activated during the engine shutdown period to pre-cool the compressor rotor before restart is attempted. This preliminary cooling action reduces thermal distortion in advance, allowing the engine to be restarted without delay while avoiding the bowed rotor condition that would otherwise require waiting
Solution Approach 2:
Cooling air is directed through nozzles positioned in the compressor frame to blow cooling airflow across the compressor rotor. This pneumatic cooling system rapidly removes heat from the rotor, reducing thermal distortion and preventing bowed rotor conditions without requiring extended waiting periods
2Adaptability or versatility
If engine is operated at idle for extended periods to keep aircraft in ready state, then aircraft readiness is maintained, but engine wear and fuel burn increase
Solution Approach 1:
The system uses pneumatic cooling airflow directed through nozzles to cool the compressor rotor during idle operations. This active cooling prevents thermal distortion and bowed rotor conditions that cause wear, allowing extended idle operation to maintain aircraft readiness without increasing engine wear
Solution Approach 2:
The cooling system uses engine bleed air or external air sources to cool the compressor rotor, enabling the engine to self-regulate its thermal state during idle operation. This prevents thermal distortion and associated wear, maintaining engine reliability during extended readiness periods
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 cooling strategy effectively mitigates bowed rotor conditions, reducing component wear and enabling standard start procedures without delays, thus improving engine reliability and efficiency.
Implementation Method 1
one or more cooling airflow nozzles configured to inject a cooling airflow into the core flowpath to cool a compressor rotor
Implementation Method 2
the upper portions of the engine will be hotter than lower portions of the engine. When this occurs thermal expansion may cause deflection of components within the engine
Data Source
AI summary
A compressor frame of a gas turbine engine includes a radially outer ring, and a radially inner ring located radially inboard of the radially outer ring. The radially outer ring and the radially inner ring at least partially define a core flowpath of a gas turbine engine therebetween. A plurality of struts extend between the radially outer ring and the radially inner ring. At least one strut of the plurality of struts includes one or more cooling airflow nozzles configured to inject a cooling airflow into the core flowpath to cool a compressor rotor fluidly downstream of the plurality of struts.